Propagation: wrap commands in also_propagate array with MULIT/EXEC

Random command like SPOP with count is replicated as
some SREM operations, and store them in also_propagate
array to propagate after the call, but this would break
atomicity.

To keep the command's atomicity, wrap also_propagate
array with MULTI/EXEC.

src/module.c

@@ -574,11 +574,8 @@ void moduleHandlePropagationAfterCommandCallback(RedisModuleCtx *ctx) {
 
     /* Handle the replication of the final EXEC, since whatever a command
      * emits is always wrapped around MULTI/EXEC. */
-    robj *propargv[1];
-    propargv[0] = createStringObject("EXEC",4);
-    alsoPropagate(server.execCommand,c->db->id,propargv,1,
+    alsoPropagate(server.execCommand,c->db->id,&shared.exec,1,
         PROPAGATE_AOF|PROPAGATE_REPL);
-    decrRefCount(propargv[0]);
 
     /* If this is not a module command context (but is instead a simple
      * callback context), we have to handle directly the "also propagate"

src/multi.c

@@ -106,11 +106,13 @@ void discardCommand(client *c) {
 /* Send a MULTI command to all the slaves and AOF file. Check the execCommand
  * implementation for more information. */
 void execCommandPropagateMulti(client *c) {
-    robj *multistring = createStringObject("MULTI",5);
+    propagate(server.multiCommand,c->db->id,&shared.multi,1,
+              PROPAGATE_AOF|PROPAGATE_REPL);
+}
 
-    propagate(server.multiCommand,c->db->id,&multistring,1,
+void execCommandPropagateExec(client *c) {
+    propagate(server.execCommand,c->db->id,&shared.exec,1,
               PROPAGATE_AOF|PROPAGATE_REPL);
-    decrRefCount(multistring);
 }
 
 void execCommand(client *c) {

src/scripting.c

@@ -1591,11 +1591,8 @@ void evalGenericCommand(client *c, int evalsha) {
     if (server.lua_replicate_commands) {
         preventCommandPropagation(c);
         if (server.lua_multi_emitted) {
-            robj *propargv[1];
-            propargv[0] = createStringObject("EXEC",4);
-            alsoPropagate(server.execCommand,c->db->id,propargv,1,
+            alsoPropagate(server.execCommand,c->db->id,&shared.exec,1,
                 PROPAGATE_AOF|PROPAGATE_REPL);
-            decrRefCount(propargv[0]);
         }
     }
 

src/server.c

@@ -2244,6 +2244,8 @@ void createSharedObjects(void) {
     shared.rpoplpush = createStringObject("RPOPLPUSH",9);
     shared.zpopmin = createStringObject("ZPOPMIN",7);
     shared.zpopmax = createStringObject("ZPOPMAX",7);
+    shared.multi = createStringObject("MULTI",5);
+    shared.exec = createStringObject("EXEC",4);
     for (j = 0; j < OBJ_SHARED_INTEGERS; j++) {
         shared.integers[j] =
             makeObjectShared(createObject(OBJ_STRING,(void*)(long)j));
@@ -3366,6 +3368,18 @@ void call(client *c, int flags) {
         redisOp *rop;
 
         if (flags & CMD_CALL_PROPAGATE) {
+            int multi_emitted = 0;
+            /* Wrap the commands in server.also_propagate array,
+             * but don't wrap it if we are already in MULIT context,
+             * in case the nested MULIT/EXEC.
+             *
+             * And if the array contains only one command, no need to
+             * wrap it, since the single command is atomic. */
+            if (server.also_propagate.numops > 1 && !(c->flags & CLIENT_MULTI)) {
+                execCommandPropagateMulti(c);
+                multi_emitted = 1;
+            }
+
             for (j = 0; j < server.also_propagate.numops; j++) {
                 rop = &server.also_propagate.ops[j];
                 int target = rop->target;
@@ -3375,6 +3389,10 @@ void call(client *c, int flags) {
                 if (target)
                     propagate(rop->cmd,rop->dbid,rop->argv,rop->argc,target);
             }
+
+            if (multi_emitted) {
+                execCommandPropagateExec(c);
+            }
         }
         redisOpArrayFree(&server.also_propagate);
     }

src/server.h

@@ -923,6 +923,7 @@ struct sharedObjectsStruct {
     *busykeyerr, *oomerr, *plus, *messagebulk, *pmessagebulk, *subscribebulk,
     *unsubscribebulk, *psubscribebulk, *punsubscribebulk, *del, *unlink,
     *rpop, *lpop, *lpush, *rpoplpush, *zpopmin, *zpopmax, *emptyscan,
+    *multi, *exec,
     *select[PROTO_SHARED_SELECT_CMDS],
     *integers[OBJ_SHARED_INTEGERS],
     *mbulkhdr[OBJ_SHARED_BULKHDR_LEN], /* "*<value>\r\n" */
@@ -1751,6 +1752,7 @@ void touchWatchedKeysOnFlush(int dbid);
 void discardTransaction(client *c);
 void flagTransaction(client *c);
 void execCommandPropagateMulti(client *c);
+void execCommandPropagateExec(client *c);
 
 /* Redis object implementation */
 void decrRefCount(robj *o);