From bef356ce4ca3c95a77123ea6ff5c89b9c2a8ab36 Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Sat, 27 Jun 2020 12:51:04 -0700
Subject: [PATCH] since we already know the chunk size, no need to iterate

---
 weed/util/chunk_cache/chunk_cache.go | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/weed/util/chunk_cache/chunk_cache.go b/weed/util/chunk_cache/chunk_cache.go
index 3ae0f4ed5..17b64fb6c 100644
--- a/weed/util/chunk_cache/chunk_cache.go
+++ b/weed/util/chunk_cache/chunk_cache.go
@@ -46,9 +46,11 @@ func (c *ChunkCache) GetChunk(fileId string, chunkSize uint64) (data []byte) {
 
 func (c *ChunkCache) doGetChunk(fileId string, chunkSize uint64) (data []byte) {
 
-	data = c.memCache.GetChunk(fileId)
-	if len(data) != 0 && len(data) >= int(chunkSize) {
-		return data
+	if chunkSize < memCacheSizeLimit {
+		data = c.memCache.GetChunk(fileId)
+		if len(data) >= int(chunkSize) {
+			return data
+		}
 	}
 
 	fid, err := needle.ParseFileIdFromString(fileId)
@@ -57,9 +59,21 @@ func (c *ChunkCache) doGetChunk(fileId string, chunkSize uint64) (data []byte) {
 		return nil
 	}
 
-	for _, diskCache := range c.diskCaches {
-		data := diskCache.getChunk(fid.Key)
-		if len(data) != 0 && len(data) >= int(chunkSize) {
+	if chunkSize < onDiskCacheSizeLimit0 {
+		data = c.diskCaches[0].getChunk(fid.Key)
+		if len(data) >= int(chunkSize) {
+			return data
+		}
+	}
+	if chunkSize < onDiskCacheSizeLimit1 {
+		data = c.diskCaches[1].getChunk(fid.Key)
+		if len(data) >= int(chunkSize) {
+			return data
+		}
+	}
+	{
+		data = c.diskCaches[2].getChunk(fid.Key)
+		if len(data) >= int(chunkSize) {
 			return data
 		}
 	}