From 5adbae953b2594b97fa00e25f4c26a8ed61d97ab Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Mon, 28 May 2018 08:00:31 +0000
Subject: [PATCH] m: implement Log, have mdb.PubSub and mhttp.CfgServer use it,
 though I'm still not quite happy with it yet

---
 m/m.go         | 28 ++++++++++++++++++++++++++++
 mdb/ps.go      | 16 +++++++++++-----
 mhttp/mhttp.go |  6 ++++--
 3 files changed, 43 insertions(+), 7 deletions(-)
 create mode 100644 m/m.go

diff --git a/m/m.go b/m/m.go
new file mode 100644
index 0000000..e982a7b
--- /dev/null
+++ b/m/m.go
@@ -0,0 +1,28 @@
+// Package m is the glue which holds all the other packages in this project
+// together. While other packages in this project are intended to be able to be
+// used separately and largely independently, this package combines them in ways
+// which I specifically like.
+package m
+
+import (
+	"io"
+
+	"github.com/mediocregopher/mediocre-go-lib/mcfg"
+	"github.com/mediocregopher/mediocre-go-lib/mlog"
+)
+
+// Log returns a Logger which will automatically include with the log extra
+// contextual information based on the Cfg and the given KVs
+//
+// If the cfg is nil then mlog.DefaultLogger is returned.
+func Log(cfg *mcfg.Cfg, kvs ...mlog.KVer) *mlog.Logger {
+	fn := cfg.FullName()
+	l := mlog.DefaultLogger.WithWriteFn(func(w io.Writer, msg mlog.Message) error {
+		msg.Msg = fn + " " + msg.Msg
+		return mlog.DefaultWriteFn(w, msg)
+	})
+	if len(kvs) > 0 {
+		l = l.WithKV(kvs...)
+	}
+	return l
+}
diff --git a/mdb/ps.go b/mdb/ps.go
index 8235521..87992cf 100644
--- a/mdb/ps.go
+++ b/mdb/ps.go
@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"cloud.google.com/go/pubsub"
+	"github.com/mediocregopher/mediocre-go-lib/m"
 	"github.com/mediocregopher/mediocre-go-lib/mcfg"
 	"github.com/mediocregopher/mediocre-go-lib/mlog"
 	oldctx "golang.org/x/net/context"
@@ -31,6 +32,8 @@ type Message = pubsub.Message
 type PubSub struct {
 	proj, credFile string
 	*pubsub.Client
+
+	log *mlog.Logger
 }
 
 // NewPubSub initializes and returns PubSub instance for the given projectID and
@@ -40,9 +43,10 @@ func NewPubSub(ctx context.Context, projectID, credFile string) (*PubSub, error)
 		proj:     projectID,
 		credFile: credFile,
 	}
+	ps.log = mlog.DefaultLogger.WithKV(ps.KV())
 	var err error
 	ps.Client, err = pubsub.NewClient(ctx, ps.proj, ps.clientOpts()...)
-	return ps, err
+	return ps, mlog.ErrWithKV(err, ps)
 }
 
 // CfgPubSub configures and returns a PubSub instance which will be usable once
@@ -59,12 +63,14 @@ func CfgPubSub(cfg *mcfg.Cfg, defaultProject string) *PubSub {
 	cfg.Start.Then(func(ctx context.Context) error {
 		ps.proj = *proj
 		ps.credFile = *credFile
-		mlog.Info("connecting to pubsub", &ps)
+		log := m.Log(cfg, ps.KV())
+		log.Info("connecting to pubsub")
 		psInner, err := NewPubSub(ctx, *proj, *credFile)
 		if err != nil {
 			return mlog.ErrWithKV(err, &ps)
 		}
 		ps = *psInner
+		ps.log = log
 		return nil
 	})
 	return &ps
@@ -235,7 +241,7 @@ func (s *Subscription) Consume(ctx context.Context, fn ConsumerFunc, opts Consum
 
 			ok, err := fn(context.Context(innerCtx), msg)
 			if err != nil {
-				mlog.Warn("error consuming pubsub message", s, mlog.ErrKV(err))
+				s.topic.ps.log.Warn("error consuming pubsub message", s, mlog.ErrKV(err))
 			}
 
 			if ok {
@@ -247,7 +253,7 @@ 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("error consuming from pubsub", s, mlog.ErrKV(err))
+			s.topic.ps.log.Warn("error consuming from pubsub", s, mlog.ErrKV(err))
 		}
 	}
 }
@@ -339,7 +345,7 @@ func (s *Subscription) BatchConsume(
 				}
 				ret, err := fn(thisCtx, msgs)
 				if err != nil {
-					mlog.Warn("error consuming pubsub batch messages", s, mlog.ErrKV(err))
+					s.topic.ps.log.Warn("error consuming pubsub batch messages", s, mlog.ErrKV(err))
 				}
 				for i := range thisGroup {
 					thisGroup[i].retCh <- ret // retCh is buffered
diff --git a/mhttp/mhttp.go b/mhttp/mhttp.go
index 8cf530c..f281e50 100644
--- a/mhttp/mhttp.go
+++ b/mhttp/mhttp.go
@@ -6,6 +6,7 @@ import (
 	"context"
 	"net/http"
 
+	"github.com/mediocregopher/mediocre-go-lib/m"
 	"github.com/mediocregopher/mediocre-go-lib/mcfg"
 	"github.com/mediocregopher/mediocre-go-lib/mlog"
 )
@@ -21,12 +22,13 @@ func CfgServer(cfg *mcfg.Cfg, h http.Handler) *http.Server {
 	cfg.Start.Then(func(ctx context.Context) error {
 		srv.Addr = *addr
 		kv := mlog.KV{"addr": *addr}
-		mlog.Info("HTTP server listening", kv)
+		log := m.Log(cfg, kv)
+		log.Info("listening")
 		go func() {
 			err := srv.ListenAndServe()
 			// TODO the listening log should happen here, somehow, now that we
 			// know the actual address being listened on
-			mlog.Fatal("http server fataled", kv, mlog.ErrKV(err))
+			log.Fatal("http server fataled", mlog.ErrKV(err))
 		}()
 		return nil
 	})