From 4f686555ce962e6632235d824512ea8fdeda003c Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Tue, 6 May 2014 15:39:14 +0200
Subject: [PATCH] Scripting: objects caching for Lua c->argv creation.
Reusing small objects when possible is a major speedup under certain
conditions, since it is able to avoid the malloc/free pattern that
otherwise is performed for every argument in the client command vector.
---
src/scripting.c | 43 ++++++++++++++++++++++++++++++++++++++++---
1 file changed, 40 insertions(+), 3 deletions(-)
diff --git a/src/scripting.c b/src/scripting.c
index 918f61ea..401ebcb2 100644
--- a/src/scripting.c
+++ b/src/scripting.c
@@ -200,6 +200,8 @@ void luaSortArray(lua_State *lua) {
lua_pop(lua,1); /* Stack: array (sorted) */
}
+#define LUA_CMD_OBJCACHE_SIZE 32
+#define LUA_CMD_OBJCACHE_MAX_LEN 64
int luaRedisGenericCommand(lua_State *lua, int raise_error) {
int j, argc = lua_gettop(lua);
struct redisCommand *cmd;
@@ -209,6 +211,8 @@ int luaRedisGenericCommand(lua_State *lua, int raise_error) {
/* Cached across calls. */
static robj **argv = NULL;
static int argv_size = 0;
+ static robj *cached_objects[LUA_CMD_OBJCACHE_SIZE];
+ static int cached_objects_len[LUA_CMD_OBJCACHE_SIZE];
/* Require at least one argument */
if (argc == 0) {
@@ -231,7 +235,20 @@ int luaRedisGenericCommand(lua_State *lua, int raise_error) {
obj_s = (char*)lua_tolstring(lua,j+1,&obj_len);
if (obj_s == NULL) break; /* Not a string. */
- argv[j] = createStringObject(obj_s, obj_len);
+
+ /* Try to use a cached object. */
+ if (cached_objects[j] && cached_objects_len[j] >= obj_len) {
+ char *s = cached_objects[j]->ptr;
+ struct sdshdr *sh = (void*)(s-(sizeof(struct sdshdr)));
+
+ argv[j] = cached_objects[j];
+ cached_objects[j] = NULL;
+ memcpy(s,obj_s,obj_len+1);
+ sh->free += sh->len - obj_len;
+ sh->len = obj_len;
+ } else {
+ argv[j] = createStringObject(obj_s, obj_len);
+ }
}
/* Check if one of the arguments passed by the Lua script
@@ -348,8 +365,28 @@ int luaRedisGenericCommand(lua_State *lua, int raise_error) {
cleanup:
/* Clean up. Command code may have changed argv/argc so we use the
* argv/argc of the client instead of the local variables. */
- for (j = 0; j < c->argc; j++)
- decrRefCount(c->argv[j]);
+ for (j = 0; j < c->argc; j++) {
+ robj *o = c->argv[j];
+
+ /* Try to cache the object in the cached_objects array.
+ * The object must be small, SDS-encoded, and with refcount = 1
+ * (we must be the only owner) for us to cache it. */
+ if (j < LUA_CMD_OBJCACHE_SIZE &&
+ o->refcount == 1 &&
+ (o->encoding == REDIS_ENCODING_RAW ||
+ o->encoding == REDIS_ENCODING_EMBSTR) &&
+ sdslen(o->ptr) <= LUA_CMD_OBJCACHE_MAX_LEN)
+ {
+ struct sdshdr *sh = (void*)(((char*)(o->ptr))-(sizeof(struct sdshdr)));
+
+ if (cached_objects[j]) decrRefCount(cached_objects[j]);
+ cached_objects[j] = o;
+ cached_objects_len[j] = sh->free + sh->len;
+ } else {
+ decrRefCount(o);
+ }
+ }
+
if (c->argv != argv) {
zfree(c->argv);
argv = NULL;