[ReactNative] Fix bridge event dedupe

Author: tadeuzagallo

React/Base/RCTBridge.m

@@ -672,6 +672,8 @@ - (NSString *)description
  */
 static NSMutableDictionary *RCTLocalModuleIDs;
 static NSMutableDictionary *RCTLocalMethodIDs;
+static NSMutableArray *RCTLocalModuleNames;
+static NSMutableArray *RCTLocalMethodNames;
 static NSDictionary *RCTLocalModulesConfig()
 {
   static NSMutableDictionary *localModules;
@@ -680,6 +682,8 @@ - (NSString *)description
 
     RCTLocalModuleIDs = [[NSMutableDictionary alloc] init];
     RCTLocalMethodIDs = [[NSMutableDictionary alloc] init];
+    RCTLocalModuleNames = [[NSMutableArray alloc] init];
+    RCTLocalMethodNames = [[NSMutableArray alloc] init];
 
     localModules = [[NSMutableDictionary alloc] init];
     for (NSString *moduleDotMethod in RCTJSMethods()) {
@@ -711,6 +715,8 @@ - (NSString *)description
       // Add module and method lookup
       RCTLocalModuleIDs[moduleDotMethod] = module[@"moduleID"];
       RCTLocalMethodIDs[moduleDotMethod] = methods[methodName][@"methodID"];
+      [RCTLocalModuleNames addObject:moduleName];
+      [RCTLocalMethodNames addObject:methodName];
     }
   });
 
@@ -1072,7 +1078,7 @@ - (void)invalidate
 #pragma mark - RCTBridge methods
 
 /**
- * Like JS::call, for objective-c.
+ * Public. Can be invoked from any thread.
  */
 - (void)enqueueJSCall:(NSString *)moduleDotMethod args:(NSArray *)args
 {
@@ -1083,12 +1089,10 @@ - (void)enqueueJSCall:(NSString *)moduleDotMethod args:(NSArray *)args
   NSNumber *methodID = RCTLocalMethodIDs[moduleDotMethod];
   RCTAssert(methodID != nil, @"Method '%@' not registered.", moduleDotMethod);
 
-  if (!_loading) {
-    [self _invokeAndProcessModule:@"BatchedBridge"
-                           method:@"callFunctionReturnFlushedQueue"
-                        arguments:@[moduleID, methodID, args ?: @[]]
-                          context:RCTGetExecutorID(_javaScriptExecutor)];
-  }
+  [self _invokeAndProcessModule:@"BatchedBridge"
+                         method:@"callFunctionReturnFlushedQueue"
+                      arguments:@[moduleID, methodID, args ?: @[]]
+                        context:RCTGetExecutorID(_javaScriptExecutor)];
 }
 
 /**
@@ -1106,10 +1110,17 @@ - (void)_immediatelyCallTimer:(NSNumber *)timer
 
   if (!_loading) {
 #if BATCHED_BRIDGE
-    [self _actuallyInvokeAndProcessModule:@"BatchedBridge"
-                                   method:@"callFunctionReturnFlushedQueue"
-                                arguments:@[moduleID, methodID, @[@[timer]]]
-                                  context:RCTGetExecutorID(_javaScriptExecutor)];
+    dispatch_block_t block = ^{
+      [self _actuallyInvokeAndProcessModule:@"BatchedBridge"
+                                     method:@"callFunctionReturnFlushedQueue"
+                                  arguments:@[moduleID, methodID, @[@[timer]]]
+                                    context:RCTGetExecutorID(_javaScriptExecutor)];
+    };
+    if ([_javaScriptExecutor respondsToSelector:@selector(executeAsyncBlockOnJavaScriptQueue:)]) {
+      [_javaScriptExecutor executeAsyncBlockOnJavaScriptQueue:block];
+    } else {
+      [_javaScriptExecutor executeBlockOnJavaScriptQueue:block];
+    }
 
 #else
 
@@ -1163,33 +1174,83 @@ - (void)dispatchBlock:(dispatch_block_t)block forModule:(NSNumber *)moduleID
   }
 }
 
+/**
+ * Called by enqueueJSCall from any thread, or from _immediatelyCallTimer,
+ * on the JS thread, but only in non-batched mode.
+ */
 - (void)_invokeAndProcessModule:(NSString *)module method:(NSString *)method arguments:(NSArray *)args context:(NSNumber *)context
 {
 #if BATCHED_BRIDGE
-  RCTProfileBeginEvent();
 
-  if ([module isEqualToString:@"RCTEventEmitter"]) {
-    for (NSDictionary *call in _scheduledCalls) {
-      if ([call[@"module"] isEqualToString:module] && [call[@"method"] isEqualToString:method] && [call[@"args"][0] isEqualToString:args[0]]) {
-        [_scheduledCalls removeObject:call];
+  __weak NSMutableArray *weakScheduledCalls = _scheduledCalls;
+  __weak RCTSparseArray *weakScheduledCallbacks = _scheduledCallbacks;
+
+  [_javaScriptExecutor executeBlockOnJavaScriptQueue:^{
+    RCTProfileBeginEvent();
+
+    NSMutableArray *scheduledCalls = weakScheduledCalls;
+    RCTSparseArray *scheduledCallbacks = weakScheduledCallbacks;
+    if (!scheduledCalls || !scheduledCallbacks) {
+      return;
+    }
+
+    /**
+     * Event deduping
+     *
+     * Right now we make a lot of assumptions about the arguments structure
+     * so just iterate if it's a `callFunctionReturnFlushedQueue()`
+     */
+    if ([method isEqualToString:@"callFunctionReturnFlushedQueue"]) {
+      NSString *moduleName = RCTLocalModuleNames[[args[0] integerValue]];
+      /**
+       * Keep going if it any event emmiter, e.g. RCT(Device|NativeApp)?EventEmitter
+       */
+      if ([moduleName hasSuffix:@"EventEmitter"]) {
+        for (NSDictionary *call in [scheduledCalls copy]) {
+          NSArray *callArgs = call[@"args"];
+          /**
+           * If it's the same module && method call on the bridge &&
+           * the same EventEmitter module && method
+           */
+          if (
+            [call[@"module"] isEqualToString:module] &&
+            [call[@"method"] isEqualToString:method] &&
+            [callArgs[0] isEqual:args[0]] &&
+            [callArgs[1] isEqual:args[1]]
+          ) {
+            /**
+             * args[2] contains the actual arguments for the event call, where
+             * args[2][0] is the target for RCTEventEmitter or the eventName
+             *   for the other EventEmitters
+             * if RCTEventEmitter we need to compare args[2][1] that will be
+             *   the eventName
+             */
+            if (
+              [args[2][0] isEqual:callArgs[2][0]] &&
+              ([moduleName isEqualToString:@"RCTEventEmitter"] ? [args[2][1] isEqual:callArgs[2][1]] : YES)
+            ) {
+              [scheduledCalls removeObject:call];
+            }
+          }
+        }
       }
     }
-  }
 
-  id call = @{
-    @"module": module,
-    @"method": method,
-    @"args": args,
-    @"context": context ?: @0,
-  };
+    id call = @{
+      @"module": module,
+      @"method": method,
+      @"args": args,
+      @"context": context ?: @0,
+    };
 
-  if ([method isEqualToString:@"invokeCallbackAndReturnFlushedQueue"]) {
-    _scheduledCallbacks[args[0]] = call;
-  } else {
-    [_scheduledCalls addObject:call];
-  }
+    if ([method isEqualToString:@"invokeCallbackAndReturnFlushedQueue"]) {
+      scheduledCallbacks[args[0]] = call;
+    } else {
+      [scheduledCalls addObject:call];
+    }
 
-  RCTProfileEndEvent(@"enqueue_call", @"objc_call", call);
+    RCTProfileEndEvent(@"enqueue_call", @"objc_call", call);
+  }];
 }
 
 - (void)_actuallyInvokeAndProcessModule:(NSString *)module method:(NSString *)method arguments:(NSArray *)args context:(NSNumber *)context

React/Base/RCTJavaScriptExecutor.h

@@ -49,6 +49,15 @@ typedef void (^RCTJavaScriptCallback)(id json, NSError *error);
  */
 - (void)executeBlockOnJavaScriptQueue:(dispatch_block_t)block;
 
+@optional
+
+/**
+ * Special case for Timers + ContextExecutor - instead of the default
+ *   if jsthread then call else dispatch call on jsthread
+ * ensure the call is made async on the jsthread
+ */
+- (void)executeAsyncBlockOnJavaScriptQueue:(dispatch_block_t)block;
+
 @end
 
 static const char *RCTJavaScriptExecutorID = "RCTJavaScriptExecutorID";

React/Executors/RCTContextExecutor.m

@@ -312,12 +312,20 @@ - (void)executeApplicationScript:(NSString *)script
 
 - (void)executeBlockOnJavaScriptQueue:(dispatch_block_t)block
 {
-  /**
-   * Always dispatch async, ensure there are no sync calls on the JS thread
-   * otherwise timers can cause a deadlock
-   */
-  [self performSelector:@selector(_runBlock:)
-               onThread:_javaScriptThread withObject:block waitUntilDone:NO];
+   if ([NSThread currentThread] != _javaScriptThread) {
+     [self performSelector:@selector(executeBlockOnJavaScriptQueue:)
+                  onThread:_javaScriptThread withObject:block waitUntilDone:NO];
+   } else {
+     block();
+   }
+}
+
+- (void)executeAsyncBlockOnJavaScriptQueue:(dispatch_block_t)block
+{
+  [self performSelector:@selector(executeBlockOnJavaScriptQueue:)
+               onThread:_javaScriptThread
+             withObject:block
+          waitUntilDone:NO];
 }
 
 - (void)_runBlock:(dispatch_block_t)block