improve performance of accesslog (#155)

pkg/vfs/accesslog.go

@@ -21,39 +21,41 @@ import (
 	"time"
 )
 
-const (
-	maxLineLength = 1000
-)
+type logReader struct {
+	sync.Mutex
+	buffer chan []byte
+	last   []byte
+}
 
 var (
 	readerLock sync.Mutex
-	readers    map[uint64]chan []byte
+	readers    map[uint64]*logReader
 )
 
 func init() {
-	readers = make(map[uint64]chan []byte)
+	readers = make(map[uint64]*logReader)
 }
 
 func logit(ctx Context, format string, args ...interface{}) {
 	used := ctx.Duration()
 	readerLock.Lock()
 	defer readerLock.Unlock()
-	if len(readers) == 0 || used > time.Second*10 {
+	if len(readers) == 0 && used < time.Second*10 {
 		return
 	}
 
 	cmd := fmt.Sprintf(format, args...)
 	t := time.Now()
 	ts := t.Format("2006.01.02 15:04:05.000000")
 	cmd += fmt.Sprintf(" <%.6f>", used.Seconds())
-	if ctx.Pid() != 0 && used > time.Second*10 {
+	if ctx.Pid() != 0 && used >= time.Second*10 {
 		logger.Infof("slow operation: %s", cmd)
 	}
 	line := []byte(fmt.Sprintf("%s [uid:%d,gid:%d,pid:%d] %s\n", ts, ctx.Uid(), ctx.Gid(), ctx.Pid(), cmd))
 
-	for _, ch := range readers {
+	for _, r := range readers {
 		select {
-		case ch <- line:
+		case r.buffer <- line:
 		default:
 		}
 	}
@@ -62,7 +64,7 @@ func logit(ctx Context, format string, args ...interface{}) {
 func openAccessLog(fh uint64) uint64 {
 	readerLock.Lock()
 	defer readerLock.Unlock()
-	readers[fh] = make(chan []byte, 1024)
+	readers[fh] = &logReader{buffer: make(chan []byte, 10240)}
 	return fh
 }
 
@@ -74,27 +76,35 @@ func closeAccessLog(fh uint64) {
 
 func readAccessLog(fh uint64, buf []byte) int {
 	readerLock.Lock()
-	buffer, ok := readers[fh]
+	r, ok := readers[fh]
 	readerLock.Unlock()
 	if !ok {
 		return 0
 	}
+	r.Lock()
+	defer r.Unlock()
 	var n int
+	if len(r.last) > 0 {
+		n = copy(buf, r.last)
+		r.last = r.last[n:]
+	}
 	var t = time.NewTimer(time.Second)
-	select {
-	case l := <-buffer:
-		n = copy(buf, l)
-		for n+maxLineLength <= len(buf) {
-			select {
-			case l = <-buffer:
-				n += copy(buf[n:], l)
-			default:
+	defer t.Stop()
+	for n < len(buf) {
+		select {
+		case line := <-r.buffer:
+			l := copy(buf[n:], line)
+			n += l
+			if l < len(line) {
+				r.last = line[l:]
 				return n
 			}
+		case <-t.C:
+			if n == 0 {
+				n = copy(buf, []byte("#\n"))
+			}
+			return n
 		}
-		return n
-	case <-t.C:
-		n = copy(buf, []byte("#\n"))
 	}
 	return n
 }