switch to next file before maxBytesPerFile is reached

rather than switching *after* maxBytesPerFile is reached

fixes #30

Author: ploxiln

diskqueue.go

@@ -358,6 +358,33 @@ func (d *diskQueue) readOne() ([]byte, error) {
 func (d *diskQueue) writeOne(data []byte) error {
 	var err error
 
+	dataLen := int32(len(data))
+	totalBytes := int64(4 + dataLen)
+
+	if dataLen < d.minMsgSize || dataLen > d.maxMsgSize {
+		return fmt.Errorf("invalid message write size (%d) minMsgSize=%d maxMsgSize=%d", dataLen, d.minMsgSize, d.maxMsgSize)
+	}
+
+	// will not wrap-around if maxBytesPerFile + maxMsgSize < Int64Max
+	if d.writePos > 0 && d.writePos+totalBytes > d.maxBytesPerFile {
+		if d.readFileNum == d.writeFileNum {
+			d.maxBytesPerFileRead = d.writePos
+		}
+
+		d.writeFileNum++
+		d.writePos = 0
+
+		// sync every time we start writing to a new file
+		err = d.sync()
+		if err != nil {
+			d.logf(ERROR, "DISKQUEUE(%s) failed to sync - %s", d.name, err)
+		}
+
+		if d.writeFile != nil {
+			d.writeFile.Close()
+			d.writeFile = nil
+		}
+	}
 	if d.writeFile == nil {
 		curFileName := d.fileName(d.writeFileNum)
 		d.writeFile, err = os.OpenFile(curFileName, os.O_RDWR|os.O_CREATE, 0600)
@@ -377,12 +404,6 @@ func (d *diskQueue) writeOne(data []byte) error {
 		}
 	}
 
-	dataLen := int32(len(data))
-
-	if dataLen < d.minMsgSize || dataLen > d.maxMsgSize {
-		return fmt.Errorf("invalid message write size (%d) minMsgSize=%d maxMsgSize=%d", dataLen, d.minMsgSize, d.maxMsgSize)
-	}
-
 	d.writeBuf.Reset()
 	err = binary.Write(&d.writeBuf, binary.BigEndian, dataLen)
 	if err != nil {
@@ -402,30 +423,9 @@ func (d *diskQueue) writeOne(data []byte) error {
 		return err
 	}
 
-	totalBytes := int64(4 + dataLen)
 	d.writePos += totalBytes
 	d.depth += 1
 
-	if d.writePos >= d.maxBytesPerFile {
-		if d.readFileNum == d.writeFileNum {
-			d.maxBytesPerFileRead = d.writePos
-		}
-
-		d.writeFileNum++
-		d.writePos = 0
-
-		// sync every time we start writing to a new file
-		err = d.sync()
-		if err != nil {
-			d.logf(ERROR, "DISKQUEUE(%s) failed to sync - %s", d.name, err)
-		}
-
-		if d.writeFile != nil {
-			d.writeFile.Close()
-			d.writeFile = nil
-		}
-	}
-
 	return err
 }
 

diskqueue_test.go

@@ -108,23 +108,23 @@ func TestDiskQueueRoll(t *testing.T) {
 		panic(err)
 	}
 	defer os.RemoveAll(tmpDir)
-	msg := bytes.Repeat([]byte{0}, 10)
+	msg := []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}
 	ml := int64(len(msg))
 	dq := New(dqName, tmpDir, 10*(ml+4), int32(ml), 1<<10, 2500, 2*time.Second, l)
 	defer dq.Close()
 	NotNil(t, dq)
 	Equal(t, int64(0), dq.Depth())
 
-	for i := 0; i < 10; i++ {
+	for i := 0; i < 11; i++ {
 		err := dq.Put(msg)
 		Nil(t, err)
 		Equal(t, int64(i+1), dq.Depth())
 	}
 
 	Equal(t, int64(1), dq.(*diskQueue).writeFileNum)
-	Equal(t, int64(0), dq.(*diskQueue).writePos)
+	Equal(t, int64(ml+4), dq.(*diskQueue).writePos)
 
-	for i := 10; i > 0; i-- {
+	for i := 11; i > 0; i-- {
 		Equal(t, msg, <-dq.ReadChan())
 		Equal(t, int64(i-1), dq.Depth())
 	}
@@ -216,7 +216,11 @@ func TestDiskQueueCorruption(t *testing.T) {
 	dq := New(dqName, tmpDir, 1000, 10, 1<<10, 5, 2*time.Second, l)
 	defer dq.Close()
 
-	msg := make([]byte, 123) // 127 bytes per message, 8 (1016 bytes) messages per file
+	msg := make([]byte, 120) // 124 bytes per message, 8 messages (992 bytes) per file
+	msg[0] = 91
+	msg[62] = 4
+	msg[119] = 211
+
 	for i := 0; i < 25; i++ {
 		dq.Put(msg)
 	}
@@ -225,7 +229,7 @@ func TestDiskQueueCorruption(t *testing.T) {
 
 	// corrupt the 2nd file
 	dqFn := dq.(*diskQueue).fileName(1)
-	os.Truncate(dqFn, 500) // 3 valid messages, 5 corrupted
+	os.Truncate(dqFn, 400) // 3 valid messages, 5 corrupted
 
 	for i := 0; i < 19; i++ { // 1 message leftover in 4th file
 		Equal(t, msg, <-dq.ReadChan())
@@ -451,14 +455,14 @@ func TestDiskQueueResize(t *testing.T) {
 	NotNil(t, dq)
 	Equal(t, int64(0), dq.Depth())
 
-	for i := 0; i < 8; i++ {
+	for i := 0; i < 9; i++ {
 		msg[0] = byte(i)
 		err := dq.Put(msg)
 		Nil(t, err)
 	}
 	Equal(t, int64(1), dq.(*diskQueue).writeFileNum)
-	Equal(t, int64(0), dq.(*diskQueue).writePos)
-	Equal(t, int64(8), dq.Depth())
+	Equal(t, int64(ml+4), dq.(*diskQueue).writePos)
+	Equal(t, int64(9), dq.Depth())
 
 	dq.Close()
 	dq = New(dqName, tmpDir, 10*(ml+4), int32(ml), 1<<10, 2500, time.Second, l)
@@ -469,10 +473,10 @@ func TestDiskQueueResize(t *testing.T) {
 		Nil(t, err)
 	}
 	Equal(t, int64(2), dq.(*diskQueue).writeFileNum)
-	Equal(t, int64(0), dq.(*diskQueue).writePos)
-	Equal(t, int64(18), dq.Depth())
+	Equal(t, int64(ml+4), dq.(*diskQueue).writePos)
+	Equal(t, int64(19), dq.Depth())
 
-	for i := 0; i < 8; i++ {
+	for i := 0; i < 9; i++ {
 		msg[0] = byte(i)
 		Equal(t, msg, <-dq.ReadChan())
 	}