mlog: refactor to use Clone/Set instead of With pattern, implement CtxSetAll

cmd/totp-proxy/main.go

@@ -60,7 +60,9 @@ func main() {
 	})
 
 	authHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		authLogger := logger.WithKV(mlog.CtxKV(r.Context()))
+		// TODO mlog.FromHTTP?
+		authLogger := logger.Clone()
+		authLogger.SetKV(mlog.CtxKV(r.Context()))
 
 		unauthorized := func() {
 			w.Header().Add("WWW-Authenticate", "Basic")

mhttp/mhttp.go

@@ -28,7 +28,9 @@ func MListenAndServe(ctx mctx.Context, h http.Handler) *http.Server {
 	ctx = mctx.ChildOf(ctx, "http")
 	listener := mnet.MListen(ctx, "tcp", "")
 	listener.NoCloseOnStop = true // http.Server.Shutdown will do this
-	logger := mlog.From(ctx).WithKV(listener)
+
+	logger := mlog.From(ctx)
+	logger.SetKV(listener)
 
 	srv := http.Server{Handler: h}
 	mrun.OnStart(ctx, func(mctx.Context) error {

mhttp/mhttp_test.go

@@ -15,8 +15,11 @@ import (
 )
 
 func TestMListenAndServe(t *T) {
+	// TODO mtest.NewCtx
 	ctx := mctx.ChildOf(mctx.New(), "test")
-	mlog.CtxSet(ctx, mlog.From(ctx).WithMaxLevel(mlog.DebugLevel))
+	logger := mlog.From(ctx)
+	logger.SetMaxLevel(mlog.DebugLevel)
+	mlog.CtxSet(ctx, logger)
 
 	h := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
 		io.Copy(rw, r.Body)

mlog/ctx.go

@@ -21,6 +21,24 @@ func CtxSet(ctx mctx.Context, l *Logger) {
 	})
 }
 
+// CtxSetAll traverses the given Context's children, breadth-first. It calls the
+// callback for each Context which has a Logger set on it, replacing that Logger
+// with the returned one.
+//
+// This is useful, for example, when changing the log level of all Loggers in an
+// app.
+func CtxSetAll(ctx mctx.Context, callback func(mctx.Context, *Logger) *Logger) {
+	mctx.BreadthFirstVisit(ctx, func(ctx mctx.Context) bool {
+		mctx.GetSetMutableValue(ctx, false, ctxKey(0), func(i interface{}) interface{} {
+			if i == nil {
+				return nil
+			}
+			return callback(ctx, i.(*Logger))
+		})
+		return true
+	})
+}
+
 type ctxPathStringer struct {
 	str     Stringer
 	pathStr string
@@ -39,39 +57,31 @@ func (cp ctxPathStringer) String() string {
 // Context parent's Logger. If the parent hasn't had From called on it its
 // parent will be queried instead, and so on.
 func From(ctx mctx.Context) *Logger {
-	var from func(mctx.Context) *Logger
-	from = func(ctx mctx.Context) *Logger {
-		return mctx.GetSetMutableValue(ctx, true, ctxKey(0), func(interface{}) interface{} {
+	return mctx.GetSetMutableValue(ctx, true, ctxKey(0), func(interface{}) interface{} {
+		ctxPath := mctx.Path(ctx)
+		if len(ctxPath) == 0 {
+			// we're at the root node and it doesn't have a Logger set, use
+			// the default
+			return NewLogger()
+		}
 
-			ctxPath := mctx.Path(ctx)
-			if len(ctxPath) == 0 {
-				// we're at the root node and it doesn't have a Logger set, use
-				// the default
-				return NewLogger()
-			}
+		// set up child's logger
+		pathStr := "/" + path.Join(ctxPath...)
 
-			// set up child's logger
-			pathStr := "/"
-			if len(ctxPath) > 0 {
-				pathStr += path.Join(ctxPath...)
-			}
-
-			parentL := from(mctx.Parent(ctx))
-			prevH := parentL.Handler()
-			return parentL.WithHandler(func(msg Message) error {
-				// if the Description is already a ctxPathStringer it can be
-				// assumed this Message was passed in from a child Logger.
-				if _, ok := msg.Description.(ctxPathStringer); !ok {
-					msg.Description = ctxPathStringer{
-						str:     msg.Description,
-						pathStr: pathStr,
-					}
+		parentL := From(mctx.Parent(ctx))
+		parentH := parentL.Handler()
+		thisL := parentL.Clone()
+		thisL.SetHandler(func(msg Message) error {
+			// if the Description is already a ctxPathStringer it can be
+			// assumed this Message was passed in from a child Logger.
+			if _, ok := msg.Description.(ctxPathStringer); !ok {
+				msg.Description = ctxPathStringer{
+					str:     msg.Description,
+					pathStr: pathStr,
 				}
-				return prevH(msg)
-			})
-
-		}).(*Logger)
-	}
-
-	return from(ctx)
+			}
+			return parentH(msg)
+		})
+		return thisL
+	}).(*Logger)
 }

mlog/ctx_test.go

@@ -14,7 +14,8 @@ func TestContextStuff(t *T) {
 	ctx1b := mctx.ChildOf(ctx1, "b")
 
 	var descrs []string
-	l := NewLogger().WithHandler(func(msg Message) error {
+	l := NewLogger()
+	l.SetHandler(func(msg Message) error {
 		descrs = append(descrs, msg.Description.String())
 		return nil
 	})
@@ -23,6 +24,7 @@ func TestContextStuff(t *T) {
 	From(ctx1a).Info("ctx1a")
 	From(ctx1).Info("ctx1")
 	From(ctx).Info("ctx")
+	From(ctx1b).Debug("ctx1b (shouldn't show up)")
 	From(ctx1b).Info("ctx1b")
 
 	ctx2 := mctx.ChildOf(ctx, "2")
@@ -36,4 +38,23 @@ func TestContextStuff(t *T) {
 		massert.Equal(descrs[3], "(/1/b) ctx1b"),
 		massert.Equal(descrs[4], "(/2) ctx2"),
 	))
+
+	// use CtxSetAll to change all MaxLevels in-place
+	ctx2L := From(ctx2)
+	CtxSetAll(ctx, func(_ mctx.Context, l *Logger) *Logger {
+		l.SetMaxLevel(DebugLevel)
+		return l
+	})
+
+	descrs = descrs[:0]
+	From(ctx).Info("ctx")
+	From(ctx).Debug("ctx debug")
+	ctx2L.Debug("ctx2L debug")
+
+	massert.Fatal(t, massert.All(
+		massert.Len(descrs, 3),
+		massert.Equal(descrs[0], "ctx"),
+		massert.Equal(descrs[1], "ctx debug"),
+		massert.Equal(descrs[2], "(/2) ctx2L debug"),
+	))
 }

mlog/mlog.go

@@ -264,9 +264,10 @@ func DefaultHandler() Handler {
 }
 
 // Logger directs Messages to an internal Handler and provides convenient
-// methods for creating and modifying its own behavior.
+// methods for creating and modifying its own behavior. All methods are
+// thread-safe.
 type Logger struct {
-	w        io.Writer
+	l        *sync.RWMutex
 	h        Handler
 	maxLevel uint
 	kv       KVer
@@ -278,54 +279,50 @@ type Logger struct {
 // to the DefaultHandler.
 func NewLogger() *Logger {
 	return &Logger{
+		l:        new(sync.RWMutex),
 		h:        DefaultHandler(),
 		maxLevel: InfoLevel.Uint(),
 	}
 }
 
-// Handler returns the Handler currently in use by the Logger.
-func (l *Logger) Handler() Handler {
-	return l.h
-}
-
-func (l *Logger) clone() *Logger {
+// Clone returns an identical instance of the Logger which can be modified
+// independently of the original.
+func (l *Logger) Clone() *Logger {
 	l2 := *l
+	l2.l = new(sync.RWMutex)
 	return &l2
 }
 
-// WithMaxLevelUint returns a copy of the Logger which will not log any messages
-// with a higher Level.Uint value than the one given. The returned Logger is
-// identical in all other aspects.
-func (l *Logger) WithMaxLevelUint(i uint) *Logger {
-	l = l.clone()
-	l.maxLevel = i
-	return l
+// SetMaxLevel sets the Logger to not log any messages with a higher Level.Uint
+// value than of the one given.
+func (l *Logger) SetMaxLevel(lvl Level) {
+	l.l.Lock()
+	defer l.l.Unlock()
+	l.maxLevel = lvl.Uint()
 }
 
-// WithMaxLevel returns a copy of the Logger which will not log any messages
-// with a higher Level.Uint value than of the Level given. The returned Logger
-// is identical in all other aspects.
-func (l *Logger) WithMaxLevel(lvl Level) *Logger {
-	return l.WithMaxLevelUint(lvl.Uint())
-}
-
-// WithHandler returns a copy of the Logger which will use the given Handler in
-// order to process messages. The returned Logger is identical in all other
-// aspects.
-func (l *Logger) WithHandler(h Handler) *Logger {
-	l = l.clone()
+// SetHandler sets the Logger to use the given Handler in order to process
+// Messages.
+func (l *Logger) SetHandler(h Handler) {
+	l.l.Lock()
+	defer l.l.Unlock()
 	l.h = h
-	return l
 }
 
-// WithKV returns a copy of the Logger which will use the merging of the given
-// KVers as a base KVer for all log messages. If the original Logger already had
-// a base KVer (via a previous WithKV call) then this set will be merged onto
-// that one.
-func (l *Logger) WithKV(kvs ...KVer) *Logger {
-	l = l.clone()
+// Handler returns the Handler currently in use by the Logger.
+func (l *Logger) Handler() Handler {
+	l.l.RLock()
+	defer l.l.RUnlock()
+	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...)
-	return l
 }
 
 // Log can be used to manually log a message of some custom defined Level.
@@ -333,6 +330,9 @@ func (l *Logger) WithKV(kvs ...KVer) *Logger {
 // If the Level is a fatal (Uint() == 0) then calling this will never return,
 // and the process will have os.Exit(1) called.
 func (l *Logger) Log(msg Message) {
+	l.l.RLock()
+	defer l.l.RUnlock()
+
 	if l.maxLevel < msg.Level.Uint() {
 		return
 	}

mlog/mlog_test.go

@@ -41,7 +41,8 @@ func TestLogger(t *T) {
 		return DefaultFormat(buf, msg)
 	}
 
-	l := NewLogger().WithHandler(h)
+	l := NewLogger()
+	l.SetHandler(h)
 	l.testMsgWrittenCh = make(chan struct{}, 10)
 
 	assertOut := func(expected string) massert.Assertion {
@@ -68,7 +69,7 @@ func TestLogger(t *T) {
 		assertOut("~ ERROR -- buz\n"),
 	))
 
-	l = l.WithMaxLevel(WarnLevel)
+	l.SetMaxLevel(WarnLevel)
 	l.Debug("foo")
 	l.Info("bar")
 	l.Warn("baz")
@@ -78,8 +79,9 @@ func TestLogger(t *T) {
 		assertOut("~ ERROR -- buz -- a=\"b\"\n"),
 	))
 
-	l2 := l.WithMaxLevel(InfoLevel)
-	l2 = l2.WithHandler(func(msg Message) error {
+	l2 := l.Clone()
+	l2.SetMaxLevel(InfoLevel)
+	l2.SetHandler(func(msg Message) error {
 		msg.Description = String(strings.ToUpper(msg.Description.String()))
 		return h(msg)
 	})
@@ -92,7 +94,8 @@ func TestLogger(t *T) {
 		assertOut("~ ERROR -- buz\n"),
 	))
 
-	l3 := l2.WithKV(KV{"a": 1})
+	l3 := l2.Clone()
+	l3.SetKV(KV{"a": 1})
 	l3.Info("foo", KV{"b": 2})
 	l3.Info("bar", KV{"a": 2, "b": 3})
 	massert.Fatal(t, massert.All(

mnet/mnet.go

@@ -38,7 +38,8 @@ func MListen(ctx mctx.Context, network, defaultAddr string) *MListener {
 	addr := mcfg.String(ctx, "listen-addr", defaultAddr, network+" address to listen on in format [host]:port. If port is 0 then a random one will be chosen")
 
 	l := new(MListener)
-	l.log = mlog.From(ctx).WithKV(l)
+	l.log = mlog.From(ctx)
+	l.log.SetKV(l)
 
 	mrun.OnStart(ctx, func(mctx.Context) error {
 		var err error

mnet/mnet_test.go

@@ -39,8 +39,11 @@ func TestIsReservedIP(t *T) {
 }
 
 func TestMListen(t *T) {
+	// TODO mtest.NewCtx
 	ctx := mctx.ChildOf(mctx.New(), "test")
-	mlog.CtxSet(ctx, mlog.From(ctx).WithMaxLevel(mlog.DebugLevel))
+	logger := mlog.From(ctx)
+	logger.SetMaxLevel(mlog.DebugLevel)
+	mlog.CtxSet(ctx, logger)
 
 	l := MListen(ctx, "", "")
 	if err := mcfg.Populate(ctx, nil); err != nil {