Create a logging policy using sync/atomic load and store value

back/cmd/openbsrv/httpsrv.go

@@ -1,8 +1,9 @@
 package main
 
 import (
-	"github.com/OpenEugene/openboard/back/internal/httpsrv"
 	"github.com/codemodus/hedrs"
+
+	"github.com/OpenEugene/openboard/back/internal/httpsrv"
 )
 
 type httpSrv struct {

back/cmd/openbsrv/main.go

@@ -7,17 +7,32 @@ import (
 	"path"
 
 	"github.com/codemodus/sigmon/v2"
+
+	"github.com/OpenEugene/openboard/back/internal/dbg"
+	"github.com/OpenEugene/openboard/back/internal/log"
 )
 
 func main() {
-	if err := run(); err != nil {
+	config := log.Config{
+		Err: log.Output{
+			Out:    os.Stderr,
+			Prefix: "[ERROR] ",
+		},
+		Inf: log.Output{
+			Out:    os.Stdout,
+			Prefix: "[INFO] ",
+		},
+	}
+	log := log.New(config)
+
+	if err := run(log); err != nil {
 		cmd := path.Base(os.Args[0])
-		fmt.Fprintf(os.Stderr, "%s: %s\n", cmd, err)
+		log.Error("%s: %s", cmd, err)
 		os.Exit(1)
 	}
 }
 
-func run() error {
+func run(log *log.Log) error {
 	var (
 		dbdrvr    = "mysql"
 		dbname    = "openeug_openb_dev"
@@ -28,6 +43,7 @@ func run() error {
 		migrate   bool
 		rollback  bool
 		skipsrv   bool
+		debug     bool
 		frontDir  = "../../../front/public"
 		migTblPfx = "mig_"
 	)
@@ -40,13 +56,19 @@ func run() error {
 	flag.BoolVar(&migrate, "migrate", migrate, "migrate up")
 	flag.BoolVar(&rollback, "rollback", rollback, "migrate dn")
 	flag.BoolVar(&skipsrv, "skipsrv", skipsrv, "skip server run")
+	flag.BoolVar(&debug, "debug", debug, "debug true or false")
 	flag.StringVar(&frontDir, "frontdir", frontDir, "front public assets directory")
 	flag.Parse()
 
 	sm := sigmon.New(nil)
 	sm.Start()
 	defer sm.Stop()
 
+	if debug {
+		dbg.SetDebugOut(os.Stdout)
+	}
+
+	dbg.Logf("set up SQL database at %s:%s.", dbaddr, dbport)
 	db, err := newSQLDB(dbdrvr, dbCreds(dbname, dbuser, dbpass, dbaddr, dbport))
 	if err != nil {
 		return err
@@ -67,7 +89,7 @@ func run() error {
 		if mres.HasError() {
 			return mres.ErrsErr()
 		}
-		fmt.Println(migType+":", mres)
+		log.Info("%s: %s", migType, mres)
 	}
 
 	if skipsrv {
@@ -85,15 +107,15 @@ func run() error {
 		return err
 	}
 
-	m := newServerMgmt(gsrv, hsrv, fsrv)
+	m := newServerMgmt(log, gsrv, hsrv, fsrv)
 
 	sm.Set(func(s *sigmon.State) {
 		if err := m.stop(); err != nil {
-			fmt.Fprintln(os.Stderr, err)
+			log.Error(err.Error())
 		}
 	})
 
-	fmt.Println("to gracefully stop the application, send signal like TERM (CTRL-C) or HUP")
+	log.Info("to gracefully stop the application, send signal like TERM (CTRL-C) or HUP")
 
 	return m.serve()
 }

back/cmd/openbsrv/srvmgmt.go

@@ -1,10 +1,10 @@
 package main
 
 import (
-	"fmt"
-	"os"
 	"sync"
 	"time"
+
+	"github.com/OpenEugene/openboard/back/internal/log"
 )
 
 type server interface {
@@ -13,12 +13,14 @@ type server interface {
 }
 
 type serverMgmt struct {
-	ss []server
+	ss  []server
+	log *log.Log
 }
 
-func newServerMgmt(ss ...server) *serverMgmt {
+func newServerMgmt(log *log.Log, ss ...server) *serverMgmt {
 	return &serverMgmt{
-		ss: ss,
+		ss:  ss,
+		log: log,
 	}
 }
 
@@ -32,7 +34,7 @@ func (m *serverMgmt) serve() error {
 
 			// TODO: gather returned errors
 			if err := s.Serve(); err != nil {
-				fmt.Fprintln(os.Stderr, "server error:", err)
+				m.log.Error("server error: %v", err)
 			}
 		}(s)
 
@@ -49,7 +51,7 @@ func (m *serverMgmt) stop() error {
 		go func(s server) {
 			// TODO: gather returned errors
 			if err := s.Stop(); err != nil {
-				fmt.Fprintln(os.Stderr, "stop error:", err)
+				m.log.Error("stop error: %v", err)
 			}
 		}(s)
 	}

back/internal/authsvc/authsvc.go

@@ -3,8 +3,9 @@ package authsvc
 import (
 	"context"
 
-	"github.com/OpenEugene/openboard/back/internal/pb"
 	"google.golang.org/grpc"
+
+	"github.com/OpenEugene/openboard/back/internal/pb"
 )
 
 var _ pb.AuthServer = &AuthSvc{}
@@ -30,7 +31,6 @@ func (s *AuthSvc) RegisterWithGRPCServer(g *grpc.Server) error {
 // AddAuth implements part of the pb.AuthServer interface.
 func (s *AuthSvc) AddAuth(ctx context.Context, req *pb.AddAuthReq) (*pb.AuthResp, error) {
 	// TODO: implement AddAuth
-
 	return nil, nil
 }
 

back/internal/dbg/dbg.go

@@ -0,0 +1,59 @@
+package dbg
+
+import (
+	"io"
+	"log"
+	"sync/atomic"
+)
+
+// dbgLog is thread-safe.
+type dbgLog struct {
+	log *log.Logger
+	out io.Writer
+}
+
+var atomicV atomic.Value
+var dbg = new()
+
+func new() *dbgLog {
+	var dl dbgLog
+	atomicV.Store(&dl)
+	return &dl
+}
+
+func (dl *dbgLog) println(text string) {
+	dbg.log.Println(text)
+}
+
+func (dl *dbgLog) printf(format string, as ...interface{}) {
+	dbg.log.Printf(format+"\n", as...)
+}
+
+func Log(text string) {
+	dbgLoad := atomicV.Load().(*dbgLog)
+	if dbgLoad.out == nil {
+		return
+	}
+	dbgLoad.println(text)
+}
+
+func Logf(format string, as ...interface{}) {
+	dbgLoad := atomicV.Load().(*dbgLog)
+	if dbgLoad.out == nil {
+		return
+	}
+	dbgLoad.printf(format, as...)
+}
+
+func SetDebugOut(out io.Writer) {
+	dbgLoad := atomicV.Load().(*dbgLog)
+	dbgLoad.out = out
+
+	if out != nil {
+		dbgLoad.log = log.New(out, "", 0)
+	} else {
+		dbgLoad.log = log.Default()
+	}
+
+	atomicV.Store(dbgLoad)
+}

back/internal/log/log.go

@@ -0,0 +1,37 @@
+package log
+
+import (
+	"io"
+	"log"
+)
+
+type Output struct {
+	Out    io.Writer
+	Prefix string
+	Flag   int
+}
+
+type Config struct {
+	Err Output
+	Inf Output
+}
+
+type Log struct {
+	err *log.Logger
+	inf *log.Logger
+}
+
+func New(c Config) *Log {
+	return &Log{
+		inf: log.New(c.Inf.Out, c.Inf.Prefix, c.Inf.Flag),
+		err: log.New(c.Err.Out, c.Err.Prefix, c.Inf.Flag),
+	}
+}
+
+func (log *Log) Info(format string, as ...interface{}) {
+	log.inf.Printf(format+"\n", as...)
+}
+
+func (log *Log) Error(format string, as ...interface{}) {
+	log.err.Printf(format+"\n", as...)
+}

back/internal/postsvc/postsvc.go

@@ -4,10 +4,11 @@ import (
 	"context"
 	"database/sql"
 
+	"google.golang.org/grpc"
+
 	"github.com/OpenEugene/openboard/back/internal/pb"
 	"github.com/OpenEugene/openboard/back/internal/postsvc/internal/postdb"
 	"github.com/OpenEugene/openboard/back/internal/postsvc/internal/postdb/mysqlmig"
-	"google.golang.org/grpc"
 )
 
 var _ pb.PostServer = &PostSvc{}