Add mutex writer wrapper for logger.

mutex_writer.go

@@ -0,0 +1,40 @@
+// Copyright 2022 The ZKits Project 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 logger
+
+import (
+	"io"
+	"sync"
+)
+
+// NewMutexWriter creates and returns a mutex writer.
+// Mutually exclusive writers ensure mutual exclusion of individual write calls.
+func NewMutexWriter(w io.Writer) io.Writer {
+	return &mutexWriter{w: w}
+}
+
+// This is an implementation of the built-in mutex writer.
+type mutexWriter struct {
+	w  io.Writer
+	mu sync.Mutex
+}
+
+// Write is an implementation of the io.Writer interface.
+func (w *mutexWriter) Write(p []byte) (n int, err error) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	n, err = w.w.Write(p)
+	return
+}

mutex_writer_test.go

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+// Copyright 2022 The ZKits Project 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 logger
+
+import (
+	"bytes"
+	"sync"
+	"testing"
+)
+
+func TestNewMutexWriter(t *testing.T) {
+	w := new(bytes.Buffer)
+	if got := NewMutexWriter(w); got == nil {
+		t.Fatal("NewMutexWriter(): return nil")
+	}
+}
+
+type testUnsafeWriter struct {
+	n uint32
+	m map[uint32][]byte
+}
+
+func (w *testUnsafeWriter) Write(p []byte) (int, error) {
+	w.n++
+	p2 := make([]byte, len(p))
+	copy(p2, p)
+	w.m[w.n] = p2
+	return len(p2), nil
+}
+
+func TestMutexWriter_Write(t *testing.T) {
+	iw := &testUnsafeWriter{
+		m: make(map[uint32][]byte),
+	}
+	w := NewMutexWriter(iw)
+	l := New("test").SetOutput(w)
+	wg := new(sync.WaitGroup)
+	wg.Add(10)
+	for i := 0; i < 10; i++ {
+		go func() {
+			defer wg.Done()
+			l.Info("test")
+		}()
+	}
+	wg.Wait()
+	if len(iw.m) != 10 {
+		t.Fatalf("MutexWriter: want %d, got %d", 10, len(iw.m))
+	}
+	if iw.n != 10 {
+		t.Fatalf("MutexWriter: want %d, got %d", 10, iw.n)
+	}
+}