1 files changed, 44 insertions, 0 deletions
diff --git a/weed/filesys/page_writer_pattern.go b/weed/filesys/page_writer_pattern.go
new file mode 100644
index 000000000..fdd796215
--- /dev/null
+++ b/weed/filesys/page_writer_pattern.go
@@ -0,0 +1,44 @@
+package filesys
+
+import "fmt"
+
+type WriterPattern struct {
+	isStreaming     bool
+	lastWriteOffset int64
+	chunkSize       int64
+	fileName        string
+}
+
+// For streaming write: only cache the first chunk
+// For random write: fall back to temp file approach
+// writes can only change from streaming mode to non-streaming mode
+
+func NewWriterPattern(fileName string, chunkSize int64) *WriterPattern {
+	return &WriterPattern{
+		isStreaming:     true,
+		lastWriteOffset: 0,
+		chunkSize:       chunkSize,
+		fileName:        fileName,
+	}
+}
+
+func (rp *WriterPattern) MonitorWriteAt(offset int64, size int) {
+	if rp.lastWriteOffset == 0 {
+	}
+	if rp.lastWriteOffset > offset {
+		if rp.isStreaming {
+			fmt.Printf("file %s ==> non streaming at [%d,%d)\n", rp.fileName, offset, offset+int64(size))
+		}
+		fmt.Printf("write %s [%d,%d)\n", rp.fileName, offset, offset+int64(size))
+		rp.isStreaming = false
+	}
+	rp.lastWriteOffset = offset
+}
+
+func (rp *WriterPattern) IsStreamingMode() bool {
+	return rp.isStreaming
+}
+
+func (rp *WriterPattern) IsRandomMode() bool {
+	return !rp.isStreaming
+}