clientv3: add Lvl method to logger

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>

clientv3/logger.go

@@ -23,10 +23,23 @@ import (
 
 // Logger is the logger used by client library.
 // It implements grpclog.LoggerV2 interface.
-type Logger grpclog.LoggerV2
+type Logger interface {
+	grpclog.LoggerV2
+
+	// Lvl returns logger if logger's verbosity level >= "lvl".
+	// Otherwise, logger that discards all logs.
+	Lvl(lvl int) Logger
+
+	// to satisfy capnslog
+
+	Print(args ...interface{})
+	Printf(format string, args ...interface{})
+	Println(args ...interface{})
+}
 
 var (
-	logger settableLogger
+	loggerMu sync.RWMutex
+	logger   Logger
 )
 
 type settableLogger struct {
@@ -36,38 +49,35 @@ type settableLogger struct {
 
 func init() {
 	// disable client side logs by default
-	logger.mu.Lock()
-	logger.l = grpclog.NewLoggerV2(ioutil.Discard, ioutil.Discard, ioutil.Discard)
-
-	// logger has to override the grpclog at initialization so that
-	// any changes to the grpclog go through logger with locking
-	// instead of through SetLogger
-	//
-	// now updates only happen through settableLogger.set
-	grpclog.SetLoggerV2(&logger)
-	logger.mu.Unlock()
+	logger = &settableLogger{}
+	SetLogger(grpclog.NewLoggerV2(ioutil.Discard, ioutil.Discard, ioutil.Discard))
 }
 
-// SetLogger sets client-side Logger. By default, logs are disabled.
-func SetLogger(l Logger) {
-	logger.set(l)
+// SetLogger sets client-side Logger.
+func SetLogger(l grpclog.LoggerV2) {
+	loggerMu.Lock()
+	logger = NewLogger(l)
+	// override grpclog so that any changes happen with locking
+	grpclog.SetLoggerV2(logger)
+	loggerMu.Unlock()
 }
 
 // GetLogger returns the current logger.
 func GetLogger() Logger {
-	return logger.get()
+	loggerMu.RLock()
+	l := logger
+	loggerMu.RUnlock()
+	return l
 }
 
-func (s *settableLogger) set(l Logger) {
-	s.mu.Lock()
-	logger.l = l
-	grpclog.SetLoggerV2(&logger)
-	s.mu.Unlock()
+// NewLogger returns a new Logger with grpclog.LoggerV2.
+func NewLogger(gl grpclog.LoggerV2) Logger {
+	return &settableLogger{l: gl}
 }
 
-func (s *settableLogger) get() Logger {
+func (s *settableLogger) get() grpclog.LoggerV2 {
 	s.mu.RLock()
-	l := logger.l
+	l := s.l
 	s.mu.RUnlock()
 	return l
 }
@@ -94,3 +104,32 @@ func (s *settableLogger) Print(args ...interface{})                 { s.get().In
 func (s *settableLogger) Printf(format string, args ...interface{}) { s.get().Infof(format, args...) }
 func (s *settableLogger) Println(args ...interface{})               { s.get().Infoln(args...) }
 func (s *settableLogger) V(l int) bool                              { return s.get().V(l) }
+func (s *settableLogger) Lvl(lvl int) Logger {
+	s.mu.RLock()
+	l := s.l
+	s.mu.RUnlock()
+	if l.V(lvl) {
+		return s
+	}
+	return &noLogger{}
+}
+
+type noLogger struct{}
+
+func (*noLogger) Info(args ...interface{})                    {}
+func (*noLogger) Infof(format string, args ...interface{})    {}
+func (*noLogger) Infoln(args ...interface{})                  {}
+func (*noLogger) Warning(args ...interface{})                 {}
+func (*noLogger) Warningf(format string, args ...interface{}) {}
+func (*noLogger) Warningln(args ...interface{})               {}
+func (*noLogger) Error(args ...interface{})                   {}
+func (*noLogger) Errorf(format string, args ...interface{})   {}
+func (*noLogger) Errorln(args ...interface{})                 {}
+func (*noLogger) Fatal(args ...interface{})                   {}
+func (*noLogger) Fatalf(format string, args ...interface{})   {}
+func (*noLogger) Fatalln(args ...interface{})                 {}
+func (*noLogger) Print(args ...interface{})                   {}
+func (*noLogger) Printf(format string, args ...interface{})   {}
+func (*noLogger) Println(args ...interface{})                 {}
+func (*noLogger) V(l int) bool                                { return false }
+func (ng *noLogger) Lvl(lvl int) Logger                       { return ng }

clientv3/logger_test.go

@@ -0,0 +1,51 @@
+// Copyright 2017 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package clientv3
+
+import (
+	"bytes"
+	"io/ioutil"
+	"strings"
+	"testing"
+
+	"google.golang.org/grpc/grpclog"
+)
+
+func TestLogger(t *testing.T) {
+	buf := new(bytes.Buffer)
+
+	l := NewLogger(grpclog.NewLoggerV2WithVerbosity(buf, buf, buf, 10))
+	l.Infof("hello world!")
+	if !strings.Contains(buf.String(), "hello world!") {
+		t.Fatalf("expected 'hello world!', got %q", buf.String())
+	}
+	buf.Reset()
+
+	l.Lvl(10).Infof("Level 10")
+	l.Lvl(30).Infof("Level 30")
+	if !strings.Contains(buf.String(), "Level 10") {
+		t.Fatalf("expected 'Level 10', got %q", buf.String())
+	}
+	if strings.Contains(buf.String(), "Level 30") {
+		t.Fatalf("unexpected 'Level 30', got %q", buf.String())
+	}
+	buf.Reset()
+
+	l = NewLogger(grpclog.NewLoggerV2(ioutil.Discard, ioutil.Discard, ioutil.Discard))
+	l.Infof("ignore this")
+	if len(buf.Bytes()) > 0 {
+		t.Fatalf("unexpected logs %q", buf.String())
+	}
+}