[sheepdog] [PATCH] object cache: reuse the pulled buffer for read request

[levin li]

From: levin li <xingke.lwp at taobao.com>


Signed-off-by: levin li <xingke.lwp at taobao.com>
---
 sheep/object_cache.c |   37 ++++++++++++++++++++++++++++++-------
 1 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/sheep/object_cache.c b/sheep/object_cache.c
index 3b6ecbe..ca95287 100644
--- a/sheep/object_cache.c
+++ b/sheep/object_cache.c
@@ -740,7 +740,8 @@ out:
 
 
 /* Fetch the object, cache it in success */
-static int object_cache_pull(struct object_cache *oc, uint32_t idx)
+static int object_cache_pull(struct object_cache *oc, uint32_t idx,
+			     void **buffer)
 {
 	struct sd_req hdr;
 	int ret = SD_RES_NO_MEM;
@@ -776,7 +777,11 @@ static int object_cache_pull(struct object_cache *oc, uint32_t idx)
 		else if (ret == SD_RES_OID_EXIST)
 			ret = SD_RES_SUCCESS;
 	}
-	free(buf);
+
+	if (ret != SD_RES_SUCCESS)
+		free(buf);
+	else
+		*buffer = buf;
 out:
 	return ret;
 }
@@ -952,6 +957,12 @@ int bypass_object_cache(struct request *req)
 	return 0;
 }
 
+static void read_cache_buffer(void *buffer, void *data, size_t count,
+			      off_t offset)
+{
+	memcpy(data, (char *)buffer + offset, count);
+}
+
 int object_cache_handle_request(struct request *req)
 {
 	struct sd_req *hdr = &req->rq;
@@ -961,6 +972,7 @@ int object_cache_handle_request(struct request *req)
 	struct object_cache *cache;
 	struct object_cache_entry *entry;
 	int ret, create = 0;
+	void *data_buf = NULL;
 
 	dprintf("%08"PRIx32", len %"PRIu32", off %"PRIu64"\n", idx,
 		hdr->data_length, hdr->obj.offset);
@@ -973,7 +985,7 @@ int object_cache_handle_request(struct request *req)
 retry:
 	ret = object_cache_lookup(cache, idx, create);
 	if (ret == SD_RES_NO_CACHE) {
-		ret = object_cache_pull(cache, idx);
+		ret = object_cache_pull(cache, idx, &data_buf);
 		if (ret != SD_RES_SUCCESS)
 			return ret;
 	} else if (ret == SD_RES_EIO)
@@ -983,6 +995,10 @@ retry:
 	if (!entry) {
 		dprintf("oid %"PRIx64" maybe reclaimed\n",
 			idx_to_oid(vid, idx));
+		if (data_buf) {
+			free(data_buf);
+			data_buf = NULL;
+		}
 		goto retry;
 	}
 
@@ -994,16 +1010,23 @@ retry:
 		update_cache_entry(cache, idx, hdr->data_length,
 				   hdr->obj.offset);
 	} else {
-		ret = read_cache_object(cache->vid, idx, req->data,
-					hdr->data_length, hdr->obj.offset);
-		if (ret != SD_RES_SUCCESS)
-			goto err;
+		if (data_buf) {
+			read_cache_buffer(data_buf, req->data, hdr->data_length,
+					  hdr->obj.offset);
+		} else {
+			ret = read_cache_object(cache->vid, idx, req->data,
+						hdr->data_length,
+						hdr->obj.offset);
+			if (ret != SD_RES_SUCCESS)
+				goto err;
+		}
 		req->rp.data_length = hdr->data_length;
 
 		cds_list_del_rcu(&entry->lru_list);
 		cds_list_add_rcu(&entry->lru_list, &sys_cache.cache_lru_list);
 	}
 err:
+	free(data_buf);
 	put_cache_entry(entry);
 	return ret;
 }
-- 
1.7.1