SORT is now more deterministic: does not accept to compare by score items that have...

[redis.git] / src / scripting.c

diff --git a/src/scripting.c b/src/scripting.c
index 469d78708caf9cef1824632fbb067c856911dd8c..2eac840c52e5707829a57f5deab6950d9bf086cc 100644 (file)
--- a/src/scripting.c
+++ b/src/scripting.c
@@ -1,16 +1,20 @@
 #include "redis.h"
 #include "sha1.h"
 #include "redis.h"
 #include "sha1.h"

+#include "rand.h"

 
 #include <lua.h>
 #include <lauxlib.h>
 #include <lualib.h>
 #include <ctype.h>
 
 #include <lua.h>
 #include <lauxlib.h>
 #include <lualib.h>
 #include <ctype.h>

+#include <math.h>

 
 char *redisProtocolToLuaType_Int(lua_State *lua, char *reply);
 char *redisProtocolToLuaType_Bulk(lua_State *lua, char *reply);
 char *redisProtocolToLuaType_Status(lua_State *lua, char *reply);
 char *redisProtocolToLuaType_Error(lua_State *lua, char *reply);
 char *redisProtocolToLuaType_MultiBulk(lua_State *lua, char *reply);
 
 char *redisProtocolToLuaType_Int(lua_State *lua, char *reply);
 char *redisProtocolToLuaType_Bulk(lua_State *lua, char *reply);
 char *redisProtocolToLuaType_Status(lua_State *lua, char *reply);
 char *redisProtocolToLuaType_Error(lua_State *lua, char *reply);
 char *redisProtocolToLuaType_MultiBulk(lua_State *lua, char *reply);

+int redis_math_random (lua_State *L);
+int redis_math_randomseed (lua_State *L);

 
 /* Take a Redis reply in the Redis protocol format and convert it into a
  * Lua type. Thanks to this function, and the introduction of not connected
 
 /* Take a Redis reply in the Redis protocol format and convert it into a
  * Lua type. Thanks to this function, and the introduction of not connected


@@ -23,7 +27,7 @@ char *redisProtocolToLuaType_MultiBulk(lua_State *lua, char *reply);
  * 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
  * 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.
  *
  * The reply string can be altered during the parsing as it is discared
  * after the conversion is completed.
  *


@@ -124,7 +128,38 @@ void luaPushError(lua_State *lua, char *error) {
     lua_settable(lua,-3);
 }
 
     lua_settable(lua,-3);
 }
 

-int luaRedisCommand(lua_State *lua) {
+/* 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;
     robj **argv;
     int j, argc = lua_gettop(lua);
     struct redisCommand *cmd;
     robj **argv;


@@ -154,24 +189,38 @@ int luaRedisCommand(lua_State *lua) {
         return 1;
     }
 
         return 1;
     }
 

+    /* Setup our fake client for command execution */
+    c->argv = argv;
+    c->argc = argc;
+

     /* Command lookup */
     cmd = lookupCommand(argv[0]->ptr);
     if (!cmd || ((cmd->arity > 0 && cmd->arity != argc) ||
                    (argc < -cmd->arity)))
     {
     /* Command lookup */
     cmd = lookupCommand(argv[0]->ptr);
     if (!cmd || ((cmd->arity > 0 && cmd->arity != argc) ||
                    (argc < -cmd->arity)))
     {

-        for (j = 0; j < argc; j++) decrRefCount(argv[j]);
-        zfree(argv);

         if (cmd)
             luaPushError(lua,
                 "Wrong number of args calling Redis command From Lua script");
         else
             luaPushError(lua,"Unknown Redis command called from Lua script");
         if (cmd)
             luaPushError(lua,
                 "Wrong number of args calling Redis command From Lua script");
         else
             luaPushError(lua,"Unknown Redis command called from Lua script");

-        return 1;
+        goto cleanup;

     }
 
     }
 

-    /* Run the command in the context of a fake client */
-    c->argv = argv;
-    c->argc = argc;
+    if (cmd->flags & REDIS_CMD_NOSCRIPT) {
+        luaPushError(lua, "This Redis command is not allowed from scripts");
+        goto cleanup;
+    }
+
+    if (cmd->flags & REDIS_CMD_WRITE && server.lua_random_dirty) {
+        luaPushError(lua,
+            "Write commands not allowed after non deterministic commands");
+        goto cleanup;
+    }
+
+    if (cmd->flags & REDIS_CMD_RANDOM) server.lua_random_dirty = 1;
+    if (cmd->flags & REDIS_CMD_WRITE) server.lua_write_dirty = 1;
+
+    /* Run the command */

     cmd->proc(c);
 
     /* Convert the result of the Redis command into a suitable Lua type.
     cmd->proc(c);
 
     /* Convert the result of the Redis command into a suitable Lua type.


@@ -188,18 +237,44 @@ int luaRedisCommand(lua_State *lua) {
         reply = sdscatlen(reply,o->ptr,sdslen(o->ptr));
         listDelNode(c->reply,listFirst(c->reply));
     }
         reply = sdscatlen(reply,o->ptr,sdslen(o->ptr));
         listDelNode(c->reply,listFirst(c->reply));
     }

+    if (raise_error && reply[0] != '-') raise_error = 0;

     redisProtocolToLuaType(lua,reply);
     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);
 
     sdsfree(reply);
 

+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]);
     zfree(c->argv);
 
     /* 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]);
     zfree(c->argv);
 

+    if (raise_error) {
+        /* If we are here we should have an error in the stack, in the
+         * form of a table with an "err" field. Extract the string to
+         * return the plain error. */
+        lua_pushstring(lua,"err");
+        lua_gettable(lua,-2);
+        return lua_error(lua);
+    }

     return 1;
 }
 
     return 1;
 }
 

+int luaRedisCallCommand(lua_State *lua) {
+    return luaRedisGenericCommand(lua,1);
+}
+
+int luaRedisPCallCommand(lua_State *lua) {
+    return luaRedisGenericCommand(lua,0);
+}
+

 int luaLogCommand(lua_State *lua) {
     int j, argc = lua_gettop(lua);
     int level;
 int luaLogCommand(lua_State *lua) {
     int j, argc = lua_gettop(lua);
     int level;


@@ -238,25 +313,74 @@ int luaLogCommand(lua_State *lua) {
 void luaMaskCountHook(lua_State *lua, lua_Debug *ar) {
     long long elapsed;
     REDIS_NOTUSED(ar);
 void luaMaskCountHook(lua_State *lua, lua_Debug *ar) {
     long long elapsed;
     REDIS_NOTUSED(ar);

+    REDIS_NOTUSED(lua);

 
     elapsed = (ustime()/1000) - server.lua_time_start;
 
     elapsed = (ustime()/1000) - server.lua_time_start;

-    if (elapsed >= server.lua_time_limit) {
-        redisLog(REDIS_NOTICE,"Lua script aborted for max execution time after %lld milliseconds of running time.",elapsed);
-        lua_pushstring(lua,"Script aborted for max execution time.");
+    if (elapsed >= server.lua_time_limit && server.lua_timedout == 0) {
+        redisLog(REDIS_WARNING,"Lua slow script detected: still in execution after %lld milliseconds. You can try killing the script using the SCRIPT KILL command.",elapsed);
+        server.lua_timedout = 1;
+        /* Once the script timeouts we reenter the event loop to permit others
+         * to call SCRIPT KILL or SHUTDOWN NOSAVE if needed. For this reason
+         * we need to mask the client executing the script from the event loop.
+         * If we don't do that the client may disconnect and could no longer be
+         * here when the EVAL command will return. */
+         aeDeleteFileEvent(server.el, server.lua_caller->fd, AE_READABLE);
+    }
+    if (server.lua_timedout)
+        aeProcessEvents(server.el, AE_FILE_EVENTS|AE_DONT_WAIT);
+    if (server.lua_kill) {
+        redisLog(REDIS_WARNING,"Lua script killed by user with SCRIPT KILL.");
+        lua_pushstring(lua,"Script killed by user with SCRIPT KILL...");

         lua_error(lua);
     }
 }
 
         lua_error(lua);
     }
 }
 

+void luaLoadLib(lua_State *lua, const char *libname, lua_CFunction luafunc) {
+  lua_pushcfunction(lua, luafunc);
+  lua_pushstring(lua, libname);
+  lua_call(lua, 1, 0);
+}
+
+LUALIB_API int (luaopen_cjson) (lua_State *L);
+
+void luaLoadLibraries(lua_State *lua) {
+    luaLoadLib(lua, "", luaopen_base);
+    luaLoadLib(lua, LUA_TABLIBNAME, luaopen_table);
+    luaLoadLib(lua, LUA_STRLIBNAME, luaopen_string);
+    luaLoadLib(lua, LUA_MATHLIBNAME, luaopen_math);
+    luaLoadLib(lua, LUA_DBLIBNAME, luaopen_debug); 
+    luaLoadLib(lua, "cjson", luaopen_cjson); 
+
+#if 0 /* Stuff that we don't load currently, for sandboxing concerns. */
+    luaLoadLib(lua, LUA_LOADLIBNAME, luaopen_package);
+    luaLoadLib(lua, LUA_OSLIBNAME, luaopen_os);
+#endif
+}
+
+/* Initialize the scripting environment.
+ * It is possible to call this function to reset the scripting environment
+ * assuming that we call scriptingRelease() before.
+ * See scriptingReset() for more information. */

 void scriptingInit(void) {
     lua_State *lua = lua_open();
 void scriptingInit(void) {
     lua_State *lua = lua_open();

-    luaL_openlibs(lua);
+    luaLoadLibraries(lua);
+
+    /* Initialize a dictionary we use to map SHAs to scripts.
+     * This is useful for replication, as we need to replicate EVALSHA
+     * as EVAL, so we need to remember the associated script. */
+    server.lua_scripts = dictCreate(&dbDictType,NULL);

 
     /* Register the redis commands table and fields */
     lua_newtable(lua);
 
     /* redis.call */
     lua_pushstring(lua,"call");
 
     /* Register the redis commands table and fields */
     lua_newtable(lua);
 
     /* redis.call */
     lua_pushstring(lua,"call");

-    lua_pushcfunction(lua,luaRedisCommand);
+    lua_pushcfunction(lua,luaRedisCallCommand);
+    lua_settable(lua,-3);
+
+    /* redis.pcall */
+    lua_pushstring(lua,"pcall");
+    lua_pushcfunction(lua,luaRedisPCallCommand);

     lua_settable(lua,-3);
 
     /* redis.log and log levels. */
     lua_settable(lua,-3);
 
     /* redis.log and log levels. */


@@ -283,14 +407,55 @@ void scriptingInit(void) {
     /* Finally set the table as 'redis' global var. */
     lua_setglobal(lua,"redis");
 
     /* Finally set the table as 'redis' global var. */
     lua_setglobal(lua,"redis");
 

+    /* Replace math.random and math.randomseed with our implementations. */
+    lua_getglobal(lua,"math");
+
+    lua_pushstring(lua,"random");
+    lua_pushcfunction(lua,redis_math_random);
+    lua_settable(lua,-3);
+
+    lua_pushstring(lua,"randomseed");
+    lua_pushcfunction(lua,redis_math_randomseed);
+    lua_settable(lua,-3);
+
+    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
     /* Create the (non connected) client that we use to execute Redis commands

-     * inside the Lua interpreter */
-    server.lua_client = createClient(-1);
-    server.lua_client->flags |= REDIS_LUA_CLIENT;
+     * inside the Lua interpreter.
+     * Note: there is no need to create it again when this function is called
+     * by scriptingReset(). */
+    if (server.lua_client == NULL) {
+        server.lua_client = createClient(-1);
+        server.lua_client->flags |= REDIS_LUA_CLIENT;
+    }

 
     server.lua = lua;
 }
 
 
     server.lua = lua;
 }
 

+/* Release resources related to Lua scripting.
+ * This function is used in order to reset the scripting environment. */
+void scriptingRelease(void) {
+    dictRelease(server.lua_scripts);
+    lua_close(server.lua);
+}
+
+void scriptingReset(void) {
+    scriptingRelease();
+    scriptingInit();
+}
+

 /* Hash the scripit into a SHA1 digest. We use this as Lua function name.
  * Digest should point to a 41 bytes buffer: 40 for SHA1 converted into an
  * hexadecimal number, plus 1 byte for null term. */
 /* Hash the scripit into a SHA1 digest. We use this as Lua function name.
  * Digest should point to a 41 bytes buffer: 40 for SHA1 converted into an
  * hexadecimal number, plus 1 byte for null term. */


@@ -388,11 +553,71 @@ void luaSetGlobalArray(lua_State *lua, char *var, robj **elev, int elec) {
     lua_setglobal(lua,var);
 }
 
     lua_setglobal(lua,var);
 }
 

+/* Define a lua function with the specified function name and body.
+ * The function name musts be a 2 characters long string, since all the
+ * functions we defined in the Lua context are in the form:
+ *
+ *   f_<hex sha1 sum>
+ *
+ * On success REDIS_OK is returned, and nothing is left on the Lua stack.
+ * On error REDIS_ERR is returned and an appropriate error is set in the
+ * client context. */
+int luaCreateFunction(redisClient *c, lua_State *lua, char *funcname, robj *body) {
+    sds funcdef = sdsempty();
+
+    funcdef = sdscat(funcdef,"function ");
+    funcdef = sdscatlen(funcdef,funcname,42);
+    funcdef = sdscatlen(funcdef,"() ",3);
+    funcdef = sdscatlen(funcdef,body->ptr,sdslen(body->ptr));
+    funcdef = sdscatlen(funcdef," end",4);
+
+    if (luaL_loadbuffer(lua,funcdef,sdslen(funcdef),"func definition")) {
+        addReplyErrorFormat(c,"Error compiling script (new function): %s\n",
+            lua_tostring(lua,-1));
+        lua_pop(lua,1);
+        sdsfree(funcdef);
+        return REDIS_ERR;
+    }
+    sdsfree(funcdef);
+    if (lua_pcall(lua,0,0,0)) {
+        addReplyErrorFormat(c,"Error running script (new function): %s\n",
+            lua_tostring(lua,-1));
+        lua_pop(lua,1);
+        return REDIS_ERR;
+    }
+
+    /* We also save a SHA1 -> Original script map in a dictionary
+     * so that we can replicate / write in the AOF all the
+     * EVALSHA commands as EVAL using the original script. */
+    {
+        int retval = dictAdd(server.lua_scripts,
+                             sdsnewlen(funcname+2,40),body);
+        redisAssertWithInfo(c,NULL,retval == DICT_OK);
+        incrRefCount(body);
+    }
+    return REDIS_OK;
+}
+

 void evalGenericCommand(redisClient *c, int evalsha) {
     lua_State *lua = server.lua;
     char funcname[43];
     long long numkeys;
 
 void evalGenericCommand(redisClient *c, int evalsha) {
     lua_State *lua = server.lua;
     char funcname[43];
     long long numkeys;
 

+    /* We want the same PRNG sequence at every call so that our PRNG is
+     * not affected by external state. */
+    redisSrand48(0);
+
+    /* We set this flag to zero to remember that so far no random command
+     * was called. This way we can allow the user to call commands like
+     * SRANDMEMBER or RANDOMKEY from Lua scripts as far as no write command
+     * is called (otherwise the replication and AOF would end with non
+     * deterministic sequences).
+     *
+     * Thanks to this flag we'll raise an error every time a write command
+     * is called after a random command was used. */
+    server.lua_random_dirty = 0;
+    server.lua_write_dirty = 0;
+

     /* Get the number of arguments that are keys */
     if (getLongLongFromObjectOrReply(c,c->argv[2],&numkeys,NULL) != REDIS_OK)
         return;
     /* Get the number of arguments that are keys */
     if (getLongLongFromObjectOrReply(c,c->argv[2],&numkeys,NULL) != REDIS_OK)
         return;


@@ -418,43 +643,21 @@ void evalGenericCommand(redisClient *c, int evalsha) {
         funcname[42] = '\0';
     }
 
         funcname[42] = '\0';
     }
 

+    /* Try to lookup the Lua function */

     lua_getglobal(lua, funcname);
     if (lua_isnil(lua,1)) {
     lua_getglobal(lua, funcname);
     if (lua_isnil(lua,1)) {

-        sds funcdef;
-      
+        lua_pop(lua,1); /* remove the nil from the stack */

         /* Function not defined... let's define it if we have the
          * body of the funciton. If this is an EVALSHA call we can just
          * return an error. */
         if (evalsha) {
             addReply(c, shared.noscripterr);
         /* Function not defined... let's define it if we have the
          * body of the funciton. If this is an EVALSHA call we can just
          * return an error. */
         if (evalsha) {
             addReply(c, shared.noscripterr);

-            lua_pop(lua,1); /* remove the nil from the stack */
-            return;
-        }
-        funcdef = sdsempty();
-
-        lua_pop(lua,1); /* remove the nil from the stack */
-        funcdef = sdscat(funcdef,"function ");
-        funcdef = sdscatlen(funcdef,funcname,42);
-        funcdef = sdscatlen(funcdef," ()\n",4);
-        funcdef = sdscatlen(funcdef,c->argv[1]->ptr,sdslen(c->argv[1]->ptr));
-        funcdef = sdscatlen(funcdef,"\nend\n",5);
-        /* printf("Defining:\n%s\n",funcdef); */
-
-        if (luaL_loadbuffer(lua,funcdef,sdslen(funcdef),"func definition")) {
-            addReplyErrorFormat(c,"Error compiling script (new function): %s\n",
-                lua_tostring(lua,-1));
-            lua_pop(lua,1);
-            sdsfree(funcdef);
-            return;
-        }
-        sdsfree(funcdef);
-        if (lua_pcall(lua,0,0,0)) {
-            addReplyErrorFormat(c,"Error running script (new function): %s\n",
-                lua_tostring(lua,-1));
-            lua_pop(lua,1);

             return;
         }
             return;
         }

+        if (luaCreateFunction(c,lua,funcname,c->argv[1]) == REDIS_ERR) return;
+        /* Now the following is guaranteed to return non nil */

         lua_getglobal(lua, funcname);
         lua_getglobal(lua, funcname);

+        redisAssert(!lua_isnil(lua,1));

     }
 
     /* Populate the argv and keys table accordingly to the arguments that
     }
 
     /* Populate the argv and keys table accordingly to the arguments that


@@ -469,9 +672,8 @@ void evalGenericCommand(redisClient *c, int evalsha) {
      * is running for too much time.
      * We set the hook only if the time limit is enabled as the hook will
      * make the Lua script execution slower. */
      * is running for too much time.
      * We set the hook only if the time limit is enabled as the hook will
      * make the Lua script execution slower. */

-    if (server.lua_time_limit > 0) {
+    if (server.lua_time_limit > 0 && server.masterhost == NULL) {

         lua_sethook(lua,luaMaskCountHook,LUA_MASKCOUNT,100000);
         lua_sethook(lua,luaMaskCountHook,LUA_MASKCOUNT,100000);

-        server.lua_time_start = ustime()/1000;

     } else {
         lua_sethook(lua,luaMaskCountHook,0,0);
     }
     } else {
         lua_sethook(lua,luaMaskCountHook,0,0);
     }


@@ -479,7 +681,18 @@ void evalGenericCommand(redisClient *c, int evalsha) {
     /* At this point whatever this script was never seen before or if it was
      * already defined, we can call it. We have zero arguments and expect
      * a single return value. */
     /* At this point whatever this script was never seen before or if it was
      * already defined, we can call it. We have zero arguments and expect
      * a single return value. */

+    server.lua_caller = c;
+    server.lua_time_start = ustime()/1000;
+    server.lua_kill = 0;

     if (lua_pcall(lua,0,1,0)) {
     if (lua_pcall(lua,0,1,0)) {

+        if (server.lua_timedout) {
+            server.lua_timedout = 0;
+            /* Restore the readable handler that was unregistered when the
+             * script timeout was detected. */
+            aeCreateFileEvent(server.el,c->fd,AE_READABLE,
+                              readQueryFromClient,c);
+        }
+        server.lua_caller = NULL;

         selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
         addReplyErrorFormat(c,"Error running script (call to %s): %s\n",
             funcname, lua_tostring(lua,-1));
         selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
         addReplyErrorFormat(c,"Error running script (call to %s): %s\n",
             funcname, lua_tostring(lua,-1));


@@ -487,9 +700,30 @@ void evalGenericCommand(redisClient *c, int evalsha) {
         lua_gc(lua,LUA_GCCOLLECT,0);
         return;
     }
         lua_gc(lua,LUA_GCCOLLECT,0);
         return;
     }

+    server.lua_timedout = 0;
+    server.lua_caller = NULL;

     selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
     luaReplyToRedisReply(c,lua);
     lua_gc(lua,LUA_GCSTEP,1);
     selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
     luaReplyToRedisReply(c,lua);
     lua_gc(lua,LUA_GCSTEP,1);

+
+    /* If we have slaves attached we want to replicate this command as
+     * EVAL instead of EVALSHA. We do this also in the AOF as currently there
+     * is no easy way to propagate a command in a different way in the AOF
+     * and in the replication link.
+     *
+     * IMPROVEMENT POSSIBLE:
+     * 1) Replicate this command as EVALSHA in the AOF.
+     * 2) Remember what slave already received a given script, and replicate
+     *    the EVALSHA against this slaves when possible.
+     */
+    if (evalsha) {
+        robj *script = dictFetchValue(server.lua_scripts,c->argv[1]->ptr);
+
+        redisAssertWithInfo(c,NULL,script != NULL);
+        rewriteClientCommandArgument(c,0,
+            resetRefCount(createStringObject("EVAL",4)));
+        rewriteClientCommandArgument(c,1,script);
+    }

 }
 
 void evalCommand(redisClient *c) {
 }
 
 void evalCommand(redisClient *c) {


@@ -507,3 +741,92 @@ void evalShaCommand(redisClient *c) {
     }
     evalGenericCommand(c,1);
 }
     }
     evalGenericCommand(c,1);
 }

+
+/* We replace math.random() with our implementation that is not affected
+ * by specific libc random() implementations and will output the same sequence
+ * (for the same seed) in every arch. */
+
+/* The following implementation is the one shipped with Lua itself but with
+ * rand() replaced by redisLrand48(). */
+int redis_math_random (lua_State *L) {
+  /* the `%' avoids the (rare) case of r==1, and is needed also because on
+     some systems (SunOS!) `rand()' may return a value larger than RAND_MAX */
+  lua_Number r = (lua_Number)(redisLrand48()%REDIS_LRAND48_MAX) /
+                                (lua_Number)REDIS_LRAND48_MAX;
+  switch (lua_gettop(L)) {  /* check number of arguments */
+    case 0: {  /* no arguments */
+      lua_pushnumber(L, r);  /* Number between 0 and 1 */
+      break;
+    }
+    case 1: {  /* only upper limit */
+      int u = luaL_checkint(L, 1);
+      luaL_argcheck(L, 1<=u, 1, "interval is empty");
+      lua_pushnumber(L, floor(r*u)+1);  /* int between 1 and `u' */
+      break;
+    }
+    case 2: {  /* lower and upper limits */
+      int l = luaL_checkint(L, 1);
+      int u = luaL_checkint(L, 2);
+      luaL_argcheck(L, l<=u, 2, "interval is empty");
+      lua_pushnumber(L, floor(r*(u-l+1))+l);  /* int between `l' and `u' */
+      break;
+    }
+    default: return luaL_error(L, "wrong number of arguments");
+  }
+  return 1;
+}
+
+int redis_math_randomseed (lua_State *L) {
+  redisSrand48(luaL_checkint(L, 1));
+  return 0;
+}
+
+/* ---------------------------------------------------------------------------
+ * SCRIPT command for script environment introspection and control
+ * ------------------------------------------------------------------------- */
+
+void scriptCommand(redisClient *c) {
+    if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr,"flush")) {
+        scriptingReset();
+        addReply(c,shared.ok);
+        server.dirty++; /* Replicating this command is a good idea. */
+    } else if (c->argc >= 2 && !strcasecmp(c->argv[1]->ptr,"exists")) {
+        int j;
+
+        addReplyMultiBulkLen(c, c->argc-2);
+        for (j = 2; j < c->argc; j++) {
+            if (dictFind(server.lua_scripts,c->argv[j]->ptr))
+                addReply(c,shared.cone);
+            else
+                addReply(c,shared.czero);
+        }
+    } else if (c->argc == 3 && !strcasecmp(c->argv[1]->ptr,"load")) {
+        char funcname[43];
+        sds sha;
+
+        funcname[0] = 'f';
+        funcname[1] = '_';
+        hashScript(funcname+2,c->argv[2]->ptr,sdslen(c->argv[2]->ptr));
+        sha = sdsnewlen(funcname+2,40);
+        if (dictFind(server.lua_scripts,sha) == NULL) {
+            if (luaCreateFunction(c,server.lua,funcname,c->argv[2])
+                    == REDIS_ERR) {
+                sdsfree(sha);
+                return;
+            }
+        }
+        addReplyBulkCBuffer(c,funcname+2,40);
+        sdsfree(sha);
+    } else if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr,"kill")) {
+        if (server.lua_caller == NULL) {
+            addReplyError(c,"No scripts in execution right now.");
+        } else if (server.lua_write_dirty) {
+            addReplyError(c, "Sorry the script already executed write commands against the dataset. You can either wait the script termination or kill the server in an hard way using the SHUTDOWN NOSAVE command.");
+        } else {
+            server.lua_kill = 1;
+            addReply(c,shared.ok);
+        }
+    } else {
+        addReplyError(c, "Unknown SCRIPT subcommand or wrong # of args.");
+    }
+}