From b21a67bbe67ba479d09ae74206c00ced16272449 Mon Sep 17 00:00:00 2001
From: chrislu <chris.lu@gmail.com>
Date: Mon, 20 Dec 2021 11:53:48 -0800
Subject: [PATCH] add writer pattern object for later use

---
 weed/filesys/page_writer/writer_pattern.go | 31 ++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 weed/filesys/page_writer/writer_pattern.go

diff --git a/weed/filesys/page_writer/writer_pattern.go b/weed/filesys/page_writer/writer_pattern.go
new file mode 100644
index 000000000..c7641c37f
--- /dev/null
+++ b/weed/filesys/page_writer/writer_pattern.go
@@ -0,0 +1,31 @@
+package page_writer
+
+type WriterPattern struct {
+	isStreaming     bool
+	lastWriteOffset int64
+}
+
+// For streaming write: only cache the first chunk
+// For random write: fall back to temp file approach
+
+func NewWriterPattern() *WriterPattern {
+	return &WriterPattern{
+		isStreaming:     true,
+		lastWriteOffset: 0,
+	}
+}
+
+func (rp *WriterPattern) MonitorWriteAt(offset int64, size int) {
+	if rp.lastWriteOffset > offset {
+		rp.isStreaming = false
+	}
+	rp.lastWriteOffset = offset
+}
+
+func (rp *WriterPattern) IsStreamingMode() bool {
+	return rp.isStreaming
+}
+
+func (rp *WriterPattern) IsRandomMode() bool {
+	return !rp.isStreaming
+}