just refactoring

weed/filesys/page_writer/page_chunk.go

@@ -1,12 +1,64 @@
 package page_writer
 
 import (
+	"github.com/chrislusf/seaweedfs/weed/util"
+	"github.com/chrislusf/seaweedfs/weed/util/mem"
 	"io"
 )
 
 type SaveToStorageFunc func(reader io.Reader, offset int64, size int64, cleanupFn func())
 
+type PageChunk interface {
+	FreeResource()
+	WriteDataAt(src []byte, offset int64) (n int)
+	ReadDataAt(p []byte, off int64, logicChunkIndex LogicChunkIndex, chunkSize int64) (maxStop int64)
+	IsComplete(chunkSize int64) bool
+	SaveContent(saveFn SaveToStorageFunc, logicChunkIndex LogicChunkIndex, chunkSize int64)
+}
+
+var (
+	_ = PageChunk(&MemChunk{})
+)
+
 type MemChunk struct {
 	buf   []byte
 	usage *ChunkWrittenIntervalList
 }
+
+func (mc *MemChunk) FreeResource() {
+	mem.Free(mc.buf)
+}
+
+func (mc *MemChunk) WriteDataAt(src []byte, offset int64) (n int) {
+	n = copy(mc.buf[offset:], src)
+	mc.usage.MarkWritten(offset, offset+int64(n))
+	return
+}
+
+func (mc *MemChunk) ReadDataAt(p []byte, off int64, logicChunkIndex LogicChunkIndex, chunkSize int64) (maxStop int64) {
+	memChunkBaseOffset := int64(logicChunkIndex) * chunkSize
+	for t := mc.usage.head.next; t != mc.usage.tail; t = t.next {
+		logicStart := max(off, int64(logicChunkIndex)*chunkSize+t.StartOffset)
+		logicStop := min(off+int64(len(p)), memChunkBaseOffset+t.stopOffset)
+		if logicStart < logicStop {
+			copy(p[logicStart-off:logicStop-off], mc.buf[logicStart-memChunkBaseOffset:logicStop-memChunkBaseOffset])
+			maxStop = max(maxStop, logicStop)
+		}
+	}
+	return
+}
+
+func (mc *MemChunk) IsComplete(chunkSize int64) bool {
+	return mc.usage.IsComplete(chunkSize)
+}
+
+func (mc *MemChunk) SaveContent(saveFn SaveToStorageFunc, logicChunkIndex LogicChunkIndex, chunkSize int64) {
+	if saveFn == nil {
+		return
+	}
+	for t := mc.usage.head.next; t != mc.usage.tail; t = t.next {
+		reader := util.NewBytesReader(mc.buf[t.StartOffset:t.stopOffset])
+		saveFn(reader, int64(logicChunkIndex)*chunkSize+t.StartOffset, t.Size(), func() {
+		})
+	}
+}