Alda/backoff retry fix (#180)

* Add backoff retry for http requests with invalid status code (i.e., >= 400).

* Added datafile download tests when backoff retry is enabled via status code 400 and internal error.

* Added tests for event dispatch with backoff retry triggered by internal error and status code 400.

* Removed status code 400 backoff retry test for datafile manager and event dispatcher. This is a little redundant and takes a lot of time. Also bumped up the timeout for the backoff retry tests.

* Fixed event error check in get all events -- this was causing an exception to be thrown.

* Decreased retries. A total of three tries should suffice.

* Use a strong reference to self since we are doing a recursive call and the referencing object (the network service manager) does not necessary have a strong reference to the HTTPRequestManager. This was causing the recursion to not complete and, the call back for the datafile download and event dispatch during a backoff retry never returned the callback.

* Bumped the wait time for the event dispatcher backoff retry.

* Removed the strong reference for the http request manager blocks. Resolved the recursion failure by added url parameters to the http request request manager so that the network service can create and own the object. Fixed the corresponding tests for the http request manager.

* Fixed the event data store error chck.

* Changed the network service to own the http request manager.

* Cleaned up the datafile manager tests.

* Improved logic for response and error checks for backoff retry per Kelly's suggestion.

Author: alda-optimizely

OptimizelySDKCore/OptimizelySDKCore/OPTLYHTTPRequestManager.h

@@ -26,46 +26,49 @@ typedef void (^OPTLYHTTPRequestManagerResponse)(NSData * _Nullable data, NSURLRe
 
 @interface OPTLYHTTPRequestManager : NSObject
 
-@property (nonatomic, strong, nonnull) NSURL *url;
-
-/// Network service must be initialized with a URL
-- (nullable id)initWithURL:(nonnull NSURL *)url;
-
 /**
  * GET data from the URL inititialized
  *
+ * @param url The url to make the GET request.
  * @param completion The completion block of type OPTLYHTTPRequestManagerResponse
  */
-- (void)GETWithCompletion:(nullable OPTLYHTTPRequestManagerResponse)completion;
+- (void)GETWithURL:(nonnull  NSURL *)url
+        completion:(nullable OPTLYHTTPRequestManagerResponse)completion;
 
 /**
  * GET data from the URL inititialized with the option of doing an exponential backoff and retry
  *
+ * @param url The url to make the GET request.
  * @param backoffRetryInterval The backoff retry time interval for the exponential backoff (in ms)
  * @param retries The total number of backoff retry attempts
  * @param completion The completion block of type OPTLYHTTPRequestManagerResponse
  */
 - (void)GETWithBackoffRetryInterval:(NSInteger)backoffRetryInterval
+                                url:(nonnull NSURL *)url
                             retries:(NSInteger)retries
                   completionHandler:(nullable OPTLYHTTPRequestManagerResponse)completion;
 /**
  * GET data with parameters
  *
+ * @param url The url to make the GET request.
  * @param parameters Dictionary of GET request parameter values
  * @param completion The completion block of type OPTLYHTTPRequestManagerResponse
  */
 - (void)GETWithParameters:(nullable NSDictionary *)parameters
+                      url:(nonnull NSURL *)url
         completionHandler:(nullable OPTLYHTTPRequestManagerResponse)completion;
 
 /**
  * GET data with parameters with the option of doing an exponential backoff and retry
  *
+ * @param url The url to make the GET request.
  * @param parameters Dictionary of GET request parameter values
  * @param backoffRetryInterval The backoff retry time interval the exponential backoff (in ms)
  * @param retries The total number of backoff retry attempts
  * @param completion The completion block of type OPTLYHTTPRequestManagerResponse
  */
 - (void)GETWithParameters:(nullable NSDictionary *)parameters
+                      url:(nonnull NSURL *)url
      backoffRetryInterval:(NSInteger)backoffRetryInterval
                   retries:(NSInteger)retries
         completionHandler:(nullable OPTLYHTTPRequestManagerResponse)completion;
@@ -76,10 +79,12 @@ typedef void (^OPTLYHTTPRequestManagerResponse)(NSData * _Nullable data, NSURLRe
  * "If-Modified-Since" field, an entity will not be returned from the server; instead,
  * a 304 (not modified) response will be returned without any message-body.
  *
+ * @param url The url to make the GET request.
  * @param lastModifiedDate - The date since the URL request was last modified
  * @param completion - The completion block of type OPTLYHTTPRequestManagerResponse
  */
 - (void)GETIfModifiedSince:(nonnull NSString *)lastModifiedDate
+                       url:(nonnull NSURL *)url
          completionHandler:(nullable OPTLYHTTPRequestManagerResponse)completion;
 
 /**
@@ -88,34 +93,40 @@ typedef void (^OPTLYHTTPRequestManagerResponse)(NSData * _Nullable data, NSURLRe
  * "If-Modified-Since" field, an entity will not be returned from the server; instead,
  * a 304 (not modified) response will be returned without any message-body.
  *
+ * @param url The url to make the GET request.
  * @param lastModifiedDate The date since the URL request was last modified
  * @param backoffRetryInterval The backoff retry time interval the exponential backoff (in ms)
  * @param retries The total number of backoff retry attempts
  * @param completion The completion block of type OPTLYHTTPRequestManagerResponse
  */
 - (void)GETIfModifiedSince:(nonnull NSString *)lastModifiedDate
+                       url:(nonnull NSURL *)url
       backoffRetryInterval:(NSInteger)backoffRetryInterval
                    retries:(NSInteger)retries
          completionHandler:(nullable OPTLYHTTPRequestManagerResponse)completion;
 
 /**
  * POST data with parameters
  *
+ * @param url The url to make the POST request.
  * @param parameters Dictionary of POST request parameter values
  * @param completion The completion block of type OPTLYHTTPRequestManagerResponse
  */
 - (void)POSTWithParameters:(nonnull NSDictionary *)parameters
+                       url:(nonnull NSURL *)url
          completionHandler:(nullable OPTLYHTTPRequestManagerResponse)completion;
 
 /**
  * POST data with parameters with an exponential backoff and retry attempt
  *
+ * @param url The url to make the POST request.
  * @param parameters Dictionary of POST request parameter values
  * @param backoffRetryInterval The backoff retry time interval the exponential backoff (in ms)
  * @param retries The total number of backoff retry attempts
  * @param completion The completion block of type OPTLYHTTPRequestManagerResponse
  */
 - (void)POSTWithParameters:(nonnull NSDictionary *)parameters
+                       url:(nonnull NSURL *)url
       backoffRetryInterval:(NSInteger)backoffRetryInterval
                    retries:(NSInteger)retries
          completionHandler:(nullable OPTLYHTTPRequestManagerResponse)completion;

OptimizelySDKCore/OptimizelySDKCore/OPTLYHTTPRequestManager.m

@@ -42,14 +42,6 @@ - (id)init
     return self;
 }
 
-- (id)initWithURL:(NSURL *)url
-{
-    if (self = [super init]) {
-        _url = url;
-    }
-    return self;
-}
-
 // Create global serial GCD queue for NSURL tasks
 dispatch_queue_t networkTasksQueue()
 {
@@ -62,29 +54,33 @@ dispatch_queue_t networkTasksQueue()
 }
 
 # pragma mark - GET
-- (void)GETWithCompletion:(OPTLYHTTPRequestManagerResponse)completion {
-    [self GETWithParameters:nil completionHandler:completion];
+- (void)GETWithURL:(NSURL *)url
+        completion:(OPTLYHTTPRequestManagerResponse)completion {
+    [self GETWithParameters:nil url:url completionHandler:completion];
 }
 
 - (void)GETWithBackoffRetryInterval:(NSInteger)backoffRetryInterval
+                                url:(NSURL *)url
                             retries:(NSInteger)retries
                   completionHandler:(OPTLYHTTPRequestManagerResponse)completion
 {
     // TODO: Wrap this in a TEST preprocessor definition
     self.delaysTest = [NSMutableArray new];
 
     [self GETWithParameters:nil
+                        url:url
        backoffRetryInterval:backoffRetryInterval
                     retries:retries
           completionHandler:completion];
 }
 
 # pragma mark - GET (with parameters)
 - (void)GETWithParameters:(NSDictionary *)parameters
+                      url:(NSURL *)url
         completionHandler:(OPTLYHTTPRequestManagerResponse)completion
 {
     NSURLSession *ephemeralSession = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration ephemeralSessionConfiguration]];
-    NSURL *urlWithParameterQuery = [self buildQueryURL:self.url withParameters:parameters];
+    NSURL *urlWithParameterQuery = [self buildQueryURL:url withParameters:parameters];
     NSURLSessionDataTask *downloadTask = [ephemeralSession dataTaskWithURL:urlWithParameterQuery
                                                          completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                              if (completion) {
@@ -96,6 +92,7 @@ - (void)GETWithParameters:(NSDictionary *)parameters
 }
 
 - (void)GETWithParameters:(NSDictionary *)parameters
+                      url:(NSURL *)url
      backoffRetryInterval:(NSInteger)backoffRetryInterval
                   retries:(NSInteger)retries
         completionHandler:(OPTLYHTTPRequestManagerResponse)completion
@@ -104,6 +101,7 @@ - (void)GETWithParameters:(NSDictionary *)parameters
     self.delaysTest = [NSMutableArray new];
 
     [self GETWithParameters:parameters
+                        url:url
        backoffRetryInterval:backoffRetryInterval
                     retries:retries
           completionHandler:completion
@@ -112,6 +110,7 @@ - (void)GETWithParameters:(NSDictionary *)parameters
 }
 
 - (void)GETWithParameters:(NSDictionary *)parameters
+                      url:(NSURL *)url
      backoffRetryInterval:(NSInteger)backoffRetryInterval
                   retries:(NSInteger)retries
         completionHandler:(OPTLYHTTPRequestManagerResponse)completion
@@ -141,32 +140,36 @@ - (void)GETWithParameters:(NSDictionary *)parameters
     }
 
     __weak typeof(self) weakSelf = self;
-    [self GETWithParameters:parameters completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
-        if (error) {
-            dispatch_time_t delayTime = [weakSelf backoffDelay:backoffRetryAttempt
-                                          backoffRetryInterval:backoffRetryInterval];
-            dispatch_after(delayTime, networkTasksQueue(), ^(void){
-                
-                [weakSelf GETWithParameters:parameters
-                       backoffRetryInterval:backoffRetryInterval
-                                    retries:retries
-                          completionHandler:completion
-                        backoffRetryAttempt:backoffRetryAttempt+1
-                                      error:error];
-            });
-        } else {
-            if (completion) {
-                completion(data, response, error);
-            }
-        }
-    }];
+    [self GETWithParameters:parameters
+                        url:url
+          completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
+              if (error) {
+                  dispatch_time_t delayTime = [weakSelf backoffDelay:backoffRetryAttempt
+                                                backoffRetryInterval:backoffRetryInterval];
+                  dispatch_after(delayTime, networkTasksQueue(), ^(void){
+                      
+                      [weakSelf GETWithParameters:parameters
+                                              url:url
+                             backoffRetryInterval:backoffRetryInterval
+                                          retries:retries
+                                completionHandler:completion
+                              backoffRetryAttempt:backoffRetryAttempt+1
+                                            error:error];
+                  });
+              } else {
+                  if (completion) {
+                      completion(data, response, error);
+                  }
+              }
+          }];
 }
 
 # pragma mark - GET (if modified)
 - (void)GETIfModifiedSince:(NSString *)lastModifiedDate
+                       url:(NSURL *)url
          completionHandler:(OPTLYHTTPRequestManagerResponse)completion
 {
-    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[self url]];
+    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
     [request setValue:lastModifiedDate forHTTPHeaderField:@"If-Modified-Since"];
 
     NSURLSession *ephemeralSession = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration ephemeralSessionConfiguration]];
@@ -180,6 +183,7 @@ - (void)GETIfModifiedSince:(NSString *)lastModifiedDate
 }
 
 - (void)GETIfModifiedSince:(NSString *)lastModifiedDate
+                       url:(NSURL *)url
       backoffRetryInterval:(NSInteger)backoffRetryInterval
                    retries:(NSInteger)retries
          completionHandler:(OPTLYHTTPRequestManagerResponse)completion
@@ -188,6 +192,7 @@ - (void)GETIfModifiedSince:(NSString *)lastModifiedDate
     self.delaysTest = [NSMutableArray new];
 
     [self GETIfModifiedSince:lastModifiedDate
+                         url:url
         backoffRetryInterval:backoffRetryInterval
                      retries:retries
            completionHandler:completion
@@ -196,6 +201,7 @@ - (void)GETIfModifiedSince:(NSString *)lastModifiedDate
 }
 
 - (void)GETIfModifiedSince:(NSString *)lastModifiedDate
+                       url:(NSURL *)url
       backoffRetryInterval:(NSInteger)backoffRetryInterval
                    retries:(NSInteger)retries
          completionHandler:(OPTLYHTTPRequestManagerResponse)completion
@@ -224,33 +230,42 @@ - (void)GETIfModifiedSince:(NSString *)lastModifiedDate
     }
 
     __weak typeof(self) weakSelf = self;
-    [self GETIfModifiedSince:lastModifiedDate completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
-        if (error) {
-            dispatch_time_t delayTime = [weakSelf backoffDelay:backoffRetryAttempt
-                                          backoffRetryInterval:backoffRetryInterval];
-            dispatch_after(delayTime, networkTasksQueue(), ^(void){
-                [weakSelf GETIfModifiedSince:lastModifiedDate
-                        backoffRetryInterval:backoffRetryInterval
-                                     retries:retries
-                           completionHandler:completion
-                         backoffRetryAttempt:backoffRetryAttempt+1
-                                       error:error];
-            });
-        } else {
-            if (completion) {
-                completion(data, response, error);
-            }
-        }
-    }];
+    [self GETIfModifiedSince:lastModifiedDate
+                         url:url
+           completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
+               NSInteger statusCode = 503;
+               if (response != nil && error == nil) {
+                   NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
+                   statusCode = (long)[httpResponse statusCode];
+               }
+               if (error != nil || statusCode >= 400) {
+                   dispatch_time_t delayTime = [weakSelf backoffDelay:backoffRetryAttempt
+                                                 backoffRetryInterval:backoffRetryInterval];
+                   dispatch_after(delayTime, networkTasksQueue(), ^(void){
+                       [weakSelf GETIfModifiedSince:lastModifiedDate
+                                                url:url
+                               backoffRetryInterval:backoffRetryInterval
+                                            retries:retries
+                                  completionHandler:completion
+                                backoffRetryAttempt:backoffRetryAttempt+1
+                                              error:error];
+                   });
+               } else {
+                   if (completion) {
+                       completion(data, response, error);
+                   }
+               }
+           }];
 }
 
 
 # pragma mark - POST
 - (void)POSTWithParameters:(NSDictionary *)parameters
+                       url:(NSURL *)url
          completionHandler:(OPTLYHTTPRequestManagerResponse)completion
 {
     NSURLSession *ephemeralSession = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration ephemeralSessionConfiguration]];
-    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[self url]];
+    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
     [request setHTTPMethod:kHTTPRequestMethodPost];
 
     NSError *JSONSerializationError = nil;
@@ -277,6 +292,7 @@ - (void)POSTWithParameters:(NSDictionary *)parameters
 }
 
 - (void)POSTWithParameters:(nonnull NSDictionary *)parameters
+                       url:(NSURL *)url
       backoffRetryInterval:(NSInteger)backoffRetryInterval
                    retries:(NSInteger)retries
          completionHandler:(nullable OPTLYHTTPRequestManagerResponse)completion
@@ -285,6 +301,7 @@ - (void)POSTWithParameters:(nonnull NSDictionary *)parameters
     self.delaysTest = [NSMutableArray new];
 
     [self POSTWithParameters:parameters
+                         url:url
         backoffRetryInterval:backoffRetryInterval
                      retries:retries
            completionHandler:completion
@@ -293,6 +310,7 @@ - (void)POSTWithParameters:(nonnull NSDictionary *)parameters
 }
 
 - (void)POSTWithParameters:(NSDictionary *)parameters
+                       url:(NSURL *)url
       backoffRetryInterval:(NSInteger)backoffRetryInterval
                    retries:(NSInteger)retries
          completionHandler:(OPTLYHTTPRequestManagerResponse)completion
@@ -321,24 +339,27 @@ - (void)POSTWithParameters:(NSDictionary *)parameters
     }
 
     __weak typeof(self) weakSelf = self;
-    [self POSTWithParameters:parameters completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
-        if (error) {
-            dispatch_time_t delayTime = [weakSelf backoffDelay:backoffRetryAttempt
-                                          backoffRetryInterval:backoffRetryInterval];
-            dispatch_after(delayTime, networkTasksQueue(), ^(void){
-                [weakSelf POSTWithParameters:parameters
-                        backoffRetryInterval:backoffRetryInterval
-                                     retries:retries
-                           completionHandler:completion
-                         backoffRetryAttempt:backoffRetryAttempt+1
-                                       error:error];
-            });
-        } else {
-            if (completion) {
-                completion(data, response, error);
-            }
-        }
-    }];
+    [self POSTWithParameters:parameters
+                         url:url
+           completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
+               if (error) {
+                   dispatch_time_t delayTime = [weakSelf backoffDelay:backoffRetryAttempt
+                                                 backoffRetryInterval:backoffRetryInterval];
+                   dispatch_after(delayTime, networkTasksQueue(), ^(void){
+                       [weakSelf POSTWithParameters:parameters
+                                                url:url
+                               backoffRetryInterval:backoffRetryInterval
+                                            retries:retries
+                                  completionHandler:completion
+                                backoffRetryAttempt:backoffRetryAttempt+1
+                                              error:error];
+                   });
+               } else {
+                   if (completion) {
+                       completion(data, response, error);
+                   }
+               }
+           }];
 }
 
 # pragma mark - Helper Methods