Fix rotating log makes dfdaemon.log file huge size

When the size of dfdaemon.log file large than 20M, the size of log file will continuous growth up. Use Mmap to copy the file which need be truncated. Related to issue: dragonflyoss/dragonfly#364 Signed-off-by: godliness <[email protected]>
godliness · Feb 2, 2019 · 724d23b · 724d23b
1 parent f4734b3
commit 724d23b
Showing 1 changed file with 32 additions and 23 deletions.
diff --git a/dfdaemon/initializer/initializer.go b/dfdaemon/initializer/initializer.go
@@ -18,7 +18,6 @@ package initializer
 
 import (
 	"fmt"
-	"io"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -102,32 +101,35 @@ func cleanLocalRepo(options *options.Options) {
 }
 
 // rotateLog truncates the logs file by a certain amount bytes.
-func rotateLog(logFile *os.File, logFilePath string) {
+func rotateLog(logFile *os.File) error {
+	stat, err := logFile.Stat()
+	if err != nil {
+		return err
+	}
 	logSizeLimit := int64(20 * 1024 * 1024)
-	for {
-		time.Sleep(time.Second * 60)
-		stat, err := os.Stat(logFilePath)
+	// if it exceeds the 20MB limitation
+	if stat.Size() > logSizeLimit {
+		log.SetOutput(ioutil.Discard)
+		// make sure set the output of log back to logFile when error be raised.
+		defer log.SetOutput(logFile)
+		logFile.Sync()
+		truncateSize := logSizeLimit/2 - 1
+		mem, err := syscall.Mmap(int(logFile.Fd()), 0, int(stat.Size()), syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED)
 		if err != nil {
-			log.Errorf("failed to stat %s: %s", logFilePath, err)
-			continue
+			return err
 		}
-		// if it exceeds the 20MB limitation
-		if stat.Size() > logSizeLimit {
-			log.SetOutput(ioutil.Discard)
-			logFile.Sync()
-			if transFile, err := os.Open(logFilePath); err == nil {
-				// move the pointer to be (end - 10MB)
-				transFile.Seek(-10*1024*1024, 2)
-				// move the pointer to head
-				logFile.Seek(0, 0)
-				count, _ := io.Copy(logFile, transFile)
-				logFile.Truncate(count)
-				log.SetOutput(logFile)
-				transFile.Close()
-			}
+		copy(mem[0:], mem[truncateSize:])
+		if err := syscall.Munmap(mem); err != nil {
+			return err
+		}
+		if err := logFile.Truncate(stat.Size() - truncateSize); err != nil {
+			return err
+		}
+		if _, err := logFile.Seek(truncateSize, 0); err != nil {
+			return err
 		}
 	}
-
+	return nil
 }
 
 func initLogger() {
@@ -148,7 +150,14 @@ func initLogger() {
 		if logFile, err := os.OpenFile(logFilePath, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0644); err == nil {
 			logFile.Seek(0, 2)
 			log.SetOutput(logFile)
-			go rotateLog(logFile, logFilePath)
+			go func(logFile *os.File) {
+				ticker := time.NewTicker(60 * time.Second)
+				for range ticker.C {
+					if err := rotateLog(logFile); err != nil {
+						log.Errorf("failed to rotate log %s: %v", logFile.Name(), err)
+					}
+				}
+			}(logFile)
 		}
 	}