Fix module assertion crash when timer and timeout are unlocked in the…

… same event loop

src/blocked.c

@@ -707,6 +707,11 @@ static void moduleUnblockClientOnKey(client *c, robj *key) {
  * we want to remove the pending flag to indicate we already responded to the
  * command with timeout reply. */
 void unblockClientOnTimeout(client *c) {
+    if (c->bstate.btype == BLOCKED_MODULE) {
+        /* The client has been unlocked (in the moduleUnblocked list), return ASAP. */
+        if (moduleClientUnblocked(c)) return;
+    }
+
     replyToBlockedClientTimedOut(c);
     if (c->flags & CLIENT_PENDING_COMMAND)
         c->flags &= ~CLIENT_PENDING_COMMAND;

src/module.c

@@ -7698,6 +7698,13 @@ void RM_LatencyAddSample(const char *event, mstime_t latency) {
  * https://redis.io/topics/modules-blocking-ops.
  * -------------------------------------------------------------------------- */
 
+/* Returns 1 if the client already in the moduleUnblocked list, 0 otherwise. */
+int moduleClientUnblocked(client *c) {
+    RedisModuleBlockedClient *bc = c->bstate.module_blocked_handle;
+
+    return bc->unblocked == 1;
+}
+
 /* This is called from blocked.c in order to unblock a client: may be called
  * for multiple reasons while the client is in the middle of being blocked
  * because the client is terminated, but is also called for cleanup when a

src/server.h

@@ -2532,6 +2532,7 @@ const char *moduleTypeModuleName(moduleType *mt);
 const char *moduleNameFromCommand(struct redisCommand *cmd);
 void moduleFreeContext(struct RedisModuleCtx *ctx);
 void moduleCallCommandUnblockedHandler(client *c);
+int moduleClientUnblocked(client *c);
 void unblockClientFromModule(client *c);
 void moduleHandleBlockedClients(void);
 void moduleBlockedClientTimedOut(client *c, int from_module);

tests/unit/moduleapi/blockedclient.tcl

@@ -290,6 +290,12 @@ foreach call_type {nested normal} {
         after 120
         $rd close
     }
+
+    test {block time is equal to timer period} {
+        # These time is equal, they will be unlocked in the same event loop,
+        # when the client is unlock, we will get the OK reply from timer.
+        assert_match "OK" [r unblock_by_timer 100 100]
+    }
 
     test "Unload the module - blockedclient" {
         assert_equal {OK} [r module unload blockedclient]