Remove the NOTIFY_MODULE flag and simplify the module notification flow if there aren't subscribers

src/module.c

@@ -3748,8 +3748,6 @@ int RM_SubscribeToKeyspaceEvents(RedisModuleCtx *ctx, int types, RedisModuleNoti
     sub->notify_callback = callback;
     sub->active = 0;
 
-    /* Let the notification system know that modules are interested in notifications */
-    server.notify_keyspace_events |= NOTIFY_MODULE;
     listAddNodeTail(moduleKeyspaceSubscribers, sub);
     return REDISMODULE_OK;
 
@@ -3759,6 +3757,10 @@ int RM_SubscribeToKeyspaceEvents(RedisModuleCtx *ctx, int types, RedisModuleNoti
  * This gets called  only if at least one module requested to be notified on
  * keyspace notifications */
 void moduleNotifyKeyspaceEvent(int type, const char *event, robj *key, int dbid) {
+    
+    /* Don't do anything if there aren't any subscribers */
+    if (listLength(moduleKeyspaceSubscribers) == 0) return;
+    
     listIter li;
     listNode *ln;
 
@@ -3805,10 +3807,6 @@ void moduleUnsubscribeNotifications(RedisModule *module) {
             zfree(sub);
         }
     }
-    /* If no subscribers are left - do not call the module norification function */
-    if (listLength(moduleKeyspaceSubscribers) == 0) {
-        server.notify_keyspace_events &= ~NOTIFY_MODULE;
-    }
 }
 
 

src/notify.c

@@ -102,8 +102,7 @@ void notifyKeyspaceEvent(int type, char *event, robj *key, int dbid) {
      * This bypasses the notifications configuration, but the module engine
      * will only call event subscribers if the event type matches the types
      * they are interested in. */
-    if (server.notify_keyspace_events & NOTIFY_MODULE) 
-        moduleNotifyKeyspaceEvent(type, event, key, dbid);
+     moduleNotifyKeyspaceEvent(type, event, key, dbid);
     
     /* If notifications for this class of events are off, return ASAP. */
     if (!(server.notify_keyspace_events & type)) return;

src/server.h

@@ -425,7 +425,6 @@ typedef long long mstime_t; /* millisecond time type. */
 #define NOTIFY_ZSET (1<<7)        /* z */
 #define NOTIFY_EXPIRED (1<<8)     /* x */
 #define NOTIFY_EVICTED (1<<9)     /* e */
-#define NOTIFY_MODULE (1<<11)     /* modules are interested in notifications */
 #define NOTIFY_ALL (NOTIFY_GENERIC | NOTIFY_STRING | NOTIFY_LIST | NOTIFY_SET | NOTIFY_HASH | NOTIFY_ZSET | NOTIFY_EXPIRED | NOTIFY_EVICTED) /* A flag */
 
 /* Get the first bind addr or NULL */