Fixed "Unrecognized request token" red box

Summary: public

There was a race condition issue in RCTDownLoadTask whereby the request handler would sometimes call one of the delegate methods before setup was complete, causing an error to be logged because the request token had not been set, and causing te request to fail because the class was not yet set up.

This diff fixes that issue by adding an explicit `start` method to RCTDownloadTask, and changing the setup order to allow for the request to call back immediately without this being treated as an error.

Reviewed By: tadeuzagallo

Differential Revision: D2553628

fb-gh-sync-id: 5ca4e791574a632ccbf2e873e28ac88bffdf851d

Libraries/Image/RCTImageDownloader.m

@@ -96,6 +96,7 @@ RCT_EXPORT_MODULE()
   if (progressBlock) {
     task.downloadProgressBlock = progressBlock;
   }
+  [task start];
   return ^{ [task cancel]; };
 }
 

Libraries/Network/RCTDownloadTask.h

@@ -35,6 +35,7 @@ typedef void (^RCTURLRequestResponseBlock)(NSURLResponse *response);
                         handler:(id<RCTURLRequestHandler>)handler
                 completionBlock:(RCTURLRequestCompletionBlock)completionBlock NS_DESIGNATED_INITIALIZER;
 
+- (void)start;
 - (void)cancel;
 
 @end

Libraries/Network/RCTDownloadTask.m

@@ -29,18 +29,16 @@
   static NSUInteger requestID = 0;
 
   if ((self = [super init])) {
-    if (!(_requestToken = [handler sendRequest:request withDelegate:self])) {
-      return nil;
-    }
     _requestID = @(requestID++);
     _request = request;
     _handler = handler;
     _completionBlock = completionBlock;
-    _selfReference = self;
   }
   return self;
 }
 
+RCT_NOT_IMPLEMENTED(- (instancetype)init)
+
 - (void)invalidate
 {
   _selfReference = nil;
@@ -51,7 +49,15 @@
   _uploadProgressBlock = nil;
 }
 
-RCT_NOT_IMPLEMENTED(- (instancetype)init)
+- (void)start
+{
+  if (_requestToken == nil) {
+    if ([self validateRequestToken:[_handler sendRequest:_request
+                                            withDelegate:self]]) {
+      _selfReference = self;
+    }
+  }
+}
 
 - (void)cancel
 {
@@ -63,6 +69,12 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 
 - (BOOL)validateRequestToken:(id)requestToken
 {
+  if (_requestToken == nil) {
+    if (requestToken == nil) {
+      return NO;
+    }
+    _requestToken = requestToken;
+  }
   if (![requestToken isEqual:_requestToken]) {
     if (RCT_DEBUG) {
       RCTLogError(@"Unrecognized request token: %@ expected: %@", requestToken, _requestToken);

Libraries/Network/RCTNetworking.m

@@ -238,6 +238,8 @@ RCT_EXPORT_MODULE()
       cancellationBlock = callback(error, data ? @{@"body": data, @"contentType": RCTNullIfNil(response.MIMEType)} : nil);
     }];
 
+    [task start];
+
     __weak RCTDownloadTask *weakTask = task;
     return ^{
       [weakTask cancel];
@@ -362,6 +364,8 @@ RCT_EXPORT_MODULE()
     _tasksByRequestID[task.requestID] = task;
     responseSender(@[task.requestID]);
   }
+
+  [task start];
 }
 
 #pragma mark - Public API