working for in memory single log buffer

weed/util/log_buffer/log_read.go

@@ -0,0 +1,74 @@
+package log_buffer
+
+import (
+	"bytes"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
+	"github.com/chrislusf/seaweedfs/weed/util"
+)
+
+func (logBuffer *LogBuffer) LoopProcessLogData(
+	startTreadTime time.Time, waitForDataFn func() bool, eachLogDataFn func(logEntry *filer_pb.LogEntry) error) (processed int64, err error) {
+	// loop through all messages
+	var bytesBuf *bytes.Buffer
+	lastReadTime := startTreadTime
+	defer func() {
+		if bytesBuf != nil {
+			logBuffer.ReleaseMeory(bytesBuf)
+		}
+	}()
+
+	for {
+
+		if bytesBuf != nil {
+			logBuffer.ReleaseMeory(bytesBuf)
+		}
+		bytesBuf = logBuffer.ReadFromBuffer(lastReadTime)
+		if bytesBuf == nil {
+			if waitForDataFn() {
+				continue
+			} else {
+				return
+			}
+		}
+
+		buf := bytesBuf.Bytes()
+
+		batchSize := 0
+		var startReadTime time.Time
+
+		for pos := 0; pos+4 < len(buf); {
+
+			size := util.BytesToUint32(buf[pos : pos+4])
+			entryData := buf[pos+4 : pos+4+int(size)]
+
+			// fmt.Printf("read buffer read %d [%d,%d) from [0,%d)\n", batchSize, pos, pos+int(size)+4, len(buf))
+
+			logEntry := &filer_pb.LogEntry{}
+			if err = proto.Unmarshal(entryData, logEntry); err != nil {
+				glog.Errorf("unexpected unmarshal messaging_pb.Message: %v", err)
+				pos += 4 + int(size)
+				continue
+			}
+			lastReadTime = time.Unix(0, logEntry.TsNs)
+			if startReadTime.IsZero() {
+				startReadTime = lastReadTime
+			}
+
+			if err = eachLogDataFn(logEntry); err != nil {
+				return
+			}
+
+			pos += 4 + int(size)
+			batchSize++
+			processed++
+		}
+
+		// fmt.Printf("sent message ts[%d,%d] size %d\n", startReadTime.UnixNano(), lastReadTime.UnixNano(), batchSize)
+	}
+
+}