Asynchronously calculate User-Agent

Sources/Core/GTLRService.m

@@ -219,6 +219,7 @@ @implementation GTLRService {
   NSString *_overrideUserAgent;
   NSDictionary *_serviceProperties;  // Properties retained for the convenience of the client app.
   NSUInteger _uploadChunkSize;       // Only applies to resumable chunked uploads.
+  dispatch_queue_t _requestCreationQueue;
 }
 
 @synthesize additionalHTTPHeaders = _additionalHTTPHeaders,
@@ -250,6 +251,9 @@ - (instancetype)init {
   if (self) {
     _parseQueue = dispatch_queue_create("com.google.GTLRServiceParse", DISPATCH_QUEUE_SERIAL);
     _callbackQueue = dispatch_get_main_queue();
+    _requestCreationQueue =
+        dispatch_queue_create("com.google.GTLRServiceRequestCreation", DISPATCH_QUEUE_SERIAL);
+
     _fetcherService = [[GTMSessionFetcherService alloc] init];
 
     // Make the session fetcher use a background delegate queue instead of bouncing
@@ -319,10 +323,26 @@ - (void)setMainBundleIDRestrictionWithAPIKey:(NSString *)apiKey {
   self.APIKeyRestrictionBundleID = [[NSBundle mainBundle] bundleIdentifier];
 }
 
-- (NSMutableURLRequest *)requestForURL:(NSURL *)url
-                                  ETag:(NSString *)etag
-                            httpMethod:(NSString *)httpMethod
-                                ticket:(GTLRServiceTicket *)ticket {
+- (void)requestForURL:(NSURL *)url
+                 ETag:(NSString *)etag
+           httpMethod:(NSString *)httpMethod
+               ticket:(GTLRServiceTicket *)ticket
+           completion:(void (^)(NSMutableURLRequest *))completion {
+  dispatch_async(_requestCreationQueue, ^{
+    NSMutableURLRequest *request = [self createRequestForURL:url
+                                                        ETag:etag
+                                                  httpMethod:httpMethod
+                                                      ticket:ticket];
+    completion(request);
+  });
+}
+
+- (NSMutableURLRequest *)createRequestForURL:(NSURL *)url
+                                        ETag:(NSString *)etag
+                                  httpMethod:(NSString *)httpMethod
+                                      ticket:(GTLRServiceTicket *)ticket {
+  // This method may block, so make sure it's not on the caller's queue when executing a query.
+  dispatch_assert_queue_debug(_requestCreationQueue);
 
   // subclasses may add headers to this
   NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url
@@ -371,19 +391,20 @@ - (NSMutableURLRequest *)requestForURL:(NSURL *)url
   return request;
 }
 
-// objectRequestForURL returns an NSMutableURLRequest for a GTLRObject
+// objectRequestForURL asynchronously returns an NSMutableURLRequest for a GTLRObject
 //
 // the object is the object being sent to the server, or nil;
 // the http method may be nil for get, or POST, PUT, DELETE
 
-- (NSMutableURLRequest *)objectRequestForURL:(NSURL *)url
-                                      object:(GTLRObject *)object
-                                 contentType:(NSString *)contentType
-                               contentLength:(NSString *)contentLength
-                                        ETag:(NSString *)etag
-                                  httpMethod:(NSString *)httpMethod
-                           additionalHeaders:(NSDictionary *)additionalHeaders
-                                      ticket:(GTLRServiceTicket *)ticket {
+- (void)objectRequestForURL:(NSURL *)url
+                     object:(GTLRObject *)object
+                contentType:(NSString *)contentType
+              contentLength:(NSString *)contentLength
+                       ETag:(NSString *)etag
+                 httpMethod:(NSString *)httpMethod
+          additionalHeaders:(NSDictionary *)additionalHeaders
+                     ticket:(GTLRServiceTicket *)ticket
+                 completion:(void (^)(NSMutableURLRequest *))completion {
   if (object) {
     // if the object being sent has an etag, add it to the request header to
     // avoid retrieving a duplicate or to avoid writing over an updated
@@ -396,10 +417,23 @@ - (NSMutableURLRequest *)objectRequestForURL:(NSURL *)url
     }
   }
 
-  NSMutableURLRequest *request = [self requestForURL:url
-                                                ETag:etag
-                                          httpMethod:httpMethod
-                                              ticket:ticket];
+  [self requestForURL:url
+                 ETag:etag
+           httpMethod:httpMethod
+               ticket:ticket
+           completion:^(NSMutableURLRequest *request) {
+             [self handleRequestCompletion:request
+                               contentType:contentType
+                             contentLength:contentLength
+                         additionalHeaders:additionalHeaders];
+             completion(request);
+           }];
+}
+
+- (void)handleRequestCompletion:(NSMutableURLRequest *)request
+                    contentType:(NSString *)contentType
+                  contentLength:(NSString *)contentLength
+              additionalHeaders:(NSDictionary<NSString *, NSString *> *)additionalHeaders {
   [request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
   [request setValue:contentType forHTTPHeaderField:@"Content-Type"];
 
@@ -421,13 +455,25 @@ - (NSMutableURLRequest *)objectRequestForURL:(NSURL *)url
     NSString *value = [headers objectForKey:key];
     [request setValue:value forHTTPHeaderField:key];
   }
-
-  return request;
 }
 
 #pragma mark -
 
 - (NSMutableURLRequest *)requestForQuery:(GTLRQuery *)query {
+  dispatch_semaphore_t requestCompleteSemaphore = dispatch_semaphore_create(0);
+
+  __block NSMutableURLRequest *result;
+  [self requestForQuery:query
+             completion:^(NSMutableURLRequest *request) {
+               result = request;
+               dispatch_semaphore_signal(requestCompleteSemaphore);
+             }];
+
+  dispatch_semaphore_wait(requestCompleteSemaphore, DISPATCH_TIME_FOREVER);
+  return result;
+}
+
+- (void)requestForQuery:(GTLRQuery *)query completion:(void (^)(NSMutableURLRequest *))completion {
   GTLR_DEBUG_ASSERT(query.bodyObject == nil,
                     @"requestForQuery: supports only GET methods, but was passed: %@", query);
   GTLR_DEBUG_ASSERT(query.uploadParameters == nil,
@@ -446,10 +492,17 @@ - (NSMutableURLRequest *)requestForQuery:(GTLRQuery *)query {
                      queryParameters:queryParameters];
   }
 
-  NSMutableURLRequest *request = [self requestForURL:url
-                                                ETag:nil
-                                          httpMethod:query.httpMethod
-                                              ticket:nil];
+  [self requestForURL:url
+                 ETag:nil
+           httpMethod:query.httpMethod
+               ticket:nil
+           completion:^(NSMutableURLRequest *request) {
+             [self handleRequestCompletion:request forQuery:query];
+             completion(request);
+           }];
+}
+
+- (void)handleRequestCompletion:(NSMutableURLRequest *)request forQuery:(GTLRQuery *)query {
   NSString *apiRestriction = self.APIKeyRestrictionBundleID;
   if ([apiRestriction length] > 0) {
     [request setValue:apiRestriction forHTTPHeaderField:kXIosBundleIdHeader];
@@ -466,8 +519,6 @@ - (NSMutableURLRequest *)requestForQuery:(GTLRQuery *)query {
     NSString *value = [headers objectForKey:key];
     [request setValue:value forHTTPHeaderField:key];
   }
-
-  return request;
 }
 
 // common fetch starting method
@@ -574,14 +625,6 @@ - (GTLRServiceTicket *)fetchObjectWithURL:(NSURL *)targetURL
     }
   }
 
-  NSURLRequest *request = [self objectRequestForURL:targetURL
-                                             object:bodyObject
-                                        contentType:contentType
-                                      contentLength:contentLength
-                                               ETag:etag
-                                         httpMethod:httpMethod
-                                  additionalHeaders:additionalHeaders
-                                             ticket:ticket];
   ticket.postedObject = bodyObject;
   ticket.executingQuery = executingQuery;
 
@@ -591,10 +634,39 @@ - (GTLRServiceTicket *)fetchObjectWithURL:(NSURL *)targetURL
     ticket.originalQuery = originalQuery;
   }
 
+  [self objectRequestForURL:targetURL
+                     object:bodyObject
+                contentType:contentType
+              contentLength:contentLength
+                       ETag:etag
+                 httpMethod:httpMethod
+          additionalHeaders:additionalHeaders
+                     ticket:ticket
+                 completion:^(NSMutableURLRequest *request) {
+                   [self handleObjectRequestCompletionWithRequest:request
+                                                      objectClass:objectClass
+                                                       dataToPost:dataToPost
+                                                     mayAuthorize:mayAuthorize
+                                                completionHandler:completionHandler
+                                                   executingQuery:executingQuery
+                                                           ticket:ticket];
+                 }];
+
+  return ticket;
+}
+
+- (void)handleObjectRequestCompletionWithRequest:(NSMutableURLRequest *)request
+                                     objectClass:(Class)objectClass
+                                      dataToPost:(NSData *)dataToPost
+                                    mayAuthorize:(BOOL)mayAuthorize
+                               completionHandler:(GTLRServiceCompletionHandler)completionHandler
+                                  executingQuery:(id<GTLRQueryProtocol>)executingQuery
+                                          ticket:(GTLRServiceTicket *)ticket {
   // Some proxy servers (and some web servers) have issues with GET URLs being
   // too long, trap that and move the query parameters into the body. The
   // uploadParams and dataToPost should be nil for a GET, but playing it safe
   // and confirming.
+  GTLRUploadParameters *uploadParams = executingQuery.uploadParameters;
   NSString *requestHTTPMethod = request.HTTPMethod;
   BOOL isDoingHTTPGet =
       (requestHTTPMethod == nil
@@ -630,7 +702,7 @@ - (GTLRServiceTicket *)fetchObjectWithURL:(NSURL *)targetURL
                         testBlock:testBlock
                        dataToPost:dataToPost
                 completionHandler:completionHandler];
-    return ticket;
+    return;
   }
 
   GTMSessionFetcherService *fetcherService = ticket.fetcherService;
@@ -814,24 +886,13 @@ - (GTLRServiceTicket *)fetchObjectWithURL:(NSURL *)targetURL
     }
 
     [self handleParsedObjectForFetcher:fetcher
-                        executingQuery:executingQuery
-                                ticket:ticket
-                                 error:error
-                          parsedObject:nil
-       hasSentParsingStartNotification:NO
-                     completionHandler:completionHandler];
+                         executingQuery:executingQuery
+                                 ticket:ticket
+                                  error:error
+                           parsedObject:nil
+        hasSentParsingStartNotification:NO
+                      completionHandler:completionHandler];
   }];  // fetcher completion handler
-
-  // If something weird happens and the networking callbacks have been called
-  // already synchronously, we don't want to return the ticket since the caller
-  // will never know when to stop retaining it, so we'll make sure the
-  // success/failure callbacks have not yet been called by checking the
-  // ticket
-  if (ticket.hasCalledCallback) {
-    return nil;
-  }
-
-  return ticket;
 }
 
 - (GTMSessionUploadFetcher *)uploadFetcherWithRequest:(NSURLRequest *)request

Sources/Core/Public/GoogleAPIClientForREST/GTLRService.h

@@ -384,7 +384,29 @@ typedef void (^GTLRServiceTestBlock)(GTLRServiceTicket *testTicket,
  *
  *  @return A request suitable for use with @c GTMSessionFetcher or @c NSURLSession
  */
-- (NSMutableURLRequest *)requestForQuery:(GTLRQuery *)query;
+- (NSMutableURLRequest *)requestForQuery:(GTLRQuery *)query
+    __attribute__((deprecated("Blocks the caller to calculate the User-Agent. Use "
+                              "-requestForQuery:completion: instead.")));
+
+/**
+ *  Creates a NSURLRequest from the query object and from properties on this service
+ *  (additionalHTTPHeaders, additionalURLQueryParameters, APIKey) without executing
+ *  it. This can be useful for using @c GTMSessionFetcher or @c NSURLSession to
+ *  perform the fetch.
+ *
+ *  For requests to non-public resources, the request will not yet be authorized;
+ *  that can be done using the GTLR service's authorizer. Creating a @c GTMSessionFetcher
+ *  from the GTLRService's @c fetcherService will take care of authorization as well.
+ *
+ *  This works only for GET queries, and only for an individual query, not a batch query.
+ *
+ *  @note @c Unlike executeQuery:, requestForQuery: does not release the query's callback blocks.
+ *
+ *  @param query The query used to create the request.
+ *  @param completion Completion invoked with the URL request suitable for use
+ *  with with @c GTMSessionFetcher or @c NSURLSession
+ */
+- (void)requestForQuery:(GTLRQuery *)query completion:(void (^)(NSMutableURLRequest *))completion;
 
 #pragma mark User Properties