Memory leak bug fix

LICENSE

@@ -1,21 +1,19 @@
-The MIT License (MIT)
+(C) Copyright 2024 Hewlett Packard Enterprise Development LP
 
-Copyright (c) 2014 Nate Finch 
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
 
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.

linux_test.go

@@ -1,12 +1,15 @@
+//go:build linux
 // +build linux
 
+// Copyright 2024 Hewlett Packard Enterprise Development LP.
+
 package lumberjack
 
 import (
 	"os"
+	"sync"
 	"syscall"
 	"testing"
-	"time"
 )
 
 func TestMaintainMode(t *testing.T) {
@@ -98,10 +101,11 @@ func TestCompressMaintainMode(t *testing.T) {
 	f.Close()
 
 	l := &Logger{
-		Compress:   true,
-		Filename:   filename,
-		MaxBackups: 1,
-		MaxSize:    100, // megabytes
+		Compress:         true,
+		Filename:         filename,
+		MaxBackups:       1,
+		MaxSize:          100, // megabytes
+		notifyCompressed: make(chan struct{}),
 	}
 	defer l.Close()
 	b := []byte("boo!")
@@ -114,9 +118,7 @@ func TestCompressMaintainMode(t *testing.T) {
 	err = l.Rotate()
 	isNil(err, t)
 
-	// we need to wait a little bit since the files get compressed on a different
-	// goroutine.
-	<-time.After(10 * time.Millisecond)
+	waitForNotify(l.notifyCompressed, t)
 
 	// a compressed version of the log file should now exist with the correct
 	// mode.
@@ -148,10 +150,11 @@ func TestCompressMaintainOwner(t *testing.T) {
 	f.Close()
 
 	l := &Logger{
-		Compress:   true,
-		Filename:   filename,
-		MaxBackups: 1,
-		MaxSize:    100, // megabytes
+		Compress:         true,
+		Filename:         filename,
+		MaxBackups:       1,
+		MaxSize:          100, // megabytes
+		notifyCompressed: make(chan struct{}),
 	}
 	defer l.Close()
 	b := []byte("boo!")
@@ -164,15 +167,14 @@ func TestCompressMaintainOwner(t *testing.T) {
 	err = l.Rotate()
 	isNil(err, t)
 
-	// we need to wait a little bit since the files get compressed on a different
-	// goroutine.
-	<-time.After(10 * time.Millisecond)
+	waitForNotify(l.notifyCompressed, t)
 
 	// a compressed version of the log file should now exist with the correct
 	// owner.
 	filename2 := backupFile(dir)
-	equals(555, fakeFS.files[filename2+compressSuffix].uid, t)
-	equals(666, fakeFS.files[filename2+compressSuffix].gid, t)
+	uid, gid := fakeFS.fileOwners(filename2 + compressSuffix)
+	equals(555, uid, t)
+	equals(666, gid, t)
 }
 
 type fakeFile struct {
@@ -182,18 +184,30 @@ type fakeFile struct {
 
 type fakeFS struct {
 	files map[string]fakeFile
+	mu    sync.Mutex
 }
 
 func newFakeFS() *fakeFS {
 	return &fakeFS{files: make(map[string]fakeFile)}
 }
 
+func (fs *fakeFS) fileOwners(name string) (int, int) {
+	fs.mu.Lock()
+	defer fs.mu.Unlock()
+	result := fs.files[name]
+	return result.uid, result.gid
+}
+
 func (fs *fakeFS) Chown(name string, uid, gid int) error {
+	fs.mu.Lock()
+	defer fs.mu.Unlock()
 	fs.files[name] = fakeFile{uid: uid, gid: gid}
 	return nil
 }
 
 func (fs *fakeFS) Stat(name string) (os.FileInfo, error) {
+	fs.mu.Lock()
+	defer fs.mu.Unlock()
 	info, err := os.Stat(name)
 	if err != nil {
 		return nil, err

lumberjack.go

@@ -1,9 +1,10 @@
+// Copyright 2024 Hewlett Packard Enterprise Development LP.
 // Package lumberjack provides a rolling logger.
 //
 // Note that this is v2.0 of lumberjack, and should be imported using gopkg.in
 // thusly:
 //
-//   import "gopkg.in/natefinch/lumberjack.v2"
+//	import "gopkg.in/natefinch/lumberjack.v2"
 //
 // The package name remains simply lumberjack, and the code resides at
 // https://github.com/natefinch/lumberjack under the v2.0 branch.
@@ -66,7 +67,7 @@ var _ io.WriteCloser = (*Logger)(nil)
 // `/var/log/foo/server.log`, a backup created at 6:30pm on Nov 11 2016 would
 // use the filename `/var/log/foo/server-2016-11-04T18-30-00.000.log`
 //
-// Cleaning Up Old Log Files
+// # Cleaning Up Old Log Files
 //
 // Whenever a new logfile gets created, old log files may be deleted.  The most
 // recent files according to the encoded timestamp will be retained, up to a
@@ -111,8 +112,18 @@ type Logger struct {
 	file *os.File
 	mu   sync.Mutex
 
-	millCh    chan bool
-	startMill sync.Once
+	wg     *sync.WaitGroup
+	millCh chan struct{}
+
+	// notifyCompressed is only set and used for tests. It is signalled when
+	// millRunOnce compresses some files. If no files are compressed,
+	// notifyCompressed is not signalled.
+	notifyCompressed chan struct{}
+
+	// notifyRemoved is only set and used for tests. It is signalled when the
+	// millRunOnce method removes some old log files. If no files are removed,
+	// notifyRemoved is not signalled.
+	notifyRemoved chan struct{}
 }
 
 var (
@@ -165,7 +176,20 @@ func (l *Logger) Write(p []byte) (n int, err error) {
 func (l *Logger) Close() error {
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	return l.close()
+
+	// Always close the mill channel, even if the close fails. This way we
+	// guarantee that the mill goroutine will exit.
+	err := l.close()
+
+	if l.millCh != nil {
+		close(l.millCh)
+		l.wg.Wait()
+		l.millCh = nil
+		l.wg = nil
+	}
+
+	// Return the result of the file close.
+	return err
 }
 
 // close closes the file if it is open.
@@ -356,20 +380,30 @@ func (l *Logger) millRunOnce() error {
 		}
 	}
 
+	filesRemoved := false
 	for _, f := range remove {
 		errRemove := os.Remove(filepath.Join(l.dir(), f.Name()))
 		if err == nil && errRemove != nil {
 			err = errRemove
 		}
+		filesRemoved = true
+	}
+	if filesRemoved && l.notifyRemoved != nil {
+		l.notifyRemoved <- struct{}{}
 	}
+
+	filesCompressed := false
 	for _, f := range compress {
 		fn := filepath.Join(l.dir(), f.Name())
 		errCompress := compressLogFile(fn, fn+compressSuffix)
 		if err == nil && errCompress != nil {
 			err = errCompress
 		}
+		filesCompressed = true
+	}
+	if filesCompressed && l.notifyCompressed != nil {
+		l.notifyCompressed <- struct{}{}
 	}
-
 	return err
 }
 
@@ -385,12 +419,18 @@ func (l *Logger) millRun() {
 // mill performs post-rotation compression and removal of stale log files,
 // starting the mill goroutine if necessary.
 func (l *Logger) mill() {
-	l.startMill.Do(func() {
-		l.millCh = make(chan bool, 1)
-		go l.millRun()
-	})
+	// It is safe to check the millCh here as we are inside the mutex lock.
+	if l.millCh == nil {
+		l.millCh = make(chan struct{}, 1)
+		l.wg = &sync.WaitGroup{}
+		l.wg.Add(1)
+		go func() {
+			l.millRun()
+			l.wg.Done()
+		}()
+	}
 	select {
-	case l.millCh <- true:
+	case l.millCh <- struct{}{}:
 	default:
 	}
 }