JS thread and Runloop in RN 47

Rcbridge is initialized with a declaration of a CADisplayLink

_jsDisplayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(_jsThreadUpdate:)];

In the _jsThreadUpdate function, the interface updates are processed. This CADisplayLink is then added to the runloop corresponding to the JS thread.

- (void)addToRunLoop:(NSRunLoop *)runLoop{  _runLoop = runLoop;  [_jsDisplayLink addToRunLoop:runLoop forMode:NSRunLoopCommonModes];}

Rctcxxbridge declares a thread

  _jsThread = [[NSThread alloc] initWithTarget:self                                      selector:@selector(runJSRunLoop)                                        object:nil];  _jsThread.name = RCTJSThreadName;  _jsThread.qualityOfService = NSOperationQualityOfServiceUserInteractive;  [_jsThread start];

and declared for this thread to be given to Runloop.

// copy thread name to pthread namepthread_setname_np([NSThread currentThread].name.UTF8String);// Set up a dummy runloop source to avoid spinningCFRunLoopSourceContext noSpinCtx = {0, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL};CFRunLoopSourceRef noSpinSource = CFRunLoopSourceCreate(NULL, 0, &noSpinCtx);CFRunLoopAddSource(CFRunLoopGetCurrent(), noSpinSource, kCFRunLoopDefaultMode);CFRelease(noSpinSource);RCT_PROFILE_END_EVENT(RCTProfileTagAlways, @"");// run the run loopwhile (kCFRunLoopRunStopped != CFRunLoopRunInMode(kCFRunLoopDefaultMode, ((NSDate *)[NSDate distantFuture]).timeIntervalSinceReferenceDate, NO)) {  RCTAssert(NO, @"not reached assertion"); // runloop spun. that's bad.}

The method of Runloop invocation performSelector

?

As follows, the reason is because of the following call:

  if ([NSThread currentThread] == _jsThread) {    [self _tryAndHandleError:block];  } else {    [self performSelector:@selector(_tryAndHandleError:)          onThread:_jsThread          withObject:block          waitUntilDone:NO];  }

Perform a function on the Runloop

  CFRunLoopPerformBlock(m_cfRunLoop, kCFRunLoopCommonModes, ^{ func(); });

Enqueues a block object on a given runloop to is executed as the Runloop cycles in specified modes.

Put CADisplayLinkAdd to the specified Runloop, and then the corresponding

?

_jsDisplayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(_jsThreadUpdate:)];[_jsDisplayLink addToRunLoop:runLoop forMode:NSRunLoopCommonModes];

JS thread and Runloop in RN 47