X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/d1c4c94ebf918b908691ab7f58f872b04d93f3f9..2c861050c17237a61fdaff4da2777c5d18ce979a:/src/scripting.c

diff --git a/src/scripting.c b/src/scripting.c
index 255184e7..2eac840c 100644
--- a/src/scripting.c
+++ b/src/scripting.c
@@ -27,7 +27,7 @@ int redis_math_randomseed (lua_State *L);
  * is like a normal client that bypasses all the slow I/O paths.
  *
  * Note: in this function we do not do any sanity check as the reply is
- * generated by Redis directly. This allows use to go faster.
+ * generated by Redis directly. This allows us to go faster.
  * The reply string can be altered during the parsing as it is discared
  * after the conversion is completed.
  *
@@ -128,6 +128,37 @@ void luaPushError(lua_State *lua, char *error) {
     lua_settable(lua,-3);
 }
 
+/* Sort the array currently in the stack. We do this to make the output
+ * of commands like KEYS or SMEMBERS something deterministic when called
+ * from Lua (to play well with AOf/replication).
+ *
+ * The array is sorted using table.sort itself, and assuming all the
+ * list elements are strings. */
+void luaSortArray(lua_State *lua) {
+    /* Initial Stack: array */
+    lua_getglobal(lua,"table");
+    lua_pushstring(lua,"sort");
+    lua_gettable(lua,-2);       /* Stack: array, table, table.sort */
+    lua_pushvalue(lua,-3);      /* Stack: array, table, table.sort, array */
+    if (lua_pcall(lua,1,0,0)) {
+        /* Stack: array, table, error */
+
+        /* We are not interested in the error, we assume that the problem is
+         * that there are 'false' elements inside the array, so we try
+         * again with a slower function but able to handle this case, that
+         * is: table.sort(table, __redis__compare_helper) */
+        lua_pop(lua,1);             /* Stack: array, table */
+        lua_pushstring(lua,"sort"); /* Stack: array, table, sort */
+        lua_gettable(lua,-2);       /* Stack: array, table, table.sort */
+        lua_pushvalue(lua,-3);      /* Stack: array, table, table.sort, array */
+        lua_getglobal(lua,"__redis__compare_helper");
+        /* Stack: array, table, table.sort, array, __redis__compare_helper */
+        lua_call(lua,2,0);
+    }
+    /* Stack: array (sorted), table */
+    lua_pop(lua,1);             /* Stack: array (sorted) */
+}
+
 int luaRedisGenericCommand(lua_State *lua, int raise_error) {
     int j, argc = lua_gettop(lua);
     struct redisCommand *cmd;
@@ -208,6 +239,14 @@ int luaRedisGenericCommand(lua_State *lua, int raise_error) {
     }
     if (raise_error && reply[0] != '-') raise_error = 0;
     redisProtocolToLuaType(lua,reply);
+    /* Sort the output array if needed, assuming it is a non-null multi bulk
+     * reply as expected. */
+    if ((cmd->flags & REDIS_CMD_SORT_FOR_SCRIPT) &&
+        (reply[0] == '*' && reply[1] != '-')) {
+        /* Skip this step if command is SORT but output was already sorted */
+        if (cmd->proc != sortCommand || server.sort_dontsort)
+            luaSortArray(lua);
+    }
     sdsfree(reply);
 
 cleanup:
@@ -381,6 +420,18 @@ void scriptingInit(void) {
 
     lua_setglobal(lua,"math");
 
+    /* Add a helper funciton that we use to sort the multi bulk output of non
+     * deterministic commands, when containing 'false' elements. */
+    {
+        char *compare_func =    "function __redis__compare_helper(a,b)\n"
+                                "  if a == false then a = '' end\n"
+                                "  if b == false then b = '' end\n"
+                                "  return a<b\n"
+                                "end\n";
+        luaL_loadbuffer(lua,compare_func,strlen(compare_func),"cmp_func_def");
+        lua_pcall(lua,0,0,0);
+    }
+
     /* Create the (non connected) client that we use to execute Redis commands
      * inside the Lua interpreter.
      * Note: there is no need to create it again when this function is called