refactor everything to use context's annotation system, making some significant changes to annotations themselves along the way

README.md

@@ -27,8 +27,15 @@ Everything here are guidelines, not actual rules.
 
 * https://github.com/golang/go/wiki/CodeReviewComments
 
+* Package names may be abbreviations of a concept, but types, functions, and
+  methods should all be full words.
+
 * When deciding if a package should initialize a struct as a value or pointer, a
   good rule is: If it's used as an immutable value it should be a value,
   otherwise it's a pointer. Even if the immutable value implementation has
   internal caching, locks, etc..., that can be hidden as pointers inside the
   struct, but the struct itself can remain a value type.
+
+* A function which takes in a `context.Context` and returns a modified copy of
+  that same `context.Context` should have a name prefixed with `With`, e.g.
+  `WithValue` or `WithLogger`. Exceptions like `Annotate` do exist.

TODO

@@ -0,0 +1,2 @@
+- read through all docs, especially package docs, make sure they make sense
+- write examples

cmd/totp-proxy/main.go

@@ -20,6 +20,7 @@ import (
 	"github.com/mediocregopher/mediocre-go-lib/m"
 	"github.com/mediocregopher/mediocre-go-lib/mcfg"
 	"github.com/mediocregopher/mediocre-go-lib/mcrypto"
+	"github.com/mediocregopher/mediocre-go-lib/mctx"
 	"github.com/mediocregopher/mediocre-go-lib/mhttp"
 	"github.com/mediocregopher/mediocre-go-lib/mlog"
 	"github.com/mediocregopher/mediocre-go-lib/mrand"
@@ -29,27 +30,27 @@ import (
 )
 
 func main() {
-	ctx := m.NewServiceCtx()
+	ctx := m.ServiceContext()
-	ctx, cookieName := mcfg.String(ctx, "cookie-name", "_totp_proxy", "String to use as the name for cookies")
+	ctx, cookieName := mcfg.WithString(ctx, "cookie-name", "_totp_proxy", "String to use as the name for cookies")
-	ctx, cookieTimeout := mcfg.Duration(ctx, "cookie-timeout", mtime.Duration{1 * time.Hour}, "Timeout for cookies")
+	ctx, cookieTimeout := mcfg.WithDuration(ctx, "cookie-timeout", mtime.Duration{1 * time.Hour}, "Timeout for cookies")
 
 	var userSecrets map[string]string
-	ctx = mcfg.RequiredJSON(ctx, "users", &userSecrets, "JSON object which maps usernames to their TOTP secret strings")
+	ctx = mcfg.WithRequiredJSON(ctx, "users", &userSecrets, "JSON object which maps usernames to their TOTP secret strings")
 
 	var secret mcrypto.Secret
-	ctx, secretStr := mcfg.String(ctx, "secret", "", "String used to sign authentication tokens. If one isn't given a new one will be generated on each startup, invalidating all previous tokens.")
+	ctx, secretStr := mcfg.WithString(ctx, "secret", "", "String used to sign authentication tokens. If one isn't given a new one will be generated on each startup, invalidating all previous tokens.")
-	ctx = mrun.OnStart(ctx, func(context.Context) error {
+	ctx = mrun.WithStartHook(ctx, func(context.Context) error {
 		if *secretStr == "" {
 			*secretStr = mrand.Hex(32)
 		}
-		mlog.Info(ctx, "generating secret")
+		mlog.Info("generating secret", ctx)
 		secret = mcrypto.NewSecret([]byte(*secretStr))
 		return nil
 	})
 
 	proxyHandler := new(struct{ http.Handler })
-	ctx, proxyURL := mcfg.RequiredString(ctx, "dst-url", "URL to proxy requests to. Only the scheme and host should be set.")
+	ctx, proxyURL := mcfg.WithRequiredString(ctx, "dst-url", "URL to proxy requests to. Only the scheme and host should be set.")
-	ctx = mrun.OnStart(ctx, func(context.Context) error {
+	ctx = mrun.WithStartHook(ctx, func(context.Context) error {
 		u, err := url.Parse(*proxyURL)
 		if err != nil {
 			return err
@@ -60,7 +61,6 @@ func main() {
 
 	authHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// TODO mlog.FromHTTP?
-		// TODO annotate this ctx
 		ctx := r.Context()
 
 		unauthorized := func() {
@@ -79,7 +79,8 @@ func main() {
 		}
 
 		if cookie, _ := r.Cookie(*cookieName); cookie != nil {
-			mlog.Debug(ctx, "authenticating with cookie", mlog.KV{"cookie": cookie.String()})
+			mlog.Debug("authenticating with cookie",
+				mctx.Annotate(ctx, "cookie", cookie.String()))
 			var sig mcrypto.Signature
 			if err := sig.UnmarshalText([]byte(cookie.Value)); err == nil {
 				err := mcrypto.VerifyString(secret, sig, "")
@@ -91,10 +92,8 @@ func main() {
 		}
 
 		if user, pass, ok := r.BasicAuth(); ok && pass != "" {
-			mlog.Debug(ctx, "authenticating with user/pass", mlog.KV{
+			mlog.Debug("authenticating with user",
-				"user": user,
+				mctx.Annotate(ctx, "user", user))
-				"pass": pass,
-			})
 			if userSecret, ok := userSecrets[user]; ok {
 				if totp.Validate(pass, userSecret) {
 					authorized()
@@ -106,6 +105,6 @@ func main() {
 		unauthorized()
 	})
 
-	ctx, _ = mhttp.MListenAndServe(ctx, authHandler)
+	ctx, _ = mhttp.WithListeningServer(ctx, authHandler)
 	m.Run(ctx)
 }

m/m.go

@@ -6,10 +6,12 @@ package m
 
 import (
 	"context"
+	"log"
 	"os"
 	"os/signal"
 
 	"github.com/mediocregopher/mediocre-go-lib/mcfg"
+	"github.com/mediocregopher/mediocre-go-lib/mctx"
 	"github.com/mediocregopher/mediocre-go-lib/merr"
 	"github.com/mediocregopher/mediocre-go-lib/mlog"
 	"github.com/mediocregopher/mediocre-go-lib/mrun"
@@ -24,25 +26,26 @@ func CfgSource() mcfg.Source {
 	}
 }
 
-// NewServiceCtx returns a Context which should be used as the root Context when
+// ServiceContext returns a Context which should be used as the root Context
-// creating long running services, such as an RPC service or database.
+// when creating long running services, such as an RPC service or database.
 //
 // The returned Context will automatically handle setting up global
 // configuration parameters like "log-level", as well as an http endpoint where
 // debug information about the running process can be accessed.
 //
 // TODO set up the debug endpoint.
-func NewServiceCtx() context.Context {
+func ServiceContext() context.Context {
 	ctx := context.Background()
 
 	// set up log level handling
 	logger := mlog.NewLogger()
-	ctx = mlog.Set(ctx, logger)
+	ctx = mlog.WithLogger(ctx, logger)
-	ctx, logLevelStr := mcfg.String(ctx, "log-level", "info", "Maximum log level which will be printed.")
+	ctx, logLevelStr := mcfg.WithString(ctx, "log-level", "info", "Maximum log level which will be printed.")
-	ctx = mrun.OnStart(ctx, func(context.Context) error {
+	ctx = mrun.WithStartHook(ctx, func(context.Context) error {
 		logLevel := mlog.LevelFromString(*logLevelStr)
+		log.Printf("setting log level to %v", logLevel)
 		if logLevel == nil {
-			return merr.New("invalid log level", "log-level", *logLevelStr)
+			return merr.New(ctx, "invalid log level", "log-level", *logLevelStr)
 		}
 		logger.SetMaxLevel(logLevel)
 		return nil
@@ -58,20 +61,20 @@ func NewServiceCtx() context.Context {
 func Run(ctx context.Context) {
 	log := mlog.From(ctx)
 	if err := mcfg.Populate(ctx, CfgSource()); err != nil {
-		log.Fatal(ctx, "error populating configuration", merr.KV(err))
+		log.Fatal("error populating configuration", ctx, merr.Context(err))
 	} else if err := mrun.Start(ctx); err != nil {
-		log.Fatal(ctx, "error triggering start event", merr.KV(err))
+		log.Fatal("error triggering start event", ctx, merr.Context(err))
 	}
 
 	{
 		ch := make(chan os.Signal, 1)
 		signal.Notify(ch, os.Interrupt)
 		s := <-ch
-		log.Info(ctx, "signal received, stopping", mlog.KV{"signal": s})
+		log.Info("signal received, stopping", mctx.Annotate(ctx, "signal", s))
 	}
 
 	if err := mrun.Stop(ctx); err != nil {
-		log.Fatal(ctx, "error triggering stop event", merr.KV(err))
+		log.Fatal("error triggering stop event", ctx, merr.Context(err))
 	}
-	log.Info(ctx, "exiting process")
+	log.Info("exiting process", ctx)
 }

m/m_test.go

@@ -1,6 +1,7 @@
 package m
 
 import (
+	"context"
 	"encoding/json"
 	. "testing"
 
@@ -13,7 +14,7 @@ import (
 
 func TestServiceCtx(t *T) {
 	t.Run("log-level", func(t *T) {
-		ctx := NewServiceCtx()
+		ctx := ServiceContext()
 
 		// pull the Logger out of the ctx and set the Handler on it, so we can check
 		// the log level
@@ -36,16 +37,16 @@ func TestServiceCtx(t *T) {
 			t.Fatal(err)
 		}
 
-		mlog.From(ctxA).Info(ctxA, "foo")
+		mlog.From(ctxA).Info("foo", ctxA)
-		mlog.From(ctxA).Debug(ctxA, "bar")
+		mlog.From(ctxA).Debug("bar", ctxA)
 		massert.Fatal(t, massert.All(
 			massert.Len(msgs, 2),
 			massert.Equal(msgs[0].Level.String(), "INFO"),
 			massert.Equal(msgs[0].Description, "foo"),
-			massert.Equal(msgs[0].Context, ctxA),
+			massert.Equal(msgs[0].Contexts, []context.Context{ctxA}),
 			massert.Equal(msgs[1].Level.String(), "DEBUG"),
 			massert.Equal(msgs[1].Description, "bar"),
-			massert.Equal(msgs[1].Context, ctxA),
+			massert.Equal(msgs[1].Contexts, []context.Context{ctxA}),
 		))
 	})
 }

mcfg/cli.go

@@ -1,6 +1,7 @@
 package mcfg
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"os"
@@ -89,7 +90,7 @@ func (cli SourceCLI) Parse(params []Param) ([]ParamValue, error) {
 				break
 			}
 			if !pvOk {
-				return nil, merr.New("unexpected config parameter", "param", arg)
+				return nil, merr.New(context.Background(), "unexpected config parameter", "param", arg)
 			}
 		}
 
@@ -120,7 +121,7 @@ func (cli SourceCLI) Parse(params []Param) ([]ParamValue, error) {
 		pvStrValOk = false
 	}
 	if pvOk && !pvStrValOk {
-		return nil, merr.New("param expected a value", "param", key)
+		return nil, merr.New(p.Context, "param expected a value", "param", key)
 	}
 	return pvs, nil
 }

mcfg/cli_test.go

@@ -15,11 +15,11 @@ import (
 
 func TestSourceCLIHelp(t *T) {
 	ctx := context.Background()
-	ctx, _ = Int(ctx, "foo", 5, "Test int param  ") // trailing space should be trimmed
+	ctx, _ = WithInt(ctx, "foo", 5, "Test int param  ") // trailing space should be trimmed
-	ctx, _ = Bool(ctx, "bar", "Test bool param.")
+	ctx, _ = WithBool(ctx, "bar", "Test bool param.")
-	ctx, _ = String(ctx, "baz", "baz", "Test string param")
+	ctx, _ = WithString(ctx, "baz", "baz", "Test string param")
-	ctx, _ = RequiredString(ctx, "baz2", "")
+	ctx, _ = WithRequiredString(ctx, "baz2", "")
-	ctx, _ = RequiredString(ctx, "baz3", "")
+	ctx, _ = WithRequiredString(ctx, "baz3", "")
 	src := SourceCLI{}
 
 	buf := new(bytes.Buffer)

mcfg/env.go

@@ -1,6 +1,7 @@
 package mcfg
 
 import (
+	"context"
 	"os"
 	"strings"
 
@@ -58,7 +59,7 @@ func (env SourceEnv) Parse(params []Param) ([]ParamValue, error) {
 	for _, kv := range kvs {
 		split := strings.SplitN(kv, "=", 2)
 		if len(split) != 2 {
-			return nil, merr.New("malformed environment key/value pair", "kv", kv)
+			return nil, merr.New(context.Background(), "malformed environment key/value pair", "kv", kv)
 		}
 		k, v := split[0], split[1]
 		if p, ok := pM[k]; ok {

mcfg/mcfg.go

@@ -110,7 +110,7 @@ func populate(params []Param, src Source) error {
 		if !p.Required {
 			continue
 		} else if _, ok := pvM[hash]; !ok {
-			return merr.New("required parameter is not set",
+			return merr.New(p.Context, "required parameter is not set",
 				"param", paramFullName(mctx.Path(p.Context), p.Name))
 		}
 	}

mcfg/mcfg_test.go

@@ -11,10 +11,10 @@ import (
 func TestPopulate(t *T) {
 	{
 		ctx := context.Background()
-		ctx, a := Int(ctx, "a", 0, "")
+		ctx, a := WithInt(ctx, "a", 0, "")
 		ctxChild := mctx.NewChild(ctx, "foo")
-		ctxChild, b := Int(ctxChild, "b", 0, "")
+		ctxChild, b := WithInt(ctxChild, "b", 0, "")
-		ctxChild, c := Int(ctxChild, "c", 0, "")
+		ctxChild, c := WithInt(ctxChild, "c", 0, "")
 		ctx = mctx.WithChild(ctx, ctxChild)
 
 		err := Populate(ctx, SourceCLI{
@@ -28,10 +28,10 @@ func TestPopulate(t *T) {
 
 	{ // test that required params are enforced
 		ctx := context.Background()
-		ctx, a := Int(ctx, "a", 0, "")
+		ctx, a := WithInt(ctx, "a", 0, "")
 		ctxChild := mctx.NewChild(ctx, "foo")
-		ctxChild, b := Int(ctxChild, "b", 0, "")
+		ctxChild, b := WithInt(ctxChild, "b", 0, "")
-		ctxChild, c := RequiredInt(ctxChild, "c", "")
+		ctxChild, c := WithRequiredInt(ctxChild, "c", "")
 		ctx = mctx.WithChild(ctx, ctxChild)
 
 		err := Populate(ctx, SourceCLI{

mcfg/param.go

@@ -45,7 +45,7 @@ type Param struct {
 	Into interface{}
 
 	// The Context this Param was added to. NOTE that this will be automatically
-	// filled in by MustAdd when the Param is added to the Context.
+	// filled in by WithParam when the Param is added to the Context.
 	Context context.Context
 }
 
@@ -74,9 +74,9 @@ func getParam(ctx context.Context, name string) (Param, bool) {
 	return param, ok
 }
 
-// MustAdd returns a Context with the given Param added to it. It will panic if
+// WithParam returns a Context with the given Param added to it. It will panic
-// a Param with the same Name already exists in the Context.
+// if a Param with the same Name already exists in the Context.
-func MustAdd(ctx context.Context, param Param) context.Context {
+func WithParam(ctx context.Context, param Param) context.Context {
 	param.Name = strings.ToLower(param.Name)
 	param.Context = ctx
 
@@ -99,113 +99,114 @@ func getLocalParams(ctx context.Context) []Param {
 	return params
 }
 
-// Int64 returns an *int64 which will be populated once Populate is run on the
+// WithInt64 returns an *int64 which will be populated once Populate is run on
-// returned Context.
+// the returned Context.
-func Int64(ctx context.Context, name string, defaultVal int64, usage string) (context.Context, *int64) {
+func WithInt64(ctx context.Context, name string, defaultVal int64, usage string) (context.Context, *int64) {
 	i := defaultVal
-	ctx = MustAdd(ctx, Param{Name: name, Usage: usage, Into: &i})
+	ctx = WithParam(ctx, Param{Name: name, Usage: usage, Into: &i})
 	return ctx, &i
 }
 
-// RequiredInt64 returns an *int64 which will be populated once Populate is run
+// WithRequiredInt64 returns an *int64 which will be populated once Populate is
-// on the returned Context, and which must be supplied by a configuration
-// Source.
-func RequiredInt64(ctx context.Context, name string, usage string) (context.Context, *int64) {
-	var i int64
-	ctx = MustAdd(ctx, Param{Name: name, Required: true, Usage: usage, Into: &i})
-	return ctx, &i
-}
-
-// Int returns an *int which will be populated once Populate is run on the
-// returned Context.
-func Int(ctx context.Context, name string, defaultVal int, usage string) (context.Context, *int) {
-	i := defaultVal
-	ctx = MustAdd(ctx, Param{Name: name, Usage: usage, Into: &i})
-	return ctx, &i
-}
-
-// RequiredInt returns an *int which will be populated once Populate is run on
-// the returned Context, and which must be supplied by a configuration Source.
-func RequiredInt(ctx context.Context, name string, usage string) (context.Context, *int) {
-	var i int
-	ctx = MustAdd(ctx, Param{Name: name, Required: true, Usage: usage, Into: &i})
-	return ctx, &i
-}
-
-// String returns a *string which will be populated once Populate is run on the
-// returned Context.
-func String(ctx context.Context, name, defaultVal, usage string) (context.Context, *string) {
-	s := defaultVal
-	ctx = MustAdd(ctx, Param{Name: name, Usage: usage, IsString: true, Into: &s})
-	return ctx, &s
-}
-
-// RequiredString returns a *string which will be populated once Populate is
 // run on the returned Context, and which must be supplied by a configuration
 // Source.
-func RequiredString(ctx context.Context, name, usage string) (context.Context, *string) {
+func WithRequiredInt64(ctx context.Context, name string, usage string) (context.Context, *int64) {
-	var s string
+	var i int64
-	ctx = MustAdd(ctx, Param{Name: name, Required: true, Usage: usage, IsString: true, Into: &s})
+	ctx = WithParam(ctx, Param{Name: name, Required: true, Usage: usage, Into: &i})
+	return ctx, &i
+}
+
+// WithInt returns an *int which will be populated once Populate is run on the
+// returned Context.
+func WithInt(ctx context.Context, name string, defaultVal int, usage string) (context.Context, *int) {
+	i := defaultVal
+	ctx = WithParam(ctx, Param{Name: name, Usage: usage, Into: &i})
+	return ctx, &i
+}
+
+// WithRequiredInt returns an *int which will be populated once Populate is run
+// on the returned Context, and which must be supplied by a configuration
+// Source.
+func WithRequiredInt(ctx context.Context, name string, usage string) (context.Context, *int) {
+	var i int
+	ctx = WithParam(ctx, Param{Name: name, Required: true, Usage: usage, Into: &i})
+	return ctx, &i
+}
+
+// WithString returns a *string which will be populated once Populate is run on
+// the returned Context.
+func WithString(ctx context.Context, name, defaultVal, usage string) (context.Context, *string) {
+	s := defaultVal
+	ctx = WithParam(ctx, Param{Name: name, Usage: usage, IsString: true, Into: &s})
 	return ctx, &s
 }
 
-// Bool returns a *bool which will be populated once Populate is run on the
+// WithRequiredString returns a *string which will be populated once Populate is
+// run on the returned Context, and which must be supplied by a configuration
+// Source.
+func WithRequiredString(ctx context.Context, name, usage string) (context.Context, *string) {
+	var s string
+	ctx = WithParam(ctx, Param{Name: name, Required: true, Usage: usage, IsString: true, Into: &s})
+	return ctx, &s
+}
+
+// WithBool returns a *bool which will be populated once Populate is run on the
 // returned Context, and which defaults to false if unconfigured.
 //
 // The default behavior of all Sources is that a boolean parameter will be set
 // to true unless the value is "", 0, or false. In the case of the CLI Source
 // the value will also be true when the parameter is used with no value at all,
 // as would be expected.
-func Bool(ctx context.Context, name, usage string) (context.Context, *bool) {
+func WithBool(ctx context.Context, name, usage string) (context.Context, *bool) {
 	var b bool
-	ctx = MustAdd(ctx, Param{Name: name, Usage: usage, IsBool: true, Into: &b})
+	ctx = WithParam(ctx, Param{Name: name, Usage: usage, IsBool: true, Into: &b})
 	return ctx, &b
 }
 
-// TS returns an *mtime.TS which will be populated once Populate is run on the
+// WithTS returns an *mtime.TS which will be populated once Populate is run on
-// returned Context.
+// the returned Context.
-func TS(ctx context.Context, name string, defaultVal mtime.TS, usage string) (context.Context, *mtime.TS) {
+func WithTS(ctx context.Context, name string, defaultVal mtime.TS, usage string) (context.Context, *mtime.TS) {
 	t := defaultVal
-	ctx = MustAdd(ctx, Param{Name: name, Usage: usage, Into: &t})
+	ctx = WithParam(ctx, Param{Name: name, Usage: usage, Into: &t})
 	return ctx, &t
 }
 
-// RequiredTS returns an *mtime.TS which will be populated once Populate is run
+// WithRequiredTS returns an *mtime.TS which will be populated once Populate is
-// on the returned Context, and which must be supplied by a configuration
+// run on the returned Context, and which must be supplied by a configuration
 // Source.
-func RequiredTS(ctx context.Context, name, usage string) (context.Context, *mtime.TS) {
+func WithRequiredTS(ctx context.Context, name, usage string) (context.Context, *mtime.TS) {
 	var t mtime.TS
-	ctx = MustAdd(ctx, Param{Name: name, Required: true, Usage: usage, Into: &t})
+	ctx = WithParam(ctx, Param{Name: name, Required: true, Usage: usage, Into: &t})
 	return ctx, &t
 }
 
-// Duration returns an *mtime.Duration which will be populated once Populate is
+// WithDuration returns an *mtime.Duration which will be populated once Populate
-// run on the returned Context.
+// is run on the returned Context.
-func Duration(ctx context.Context, name string, defaultVal mtime.Duration, usage string) (context.Context, *mtime.Duration) {
+func WithDuration(ctx context.Context, name string, defaultVal mtime.Duration, usage string) (context.Context, *mtime.Duration) {
 	d := defaultVal
-	ctx = MustAdd(ctx, Param{Name: name, Usage: usage, IsString: true, Into: &d})
+	ctx = WithParam(ctx, Param{Name: name, Usage: usage, IsString: true, Into: &d})
 	return ctx, &d
 }
 
-// RequiredDuration returns an *mtime.Duration which will be populated once
+// WithRequiredDuration returns an *mtime.Duration which will be populated once
 // Populate is run on the returned Context, and which must be supplied by a
 // configuration Source.
-func RequiredDuration(ctx context.Context, name string, defaultVal mtime.Duration, usage string) (context.Context, *mtime.Duration) {
+func WithRequiredDuration(ctx context.Context, name string, defaultVal mtime.Duration, usage string) (context.Context, *mtime.Duration) {
 	var d mtime.Duration
-	ctx = MustAdd(ctx, Param{Name: name, Required: true, Usage: usage, IsString: true, Into: &d})
+	ctx = WithParam(ctx, Param{Name: name, Required: true, Usage: usage, IsString: true, Into: &d})
 	return ctx, &d
 }
 
-// JSON reads the parameter value as a JSON value and unmarshals it into the
+// WithJSON reads the parameter value as a JSON value and unmarshals it into the
 // given interface{} (which should be a pointer). The receiver (into) is also
 // used to determine the default value.
-func JSON(ctx context.Context, name string, into interface{}, usage string) context.Context {
+func WithJSON(ctx context.Context, name string, into interface{}, usage string) context.Context {
-	return MustAdd(ctx, Param{Name: name, Usage: usage, Into: into})
+	return WithParam(ctx, Param{Name: name, Usage: usage, Into: into})
 }
 
-// RequiredJSON reads the parameter value as a JSON value and unmarshals it into
+// WithRequiredJSON reads the parameter value as a JSON value and unmarshals it
-// the given interface{} (which should be a pointer). The value must be supplied
+// into the given interface{} (which should be a pointer). The value must be
-// by a configuration Source.
+// supplied by a configuration Source.
-func RequiredJSON(ctx context.Context, name string, into interface{}, usage string) context.Context {
+func WithRequiredJSON(ctx context.Context, name string, into interface{}, usage string) context.Context {
-	return MustAdd(ctx, Param{Name: name, Required: true, Usage: usage, Into: into})
+	return WithParam(ctx, Param{Name: name, Required: true, Usage: usage, Into: into})
 }

mcfg/source_test.go

@@ -116,7 +116,7 @@ func (scs srcCommonState) applyCtxAndPV(p srcCommonParams) srcCommonState {
 		// the Sources don't actually care about the other fields of Param,
 		// those are only used by Populate once it has all ParamValues together
 	}
-	*thisCtx = MustAdd(*thisCtx, ctxP)
+	*thisCtx = WithParam(*thisCtx, ctxP)
 	ctxP, _ = getParam(*thisCtx, ctxP.Name) // get it back out to get any added fields
 
 	if !p.unset {
@@ -155,9 +155,9 @@ func (scs srcCommonState) assert(s Source) error {
 
 func TestSources(t *T) {
 	ctx := context.Background()
-	ctx, a := RequiredInt(ctx, "a", "")
+	ctx, a := WithRequiredInt(ctx, "a", "")
-	ctx, b := RequiredInt(ctx, "b", "")
+	ctx, b := WithRequiredInt(ctx, "b", "")
-	ctx, c := RequiredInt(ctx, "c", "")
+	ctx, c := WithRequiredInt(ctx, "c", "")
 
 	err := Populate(ctx, Sources{
 		SourceCLI{Args: []string{"--a=1", "--b=666"}},
@@ -173,10 +173,10 @@ func TestSources(t *T) {
 
 func TestSourceParamValues(t *T) {
 	ctx := context.Background()
-	ctx, a := RequiredInt(ctx, "a", "")
+	ctx, a := WithRequiredInt(ctx, "a", "")
 	foo := mctx.NewChild(ctx, "foo")
-	foo, b := RequiredString(foo, "b", "")
+	foo, b := WithRequiredString(foo, "b", "")
-	foo, c := Bool(foo, "c", "")
+	foo, c := WithBool(foo, "c", "")
 	ctx = mctx.WithChild(ctx, foo)
 
 	err := Populate(ctx, ParamValues{

mcrypto/pair.go

@@ -1,6 +1,7 @@
 package mcrypto
 
 import (
+	"context"
 	"crypto"
 	"crypto/rand"
 	"crypto/rsa"
@@ -58,7 +59,7 @@ func (pk PublicKey) verify(s Signature, r io.Reader) error {
 		return err
 	}
 	if err := rsa.VerifyPSS(&pk.PublicKey, crypto.SHA256, h.Sum(nil), s.sig, nil); err != nil {
-		return merr.WithValue(ErrInvalidSig, "sig", s, true)
+		return merr.Wrap(context.Background(), ErrInvalidSig, "sig", s)
 	}
 	return nil
 }
@@ -88,12 +89,12 @@ func (pk *PublicKey) UnmarshalText(b []byte) error {
 	str := string(b)
 	strEnc, ok := stripPrefix(str, pubKeyV0)
 	if !ok || len(strEnc) <= hex.EncodedLen(8) {
-		return merr.WithValue(errMalformedPublicKey, "pubKeyStr", str, true)
+		return merr.Wrap(context.Background(), errMalformedPublicKey, "pubKeyStr", str)
 	}
 
 	b, err := hex.DecodeString(strEnc)
 	if err != nil {
-		return merr.WithValue(err, "pubKeyStr", str, true)
+		return merr.Wrap(context.Background(), err, "pubKeyStr", str)
 	}
 
 	pk.E = int(binary.BigEndian.Uint64(b))
@@ -184,17 +185,17 @@ func (pk *PrivateKey) UnmarshalText(b []byte) error {
 	str := string(b)
 	strEnc, ok := stripPrefix(str, privKeyV0)
 	if !ok {
-		return merr.Wrap(errMalformedPrivateKey)
+		return merr.Wrap(context.Background(), errMalformedPrivateKey)
 	}
 
 	b, err := hex.DecodeString(strEnc)
 	if err != nil {
-		return merr.Wrap(errMalformedPrivateKey)
+		return merr.Wrap(context.Background(), errMalformedPrivateKey)
 	}
 
 	e, n := binary.Uvarint(b)
 	if n <= 0 {
-		return merr.Wrap(errMalformedPrivateKey)
+		return merr.Wrap(context.Background(), errMalformedPrivateKey)
 	}
 	pk.PublicKey.E = int(e)
 	b = b[n:]
@@ -205,7 +206,7 @@ func (pk *PrivateKey) UnmarshalText(b []byte) error {
 		}
 		l, n := binary.Uvarint(b)
 		if n <= 0 {
-			err = merr.Wrap(errMalformedPrivateKey)
+			err = merr.Wrap(context.Background(), errMalformedPrivateKey)
 		}
 		b = b[n:]
 		i := new(big.Int)

mcrypto/secret.go

@@ -1,6 +1,7 @@
 package mcrypto
 
 import (
+	"context"
 	"crypto/hmac"
 	"crypto/rand"
 	"crypto/sha256"
@@ -76,9 +77,9 @@ func (s Secret) sign(r io.Reader) (Signature, error) {
 func (s Secret) verify(sig Signature, r io.Reader) error {
 	sigB, err := s.signRaw(r, uint8(len(sig.sig)), sig.salt, sig.t)
 	if err != nil {
-		return merr.WithValue(err, "sig", sig, true)
+		return merr.Wrap(context.Background(), err, "sig", sig)
 	} else if !hmac.Equal(sigB, sig.sig) {
-		return merr.WithValue(ErrInvalidSig, "sig", sig, true)
+		return merr.Wrap(context.Background(), ErrInvalidSig, "sig", sig)
 	}
 	return nil
 }

mcrypto/sig.go

@@ -2,6 +2,7 @@ package mcrypto
 
 import (
 	"bytes"
+	"context"
 	"encoding/binary"
 	"encoding/hex"
 	"encoding/json"
@@ -66,12 +67,12 @@ func (s *Signature) UnmarshalText(b []byte) error {
 	str := string(b)
 	strEnc, ok := stripPrefix(str, sigV0)
 	if !ok || len(strEnc) < hex.EncodedLen(10) {
-		return merr.WithValue(errMalformedSig, "sigStr", str, true)
+		return merr.Wrap(context.Background(), errMalformedSig, "sigStr", str)
 	}
 
 	b, err := hex.DecodeString(strEnc)
 	if err != nil {
-		return merr.WithValue(err, "sigStr", str, true)
+		return merr.Wrap(context.Background(), err, "sigStr", str)
 	}
 
 	unixNano, b := int64(binary.BigEndian.Uint64(b[:8])), b[8:]
@@ -81,7 +82,7 @@ func (s *Signature) UnmarshalText(b []byte) error {
 		if err != nil {
 			return nil
 		} else if len(b) < 1+int(b[0]) {
-			err = merr.WithValue(errMalformedSig, "sigStr", str, true)
+			err = merr.Wrap(context.Background(), errMalformedSig, "sigStr", str)
 			return nil
 		}
 		out := b[1 : 1+b[0]]
@@ -161,7 +162,7 @@ func SignString(s Signer, in string) Signature {
 // Verify reads all data from the io.Reader and uses the Verifier to verify that
 // the Signature is for that data.
 //
-// Returns any errors from io.Reader, or ErrInvalidSig (use merry.Is(err,
+// Returns any errors from io.Reader, or ErrInvalidSig (use merr.Equal(err,
 // mcrypto.ErrInvalidSig) to check).
 func Verify(v Verifier, s Signature, r io.Reader) error {
 	return v.verify(s, r)
@@ -170,7 +171,7 @@ func Verify(v Verifier, s Signature, r io.Reader) error {
 // VerifyBytes uses the Verifier to verify that the Signature is for the given
 // []bytes.
 //
-// Returns ErrInvalidSig (use merry.Is(err, mcrypto.ErrInvalidSig) to check).
+// Returns ErrInvalidSig (use merr.Equal(err, mcrypto.ErrInvalidSig) to check).
 func VerifyBytes(v Verifier, s Signature, b []byte) error {
 	return v.verify(s, bytes.NewBuffer(b))
 }
@@ -178,7 +179,7 @@ func VerifyBytes(v Verifier, s Signature, b []byte) error {
 // VerifyString uses the Verifier to verify that the Signature is for the given
 // string.
 //
-// Returns ErrInvalidSig (use merry.Is(err, mcrypto.ErrInvalidSig) to check).
+// Returns ErrInvalidSig (use merr.Equal(err, mcrypto.ErrInvalidSig) to check).
 func VerifyString(v Verifier, s Signature, in string) error {
 	return VerifyBytes(v, s, []byte(in))
 }

mcrypto/uuid.go

@@ -2,6 +2,7 @@ package mcrypto
 
 import (
 	"bytes"
+	"context"
 	"crypto/rand"
 	"encoding/binary"
 	"encoding/hex"
@@ -68,11 +69,11 @@ func (u *UUID) UnmarshalText(b []byte) error {
 	str := string(b)
 	strEnc, ok := stripPrefix(str, uuidV0)
 	if !ok || len(strEnc) != hex.EncodedLen(16) {
-		return merr.WithValue(errMalformedUUID, "uuidStr", str, true)
+		return merr.Wrap(context.Background(), errMalformedUUID, "uuidStr", str)
 	}
 	b, err := hex.DecodeString(strEnc)
 	if err != nil {
-		return merr.WithValue(err, "uuidStr", str, true)
+		return merr.Wrap(context.Background(), err, "uuidStr", str)
 	}
 	u.b = b
 	return nil

mctx/annotate.go

@@ -3,69 +3,284 @@ package mctx
 import (
 	"context"
 	"fmt"
+	"sort"
+	"strings"
 )
 
-type annotateKey struct {
+// Annotation describes the annotation of a key/value pair made on a Context via
-	userKey interface{}
+// the Annotate call. The Path field is the Path of the Context on which the
+// call was made.
+type Annotation struct {
+	Key, Value interface{}
+	Path       []string
 }
 
+type annotation struct {
+	Annotation
+	root, prev *annotation
+}
+
+type annotationKey int
+
 // Annotate takes in one or more key/value pairs (kvs' length must be even) and
 // returns a Context carrying them. Annotations only exist on the local level,
 // i.e. a child and parent share different annotation namespaces.
+//
+// NOTE that annotations are preserved across NewChild calls, but are keyed
+// based on the passed in key _and_ the Context's Path.
 func Annotate(ctx context.Context, kvs ...interface{}) context.Context {
-	for i := 0; i < len(kvs); i += 2 {
+	if len(kvs)%2 > 0 {
-		ctx = WithLocalValue(ctx, annotateKey{kvs[i]}, kvs[i+1])
+		panic("kvs being passed to mctx.Annotate must have an even number of elements")
+	} else if len(kvs) == 0 {
+		return ctx
 	}
+
+	// if multiple annotations are passed in here it's not actually necessary to
+	// create an intermediate Context for each one, so keep curr outside and
+	// only use it later
+	var curr, root *annotation
+	prev, _ := ctx.Value(annotationKey(0)).(*annotation)
+	if prev != nil {
+		root = prev.root
+	}
+	path := Path(ctx)
+	for i := 0; i < len(kvs); i += 2 {
+		curr = &annotation{
+			Annotation: Annotation{
+				Key: kvs[i], Value: kvs[i+1],
+				Path: path,
+			},
+			prev: prev,
+		}
+		if root == nil {
+			root = curr
+		}
+		curr.root = curr
+		prev = curr
+	}
+
+	ctx = context.WithValue(ctx, annotationKey(0), curr)
 	return ctx
 }
 
-// Annotations describes a set of keys/values which were set on a Context (but
+// AnnotationSet describes a set of unique Annotation values which were
-// not its parents or children) using Annotate.
+// retrieved off a Context via the Annotations function. An AnnotationSet has a
-type Annotations [][2]interface{}
+// couple methods on it to aid in post-processing.
+type AnnotationSet []Annotation
 
-// LocalAnnotations returns all key/value pairs which have been set via Annotate
+// Annotations returns all Annotation values which have been set via Annotate on
-// on this Context (but not its parent or children). If a key was set twice then
+// this Context. If a key was set twice then only the most recent value is
-// only the most recent value is included. The returned order is
+// included.
-// non-deterministic.
+func Annotations(ctx context.Context) AnnotationSet {
-func LocalAnnotations(ctx context.Context) Annotations {
+	a, _ := ctx.Value(annotationKey(0)).(*annotation)
-	var annotations Annotations
+	if a == nil {
-	localValuesIter(ctx, func(key, val interface{}) {
+		return nil
-		aKey, ok := key.(annotateKey)
-		if !ok {
-			return
 	}
-		annotations = append(annotations, [2]interface{}{aKey.userKey, val})
+	type mKey struct {
+		pathHash string
+		key      interface{}
+	}
+	m := map[mKey]bool{}
+
+	var aa AnnotationSet
+	for {
+		if a == nil {
+			break
+		}
+
+		k := mKey{pathHash: pathHash(a.Path), key: a.Key}
+		if m[k] {
+			a = a.prev
+			continue
+		}
+
+		aa = append(aa, a.Annotation)
+		m[k] = true
+		a = a.prev
+	}
+	return aa
+}
+
+// StringMapByPath is similar to StringMap, but it first maps each annotation
+// datum by its path.
+func (aa AnnotationSet) StringMapByPath() map[string]map[string]string {
+	type mKey struct {
+		str  string
+		path string
+		typ  string
+	}
+	m := map[mKey][]Annotation{}
+	for _, a := range aa {
+		k := mKey{
+			str:  fmt.Sprint(a.Key),
+			path: "/" + strings.Join(a.Path, "/"),
+		}
+		m[k] = append(m[k], a)
+	}
+
+	nextK := func(k mKey, a Annotation) mKey {
+		if k.typ == "" {
+			k.typ = fmt.Sprintf("%T", a.Key)
+		} else {
+			panic(fmt.Sprintf("mKey %#v is somehow conflicting with another", k))
+		}
+		return k
+	}
+
+	for {
+		var any bool
+		for k, annotations := range m {
+			if len(annotations) == 1 {
+				continue
+			}
+			any = true
+			for _, a := range annotations {
+				k2 := nextK(k, a)
+				m[k2] = append(m[k2], a)
+			}
+			delete(m, k)
+		}
+		if !any {
+			break
+		}
+	}
+
+	outM := map[string]map[string]string{}
+	for k, annotations := range m {
+		a := annotations[0]
+		if outM[k.path] == nil {
+			outM[k.path] = map[string]string{}
+		}
+		kStr := k.str
+		if k.typ != "" {
+			kStr += "(" + k.typ + ")"
+		}
+		outM[k.path][kStr] = fmt.Sprint(a.Value)
+	}
+	return outM
+}
+
+// StringMap formats each of the Annotations into strings using fmt.Sprint.  If
+// any two keys format to the same string, then path information will be
+// prefaced to each one. If they still format to the same string, then type
+// information will be prefaced to each one.
+func (aa AnnotationSet) StringMap() map[string]string {
+	type mKey struct {
+		str  string
+		path string
+		typ  string
+	}
+	m := map[mKey][]Annotation{}
+	for _, a := range aa {
+		k := mKey{str: fmt.Sprint(a.Key)}
+		m[k] = append(m[k], a)
+	}
+
+	nextK := func(k mKey, a Annotation) mKey {
+		if k.path == "" {
+			k.path = "/" + strings.Join(a.Path, "/")
+		} else if k.typ == "" {
+			k.typ = fmt.Sprintf("%T", a.Key)
+		} else {
+			panic(fmt.Sprintf("mKey %#v is somehow conflicting with another", k))
+		}
+		return k
+	}
+
+	for {
+		var any bool
+		for k, annotations := range m {
+			if len(annotations) == 1 {
+				continue
+			}
+			any = true
+			for _, a := range annotations {
+				k2 := nextK(k, a)
+				m[k2] = append(m[k2], a)
+			}
+			delete(m, k)
+		}
+		if !any {
+			break
+		}
+	}
+
+	outM := map[string]string{}
+	for k, annotations := range m {
+		a := annotations[0]
+		kStr := k.str
+		if k.path != "" {
+			kStr += "(" + k.path + ")"
+		}
+		if k.typ != "" {
+			kStr += "(" + k.typ + ")"
+		}
+		outM[kStr] = fmt.Sprint(a.Value)
+	}
+	return outM
+}
+
+// StringSlice is like StringMap but it returns a slice of key/value tuples
+// rather than a map. If sorted is true then the slice will be sorted by key in
+// ascending order.
+func (aa AnnotationSet) StringSlice(sorted bool) [][2]string {
+	m := aa.StringMap()
+	slice := make([][2]string, 0, len(m))
+	for k, v := range m {
+		slice = append(slice, [2]string{k, v})
+	}
+	if sorted {
+		sort.Slice(slice, func(i, j int) bool {
+			return slice[i][0] < slice[j][0]
 		})
-	return annotations
+	}
+	return slice
 }
 
-// StringMap formats each of the key/value pairs into strings using fmt.Sprint.
+func mergeAnnotations(ctxA, ctxB context.Context) context.Context {
-// If any two keys format to the same string, then type information will be
+	annotationA, _ := ctxA.Value(annotationKey(0)).(*annotation)
-// prefaced to each one.
+	annotationB, _ := ctxB.Value(annotationKey(0)).(*annotation)
-func (aa Annotations) StringMap() map[string]string {
+	if annotationB == nil {
-	keyTypes := make(map[string]interface{}, len(aa))
+		return ctxA
-	keyVals := map[string]string{}
+	} else if annotationA == nil {
-	setKey := func(k, v interface{}) {
+		return context.WithValue(ctxA, annotationKey(0), annotationB)
-		kStr := fmt.Sprint(k)
-		oldType := keyTypes[kStr]
-		if oldType == nil {
-			keyTypes[kStr] = k
-			keyVals[kStr] = fmt.Sprint(v)
-			return
 	}
 
-		// check if oldKey is in kvm, if so it needs to be moved to account for
+	var headA, currA *annotation
-		// its type info
+	currB := annotationB
-		if oldV, ok := keyVals[kStr]; ok {
+	for {
-			delete(keyVals, kStr)
+		if currB == nil {
-			keyVals[fmt.Sprintf("%T(%s)", oldType, kStr)] = oldV
+			break
 		}
 
-		keyVals[fmt.Sprintf("%T(%s)", k, kStr)] = fmt.Sprint(v)
+		prevA := &annotation{
+			Annotation: currB.Annotation,
+			root:       annotationA.root,
+		}
+		if currA != nil {
+			currA.prev = prevA
+		}
+		currA, currB = prevA, currB.prev
+		if headA == nil {
+			headA = currA
+		}
 	}
 
-	for _, kv := range aa {
+	currA.prev = annotationA
-		setKey(kv[0], kv[1])
+	return context.WithValue(ctxA, annotationKey(0), headA)
-	}
+}
-	return keyVals
+
+// MergeAnnotations sequentially merges the annotation data of the passed in
+// Contexts into the first passed in one. Data from a Context overwrites
+// overlapping data on all passed in Contexts to the left of it. All other
+// aspects of the first Context remain the same, and that Context is returned
+// with the new set of Annotation data.
+//
+// NOTE this will panic if no Contexts are passed in.
+func MergeAnnotations(ctxs ...context.Context) context.Context {
+	ctxA := ctxs[0]
+	for _, ctxB := range ctxs[1:] {
+		ctxA = mergeAnnotations(ctxA, ctxB)
+	}
+	return ctxA
 }

mctx/annotate_test.go

@@ -13,42 +13,73 @@ func TestAnnotate(t *T) {
 	parent = Annotate(parent, "b", "bar")
 
 	child := NewChild(parent, "child")
+	child = Annotate(child, "a", "Foo")
 	child = Annotate(child, "a", "FOO")
 	child = Annotate(child, "c", "BAZ")
 	parent = WithChild(parent, child)
 
-	parentAnnotations := LocalAnnotations(parent)
+	parentAnnotations := Annotations(parent)
-	childAnnotations := LocalAnnotations(child)
+	childAnnotations := Annotations(child)
 	massert.Fatal(t, massert.All(
 		massert.Len(parentAnnotations, 2),
-		massert.Has(parentAnnotations, [2]interface{}{"a", "foo"}),
+		massert.Has(parentAnnotations, Annotation{Key: "a", Value: "foo"}),
-		massert.Has(parentAnnotations, [2]interface{}{"b", "bar"}),
+		massert.Has(parentAnnotations, Annotation{Key: "b", Value: "bar"}),
-		massert.Len(childAnnotations, 2),
+
-		massert.Has(childAnnotations, [2]interface{}{"a", "FOO"}),
+		massert.Len(childAnnotations, 4),
-		massert.Has(childAnnotations, [2]interface{}{"c", "BAZ"}),
+		massert.Has(childAnnotations, Annotation{Key: "a", Value: "foo"}),
+		massert.Has(childAnnotations, Annotation{Key: "b", Value: "bar"}),
+		massert.Has(childAnnotations,
+			Annotation{Key: "a", Path: []string{"child"}, Value: "FOO"}),
+		massert.Has(childAnnotations,
+			Annotation{Key: "c", Path: []string{"child"}, Value: "BAZ"}),
 	))
 }
 
-func TestAnnotationsStingMap(t *T) {
+func TestAnnotationsStringMap(t *T) {
 	type A int
 	type B int
-	aa := Annotations{
+	aa := AnnotationSet{
-		{"foo", "bar"},
+		{Key: 0, Path: nil, Value: "zero"},
-		{"1", "one"},
+		{Key: 1, Path: nil, Value: "one"},
-		{1, 1},
+		{Key: 1, Path: []string{"foo"}, Value: "ONE"},
-		{0, 0},
+		{Key: A(2), Path: []string{"foo"}, Value: "two"},
-		{A(0), 0},
+		{Key: B(2), Path: []string{"foo"}, Value: "TWO"},
-		{B(0), 0},
 	}
 
+	massert.Fatal(t, massert.All(
+		massert.Equal(map[string]string{
+			"0":               "zero",
+			"1(/)":            "one",
+			"1(/foo)":         "ONE",
+			"2(/foo)(mctx.A)": "two",
+			"2(/foo)(mctx.B)": "TWO",
+		}, aa.StringMap()),
+		massert.Equal(map[string]map[string]string{
+			"/": {
+				"0": "zero",
+				"1": "one",
+			},
+			"/foo": {
+				"1":         "ONE",
+				"2(mctx.A)": "two",
+				"2(mctx.B)": "TWO",
+			},
+		}, aa.StringMapByPath()),
+	))
+}
+
+func TestMergeAnnotations(t *T) {
+	ctxA := Annotate(context.Background(), 0, "zero", 1, "one")
+	ctxA = Annotate(ctxA, 0, "ZERO")
+	ctxB := Annotate(context.Background(), 2, "two")
+	ctxB = Annotate(ctxB, 1, "ONE", 2, "TWO")
+
+	ctx := MergeAnnotations(ctxA, ctxB)
 	err := massert.Equal(map[string]string{
-		"foo":       "bar",
+		"0": "ZERO",
-		"string(1)": "one",
+		"1": "ONE",
-		"int(1)":    "1",
+		"2": "TWO",
-		"int(0)":    "0",
+	}, Annotations(ctx).StringMap()).Assert()
-		"mctx.A(0)": "0",
-		"mctx.B(0)": "0",
-	}, aa.StringMap()).Assert()
 	if err != nil {
 		t.Fatal(err)
 	}

mctx/ctx.go

@@ -11,17 +11,13 @@ package mctx
 
 import (
 	"context"
+	"crypto/sha256"
+	"encoding/hex"
 	"fmt"
 )
 
 ////////////////////////////////////////////////////////////////////////////////
 
-// New returns a new context which can be used as the root context for all
-// purposes in this framework.
-//func New() Context {
-//	return &context{Context: goctx.Background()}
-//}
-
 type ancestryKey int // 0 -> children, 1 -> parent, 2 -> path
 
 const (
@@ -97,6 +93,14 @@ func pathCP(ctx context.Context) []string {
 	return outPath
 }
 
+func pathHash(path []string) string {
+	pathHash := sha256.New()
+	for _, pathEl := range path {
+		fmt.Fprintf(pathHash, "%q.", pathEl)
+	}
+	return hex.EncodeToString(pathHash.Sum(nil))
+}
+
 // Name returns the name this Context was generated with via NewChild, or false
 // if this Context was not generated via NewChild.
 func Name(ctx context.Context) (string, bool) {
@@ -119,6 +123,7 @@ func NewChild(parent context.Context, name string) context.Context {
 	}
 
 	childPath := append(pathCP(parent), name)
+
 	child := withoutLocalValues(parent)
 	child = context.WithValue(child, ancestryKeyChildren, nil)    // unset children
 	child = context.WithValue(child, ancestryKeyChildrenMap, nil) // unset children

mctx/stack.go

@@ -0,0 +1,94 @@
+package mctx
+
+import (
+	"context"
+	"fmt"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"text/tabwriter"
+)
+
+// MaxStackSize indicates the maximum number of stack frames which will be
+// stored when embedding stack traces in errors.
+var MaxStackSize = 50
+
+type ctxStackKey int
+
+// Stacktrace represents a stack trace at a particular point in execution.
+type Stacktrace struct {
+	frames []uintptr
+}
+
+// Frame returns the first frame in the stack.
+func (s Stacktrace) Frame() runtime.Frame {
+	if len(s.frames) == 0 {
+		panic("cannot call Frame on empty stack")
+	}
+
+	frame, _ := runtime.CallersFrames([]uintptr(s.frames)).Next()
+	return frame
+}
+
+// Frames returns all runtime.Frame instances for this stack.
+func (s Stacktrace) Frames() []runtime.Frame {
+	if len(s.frames) == 0 {
+		return nil
+	}
+
+	out := make([]runtime.Frame, 0, len(s.frames))
+	frames := runtime.CallersFrames([]uintptr(s.frames))
+	for {
+		frame, more := frames.Next()
+		out = append(out, frame)
+		if !more {
+			break
+		}
+	}
+	return out
+}
+
+// String returns a string representing the top-most frame of the stack.
+func (s Stacktrace) String() string {
+	if len(s.frames) == 0 {
+		return ""
+	}
+	frame := s.Frame()
+	file, dir := filepath.Base(frame.File), filepath.Dir(frame.File)
+	dir = filepath.Base(dir) // only want the first dirname, ie the pkg name
+	return fmt.Sprintf("%s/%s:%d", dir, file, frame.Line)
+}
+
+// FullString returns the full stack trace.
+func (s Stacktrace) FullString() string {
+	sb := new(strings.Builder)
+	tw := tabwriter.NewWriter(sb, 0, 4, 4, ' ', 0)
+	for _, frame := range s.Frames() {
+		file := fmt.Sprintf("%s:%d", frame.File, frame.Line)
+		fmt.Fprintf(tw, "%s\t%s\n", file, frame.Function)
+	}
+	if err := tw.Flush(); err != nil {
+		panic(err)
+	}
+	return sb.String()
+}
+
+// WithStack returns a Context with the current stacktrace embedded in it (as a
+// Stacktrace type). If skip is non-zero it will skip that many frames from the
+// top of the stack. The frame containing the WithStack call itself is always
+// excluded.
+func WithStack(ctx context.Context, skip int) context.Context {
+	stackSlice := make([]uintptr, MaxStackSize)
+	// incr skip once for WithStack, and once for runtime.Callers
+	l := runtime.Callers(skip+2, stackSlice)
+	stack := Stacktrace{frames: stackSlice[:l]}
+
+	return context.WithValue(ctx, ctxStackKey(0), stack)
+}
+
+// Stack returns the Stacktrace instance which was embedded by WithStack, or false if
+// none ever was.
+func Stack(ctx context.Context) (Stacktrace, bool) {
+	stack, ok := ctx.Value(ctxStackKey(0)).(Stacktrace)
+	return stack, ok
+}

mctx/stack_test.go

@@ -1,6 +1,7 @@
-package merr
+package mctx
 
 import (
+	"context"
 	"strings"
 	. "testing"
 
@@ -8,8 +9,9 @@ import (
 )
 
 func TestStack(t *T) {
-	foo := New("foo")
+	foo := WithStack(context.Background(), 0)
-	fooStack := GetStack(foo)
+	fooStack, ok := Stack(foo)
+	massert.Fatal(t, massert.Equal(true, ok))
 
 	// test Frame
 	frame := fooStack.Frame()
@@ -25,13 +27,13 @@ func TestStack(t *T) {
 			massert.Equal(true, strings.Contains(frames[0].File, "stack_test.go")),
 			massert.Equal(true, strings.Contains(frames[0].Function, "TestStack")),
 		),
-		"fooStack.String():\n%s", fooStack.String(),
+		"fooStack.FullString():\n%s", fooStack.FullString(),
 	))
 
 	// test that WithStack works and can be used to skip frames
 	inner := func() {
 		bar := WithStack(foo, 1)
-		barStack := GetStack(bar)
+		barStack, _ := Stack(bar)
 		frames := barStack.Frames()
 		massert.Fatal(t, massert.Comment(
 			massert.All(
@@ -39,7 +41,7 @@ func TestStack(t *T) {
 				massert.Equal(true, strings.Contains(frames[0].File, "stack_test.go")),
 				massert.Equal(true, strings.Contains(frames[0].Function, "TestStack")),
 			),
-			"barStack.String():\n%s", barStack.String(),
+			"barStack.FullString():\n%s", barStack.FullString(),
 		))
 	}
 	inner()

mdb/mbigquery/bigquery.go

@@ -42,43 +42,37 @@ type BigQuery struct {
 	tableUploaders map[[2]string]*bigquery.Uploader
 }
 
-// MNew returns a BigQuery instance which will be initialized and configured
+// WithBigQuery returns a BigQuery instance which will be initialized and
-// when the start event is triggered on the returned (see mrun.Start). The
+// configured when the start event is triggered on the returned (see
-// BigQuery instance will have Close called on it when the stop event is
+// mrun.Start). The BigQuery instance will have Close called on it when the stop
-// triggered on the returned Context (see mrun.Stop).
+// event is triggered on the returned Context (see mrun.Stop).
 //
 // gce is optional and can be passed in if there's an existing gce object which
 // should be used, otherwise a new one will be created with mdb.MGCE.
-func MNew(ctx context.Context, gce *mdb.GCE) (context.Context, *BigQuery) {
+func WithBigQuery(parent context.Context, gce *mdb.GCE) (context.Context, *BigQuery) {
+	ctx := mctx.NewChild(parent, "mbigquery")
 	if gce == nil {
-		ctx, gce = mdb.MGCE(ctx, "")
+		ctx, gce = mdb.WithGCE(ctx, "")
 	}
 
 	bq := &BigQuery{
 		gce:            gce,
 		tables:         map[[2]string]*bigquery.Table{},
 		tableUploaders: map[[2]string]*bigquery.Uploader{},
-		ctx:            mctx.NewChild(ctx, "bigquery"),
 	}
 
-	// TODO the equivalent functionality as here will be added with annotations
+	ctx = mrun.WithStartHook(ctx, func(innerCtx context.Context) error {
-	// bq.log.SetKV(bq)
+		bq.ctx = mctx.MergeAnnotations(bq.ctx, bq.gce.Context())
-
+		mlog.Info("connecting to bigquery", bq.ctx)
-	bq.ctx = mrun.OnStart(bq.ctx, func(innerCtx context.Context) error {
-		mlog.Info(bq.ctx, "connecting to bigquery")
 		var err error
 		bq.Client, err = bigquery.NewClient(innerCtx, bq.gce.Project, bq.gce.ClientOptions()...)
-		return merr.WithKV(err, bq.KV())
+		return merr.Wrap(bq.ctx, err)
 	})
-	bq.ctx = mrun.OnStop(bq.ctx, func(context.Context) error {
+	ctx = mrun.WithStopHook(ctx, func(context.Context) error {
 		return bq.Client.Close()
 	})
-	return mctx.WithChild(ctx, bq.ctx), bq
+	bq.ctx = ctx
-}
+	return mctx.WithChild(parent, ctx), bq
-
-// KV implements the mlog.KVer interface.
-func (bq *BigQuery) KV() map[string]interface{} {
-	return bq.gce.KV()
 }
 
 // Table initializes and returns the table instance with the given dataset and
@@ -100,17 +94,18 @@ func (bq *BigQuery) Table(
 		return table, bq.tableUploaders[key], nil
 	}
 
-	kv := mlog.KV{"bigQueryDataset": dataset, "bigQueryTable": tableName}
+	ctx = mctx.MergeAnnotations(ctx, bq.ctx)
-	mlog.Debug(bq.ctx, "creating/grabbing table", kv)
+	ctx = mctx.Annotate(ctx, "dataset", dataset, "table", tableName)
 
+	mlog.Debug("creating/grabbing table", bq.ctx)
 	schema, err := bigquery.InferSchema(schemaObj)
 	if err != nil {
-		return nil, nil, merr.WithKV(err, bq.KV(), kv.KV())
+		return nil, nil, merr.Wrap(ctx, err)
 	}
 
 	ds := bq.Dataset(dataset)
 	if err := ds.Create(ctx, nil); err != nil && !isErrAlreadyExists(err) {
-		return nil, nil, merr.WithKV(err, bq.KV(), kv.KV())
+		return nil, nil, merr.Wrap(ctx, err)
 	}
 
 	table := ds.Table(tableName)
@@ -119,7 +114,7 @@ func (bq *BigQuery) Table(
 		Schema: schema,
 	}
 	if err := table.Create(ctx, meta); err != nil && !isErrAlreadyExists(err) {
-		return nil, nil, merr.WithKV(err, bq.KV(), kv.KV())
+		return nil, nil, merr.Wrap(ctx, err)
 	}
 	uploader := table.Uploader()
 

mdb/mbigtable/bigtable.go

@@ -31,61 +31,56 @@ type Bigtable struct {
 	ctx context.Context
 }
 
-// MNew returns a Bigtable instance which will be initialized and configured
+// WithBigTable returns a Bigtable instance which will be initialized and
-// when the start event is triggered on the returned Context (see mrun.Start).
+// configured when the start event is triggered on the returned Context (see
-// The Bigtable instance will have Close called on it when the stop event is
+// mrun.Start). The Bigtable instance will have Close called on it when the
-// triggered on the returned Context (see mrun.Stop).
+// stop event is triggered on the returned Context (see mrun.Stop).
 //
 // gce is optional and can be passed in if there's an existing gce object which
 // should be used, otherwise a new one will be created with mdb.MGCE.
 //
 // defaultInstance can be given as the instance name to use as the default
 // parameter value. If empty the parameter will be required to be set.
-func MNew(ctx context.Context, gce *mdb.GCE, defaultInstance string) (context.Context, *Bigtable) {
+func WithBigTable(parent context.Context, gce *mdb.GCE, defaultInstance string) (context.Context, *Bigtable) {
+	ctx := mctx.NewChild(parent, "bigtable")
 	if gce == nil {
-		ctx, gce = mdb.MGCE(ctx, "")
+		ctx, gce = mdb.WithGCE(ctx, "")
 	}
 
 	bt := &Bigtable{
 		gce: gce,
-		ctx: mctx.NewChild(ctx, "bigtable"),
 	}
 
-	// TODO the equivalent functionality as here will be added with annotations
-	// bt.log.SetKV(bt)
-
 	var inst *string
 	{
 		const name, descr = "instance", "name of the bigtable instance in the project to connect to"
 		if defaultInstance != "" {
-			bt.ctx, inst = mcfg.String(bt.ctx, name, defaultInstance, descr)
+			ctx, inst = mcfg.WithString(ctx, name, defaultInstance, descr)
 		} else {
-			bt.ctx, inst = mcfg.RequiredString(bt.ctx, name, descr)
+			ctx, inst = mcfg.WithRequiredString(ctx, name, descr)
 		}
 	}
 
-	bt.ctx = mrun.OnStart(bt.ctx, func(innerCtx context.Context) error {
+	ctx = mrun.WithStartHook(ctx, func(innerCtx context.Context) error {
 		bt.Instance = *inst
-		mlog.Info(bt.ctx, "connecting to bigtable", bt)
+
+		bt.ctx = mctx.MergeAnnotations(bt.ctx, bt.gce.Context())
+		bt.ctx = mctx.Annotate(bt.ctx, "instance", bt.Instance)
+
+		mlog.Info("connecting to bigtable", bt.ctx)
 		var err error
 		bt.Client, err = bigtable.NewClient(
 			innerCtx,
 			bt.gce.Project, bt.Instance,
 			bt.gce.ClientOptions()...,
 		)
-		return merr.WithKV(err, bt.KV())
+		return merr.Wrap(bt.ctx, err)
 	})
-	bt.ctx = mrun.OnStop(bt.ctx, func(context.Context) error {
+	ctx = mrun.WithStopHook(ctx, func(context.Context) error {
 		return bt.Client.Close()
 	})
-	return mctx.WithChild(ctx, bt.ctx), bt
+	bt.ctx = ctx
-}
+	return mctx.WithChild(parent, ctx), bt
-
-// KV implements the mlog.KVer interface.
-func (bt *Bigtable) KV() map[string]interface{} {
-	kv := bt.gce.KV()
-	kv["bigtableInstance"] = bt.Instance
-	return kv
 }
 
 // EnsureTable ensures that the given table exists and has (at least) the given
@@ -93,28 +88,29 @@ func (bt *Bigtable) KV() map[string]interface{} {
 //
 // This method requires admin privileges on the bigtable instance.
 func (bt *Bigtable) EnsureTable(ctx context.Context, name string, colFams ...string) error {
-	kv := mlog.KV{"bigtableTable": name}
+	ctx = mctx.MergeAnnotations(ctx, bt.ctx)
-	mlog.Info(bt.ctx, "ensuring table", kv)
+	ctx = mctx.Annotate(ctx, "table", name)
+	mlog.Info("ensuring table", ctx)
 
-	mlog.Debug(bt.ctx, "creating admin client", kv)
+	mlog.Debug("creating admin client", ctx)
 	adminClient, err := bigtable.NewAdminClient(ctx, bt.gce.Project, bt.Instance)
 	if err != nil {
-		return merr.WithKV(err, bt.KV(), kv.KV())
+		return merr.Wrap(ctx, err)
 	}
 	defer adminClient.Close()
 
-	mlog.Debug(bt.ctx, "creating bigtable table (if needed)", kv)
+	mlog.Debug("creating bigtable table (if needed)", ctx)
 	err = adminClient.CreateTable(ctx, name)
 	if err != nil && !isErrAlreadyExists(err) {
-		return merr.WithKV(err, bt.KV(), kv.KV())
+		return merr.Wrap(ctx, err)
 	}
 
 	for _, colFam := range colFams {
-		kv := kv.Set("family", colFam)
+		ctx := mctx.Annotate(ctx, "family", colFam)
-		mlog.Debug(bt.ctx, "creating bigtable column family (if needed)", kv)
+		mlog.Debug("creating bigtable column family (if needed)", ctx)
 		err := adminClient.CreateColumnFamily(ctx, name, colFam)
 		if err != nil && !isErrAlreadyExists(err) {
-			return merr.WithKV(err, bt.KV(), kv.KV())
+			return merr.Wrap(ctx, err)
 		}
 	}
 

mdb/mbigtable/bigtable_test.go

@@ -11,9 +11,9 @@ import (
 )
 
 func TestBasic(t *T) {
-	ctx := mtest.NewCtx()
+	ctx := mtest.Context()
-	ctx = mtest.SetEnv(ctx, "GCE_PROJECT", "testProject")
+	ctx = mtest.WithEnv(ctx, "BIGTABLE_GCE_PROJECT", "testProject")
-	ctx, bt := MNew(ctx, nil, "testInstance")
+	ctx, bt := WithBigTable(ctx, nil, "testInstance")
 
 	mtest.Run(ctx, t, func() {
 		tableName := "test-" + mrand.Hex(8)

mdb/mdatastore/datastore.go

@@ -22,39 +22,33 @@ type Datastore struct {
 	ctx context.Context
 }
 
-// MNew returns a Datastore instance which will be initialized and configured
+// WithDatastore returns a Datastore instance which will be initialized and
-// when the start event is triggered on the returned Context (see mrun.Start).
+// configured when the start event is triggered on the returned Context (see
-// The Datastore instance will have Close called on it when the stop event is
+// mrun.Start). The Datastore instance will have Close called on it when the
-// triggered on the returned Context (see mrun.Stop).
+// stop event is triggered on the returned Context (see mrun.Stop).
 //
 // gce is optional and can be passed in if there's an existing gce object which
 // should be used, otherwise a new one will be created with mdb.MGCE.
-func MNew(ctx context.Context, gce *mdb.GCE) (context.Context, *Datastore) {
+func WithDatastore(parent context.Context, gce *mdb.GCE) (context.Context, *Datastore) {
+	ctx := mctx.NewChild(parent, "datastore")
 	if gce == nil {
-		ctx, gce = mdb.MGCE(ctx, "")
+		ctx, gce = mdb.WithGCE(ctx, "")
 	}
 
 	ds := &Datastore{
 		gce: gce,
-		ctx: mctx.NewChild(ctx, "datastore"),
 	}
 
-	// TODO the equivalent functionality as here will be added with annotations
+	ctx = mrun.WithStartHook(ctx, func(innerCtx context.Context) error {
-	// ds.log.SetKV(ds)
+		ds.ctx = mctx.MergeAnnotations(ds.ctx, ds.gce.Context())
-
+		mlog.Info("connecting to datastore", ds.ctx)
-	ds.ctx = mrun.OnStart(ds.ctx, func(innerCtx context.Context) error {
-		mlog.Info(ds.ctx, "connecting to datastore")
 		var err error
 		ds.Client, err = datastore.NewClient(innerCtx, ds.gce.Project, ds.gce.ClientOptions()...)
-		return merr.WithKV(err, ds.KV())
+		return merr.Wrap(ds.ctx, err)
 	})
-	ds.ctx = mrun.OnStop(ds.ctx, func(context.Context) error {
+	ctx = mrun.WithStopHook(ctx, func(context.Context) error {
 		return ds.Client.Close()
 	})
-	return mctx.WithChild(ctx, ds.ctx), ds
+	ds.ctx = ctx
-}
+	return mctx.WithChild(parent, ctx), ds
-
-// KV implements the mlog.KVer interface.
-func (ds *Datastore) KV() map[string]interface{} {
-	return ds.gce.KV()
 }

mdb/mdatastore/datastore_test.go

@@ -11,9 +11,9 @@ import (
 
 // Requires datastore emulator to be running
 func TestBasic(t *T) {
-	ctx := mtest.NewCtx()
+	ctx := mtest.Context()
-	ctx = mtest.SetEnv(ctx, "GCE_PROJECT", "test")
+	ctx = mtest.WithEnv(ctx, "DATASTORE_GCE_PROJECT", "test")
-	ctx, ds := MNew(ctx, nil)
+	ctx, ds := WithDatastore(ctx, nil)
 	mtest.Run(ctx, t, func() {
 		name := mrand.Hex(8)
 		key := datastore.NameKey("testKind", name, nil)

mdb/mdb.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/mediocregopher/mediocre-go-lib/mcfg"
 	"github.com/mediocregopher/mediocre-go-lib/mctx"
-	"github.com/mediocregopher/mediocre-go-lib/mlog"
 	"github.com/mediocregopher/mediocre-go-lib/mrun"
 	"google.golang.org/api/option"
 )
@@ -15,32 +14,36 @@ import (
 // GCE wraps configuration parameters commonly used for interacting with GCE
 // services.
 type GCE struct {
+	ctx      context.Context
 	Project  string
 	CredFile string
 }
 
-// MGCE returns a GCE instance which will be initialized and configured when the
+// WithGCE returns a GCE instance which will be initialized and configured when
-// start event is triggered on the returned Context (see mrun.Start).
+// the start event is triggered on the returned Context (see mrun.Start).
 // defaultProject is used as the default value for the mcfg parameter this
 // function creates.
-func MGCE(parent context.Context, defaultProject string) (context.Context, *GCE) {
+func WithGCE(parent context.Context, defaultProject string) (context.Context, *GCE) {
 	ctx := mctx.NewChild(parent, "gce")
-	ctx, credFile := mcfg.String(ctx, "cred-file", "", "Path to GCE credientials JSON file, if any")
+	ctx, credFile := mcfg.WithString(ctx, "cred-file", "", "Path to GCE credientials JSON file, if any")
 
 	var project *string
 	const projectUsage = "Name of GCE project to use"
 	if defaultProject == "" {
-		ctx, project = mcfg.RequiredString(ctx, "project", projectUsage)
+		ctx, project = mcfg.WithRequiredString(ctx, "project", projectUsage)
 	} else {
-		ctx, project = mcfg.String(ctx, "project", defaultProject, projectUsage)
+		ctx, project = mcfg.WithString(ctx, "project", defaultProject, projectUsage)
 	}
 
 	var gce GCE
-	ctx = mrun.OnStart(ctx, func(context.Context) error {
+	ctx = mrun.WithStartHook(ctx, func(context.Context) error {
 		gce.Project = *project
 		gce.CredFile = *credFile
+		gce.ctx = mctx.Annotate(ctx, "project", gce.Project)
 		return nil
 	})
+
+	gce.ctx = ctx
 	return mctx.WithChild(parent, ctx), &gce
 }
 
@@ -54,9 +57,7 @@ func (gce *GCE) ClientOptions() []option.ClientOption {
 	return opts
 }
 
-// KV implements the mlog.KVer interface.
+// Context returns the annotated Context from this instance's initialization.
-func (gce *GCE) KV() map[string]interface{} {
+func (gce *GCE) Context() context.Context {
-	return mlog.KV{
+	return gce.ctx
-		"gceProject": gce.Project,
-	}
 }

mdb/mpubsub/pubsub.go

@@ -4,7 +4,6 @@ package mpubsub
 
 import (
 	"context"
-	"errors"
 	"sync"
 	"time"
 
@@ -41,45 +40,40 @@ type PubSub struct {
 	ctx context.Context
 }
 
-// MNew returns a PubSub instance which will be initialized and configured when
+// WithPubSub returns a PubSub instance which will be initialized and configured
-// the start event is triggered on the returned Context (see mrun.Start). The
+// when the start event is triggered on the returned Context (see mrun.Start).
-// PubSub instance will have Close called on it when the stop event is triggered
+// The PubSub instance will have Close called on it when the stop event is
-// on the returned Context(see mrun.Stop).
+// triggered on the returned Context(see mrun.Stop).
 //
 // gce is optional and can be passed in if there's an existing gce object which
 // should be used, otherwise a new one will be created with mdb.MGCE.
-func MNew(ctx context.Context, gce *mdb.GCE) (context.Context, *PubSub) {
+func WithPubSub(parent context.Context, gce *mdb.GCE) (context.Context, *PubSub) {
+	ctx := mctx.NewChild(parent, "pubsub")
 	if gce == nil {
-		ctx, gce = mdb.MGCE(ctx, "")
+		ctx, gce = mdb.WithGCE(ctx, "")
 	}
 
 	ps := &PubSub{
 		gce: gce,
-		ctx: mctx.NewChild(ctx, "pubsub"),
 	}
 
-	// TODO the equivalent functionality as here will be added with annotations
+	ctx = mrun.WithStartHook(ctx, func(innerCtx context.Context) error {
-	// ps.log.SetKV(ps)
+		ps.ctx = mctx.MergeAnnotations(ps.ctx, ps.gce.Context())
-
+		mlog.Info("connecting to pubsub", ps.ctx)
-	ps.ctx = mrun.OnStart(ps.ctx, func(innerCtx context.Context) error {
-		mlog.Info(ps.ctx, "connecting to pubsub")
 		var err error
 		ps.Client, err = pubsub.NewClient(innerCtx, ps.gce.Project, ps.gce.ClientOptions()...)
-		return merr.WithKV(err, ps.KV())
+		return merr.Wrap(ps.ctx, err)
 	})
-	ps.ctx = mrun.OnStop(ps.ctx, func(context.Context) error {
+	ctx = mrun.WithStopHook(ctx, func(context.Context) error {
 		return ps.Client.Close()
 	})
-	return mctx.WithChild(ctx, ps.ctx), ps
+	ps.ctx = ctx
-}
+	return mctx.WithChild(parent, ctx), ps
-
-// KV implements the mlog.KVer interface
-func (ps *PubSub) KV() map[string]interface{} {
-	return ps.gce.KV()
 }
 
 // Topic provides methods around a particular topic in PubSub
 type Topic struct {
+	ctx   context.Context
 	ps    *PubSub
 	topic *pubsub.Topic
 	name  string
@@ -88,6 +82,7 @@ type Topic struct {
 // Topic returns, after potentially creating, a topic of the given name
 func (ps *PubSub) Topic(ctx context.Context, name string, create bool) (*Topic, error) {
 	t := &Topic{
+		ctx:  mctx.Annotate(ps.ctx, "topicName", name),
 		ps:   ps,
 		name: name,
 	}
@@ -98,38 +93,31 @@ func (ps *PubSub) Topic(ctx context.Context, name string, create bool) (*Topic,
 		if isErrAlreadyExists(err) {
 			t.topic = ps.Client.Topic(name)
 		} else if err != nil {
-			return nil, merr.WithKV(err, t.KV())
+			return nil, merr.Wrap(ctx, merr.Wrap(t.ctx, err))
 		}
 	} else {
 		t.topic = ps.Client.Topic(name)
-		if exists, err := t.topic.Exists(ctx); err != nil {
+		if exists, err := t.topic.Exists(t.ctx); err != nil {
-			return nil, merr.WithKV(err, t.KV())
+			return nil, merr.Wrap(ctx, merr.Wrap(t.ctx, err))
 		} else if !exists {
-			err := merr.New("topic dne")
+			return nil, merr.Wrap(ctx, merr.New(t.ctx, "topic dne"))
-			return nil, merr.WithKV(err, t.KV())
 		}
 	}
 	return t, nil
 }
 
-// KV implements the mlog.KVer interface
-func (t *Topic) KV() map[string]interface{} {
-	kv := t.ps.KV()
-	kv["topicName"] = t.name
-	return kv
-}
-
 // Publish publishes a message with the given data as its body to the Topic
 func (t *Topic) Publish(ctx context.Context, data []byte) error {
 	_, err := t.topic.Publish(ctx, &Message{Data: data}).Get(ctx)
 	if err != nil {
-		return merr.WithKV(err, t.KV())
+		return merr.Wrap(ctx, merr.Wrap(t.ctx, err))
 	}
 	return nil
 }
 
 // Subscription provides methods around a subscription to a topic in PubSub
 type Subscription struct {
+	ctx   context.Context
 	topic *Topic
 	sub   *pubsub.Subscription
 	name  string
@@ -143,6 +131,7 @@ type Subscription struct {
 func (t *Topic) Subscription(ctx context.Context, name string, create bool) (*Subscription, error) {
 	name = t.name + "_" + name
 	s := &Subscription{
+		ctx:   mctx.Annotate(t.ctx, "subName", name),
 		topic: t,
 		name:  name,
 	}
@@ -155,27 +144,19 @@ func (t *Topic) Subscription(ctx context.Context, name string, create bool) (*Su
 		if isErrAlreadyExists(err) {
 			s.sub = t.ps.Subscription(name)
 		} else if err != nil {
-			return nil, merr.WithKV(err, s.KV())
+			return nil, merr.Wrap(ctx, merr.Wrap(s.ctx, err))
 		}
 	} else {
 		s.sub = t.ps.Subscription(name)
 		if exists, err := s.sub.Exists(ctx); err != nil {
-			return nil, merr.WithKV(err, s.KV())
+			return nil, merr.Wrap(ctx, merr.Wrap(s.ctx, err))
 		} else if !exists {
-			err := merr.New("sub dne")
+			return nil, merr.Wrap(ctx, merr.New(s.ctx, "sub dne"))
-			return nil, merr.WithKV(err, s.KV())
 		}
 	}
 	return s, nil
 }
 
-// KV implements the mlog.KVer interface
-func (s *Subscription) KV() map[string]interface{} {
-	kv := s.topic.KV()
-	kv["subName"] = s.name
-	return kv
-}
-
 // ConsumerFunc is a function which messages being consumed will be passed. The
 // returned boolean and returned error are independent. If the bool is false the
 // message will be returned to the queue for retrying later. If an error is
@@ -221,12 +202,14 @@ func (s *Subscription) Consume(ctx context.Context, fn ConsumerFunc, opts Consum
 	octx := oldctx.Context(ctx)
 	for {
 		err := s.sub.Receive(octx, func(octx oldctx.Context, msg *Message) {
-			innerCtx, cancel := oldctx.WithTimeout(octx, opts.Timeout)
+			innerOCtx, cancel := oldctx.WithTimeout(octx, opts.Timeout)
 			defer cancel()
+			innerCtx := context.Context(innerOCtx)
 
-			ok, err := fn(context.Context(innerCtx), msg)
+			ok, err := fn(innerCtx, msg)
 			if err != nil {
-				mlog.Warn(s.topic.ps.ctx, "error consuming pubsub message", s, merr.KV(err))
+				mlog.Warn("error consuming pubsub message",
+					s.ctx, ctx, innerCtx, merr.Context(err))
 			}
 
 			if ok {
@@ -238,7 +221,8 @@ func (s *Subscription) Consume(ctx context.Context, fn ConsumerFunc, opts Consum
 		if octx.Err() == context.Canceled || err == nil {
 			return
 		} else if err != nil {
-			mlog.Warn(s.topic.ps.ctx, "error consuming from pubsub", s, merr.KV(err))
+			mlog.Warn("error consuming from pubsub",
+				s.ctx, ctx, merr.Context(err))
 			time.Sleep(1 * time.Second)
 		}
 	}
@@ -331,7 +315,8 @@ func (s *Subscription) BatchConsume(
 				}
 				ret, err := fn(thisCtx, msgs)
 				if err != nil {
-					mlog.Warn(s.topic.ps.ctx, "error consuming pubsub batch messages", s, merr.KV(err))
+					mlog.Warn("error consuming pubsub batch messages",
+						s.ctx, merr.Context(err))
 				}
 				for i := range thisGroup {
 					thisGroup[i].retCh <- ret // retCh is buffered
@@ -365,7 +350,7 @@ func (s *Subscription) BatchConsume(
 		case ret := <-retCh:
 			return ret, nil
 		case <-ctx.Done():
-			return false, errors.New("reading from batch grouping process timed out")
+			return false, merr.Wrap(ctx, merr.New(s.ctx, "reading from batch grouping process timed out"))
 		}
 	}, opts)
 

mdb/mpubsub/pubsub_test.go

@@ -13,9 +13,9 @@ import (
 
 // this requires the pubsub emulator to be running
 func TestPubSub(t *T) {
-	ctx := mtest.NewCtx()
+	ctx := mtest.Context()
-	ctx = mtest.SetEnv(ctx, "GCE_PROJECT", "test")
+	ctx = mtest.WithEnv(ctx, "PUBSUB_GCE_PROJECT", "test")
-	ctx, ps := MNew(ctx, nil)
+	ctx, ps := WithPubSub(ctx, nil)
 	mtest.Run(ctx, t, func() {
 		topicName := "testTopic_" + mrand.Hex(8)
 		ctx := context.Background()
@@ -47,9 +47,9 @@ func TestPubSub(t *T) {
 }
 
 func TestBatchPubSub(t *T) {
-	ctx := mtest.NewCtx()
+	ctx := mtest.Context()
-	ctx = mtest.SetEnv(ctx, "GCE_PROJECT", "test")
+	ctx = mtest.WithEnv(ctx, "PUBSUB_GCE_PROJECT", "test")
-	ctx, ps := MNew(ctx, nil)
+	ctx, ps := WithPubSub(ctx, nil)
 	mtest.Run(ctx, t, func() {
 
 		topicName := "testBatchTopic_" + mrand.Hex(8)

merr/kv.go

@@ -1,120 +0,0 @@
-package merr
-
-import (
-	"fmt"
-	"path/filepath"
-)
-
-// WithValue returns a copy of the original error, automatically wrapping it if
-// the error is not from merr (see Wrap). The returned error has a value set on
-// with for the given key.
-//
-// visible determines whether or not the value is visible in the output of
-// Error.
-func WithValue(e error, k, v interface{}, visible bool) error {
-	if e == nil {
-		return nil
-	}
-	er := wrap(e, true, 1)
-	er.attr[k] = val{val: v, visible: visible}
-	return er
-}
-
-// GetValue returns the value embedded in the error for the given key, or nil if
-// the error isn't from this package or doesn't have that key embedded.
-func GetValue(e error, k interface{}) interface{} {
-	if e == nil {
-		return nil
-	}
-	return wrap(e, false, -1).attr[k].val
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-// not really used for attributes, but w/e
-const attrKeyErr attrKey = "err"
-const attrKeyErrSrc attrKey = "errSrc"
-
-// KVer implements the mlog.KVer interface. This is defined here to avoid this
-// package needing to actually import mlog.
-type KVer struct {
-	kv map[string]interface{}
-}
-
-// KV implements the mlog.KVer interface.
-func (kv KVer) KV() map[string]interface{} {
-	return kv.kv
-}
-
-// KV returns a KVer which contains all visible values embedded in the error, as
-// well as the original error string itself. Keys will be turned into strings
-// using the fmt.Sprint function.
-//
-// If any keys conflict then their type information will be included as part of
-// the key.
-func KV(e error) KVer {
-	if e == nil {
-		return KVer{}
-	}
-
-	er := wrap(e, false, 1)
-	kvm := make(map[string]interface{}, len(er.attr)+1)
-
-	keys := map[string]interface{}{} // in this case the value is the raw key
-	setKey := func(k, v interface{}) {
-		kStr := fmt.Sprint(k)
-		oldKey := keys[kStr]
-		if oldKey == nil {
-			keys[kStr] = k
-			kvm[kStr] = v
-			return
-		}
-
-		// check if oldKey is in kvm, if so it needs to be moved to account for
-		// its type info
-		if oldV, ok := kvm[kStr]; ok {
-			delete(kvm, kStr)
-			kvm[fmt.Sprintf("%T(%s)", oldKey, kStr)] = oldV
-		}
-
-		kvm[fmt.Sprintf("%T(%s)", k, kStr)] = v
-	}
-
-	setKey(attrKeyErr, er.err.Error())
-	for k, v := range er.attr {
-		if !v.visible {
-			continue
-		}
-
-		stack, ok := v.val.(Stack)
-		if !ok {
-			setKey(k, v.val)
-			continue
-		}
-
-		// compress the stack trace to just be the top-most frame
-		frame := stack.Frame()
-		file, dir := filepath.Base(frame.File), filepath.Dir(frame.File)
-		dir = filepath.Base(dir) // only want the first dirname, ie the pkg name
-		setKey(attrKeyErrSrc, fmt.Sprintf("%s/%s:%d", dir, file, frame.Line))
-	}
-
-	return KVer{kvm}
-}
-
-type kvKey string
-
-// WithKV embeds key/value pairs into an error, just like WithValue, but it does
-// so via one or more passed in maps
-func WithKV(e error, kvMaps ...map[string]interface{}) error {
-	if e == nil {
-		return nil
-	}
-	er := wrap(e, true, 1)
-	for _, kvMap := range kvMaps {
-		for k, v := range kvMap {
-			er.attr[kvKey(k)] = val{val: v, visible: true}
-		}
-	}
-	return er
-}

merr/kv_test.go

@@ -1,98 +0,0 @@
-package merr
-
-import (
-	"strings"
-	. "testing"
-
-	"github.com/mediocregopher/mediocre-go-lib/mtest/massert"
-)
-
-func TestKV(t *T) {
-	massert.Fatal(t, massert.All(
-		massert.Nil(WithValue(nil, "foo", "bar", true)),
-		massert.Nil(WithValue(nil, "foo", "bar", false)),
-		massert.Nil(GetValue(nil, "foo")),
-		massert.Len(KV(nil).KV(), 0),
-	))
-
-	er := New("foo", "bar", "baz")
-	kv := KV(er).KV()
-	massert.Fatal(t, massert.Comment(
-		massert.All(
-			massert.Len(kv, 3),
-			massert.Equal("foo", kv["err"]),
-			massert.Equal("baz", kv["bar"]),
-			massert.Equal(true,
-				strings.HasPrefix(kv["errSrc"].(string), "merr/kv_test.go:")),
-		),
-		"kv: %#v", kv,
-	))
-
-	type A string
-	type B string
-	type C string
-
-	er = WithValue(er, "invisible", "you can't see me", false)
-	er = WithValue(er, A("k"), "1", true)
-	kv = KV(er).KV()
-	massert.Fatal(t, massert.Comment(
-		massert.All(
-			massert.Len(kv, 4),
-			massert.Equal("foo", kv["err"]),
-			massert.Equal("baz", kv["bar"]),
-			massert.Equal(true,
-				strings.HasPrefix(kv["errSrc"].(string), "merr/kv_test.go:")),
-			massert.Equal("1", kv["k"]),
-		),
-		"kv: %#v", kv,
-	))
-
-	er = WithValue(er, B("k"), "2", true)
-	kv = KV(er).KV()
-	massert.Fatal(t, massert.Comment(
-		massert.All(
-			massert.Len(kv, 5),
-			massert.Equal("foo", kv["err"]),
-			massert.Equal("baz", kv["bar"]),
-			massert.Equal(true,
-				strings.HasPrefix(kv["errSrc"].(string), "merr/kv_test.go:")),
-			massert.Equal("1", kv["merr.A(k)"]),
-			massert.Equal("2", kv["merr.B(k)"]),
-		),
-		"kv: %#v", kv,
-	))
-
-	er = WithValue(er, C("k"), "3", true)
-	kv = KV(er).KV()
-	massert.Fatal(t, massert.Comment(
-		massert.All(
-			massert.Len(kv, 6),
-			massert.Equal("foo", kv["err"]),
-			massert.Equal("baz", kv["bar"]),
-			massert.Equal(true,
-				strings.HasPrefix(kv["errSrc"].(string), "merr/kv_test.go:")),
-			massert.Equal("1", kv["merr.A(k)"]),
-			massert.Equal("2", kv["merr.B(k)"]),
-			massert.Equal("3", kv["merr.C(k)"]),
-		),
-		"kv: %#v", kv,
-	))
-
-	er = WithKV(er, map[string]interface{}{"D": 4, "k": 5})
-	kv = KV(er).KV()
-	massert.Fatal(t, massert.Comment(
-		massert.All(
-			massert.Len(kv, 8),
-			massert.Equal("foo", kv["err"]),
-			massert.Equal("baz", kv["bar"]),
-			massert.Equal(true,
-				strings.HasPrefix(kv["errSrc"].(string), "merr/kv_test.go:")),
-			massert.Equal("1", kv["merr.A(k)"]),
-			massert.Equal("2", kv["merr.B(k)"]),
-			massert.Equal("3", kv["merr.C(k)"]),
-			massert.Equal(4, kv["D"]),
-			massert.Equal(5, kv["merr.kvKey(k)"]),
-		),
-		"kv: %#v", kv,
-	))
-}

merr/merr.go

@@ -9,11 +9,12 @@
 package merr
 
 import (
+	"context"
 	"errors"
-	"fmt"
-	"sort"
 	"strings"
 	"sync"
+
+	"github.com/mediocregopher/mediocre-go-lib/mctx"
 )
 
 var strBuilderPool = sync.Pool{
@@ -27,114 +28,158 @@ func putStrBuilder(sb *strings.Builder) {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-type val struct {
-	visible bool
-	val     interface{}
-}
-
-func (v val) String() string {
-	return fmt.Sprint(v.val)
-}
-
 type err struct {
 	err  error
-	attr map[interface{}]val
+	attr map[interface{}]interface{}
 }
 
 // attr keys internal to this package
-type attrKey string
+type attrKey int
 
-func wrap(e error, cp bool, skip int) *err {
+const (
+	attrKeyCtx attrKey = iota
+)
+
+func wrap(e error, cp bool) *err {
 	if e == nil {
 		return nil
 	}
 
 	er, ok := e.(*err)
 	if !ok {
-		er := &err{err: e, attr: map[interface{}]val{}}
+		return &err{err: e}
-		if skip >= 0 {
-			setStack(er, skip+1)
-		}
-		return er
 	} else if !cp {
 		return er
 	}
 
 	er2 := &err{
 		err:  er.err,
-		attr: make(map[interface{}]val, len(er.attr)),
+		attr: make(map[interface{}]interface{}, len(er.attr)),
 	}
 	for k, v := range er.attr {
 		er2.attr[k] = v
 	}
-	if _, ok := er2.attr[attrKeyStack]; !ok && skip >= 0 {
-		setStack(er, skip+1)
-	}
 
 	return er2
 }
 
-// Wrap takes in an error and returns one wrapping it in merr's inner type,
+// Base takes in an error and checks if it is merr's internal error type. If it
-// which embeds information like the stack trace.
+// is then the underlying error which is being wrapped is returned. If it's not
-func Wrap(e error) error {
+// then the passed in error is returned as-is.
-	return wrap(e, false, 1)
+func Base(e error) error {
+	if er, ok := e.(*err); ok {
+		return er.err
+	}
+	return e
 }
 
-// New returns a new error with the given string as its error string. New
+// WithValue returns a copy of the original error, automatically wrapping it if
-// automatically wraps the error in merr's inner type, which embeds information
+// the error is not from merr (see Wrap). The returned error has an attribute
-// like the stack trace.
+// value set on it for the given key.
-//
+func WithValue(e error, k, v interface{}) error {
-// For convenience, visible key/values may be passed into New at this point. For
+	if e == nil {
-// example, the following two are equivalent:
+		return nil
-//
-//	merr.WithValue(merr.New("foo"), "bar", "baz", true)
-//	merr.New("foo", "bar", "baz")
-//
-func New(str string, kvs ...interface{}) error {
-	if len(kvs)%2 != 0 {
-		panic("key passed in without corresponding value")
 	}
-	err := wrap(errors.New(str), false, 1)
+	er := wrap(e, true)
-	for i := 0; i < len(kvs); i += 2 {
+	if er.attr == nil {
-		err.attr[kvs[i]] = val{
+		er.attr = map[interface{}]interface{}{}
-			visible: true,
-			val:     kvs[i+1],
 	}
-	}
+	er.attr[k] = v
-	return err
+	return er
 }
 
-func (er *err) visibleAttrs() [][2]string {
+// Value returns the value embedded in the error for the given key, or nil if
-	out := make([][2]string, 0, len(er.attr))
+// the error isn't from this package or doesn't have that key embedded.
-	for k, v := range er.attr {
+func Value(e error, k interface{}) interface{} {
-		if !v.visible {
+	if e == nil {
-			continue
+		return nil
 	}
-		out = append(out, [2]string{
+	return wrap(e, false).attr[k]
-			strings.Trim(fmt.Sprintf("%q", k), `"`),
+}
-			fmt.Sprint(v.val),
+
-		})
+// WrapSkip is like Wrap but also allows for skipping extra stack frames when
+// embedding the stack into the error.
+func WrapSkip(ctx context.Context, e error, skip int, kvs ...interface{}) error {
+	prevCtx, _ := Value(e, attrKeyCtx).(context.Context)
+	if prevCtx != nil {
+		ctx = mctx.MergeAnnotations(prevCtx, ctx)
 	}
 
-	sort.Slice(out, func(i, j int) bool {
+	if _, ok := mctx.Stack(ctx); !ok {
-		return out[i][0] < out[j][0]
+		ctx = mctx.WithStack(ctx, skip+1)
-	})
+	}
+	if len(kvs) > 0 {
+		ctx = mctx.Annotate(ctx, kvs...)
+	}
 
-	return out
+	return WithValue(e, attrKeyCtx, ctx)
+}
+
+// Wrap takes in an error and returns one which wraps it in merr's inner type,
+// embedding the given Context (which can later be retrieved by Ctx) at the same
+// time.
+//
+// For convenience, extra annotation information can be passed in here as well
+// via the kvs argument. See mctx.Annotate for more information.
+//
+// This function automatically embeds stack information into the Context as it's
+// being stored, using mctx.WithStack, unless the error already has stack
+// information in it.
+func Wrap(ctx context.Context, e error, kvs ...interface{}) error {
+	return WrapSkip(ctx, e, 1, kvs...)
+}
+
+// New is a shortcut for:
+//	merr.Wrap(ctx, errors.New(str), kvs...)
+func New(ctx context.Context, str string, kvs ...interface{}) error {
+	return WrapSkip(ctx, errors.New(str), 1, kvs...)
+}
+
+// TODO it would be more convenient in a lot of cases if New and Wrap took in a
+// list of Contexts.
+
+type annotateKey string
+
+func ctx(e error) context.Context {
+	ctx, _ := Value(e, attrKeyCtx).(context.Context)
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
+	if stack, ok := mctx.Stack(ctx); ok {
+		ctx = mctx.Annotate(ctx, annotateKey("errLoc"), stack.String())
+	}
+	return ctx
+}
+
+// Context returns the Context embedded in this error from the last call to Wrap
+// or New. If none is embedded this uses context.Background().
+//
+// The returned Context will have annotated on it (see mctx.Annotate) the
+// underlying error's string (as returned by Error()) and the stack location in
+// the Context. Stack locations are automatically added by New and Wrap via
+// mctx.WithStack.
+//
+// If this error is nil this returns context.Background().
+func Context(e error) context.Context {
+	if e == nil {
+		return context.Background()
+	}
+	ctx := ctx(e)
+	ctx = mctx.Annotate(ctx, annotateKey("err"), Base(e).Error())
+	return ctx
 }
 
 func (er *err) Error() string {
-	visAttrs := er.visibleAttrs()
+	ctx := ctx(er)
-	if len(visAttrs) == 0 {
-		return er.err.Error()
-	}
 
 	sb := strBuilderPool.Get().(*strings.Builder)
 	defer putStrBuilder(sb)
-
 	sb.WriteString(strings.TrimSpace(er.err.Error()))
-	for _, attr := range visAttrs {
+
-		k, v := strings.TrimSpace(attr[0]), strings.TrimSpace(attr[1])
+	annotations := mctx.Annotations(ctx).StringSlice(true)
+	for _, kve := range annotations {
+		k, v := strings.TrimSpace(kve[0]), strings.TrimSpace(kve[1])
 		sb.WriteString("\n\t* ")
 		sb.WriteString(k)
 		sb.WriteString(": ")
@@ -154,16 +199,6 @@ func (er *err) Error() string {
 	return sb.String()
 }
 
-// Base takes in an error and checks if it is merr's internal error type. If it
-// is then the underlying error which is being wrapped is returned. If it's not
-// then the passed in error is returned as-is.
-func Base(e error) error {
-	if er, ok := e.(*err); ok {
-		return er.err
-	}
-	return e
-}
-
 // Equal is a shortcut for Base(e1) == Base(e2).
 func Equal(e1, e2 error) bool {
 	return Base(e1) == Base(e2)

merr/merr_test.go

@@ -1,35 +1,33 @@
 package merr
 
 import (
+	"context"
 	"errors"
 	. "testing"
 
+	"github.com/mediocregopher/mediocre-go-lib/mctx"
 	"github.com/mediocregopher/mediocre-go-lib/mtest/massert"
 )
 
 func TestError(t *T) {
-	er := &err{
+	e := New(context.Background(), "foo",
-		err: errors.New("foo"),
+		"a", "aaa aaa\n",
-		attr: map[interface{}]val{
+		"c", "ccc\nccc\n",
-			"a":   val{val: "aaa aaa\n", visible: true},
+		"d\t", "weird key but ok",
-			"b":   val{val: "invisible"},
+	)
-			"c":   val{val: "ccc\nccc\n", visible: true},
-			"d\t": val{val: "weird key but ok", visible: true},
-		},
-	}
-	str := er.Error()
 	exp := `foo
 	* a: aaa aaa
 	* c: 
 		ccc
 		ccc
-	* d\t: weird key but ok`
+	* d: weird key but ok
-	massert.Fatal(t, massert.Equal(exp, str))
+	* errLoc: merr/merr_test.go:13`
+	massert.Fatal(t, massert.Equal(exp, e.Error()))
 }
 
 func TestBase(t *T) {
 	errFoo, errBar := errors.New("foo"), errors.New("bar")
-	erFoo := Wrap(errFoo)
+	erFoo := Wrap(context.Background(), errFoo)
 	massert.Fatal(t, massert.All(
 		massert.Nil(Base(nil)),
 		massert.Equal(errFoo, Base(erFoo)),
@@ -40,3 +38,50 @@ func TestBase(t *T) {
 		massert.Equal(false, Equal(errBar, erFoo)),
 	))
 }
+
+func TestValue(t *T) {
+	massert.Fatal(t, massert.All(
+		massert.Nil(WithValue(nil, "foo", "bar")),
+		massert.Nil(Value(nil, "foo")),
+	))
+
+	e1 := New(context.Background(), "foo")
+	e1 = WithValue(e1, "a", "A")
+	e2 := WithValue(errors.New("bar"), "a", "A")
+	massert.Fatal(t, massert.All(
+		massert.Equal("A", Value(e1, "a")),
+		massert.Equal("A", Value(e2, "a")),
+	))
+
+	e3 := WithValue(e2, "a", "AAA")
+	massert.Fatal(t, massert.All(
+		massert.Equal("A", Value(e1, "a")),
+		massert.Equal("A", Value(e2, "a")),
+		massert.Equal("AAA", Value(e3, "a")),
+	))
+}
+
+func mkErr(ctx context.Context, err error) error {
+	return Wrap(ctx, err) // it's important that this is line 65
+}
+
+func TestCtx(t *T) {
+	ctxA := mctx.Annotate(context.Background(), "0", "ZERO", "1", "one")
+	ctxB := mctx.Annotate(context.Background(), "1", "ONE", "2", "TWO")
+
+	// use mkErr so that it's easy to test that the stack info isn't overwritten
+	// when Wrap is called with ctxB.
+	e := mkErr(ctxA, errors.New("hello"))
+	e = Wrap(ctxB, e)
+
+	err := massert.Equal(map[string]string{
+		"0":      "ZERO",
+		"1":      "ONE",
+		"2":      "TWO",
+		"err":    "hello",
+		"errLoc": "merr/merr_test.go:65",
+	}, mctx.Annotations(Context(e)).StringMap()).Assert()
+	if err != nil {
+		t.Fatal(err)
+	}
+}

merr/stack.go

@@ -1,85 +0,0 @@
-package merr
-
-import (
-	"fmt"
-	"runtime"
-	"strings"
-	"text/tabwriter"
-)
-
-// MaxStackSize indicates the maximum number of stack frames which will be
-// stored when embedding stack traces in errors.
-var MaxStackSize = 50
-
-const attrKeyStack attrKey = "stack"
-
-// Stack represents a stack trace at a particular point in execution.
-type Stack []uintptr
-
-// Frame returns the first frame in the stack.
-func (s Stack) Frame() runtime.Frame {
-	if len(s) == 0 {
-		panic("cannot call Frame on empty stack")
-	}
-
-	frame, _ := runtime.CallersFrames([]uintptr(s)).Next()
-	return frame
-}
-
-// Frames returns all runtime.Frame instances for this stack.
-func (s Stack) Frames() []runtime.Frame {
-	if len(s) == 0 {
-		return nil
-	}
-
-	out := make([]runtime.Frame, 0, len(s))
-	frames := runtime.CallersFrames([]uintptr(s))
-	for {
-		frame, more := frames.Next()
-		out = append(out, frame)
-		if !more {
-			break
-		}
-	}
-	return out
-}
-
-// String returns the full stack trace.
-func (s Stack) String() string {
-	sb := strBuilderPool.Get().(*strings.Builder)
-	defer putStrBuilder(sb)
-	tw := tabwriter.NewWriter(sb, 0, 4, 4, ' ', 0)
-	for _, frame := range s.Frames() {
-		file := fmt.Sprintf("%s:%d", frame.File, frame.Line)
-		fmt.Fprintf(tw, "%s\t%s\n", file, frame.Function)
-	}
-	if err := tw.Flush(); err != nil {
-		panic(err)
-	}
-	return sb.String()
-}
-
-func setStack(er *err, skip int) {
-	stackSlice := make([]uintptr, MaxStackSize)
-	// incr skip once for setStack, and once for runtime.Callers
-	l := runtime.Callers(skip+2, stackSlice)
-	er.attr[attrKeyStack] = val{val: Stack(stackSlice[:l]), visible: true}
-}
-
-// WithStack returns a copy of the original error, automatically wrapping it if
-// the error is not from merr (see Wrap). The returned error has the embedded
-// stacktrace set to the frame calling this function.
-//
-// skip can be used to exclude that many frames from the top of the stack.
-func WithStack(e error, skip int) error {
-	er := wrap(e, true, -1)
-	setStack(er, skip+1)
-	return er
-}
-
-// GetStack returns the Stack which was embedded in the error, if the error is
-// from this package. If not then nil is returned.
-func GetStack(e error) Stack {
-	stack, _ := wrap(e, false, -1).attr[attrKeyStack].val.(Stack)
-	return stack
-}

mhttp/mhttp.go

@@ -17,13 +17,13 @@ import (
 	"github.com/mediocregopher/mediocre-go-lib/mrun"
 )
 
-// MServer is returned by MListenAndServe and simply wraps an *http.Server.
+// Server is returned by WithListeningServer and simply wraps an *http.Server.
-type MServer struct {
+type Server struct {
 	*http.Server
 	ctx context.Context
 }
 
-// MListenAndServe returns an http.Server which will be initialized and have
+// WithListeningServer returns a *Server which will be initialized and have
 // ListenAndServe called on it (asynchronously) when the start event is
 // triggered on the returned Context (see mrun.Start). The Server will have
 // Shutdown called on it when the stop event is triggered on the returned
@@ -31,25 +31,22 @@ type MServer struct {
 //
 // This function automatically handles setting up configuration parameters via
 // mcfg. The default listen address is ":0".
-func MListenAndServe(ctx context.Context, h http.Handler) (context.Context, *MServer) {
+func WithListeningServer(ctx context.Context, h http.Handler) (context.Context, *Server) {
-	srv := &MServer{
+	srv := &Server{
 		Server: &http.Server{Handler: h},
 		ctx:    mctx.NewChild(ctx, "http"),
 	}
 
-	var listener *mnet.MListener
+	var listener *mnet.Listener
-	srv.ctx, listener = mnet.MListen(srv.ctx, "tcp", "")
+	srv.ctx, listener = mnet.WithListener(srv.ctx, "tcp", "")
 	listener.NoCloseOnStop = true // http.Server.Shutdown will do this
 
-	// TODO the equivalent functionality as here will be added with annotations
+	srv.ctx = mrun.WithStartHook(srv.ctx, func(context.Context) error {
-	//logger := mlog.From(ctx)
-	//logger.SetKV(listener)
-
-	srv.ctx = mrun.OnStart(srv.ctx, func(context.Context) error {
 		srv.Addr = listener.Addr().String()
-		srv.ctx = mrun.Thread(srv.ctx, func() error {
+		srv.ctx = mrun.WithThread(srv.ctx, func() error {
-			if err := srv.Serve(listener); err != http.ErrServerClosed {
+			mlog.Info("serving requests", srv.ctx)
-				mlog.Error(srv.ctx, "error serving listener", merr.KV(err))
+			if err := srv.Serve(listener); !merr.Equal(err, http.ErrServerClosed) {
+				mlog.Error("error serving listener", srv.ctx, merr.Context(err))
 				return err
 			}
 			return nil
@@ -57,8 +54,8 @@ func MListenAndServe(ctx context.Context, h http.Handler) (context.Context, *MSe
 		return nil
 	})
 
-	srv.ctx = mrun.OnStop(srv.ctx, func(innerCtx context.Context) error {
+	srv.ctx = mrun.WithStopHook(srv.ctx, func(innerCtx context.Context) error {
-		mlog.Info(srv.ctx, "shutting down server")
+		mlog.Info("shutting down server", srv.ctx)
 		if err := srv.Shutdown(innerCtx); err != nil {
 			return err
 		}

mhttp/mhttp_test.go

@@ -13,9 +13,9 @@ import (
 )
 
 func TestMListenAndServe(t *T) {
-	ctx := mtest.NewCtx()
+	ctx := mtest.Context()
 
-	ctx, srv := MListenAndServe(ctx, http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+	ctx, srv := WithListeningServer(ctx, http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
 		io.Copy(rw, r.Body)
 	}))
 

mlog/ctx.go

@@ -1,53 +1,58 @@
 package mlog
 
-import "context"
+import (
+	"context"
+)
 
 type ctxKey int
 
-// Set returns the Context with the Logger carried by it.
+// WithLogger returns the Context with the Logger carried by it.
-func Set(ctx context.Context, l *Logger) context.Context {
+func WithLogger(ctx context.Context, l *Logger) context.Context {
 	return context.WithValue(ctx, ctxKey(0), l)
 }
 
 // DefaultLogger is an instance of Logger which is returned by From when a
-// Logger hasn't been previously Set on the Context passed in.
+// Logger hasn't been previously WithLogger on the Contexts passed in.
 var DefaultLogger = NewLogger()
 
-// From returns the Logger carried by this Context, or DefaultLogger if none is
+// From looks at each context and returns the Logger from the first Context
-// being carried.
+// which carries one via a WithLogger call. If none carry a Logger than
-func From(ctx context.Context) *Logger {
+// DefaultLogger is returned.
+func From(ctxs ...context.Context) *Logger {
+	for _, ctx := range ctxs {
 		if l, _ := ctx.Value(ctxKey(0)).(*Logger); l != nil {
 			return l
 		}
+	}
 	return DefaultLogger
 }
 
 // Debug is a shortcut for
-//	mlog.From(ctx).Debug(ctx, descr, kvs...)
+//	mlog.From(ctxs...).Debug(desc, ctxs...)
-func Debug(ctx context.Context, descr string, kvs ...KVer) {
+func Debug(descr string, ctxs ...context.Context) {
-	From(ctx).Debug(ctx, descr, kvs...)
+	From(ctxs...).Debug(descr, ctxs...)
 }
 
 // Info is a shortcut for
-//	mlog.From(ctx).Info(ctx, descr, kvs...)
+//	mlog.From(ctxs...).Info(desc, ctxs...)
-func Info(ctx context.Context, descr string, kvs ...KVer) {
+func Info(descr string, ctxs ...context.Context) {
-	From(ctx).Info(ctx, descr, kvs...)
+	From(ctxs...).Info(descr, ctxs...)
 }
 
 // Warn is a shortcut for
-//	mlog.From(ctx).Warn(ctx, descr, kvs...)
+//	mlog.From(ctxs...).Warn(desc, ctxs...)
-func Warn(ctx context.Context, descr string, kvs ...KVer) {
+func Warn(descr string, ctxs ...context.Context) {
-	From(ctx).Warn(ctx, descr, kvs...)
+	From(ctxs...).Warn(descr, ctxs...)
 }
 
 // Error is a shortcut for
-//	mlog.From(ctx).Error(ctx, descr, kvs...)
+//	mlog.From(ctxs...).Error(desc, ctxs...)
-func Error(ctx context.Context, descr string, kvs ...KVer) {
+func Error(descr string, ctxs ...context.Context) {
-	From(ctx).Error(ctx, descr, kvs...)
+	From(ctxs...).Error(descr, ctxs...)
 }
 
 // Fatal is a shortcut for
-//	mlog.From(ctx).Fatal(ctx, descr, kvs...)
+//	mlog.From(ctxs...).Fatal(desc, ctxs...)
-func Fatal(ctx context.Context, descr string, kvs ...KVer) {
+func Fatal(descr string, ctxs ...context.Context) {
-	From(ctx).Fatal(ctx, descr, kvs...)
+	From(ctxs...).Fatal(descr, ctxs...)
 }

mlog/ctx_test.go

@@ -1,67 +0,0 @@
-package mlog
-
-import (
-	"bytes"
-	"context"
-	"strings"
-	. "testing"
-
-	"github.com/mediocregopher/mediocre-go-lib/mctx"
-	"github.com/mediocregopher/mediocre-go-lib/mtest/massert"
-)
-
-func TestContextLogging(t *T) {
-
-	var lines []string
-	l := NewLogger()
-	l.SetHandler(func(msg Message) error {
-		buf := new(bytes.Buffer)
-		if err := DefaultFormat(buf, msg); err != nil {
-			t.Fatal(err)
-		}
-		lines = append(lines, strings.TrimSuffix(buf.String(), "\n"))
-		return nil
-	})
-
-	ctx := Set(context.Background(), l)
-	ctx1 := mctx.NewChild(ctx, "1")
-	ctx1a := mctx.NewChild(ctx1, "a")
-	ctx1b := mctx.NewChild(ctx1, "b")
-	ctx1 = mctx.WithChild(ctx1, ctx1a)
-	ctx1 = mctx.WithChild(ctx1, ctx1b)
-	ctx = mctx.WithChild(ctx, ctx1)
-
-	From(ctx).Info(ctx1a, "ctx1a")
-	From(ctx).Info(ctx1, "ctx1")
-	From(ctx).Info(ctx, "ctx")
-	From(ctx).Debug(ctx1b, "ctx1b (shouldn't show up)")
-	From(ctx).Info(ctx1b, "ctx1b")
-
-	ctx2 := mctx.NewChild(ctx, "2")
-	ctx = mctx.WithChild(ctx, ctx2)
-	From(ctx2).Info(ctx2, "ctx2")
-
-	massert.Fatal(t, massert.All(
-		massert.Len(lines, 5),
-		massert.Equal(lines[0], "~ INFO -- (/1/a) ctx1a"),
-		massert.Equal(lines[1], "~ INFO -- (/1) ctx1"),
-		massert.Equal(lines[2], "~ INFO -- ctx"),
-		massert.Equal(lines[3], "~ INFO -- (/1/b) ctx1b"),
-		massert.Equal(lines[4], "~ INFO -- (/2) ctx2"),
-	))
-
-	// changing MaxLevel on ctx's Logger should change it for all
-	From(ctx).SetMaxLevel(DebugLevel)
-
-	lines = lines[:0]
-	From(ctx).Info(ctx, "ctx")
-	From(ctx).Debug(ctx, "ctx debug")
-	From(ctx2).Debug(ctx2, "ctx2 debug")
-
-	massert.Fatal(t, massert.All(
-		massert.Len(lines, 3),
-		massert.Equal(lines[0], "~ INFO -- ctx"),
-		massert.Equal(lines[1], "~ DEBUG -- ctx debug"),
-		massert.Equal(lines[2], "~ DEBUG -- (/2) ctx2 debug"),
-	))
-}

mlog/errctx.go

@@ -1,30 +0,0 @@
-package mlog
-
-import (
-	"context"
-)
-
-type kvKey int
-
-// CtxWithKV embeds a KV into a Context, returning a new Context instance. If
-// the Context already has a KV embedded in it then the returned error will have
-// the merging of the two, with the given KVs taking precedence.
-func CtxWithKV(ctx context.Context, kvs ...KVer) context.Context {
-	existingKV := ctx.Value(kvKey(0))
-	var kv KV
-	if existingKV != nil {
-		kv = mergeInto(existingKV.(KV), kvs...)
-	} else {
-		kv = Merge(kvs...).KV()
-	}
-	return context.WithValue(ctx, kvKey(0), kv)
-}
-
-// CtxKV returns a copy of the KV embedded in the Context by CtxWithKV
-func CtxKV(ctx context.Context) KVer {
-	kv := ctx.Value(kvKey(0))
-	if kv == nil {
-		return KV{}
-	}
-	return kv.(KV)
-}

mlog/errctx_test.go

@@ -1,44 +0,0 @@
-package mlog
-
-import (
-	"context"
-	. "testing"
-
-	"github.com/mediocregopher/mediocre-go-lib/mtest/massert"
-)
-
-func TestCtxKV(t *T) {
-	ctx := context.Background()
-	massert.Fatal(t, massert.Equal(KV{}, CtxKV(ctx)))
-
-	kv := KV{"a": "a"}
-	ctx2 := CtxWithKV(ctx, kv)
-	massert.Fatal(t, massert.All(
-		massert.Equal(KV{}, CtxKV(ctx)),
-		massert.Equal(KV{"a": "a"}, CtxKV(ctx2)),
-	))
-
-	// changing the kv now shouldn't do anything
-	kv["a"] = "b"
-	massert.Fatal(t, massert.All(
-		massert.Equal(KV{}, CtxKV(ctx)),
-		massert.Equal(KV{"a": "a"}, CtxKV(ctx2)),
-	))
-
-	// a new CtxWithKV shouldn't affect the previous one
-	ctx3 := CtxWithKV(ctx2, KV{"b": "b"})
-	massert.Fatal(t, massert.All(
-		massert.Equal(KV{}, CtxKV(ctx)),
-		massert.Equal(KV{"a": "a"}, CtxKV(ctx2)),
-		massert.Equal(KV{"a": "a", "b": "b"}, CtxKV(ctx3)),
-	))
-
-	// make sure precedence works
-	ctx4 := CtxWithKV(ctx3, KV{"b": "bb"})
-	massert.Fatal(t, massert.All(
-		massert.Equal(KV{}, CtxKV(ctx)),
-		massert.Equal(KV{"a": "a"}, CtxKV(ctx2)),
-		massert.Equal(KV{"a": "a", "b": "b"}, CtxKV(ctx3)),
-		massert.Equal(KV{"a": "a", "b": "bb"}, CtxKV(ctx4)),
-	))
-}

mlog/mlog.go

@@ -1,28 +1,17 @@
 // Package mlog is a generic logging library. The log methods come in different
 // severities: Debug, Info, Warn, Error, and Fatal.
 //
-// The log methods take in a string describing the error, and a set of key/value
+// The log methods take in a message string and a Context. The Context can be
-// pairs giving the specific context around the error. The string is intended to
+// loaded with additional annotations which will be included in the log entry as
-// always be the same no matter what, while the key/value pairs give information
+// well (see mctx package).
-// like which userID the error happened to, or any other relevant contextual
-// information.
-//
-// Examples:
-//
-//	log := mlog.NewLogger()
-//	log.Info("Something important has occurred")
-//	log.Error("Could not open file", mlog.KV{"filename": filename}, merr.KV(err))
 //
 package mlog
 
 import (
-	"bufio"
 	"context"
-	"fmt"
+	"encoding/json"
 	"io"
 	"os"
-	"sort"
-	"strconv"
 	"strings"
 	"sync"
 
@@ -99,134 +88,12 @@ func LevelFromString(s string) Level {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-// KVer is used to provide context to a log entry in the form of a dynamic set
-// of key/value pairs which can be different for every entry.
-//
-// The returned map is read-only, and may be nil.
-type KVer interface {
-	KV() map[string]interface{}
-}
-
-// KVerFunc is a function which implements the KVer interface by calling itself.
-type KVerFunc func() map[string]interface{}
-
-// KV implements the KVer interface by calling the KVerFunc itself.
-func (kvf KVerFunc) KV() map[string]interface{} {
-	return kvf()
-}
-
-// KV is a KVer which returns a copy of itself when KV is called.
-type KV map[string]interface{}
-
-// KV implements the KVer method by returning a copy of itself.
-func (kv KV) KV() map[string]interface{} {
-	return map[string]interface{}(kv)
-}
-
-// Set returns a copy of the KV being called on with the given key/val set on
-// it. The original KV is unaffected
-func (kv KV) Set(k string, v interface{}) KV {
-	kvm := make(map[string]interface{}, len(kv)+1)
-	copyM(kvm, kv.KV())
-	kvm[k] = v
-	return KV(kvm)
-}
-
-// returns a key/value map which should not be written to. saves a map-cloning
-// if KVer is a KV
-func readOnlyKVM(kver KVer) map[string]interface{} {
-	if kver == nil {
-		return map[string]interface{}(nil)
-	} else if kv, ok := kver.(KV); ok {
-		return map[string]interface{}(kv)
-	}
-	return kver.KV()
-}
-
-func copyM(dst, src map[string]interface{}) {
-	for k, v := range src {
-		dst[k] = v
-	}
-}
-
-// this may take in any amount of nil values, but should never return nil
-func mergeInto(kv KVer, kvs ...KVer) map[string]interface{} {
-	kvm := map[string]interface{}{}
-	if kv != nil {
-		copyM(kvm, kv.KV())
-	}
-	for _, innerKV := range kvs {
-		if innerKV == nil {
-			continue
-		}
-		copyM(kvm, innerKV.KV())
-	}
-	return kvm
-}
-
-type merger struct {
-	base KVer
-	rest []KVer
-}
-
-// Merge takes in multiple KVers and returns a single KVer which is the union of
-// all the passed in ones. Key/Vals on the rightmost of the set take precedence
-// over conflicting ones to the left.
-//
-// The KVer returned will call KV() on each of the passed in KVers every time
-// its KV method is called.
-func Merge(kvs ...KVer) KVer {
-	if len(kvs) == 0 {
-		return merger{}
-	}
-	return merger{base: kvs[0], rest: kvs[1:]}
-}
-
-// MergeInto is a convenience function which acts similarly to Merge.
-func MergeInto(kv KVer, kvs ...KVer) KVer {
-	return merger{base: kv, rest: kvs}
-}
-
-func (m merger) KV() map[string]interface{} {
-	return mergeInto(m.base, m.rest...)
-}
-
-// Prefix prefixes all keys returned from the given KVer with the given prefix
-// string.
-func Prefix(kv KVer, prefix string) KVer {
-	return KVerFunc(func() map[string]interface{} {
-		kvm := readOnlyKVM(kv)
-		newKVM := make(map[string]interface{}, len(kvm))
-		for k, v := range kvm {
-			newKVM[prefix+k] = v
-		}
-		return newKVM
-	})
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
 // Message describes a message to be logged, after having already resolved the
 // KVer
 type Message struct {
-	context.Context
 	Level
 	Description string
-	KVer
+	Contexts    []context.Context
-}
-
-func stringSlice(kv KV) [][2]string {
-	slice := make([][2]string, 0, len(kv))
-	for k, v := range kv {
-		slice = append(slice, [2]string{
-			k,
-			strconv.QuoteToGraphic(fmt.Sprint(v)),
-		})
-	}
-	sort.Slice(slice, func(i, j int) bool {
-		return slice[i][0] < slice[j][0]
-	})
-	return slice
 }
 
 // Handler is a function which can process Messages in some way.
@@ -235,47 +102,39 @@ func stringSlice(kv KV) [][2]string {
 // Handler if necessary.
 type Handler func(msg Message) error
 
-// DefaultFormat formats and writes the Message to the given Writer using mlog's
+// MessageJSON is the type used to encode Messages to JSON in DefaultHandler
-// default format.
+type MessageJSON struct {
-func DefaultFormat(w io.Writer, msg Message) error {
+	Level       string `json:"level"`
-	var err error
+	Description string `json:"descr"`
-	write := func(s string, args ...interface{}) {
+
-		if err == nil {
+	// path -> key -> value
-			_, err = fmt.Fprintf(w, s, args...)
+	Annotations map[string]map[string]string `json:"annotations,omitempty"`
-		}
-	}
-	write("~ %s -- ", msg.Level.String())
-	if path := mctx.Path(msg.Context); len(path) > 0 {
-		write("(%s) ", "/"+strings.Join(path, "/"))
-	}
-	write("%s", msg.Description)
-	if msg.KVer != nil {
-		if kv := msg.KV(); len(kv) > 0 {
-			write(" --")
-			for _, kve := range stringSlice(kv) {
-				write(" %s=%s", kve[0], kve[1])
-			}
-		}
-	}
-	write("\n")
-	return err
 }
 
 // DefaultHandler initializes and returns a Handler which will write all
 // messages to os.Stderr in a thread-safe way. This is the Handler which
 // NewLogger will use automatically.
 func DefaultHandler() Handler {
+	return defaultHandler(os.Stderr)
+}
+
+func defaultHandler(out io.Writer) Handler {
 	l := new(sync.Mutex)
-	bw := bufio.NewWriter(os.Stderr)
+	enc := json.NewEncoder(out)
 	return func(msg Message) error {
 		l.Lock()
 		defer l.Unlock()
 
-		err := DefaultFormat(bw, msg)
+		msgJSON := MessageJSON{
-		if err == nil {
+			Level:       msg.Level.String(),
-			err = bw.Flush()
+			Description: msg.Description,
 		}
-		return err
+		if len(msg.Contexts) > 0 {
+			ctx := mctx.MergeAnnotations(msg.Contexts...)
+			msgJSON.Annotations = mctx.Annotations(ctx).StringMapByPath()
+		}
+
+		return enc.Encode(msgJSON)
 	}
 }
 
@@ -286,7 +145,6 @@ type Logger struct {
 	l        *sync.RWMutex
 	h        Handler
 	maxLevel uint
-	kv       KVer
 
 	testMsgWrittenCh chan struct{} // only initialized/used in tests
 }
@@ -332,15 +190,6 @@ func (l *Logger) Handler() Handler {
 	return l.h
 }
 
-// SetKV sets the Logger to use the merging of the given KVers as a base KVer
-// for all Messages. If the Logger already had a base KVer (via a previous SetKV
-// call) then this set will be merged onto that one.
-func (l *Logger) SetKV(kvs ...KVer) {
-	l.l.Lock()
-	defer l.l.Unlock()
-	l.kv = MergeInto(l.kv, kvs...)
-}
-
 // Log can be used to manually log a message of some custom defined Level.
 //
 // If the Level is a fatal (Uint() == 0) then calling this will never return,
@@ -353,12 +202,8 @@ func (l *Logger) Log(msg Message) {
 		return
 	}
 
-	if l.kv != nil {
-		msg.KVer = MergeInto(l.kv, msg.KVer)
-	}
-
 	if err := l.h(msg); err != nil {
-		go l.Error(context.Background(), "Logger.Handler returned error", merr.KV(err))
+		go l.Error("Logger.Handler returned error", merr.Context(err))
 		return
 	}
 
@@ -371,37 +216,36 @@ func (l *Logger) Log(msg Message) {
 	}
 }
 
-func mkMsg(ctx context.Context, lvl Level, descr string, kvs ...KVer) Message {
+func mkMsg(lvl Level, descr string, ctxs ...context.Context) Message {
 	return Message{
-		Context:     ctx,
 		Level:       lvl,
 		Description: descr,
-		KVer:        Merge(kvs...),
+		Contexts:    ctxs,
 	}
 }
 
-// Debug logs a DebugLevel message, merging the KVers together first
+// Debug logs a DebugLevel message.
-func (l *Logger) Debug(ctx context.Context, descr string, kvs ...KVer) {
+func (l *Logger) Debug(descr string, ctxs ...context.Context) {
-	l.Log(mkMsg(ctx, DebugLevel, descr, kvs...))
+	l.Log(mkMsg(DebugLevel, descr, ctxs...))
 }
 
-// Info logs a InfoLevel message, merging the KVers together first
+// Info logs a InfoLevel message.
-func (l *Logger) Info(ctx context.Context, descr string, kvs ...KVer) {
+func (l *Logger) Info(descr string, ctxs ...context.Context) {
-	l.Log(mkMsg(ctx, InfoLevel, descr, kvs...))
+	l.Log(mkMsg(InfoLevel, descr, ctxs...))
 }
 
-// Warn logs a WarnLevel message, merging the KVers together first
+// Warn logs a WarnLevel message.
-func (l *Logger) Warn(ctx context.Context, descr string, kvs ...KVer) {
+func (l *Logger) Warn(descr string, ctxs ...context.Context) {
-	l.Log(mkMsg(ctx, WarnLevel, descr, kvs...))
+	l.Log(mkMsg(WarnLevel, descr, ctxs...))
 }
 
-// Error logs a ErrorLevel message, merging the KVers together first
+// Error logs a ErrorLevel message.
-func (l *Logger) Error(ctx context.Context, descr string, kvs ...KVer) {
+func (l *Logger) Error(descr string, ctxs ...context.Context) {
-	l.Log(mkMsg(ctx, ErrorLevel, descr, kvs...))
+	l.Log(mkMsg(ErrorLevel, descr, ctxs...))
 }
 
-// Fatal logs a FatalLevel message, merging the KVers together first. A Fatal
+// Fatal logs a FatalLevel message. A Fatal message automatically stops the
-// message automatically stops the process with an os.Exit(1)
+// process with an os.Exit(1)
-func (l *Logger) Fatal(ctx context.Context, descr string, kvs ...KVer) {
+func (l *Logger) Fatal(descr string, ctxs ...context.Context) {
-	l.Log(mkMsg(ctx, FatalLevel, descr, kvs...))
+	l.Log(mkMsg(FatalLevel, descr, ctxs...))
 }

mlog/mlog_test.go

@@ -3,11 +3,11 @@ package mlog
 import (
 	"bytes"
 	"context"
-	"regexp"
 	"strings"
 	. "testing"
 	"time"
 
+	"github.com/mediocregopher/mediocre-go-lib/mctx"
 	"github.com/mediocregopher/mediocre-go-lib/mtest/massert"
 )
 
@@ -19,29 +19,9 @@ func TestTruncate(t *T) {
 	))
 }
 
-func TestKV(t *T) {
-	var kv KV
-	massert.Fatal(t, massert.All(
-		massert.Nil(kv.KV()),
-		massert.Len(kv.KV(), 0),
-	))
-
-	// test that the Set method returns a copy
-	kv = KV{"foo": "a"}
-	kv2 := kv.Set("bar", "wat")
-	kv["bur"] = "ok"
-	massert.Fatal(t, massert.All(
-		massert.Equal(KV{"foo": "a", "bur": "ok"}, kv),
-		massert.Equal(KV{"foo": "a", "bar": "wat"}, kv2),
-	))
-}
-
 func TestLogger(t *T) {
-	ctx := context.Background()
 	buf := new(bytes.Buffer)
-	h := func(msg Message) error {
+	h := defaultHandler(buf)
-		return DefaultFormat(buf, msg)
-	}
 
 	l := NewLogger()
 	l.SetHandler(h)
@@ -56,29 +36,31 @@ func TestLogger(t *T) {
 		out, err := buf.ReadString('\n')
 		return massert.All(
 			massert.Nil(err),
-			massert.Equal(expected, out),
+			massert.Equal(expected, strings.TrimSpace(out)),
 		)
 	}
 
 	// Default max level should be INFO
-	l.Debug(ctx, "foo")
+	l.Debug("foo")
-	l.Info(ctx, "bar")
+	l.Info("bar")
-	l.Warn(ctx, "baz")
+	l.Warn("baz")
-	l.Error(ctx, "buz")
+	l.Error("buz")
 	massert.Fatal(t, massert.All(
-		assertOut("~ INFO -- bar\n"),
+		assertOut(`{"level":"INFO","descr":"bar"}`),
-		assertOut("~ WARN -- baz\n"),
+		assertOut(`{"level":"WARN","descr":"baz"}`),
-		assertOut("~ ERROR -- buz\n"),
+		assertOut(`{"level":"ERROR","descr":"buz"}`),
 	))
 
+	ctx := context.Background()
+
 	l.SetMaxLevel(WarnLevel)
-	l.Debug(ctx, "foo")
+	l.Debug("foo")
-	l.Info(ctx, "bar")
+	l.Info("bar")
-	l.Warn(ctx, "baz")
+	l.Warn("baz")
-	l.Error(ctx, "buz", KV{"a": "b"})
+	l.Error("buz", mctx.Annotate(ctx, "a", "b", "c", "d"))
 	massert.Fatal(t, massert.All(
-		assertOut("~ WARN -- baz\n"),
+		assertOut(`{"level":"WARN","descr":"baz"}`),
-		assertOut("~ ERROR -- buz -- a=\"b\"\n"),
+		assertOut(`{"level":"ERROR","descr":"buz","annotations":{"/":{"a":"b","c":"d"}}}`),
 	))
 
 	l2 := l.Clone()
@@ -87,109 +69,12 @@ func TestLogger(t *T) {
 		msg.Description = strings.ToUpper(msg.Description)
 		return h(msg)
 	})
-	l2.Info(ctx, "bar")
+	l2.Info("bar")
-	l2.Warn(ctx, "baz")
+	l2.Warn("baz")
-	l.Error(ctx, "buz")
+	l.Error("buz")
 	massert.Fatal(t, massert.All(
-		assertOut("~ INFO -- BAR\n"),
+		assertOut(`{"level":"INFO","descr":"BAR"}`),
-		assertOut("~ WARN -- BAZ\n"),
+		assertOut(`{"level":"WARN","descr":"BAZ"}`),
-		assertOut("~ ERROR -- buz\n"),
+		assertOut(`{"level":"ERROR","descr":"buz"}`),
-	))
-
-	l3 := l2.Clone()
-	l3.SetKV(KV{"a": 1})
-	l3.Info(ctx, "foo", KV{"b": 2})
-	l3.Info(ctx, "bar", KV{"a": 2, "b": 3})
-	massert.Fatal(t, massert.All(
-		assertOut("~ INFO -- FOO -- a=\"1\" b=\"2\"\n"),
-		assertOut("~ INFO -- BAR -- a=\"2\" b=\"3\"\n"),
-	))
-
-}
-
-func TestDefaultFormat(t *T) {
-	assertFormat := func(postfix string, msg Message) massert.Assertion {
-		expectedRegex := regexp.MustCompile(`^~ ` + postfix + `\n$`)
-		buf := bytes.NewBuffer(make([]byte, 0, 128))
-		writeErr := DefaultFormat(buf, msg)
-		line, err := buf.ReadString('\n')
-		return massert.Comment(
-			massert.All(
-				massert.Nil(writeErr),
-				massert.Nil(err),
-				massert.Equal(true, expectedRegex.MatchString(line)),
-			),
-			"line:%q", line,
-		)
-	}
-
-	msg := Message{
-		Context:     context.Background(),
-		Level:       InfoLevel,
-		Description: "this is a test",
-	}
-	massert.Fatal(t, assertFormat("INFO -- this is a test", msg))
-
-	msg.KVer = KV{}
-	massert.Fatal(t, assertFormat("INFO -- this is a test", msg))
-
-	msg.KVer = KV{"foo": "a"}
-	massert.Fatal(t, assertFormat("INFO -- this is a test -- foo=\"a\"", msg))
-
-	msg.KVer = KV{"foo": "a", "bar": "b"}
-	massert.Fatal(t,
-		assertFormat("INFO -- this is a test -- bar=\"b\" foo=\"a\"", msg))
-}
-
-func TestMerge(t *T) {
-	assertMerge := func(exp KV, kvs ...KVer) massert.Assertion {
-		return massert.Equal(exp.KV(), Merge(kvs...).KV())
-	}
-
-	massert.Fatal(t, massert.All(
-		assertMerge(KV{}),
-		assertMerge(KV{}, nil),
-		assertMerge(KV{}, nil, nil),
-
-		assertMerge(KV{"a": "a"}, KV{"a": "a"}),
-		assertMerge(KV{"a": "a"}, nil, KV{"a": "a"}),
-		assertMerge(KV{"a": "a"}, KV{"a": "a"}, nil),
-
-		assertMerge(
-			KV{"a": "a", "b": "b"},
-			KV{"a": "a"}, KV{"b": "b"},
-		),
-		assertMerge(
-			KV{"a": "a", "b": "b"},
-			KV{"a": "a"}, KV{"b": "b"},
-		),
-		assertMerge(
-			KV{"a": "b"},
-			KV{"a": "a"}, KV{"a": "b"},
-		),
-	))
-
-	// Merge should _not_ call KV() on the inner KVers until the outer one is
-	// called.
-	{
-		kv := KV{"a": "a"}
-		mergedKV := Merge(kv)
-		kv["a"] = "b"
-		massert.Fatal(t, massert.All(
-			massert.Equal(KV{"a": "b"}, kv),
-			massert.Equal(map[string]interface{}{"a": "b"}, kv.KV()),
-			massert.Equal(map[string]interface{}{"a": "b"}, mergedKV.KV()),
-		))
-	}
-}
-
-func TestPrefix(t *T) {
-	kv := KV{"foo": "bar"}
-	prefixKV := Prefix(kv, "aa")
-
-	massert.Fatal(t, massert.All(
-		massert.Equal(map[string]interface{}{"foo": "bar"}, kv.KV()),
-		massert.Equal(map[string]interface{}{"aafoo": "bar"}, prefixKV.KV()),
-		massert.Equal(map[string]interface{}{"foo": "bar"}, kv.KV()),
 	))
 }

mnet/mnet.go

@@ -8,13 +8,13 @@ import (
 	"strings"
 
 	"github.com/mediocregopher/mediocre-go-lib/mcfg"
-	"github.com/mediocregopher/mediocre-go-lib/merr"
+	"github.com/mediocregopher/mediocre-go-lib/mctx"
 	"github.com/mediocregopher/mediocre-go-lib/mlog"
 	"github.com/mediocregopher/mediocre-go-lib/mrun"
 )
 
-// MListener is returned by MListen and simply wraps a net.Listener.
+// Listener is returned by WithListen and simply wraps a net.Listener.
-type MListener struct {
+type Listener struct {
 	net.Listener
 	ctx context.Context
 
@@ -23,13 +23,13 @@ type MListener struct {
 	NoCloseOnStop bool
 }
 
-// MListen returns an MListener which will be initialized when the start event
+// WithListener returns a Listener which will be initialized when the start
-// is triggered on the returned Context (see mrun.Start), and closed when the
+// event is triggered on the returned Context (see mrun.Start), and closed when
-// stop event is triggered on the returned Context (see mrun.Stop).
+// the stop event is triggered on the returned Context (see mrun.Stop).
 //
 // network defaults to "tcp" if empty. defaultAddr defaults to ":0" if empty,
 // and will be configurable via mcfg.
-func MListen(ctx context.Context, network, defaultAddr string) (context.Context, *MListener) {
+func WithListener(ctx context.Context, network, defaultAddr string) (context.Context, *Listener) {
 	if network == "" {
 		network = "tcp"
 	}
@@ -37,59 +37,52 @@ func MListen(ctx context.Context, network, defaultAddr string) (context.Context,
 		defaultAddr = ":0"
 	}
 
-	l := new(MListener)
+	l := &Listener{
+		ctx: mctx.NewChild(ctx, "net"),
+	}
 
-	// TODO the equivalent functionality as here will be added with annotations
+	var addr *string
-	//l.log = mlog.From(ctx)
+	l.ctx, addr = mcfg.WithString(l.ctx, "listen-addr", defaultAddr, strings.ToUpper(network)+" address to listen on in format [host]:port. If port is 0 then a random one will be chosen")
-	//l.log.SetKV(l)
+	l.ctx = mrun.WithStartHook(l.ctx, func(context.Context) error {
-
-	ctx, addr := mcfg.String(ctx, "listen-addr", defaultAddr, strings.ToUpper(network)+" address to listen on in format [host]:port. If port is 0 then a random one will be chosen")
-	ctx = mrun.OnStart(ctx, func(context.Context) error {
 		var err error
 		if l.Listener, err = net.Listen(network, *addr); err != nil {
 			return err
 		}
-		mlog.Info(l.ctx, "listening")
+		l.ctx = mctx.Annotate(l.ctx, "addr", l.Addr().String())
+		mlog.Info("listening", l.ctx)
 		return nil
 	})
 
 	// TODO track connections and wait for them to complete before shutting
 	// down?
-	ctx = mrun.OnStop(ctx, func(context.Context) error {
+	l.ctx = mrun.WithStopHook(l.ctx, func(context.Context) error {
 		if l.NoCloseOnStop {
 			return nil
 		}
-		mlog.Info(l.ctx, "stopping listener")
+		mlog.Info("stopping listener", l.ctx)
 		return l.Close()
 	})
 
-	l.ctx = ctx
+	return mctx.WithChild(ctx, l.ctx), l
-	return ctx, l
 }
 
 // Accept wraps a call to Accept on the underlying net.Listener, providing debug
 // logging.
-func (l *MListener) Accept() (net.Conn, error) {
+func (l *Listener) Accept() (net.Conn, error) {
 	conn, err := l.Listener.Accept()
 	if err != nil {
 		return conn, err
 	}
-	mlog.Debug(l.ctx, "connection accepted", mlog.KV{"remoteAddr": conn.RemoteAddr()})
+	mlog.Debug("connection accepted",
+		mctx.Annotate(l.ctx, "remoteAddr", conn.RemoteAddr().String()))
 	return conn, nil
 }
 
 // Close wraps a call to Close on the underlying net.Listener, providing debug
 // logging.
-func (l *MListener) Close() error {
+func (l *Listener) Close() error {
-	mlog.Debug(l.ctx, "listener closing")
+	mlog.Info("listener closing", l.ctx)
-	err := l.Listener.Close()
+	return l.Listener.Close()
-	mlog.Debug(l.ctx, "listener closed", merr.KV(err))
-	return err
-}
-
-// KV implements the mlog.KVer interface.
-func (l *MListener) KV() map[string]interface{} {
-	return map[string]interface{}{"addr": l.Addr().String()}
 }
 
 ////////////////////////////////////////////////////////////////////////////////

mnet/mnet_test.go

@@ -35,9 +35,9 @@ func TestIsReservedIP(t *T) {
 	))
 }
 
-func TestMListen(t *T) {
+func TestWithListener(t *T) {
-	ctx := mtest.NewCtx()
+	ctx := mtest.Context()
-	ctx, l := MListen(ctx, "", "")
+	ctx, l := WithListener(ctx, "", "")
 	mtest.Run(ctx, t, func() {
 		go func() {
 			conn, err := net.Dial("tcp", l.Addr().String())

mrun/hook.go

@@ -7,7 +7,7 @@ import (
 )
 
 // Hook describes a function which can be registered to trigger on an event via
-// the RegisterHook function.
+// the WithHook function.
 type Hook func(context.Context) error
 
 type ctxKey int
@@ -65,12 +65,12 @@ func getHookEls(ctx context.Context, userKey interface{}) ([]hookEl, int, int) {
 	return hookEls, len(children), lastNumHooks
 }
 
-// RegisterHook registers a Hook under a typed key. The Hook will be called when
+// WithHook registers a Hook under a typed key. The Hook will be called when
 // TriggerHooks is called with that same key. Multiple Hooks can be registered
 // for the same key, and will be called sequentially when triggered.
 //
 // Hooks will be called with whatever Context is passed into TriggerHooks.
-func RegisterHook(ctx context.Context, key interface{}, hook Hook) context.Context {
+func WithHook(ctx context.Context, key interface{}, hook Hook) context.Context {
 	hookEls, numChildren, numHooks := getHookEls(ctx, key)
 	hookEls = append(hookEls, hookEl{hook: hook})
 
@@ -100,9 +100,9 @@ func triggerHooks(ctx context.Context, userKey interface{}, next func([]hookEl)
 	return nil
 }
 
-// TriggerHooks causes all Hooks registered with RegisterHook on the Context
+// TriggerHooks causes all Hooks registered with WithHook on the Context (and
-// (and its predecessors) under the given key to be called in the order they
+// its predecessors) under the given key to be called in the order they were
-// were registered.
+// registered.
 //
 // If any Hook returns an error no further Hooks will be called and that error
 // will be returned.
@@ -113,15 +113,15 @@ func triggerHooks(ctx context.Context, userKey interface{}, next func([]hookEl)
 //
 //	// parent context has hookA registered
 //	ctx := context.Background()
-//	ctx = RegisterHook(ctx, 0, hookA)
+//	ctx = WithHook(ctx, 0, hookA)
 //
 //	// child context has hookB registered
 //	childCtx := mctx.NewChild(ctx, "child")
-//	childCtx = RegisterHook(childCtx, 0, hookB)
+//	childCtx = WithHook(childCtx, 0, hookB)
 //	ctx = mctx.WithChild(ctx, childCtx) // needed to link childCtx to ctx
 //
 //	// parent context has another Hook, hookC, registered
-//	ctx = RegisterHook(ctx, 0, hookC)
+//	ctx = WithHook(ctx, 0, hookC)
 //
 //	// The Hooks will be triggered in the order: hookA, hookB, then hookC
 //	err := TriggerHooks(ctx, 0)
@@ -148,33 +148,33 @@ const (
 	stop
 )
 
-// OnStart registers the given Hook to run when Start is called. This is a
+// WithStartHook registers the given Hook to run when Start is called. This is a
-// special case of RegisterHook.
+// special case of WithHook.
 //
 // As a convention Hooks running on the start event should block only as long as
 // it takes to ensure that whatever is running can do so successfully. For
 // short-lived tasks this isn't a problem, but long-lived tasks (e.g. a web
 // server) will want to use the Hook only to initialize, and spawn off a
 // go-routine to do their actual work. Long-lived tasks should set themselves up
-// to stop on the stop event (see OnStop).
+// to stop on the stop event (see WithStopHook).
-func OnStart(ctx context.Context, hook Hook) context.Context {
+func WithStartHook(ctx context.Context, hook Hook) context.Context {
-	return RegisterHook(ctx, start, hook)
+	return WithHook(ctx, start, hook)
 }
 
-// Start runs all Hooks registered using OnStart. This is a special case of
+// Start runs all Hooks registered using WithStartHook. This is a special case
-// TriggerHooks.
+// of TriggerHooks.
 func Start(ctx context.Context) error {
 	return TriggerHooks(ctx, start)
 }
 
-// OnStop registers the given Hook to run when Stop is called. This is a special
+// WithStopHook registers the given Hook to run when Stop is called. This is a
-// case of RegisterHook.
+// special case of WithHook.
-func OnStop(ctx context.Context, hook Hook) context.Context {
+func WithStopHook(ctx context.Context, hook Hook) context.Context {
-	return RegisterHook(ctx, stop, hook)
+	return WithHook(ctx, stop, hook)
 }
 
-// Stop runs all Hooks registered using OnStop in the reverse order in which
+// Stop runs all Hooks registered using WithStopHook in the reverse order in
-// they were registered. This is a special case of TriggerHooks.
+// which they were registered. This is a special case of TriggerHooks.
 func Stop(ctx context.Context) error {
 	return TriggerHooksReverse(ctx, stop)
 }

mrun/hook_test.go

@@ -18,20 +18,20 @@ func TestHooks(t *T) {
 	}
 
 	ctx := context.Background()
-	ctx = RegisterHook(ctx, 0, mkHook(1))
+	ctx = WithHook(ctx, 0, mkHook(1))
-	ctx = RegisterHook(ctx, 0, mkHook(2))
+	ctx = WithHook(ctx, 0, mkHook(2))
 
 	ctxA := mctx.NewChild(ctx, "a")
-	ctxA = RegisterHook(ctxA, 0, mkHook(3))
+	ctxA = WithHook(ctxA, 0, mkHook(3))
-	ctxA = RegisterHook(ctxA, 999, mkHook(999)) // different key
+	ctxA = WithHook(ctxA, 999, mkHook(999)) // different key
 	ctx = mctx.WithChild(ctx, ctxA)
 
-	ctx = RegisterHook(ctx, 0, mkHook(4))
+	ctx = WithHook(ctx, 0, mkHook(4))
 
 	ctxB := mctx.NewChild(ctx, "b")
-	ctxB = RegisterHook(ctxB, 0, mkHook(5))
+	ctxB = WithHook(ctxB, 0, mkHook(5))
 	ctxB1 := mctx.NewChild(ctxB, "1")
-	ctxB1 = RegisterHook(ctxB1, 0, mkHook(6))
+	ctxB1 = WithHook(ctxB1, 0, mkHook(6))
 	ctxB = mctx.WithChild(ctxB, ctxB1)
 	ctx = mctx.WithChild(ctx, ctxB)
 

mrun/mrun.go

@@ -36,10 +36,10 @@ func (fe *futureErr) set(err error) {
 
 type threadCtxKey int
 
-// Thread spawns a go-routine which executes the given function. The returned
+// WithThread spawns a go-routine which executes the given function. The
-// Context tracks this go-routine, which can then be passed into the Wait
+// returned Context tracks this go-routine, which can then be passed into the
-// function to block until the spawned go-routine returns.
+// Wait function to block until the spawned go-routine returns.
-func Thread(ctx context.Context, fn func() error) context.Context {
+func WithThread(ctx context.Context, fn func() error) context.Context {
 	futErr := newFutureErr()
 	oldFutErrs, _ := ctx.Value(threadCtxKey(0)).([]*futureErr)
 	futErrs := make([]*futureErr, len(oldFutErrs), len(oldFutErrs)+1)

mrun/mrun_test.go

@@ -30,7 +30,7 @@ func TestThreadWait(t *T) {
 		t.Run("noBlock", func(t *T) {
 			t.Run("noErr", func(t *T) {
 				ctx := context.Background()
-				ctx = Thread(ctx, func() error { return nil })
+				ctx = WithThread(ctx, func() error { return nil })
 				if err := Wait(ctx, nil); err != nil {
 					t.Fatal(err)
 				}
@@ -38,7 +38,7 @@ func TestThreadWait(t *T) {
 
 			t.Run("err", func(t *T) {
 				ctx := context.Background()
-				ctx = Thread(ctx, func() error { return testErr })
+				ctx = WithThread(ctx, func() error { return testErr })
 				if err := Wait(ctx, nil); err != testErr {
 					t.Fatalf("should have got test error, got: %v", err)
 				}
@@ -48,7 +48,7 @@ func TestThreadWait(t *T) {
 		t.Run("block", func(t *T) {
 			t.Run("noErr", func(t *T) {
 				ctx := context.Background()
-				ctx = Thread(ctx, func() error {
+				ctx = WithThread(ctx, func() error {
 					time.Sleep(1 * time.Second)
 					return nil
 				})
@@ -59,7 +59,7 @@ func TestThreadWait(t *T) {
 
 			t.Run("err", func(t *T) {
 				ctx := context.Background()
-				ctx = Thread(ctx, func() error {
+				ctx = WithThread(ctx, func() error {
 					time.Sleep(1 * time.Second)
 					return testErr
 				})
@@ -70,7 +70,7 @@ func TestThreadWait(t *T) {
 
 			t.Run("canceled", func(t *T) {
 				ctx := context.Background()
-				ctx = Thread(ctx, func() error {
+				ctx = WithThread(ctx, func() error {
 					time.Sleep(5 * time.Second)
 					return testErr
 				})
@@ -90,7 +90,7 @@ func TestThreadWait(t *T) {
 		t.Run("noBlock", func(t *T) {
 			t.Run("noErr", func(t *T) {
 				ctx, childCtx := ctxWithChild()
-				childCtx = Thread(childCtx, func() error { return nil })
+				childCtx = WithThread(childCtx, func() error { return nil })
 				ctx = mctx.WithChild(ctx, childCtx)
 				if err := Wait(ctx, nil); err != nil {
 					t.Fatal(err)
@@ -99,7 +99,7 @@ func TestThreadWait(t *T) {
 
 			t.Run("err", func(t *T) {
 				ctx, childCtx := ctxWithChild()
-				childCtx = Thread(childCtx, func() error { return testErr })
+				childCtx = WithThread(childCtx, func() error { return testErr })
 				ctx = mctx.WithChild(ctx, childCtx)
 				if err := Wait(ctx, nil); err != testErr {
 					t.Fatalf("should have got test error, got: %v", err)
@@ -110,7 +110,7 @@ func TestThreadWait(t *T) {
 		t.Run("block", func(t *T) {
 			t.Run("noErr", func(t *T) {
 				ctx, childCtx := ctxWithChild()
-				childCtx = Thread(childCtx, func() error {
+				childCtx = WithThread(childCtx, func() error {
 					time.Sleep(1 * time.Second)
 					return nil
 				})
@@ -122,7 +122,7 @@ func TestThreadWait(t *T) {
 
 			t.Run("err", func(t *T) {
 				ctx, childCtx := ctxWithChild()
-				childCtx = Thread(childCtx, func() error {
+				childCtx = WithThread(childCtx, func() error {
 					time.Sleep(1 * time.Second)
 					return testErr
 				})
@@ -134,7 +134,7 @@ func TestThreadWait(t *T) {
 
 			t.Run("canceled", func(t *T) {
 				ctx, childCtx := ctxWithChild()
-				childCtx = Thread(childCtx, func() error {
+				childCtx = WithThread(childCtx, func() error {
 					time.Sleep(5 * time.Second)
 					return testErr
 				})

mtest/mtest.go

@@ -12,18 +12,18 @@ import (
 
 type envCtxKey int
 
-// NewCtx creates and returns a root Context suitable for testing.
+// Context creates and returns a root Context suitable for testing.
-func NewCtx() context.Context {
+func Context() context.Context {
 	ctx := context.Background()
 	logger := mlog.NewLogger()
 	logger.SetMaxLevel(mlog.DebugLevel)
-	return mlog.Set(ctx, logger)
+	return mlog.WithLogger(ctx, logger)
 }
 
-// SetEnv sets the given environment variable on the given Context, such that it
+// WithEnv sets the given environment variable on the given Context, such that
-// will be used as if it was a real environment variable when the Run function
+// it will be used as if it was a real environment variable when the Run
-// from this package is called.
+// function from this package is called.
-func SetEnv(ctx context.Context, key, val string) context.Context {
+func WithEnv(ctx context.Context, key, val string) context.Context {
 	prevEnv, _ := ctx.Value(envCtxKey(0)).([][2]string)
 	env := make([][2]string, len(prevEnv), len(prevEnv)+1)
 	copy(env, prevEnv)
@@ -33,7 +33,7 @@ func SetEnv(ctx context.Context, key, val string) context.Context {
 
 // Run performs the following using the given Context:
 //
-// - Calls mcfg.Populate using any variables set by SetEnv.
+// - Calls mcfg.Populate using any variables set by WithEnv.
 //
 // - Calls mrun.Start
 //
@@ -42,7 +42,7 @@ func SetEnv(ctx context.Context, key, val string) context.Context {
 // - Calls mrun.Stop
 //
 // The intention is that Run is used within a test on a Context created via
-// NewCtx, after any setup functions have been called (e.g. mnet.MListen).
+// NewCtx, after any setup functions have been called (e.g. mnet.WithListener).
 func Run(ctx context.Context, t *testing.T, body func()) {
 	envTups, _ := ctx.Value(envCtxKey(0)).([][2]string)
 	env := make([]string, 0, len(envTups))

mtest/mtest_test.go

@@ -7,9 +7,9 @@ import (
 )
 
 func TestRun(t *T) {
-	ctx := NewCtx()
+	ctx := Context()
-	ctx, arg := mcfg.RequiredString(ctx, "arg", "Required by this test")
+	ctx, arg := mcfg.WithRequiredString(ctx, "arg", "Required by this test")
-	ctx = SetEnv(ctx, "ARG", "foo")
+	ctx = WithEnv(ctx, "ARG", "foo")
 	Run(ctx, t, func() {
 		if *arg != "foo" {
 			t.Fatalf(`arg not set to "foo", is set to %q`, *arg)