Merge pull request #3 from microsoftgraph/vidadhee/RetryHandler

Add Retry Handler

Author: dadheech115

MSGraphCoreSDK/MSGraphCoreSDK.xcodeproj/project.pbxproj

@@ -12,6 +12,9 @@
 		E5069AD9211C1AD500432372 /* MSGraphCoreSDKTests.m in Sources */ = {isa = PBXBuildFile; fileRef = E5069AD8211C1AD500432372 /* MSGraphCoreSDKTests.m */; };
 		E5069ADB211C1AD500432372 /* MSGraphCoreSDK.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = E5DC73DA211412BF0040BAB6 /* MSGraphCoreSDK.framework */; };
 		E5069AE2211C323D00432372 /* MSURLSessionManagerTests.m in Sources */ = {isa = PBXBuildFile; fileRef = E5069AE1211C323D00432372 /* MSURLSessionManagerTests.m */; };
+		E51E616C216DE4D300F1B3C0 /* MSRetryHandler.h in Headers */ = {isa = PBXBuildFile; fileRef = E51E616A216DE4D300F1B3C0 /* MSRetryHandler.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		E51E616D216DE4D300F1B3C0 /* MSRetryHandler.m in Sources */ = {isa = PBXBuildFile; fileRef = E51E616B216DE4D300F1B3C0 /* MSRetryHandler.m */; };
+		E51E616F216E073F00F1B3C0 /* MSRetryHandlerTests.m in Sources */ = {isa = PBXBuildFile; fileRef = E51E616E216E073F00F1B3C0 /* MSRetryHandlerTests.m */; };
 		E52AD978212D27DC005FED47 /* MSURLSessionDataTask.m in Sources */ = {isa = PBXBuildFile; fileRef = E52AD970212D27DB005FED47 /* MSURLSessionDataTask.m */; };
 		E52AD979212D27DC005FED47 /* MSURLSessionTask.m in Sources */ = {isa = PBXBuildFile; fileRef = E52AD971212D27DB005FED47 /* MSURLSessionTask.m */; };
 		E52AD97A212D27DC005FED47 /* MSURLSessionUploadTask.h in Headers */ = {isa = PBXBuildFile; fileRef = E52AD972212D27DB005FED47 /* MSURLSessionUploadTask.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -71,6 +74,9 @@
 		E5069AD8211C1AD500432372 /* MSGraphCoreSDKTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MSGraphCoreSDKTests.m; sourceTree = "<group>"; };
 		E5069ADA211C1AD500432372 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		E5069AE1211C323D00432372 /* MSURLSessionManagerTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MSURLSessionManagerTests.m; sourceTree = "<group>"; };
+		E51E616A216DE4D300F1B3C0 /* MSRetryHandler.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MSRetryHandler.h; sourceTree = "<group>"; };
+		E51E616B216DE4D300F1B3C0 /* MSRetryHandler.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MSRetryHandler.m; sourceTree = "<group>"; };
+		E51E616E216E073F00F1B3C0 /* MSRetryHandlerTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MSRetryHandlerTests.m; sourceTree = "<group>"; };
 		E52AD970212D27DB005FED47 /* MSURLSessionDataTask.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MSURLSessionDataTask.m; sourceTree = "<group>"; };
 		E52AD971212D27DB005FED47 /* MSURLSessionTask.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MSURLSessionTask.m; sourceTree = "<group>"; };
 		E52AD972212D27DB005FED47 /* MSURLSessionUploadTask.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MSURLSessionUploadTask.h; sourceTree = "<group>"; };
@@ -156,6 +162,7 @@
 		E5069AC3211AACCD00432372 /* Implementations */ = {
 			isa = PBXGroup;
 			children = (
+				E5190C7F216DE371001699B5 /* RetryHandler */,
 				E5ECE0A12146655000A289C2 /* RedirectHandler */,
 				E5069AC4211AACED00432372 /* Authentication */,
 				E5DC73ED211418040040BAB6 /* HTTPProvider */,
@@ -198,6 +205,15 @@
 			path = MSGraphCoreSDKTests;
 			sourceTree = "<group>";
 		};
+		E5190C7F216DE371001699B5 /* RetryHandler */ = {
+			isa = PBXGroup;
+			children = (
+				E51E616A216DE4D300F1B3C0 /* MSRetryHandler.h */,
+				E51E616B216DE4D300F1B3C0 /* MSRetryHandler.m */,
+			);
+			path = RetryHandler;
+			sourceTree = "<group>";
+		};
 		E52AD96F212D271C005FED47 /* Session Tasks */ = {
 			isa = PBXGroup;
 			children = (
@@ -257,6 +273,7 @@
 				E573EE0A213427ED00C5E884 /* MSURLSessionTaskDelegateTests.m */,
 				E566782D2150BC4F00C6B7AE /* MSRedirectHandlerTests.m */,
 				E566782F2150E1AF00C6B7AE /* MSAuthenticationHandlerTests.m */,
+				E51E616E216E073F00F1B3C0 /* MSRetryHandlerTests.m */,
 			);
 			path = Implementations;
 			sourceTree = "<group>";
@@ -399,6 +416,7 @@
 				E5DC7406211418050040BAB6 /* MSURLSessionTaskDelegate.h in Headers */,
 				E5ECE09721427A6400A289C2 /* MSMiddlewareFactory.h in Headers */,
 				E5ECE0A42146657900A289C2 /* MSRedirectHandler.h in Headers */,
+				E51E616C216DE4D300F1B3C0 /* MSRetryHandler.h in Headers */,
 				E5DC73DF211412BF0040BAB6 /* MSGraphCoreSDK.h in Headers */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -503,6 +521,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				E573EE0D213525BA00C5E884 /* MSGraphWorkloadsTests.m in Sources */,
+				E51E616F216E073F00F1B3C0 /* MSRetryHandlerTests.m in Sources */,
 				E573EE072133FFF200C5E884 /* MSHTTPClientTests.m in Sources */,
 				E52AD9E6212E8845005FED47 /* MSGraphCoreSDKTests.h in Sources */,
 				E56678302150E1AF00C6B7AE /* MSAuthenticationHandlerTests.m in Sources */,
@@ -530,6 +549,7 @@
 				E52AD97F212D27DC005FED47 /* MSURLSessionDownloadTask.m in Sources */,
 				E5DC7405211418050040BAB6 /* MSURLSessionManager.m in Sources */,
 				E52AD979212D27DC005FED47 /* MSURLSessionTask.m in Sources */,
+				E51E616D216DE4D300F1B3C0 /* MSRetryHandler.m in Sources */,
 				E5DC7408211418050040BAB6 /* MSURLSessionTaskDelegate.m in Sources */,
 				E52AD97E212D27DC005FED47 /* MSURLSessionUploadTask.m in Sources */,
 				E52AD978212D27DC005FED47 /* MSURLSessionDataTask.m in Sources */,

MSGraphCoreSDK/MSGraphCoreSDK/Common/MSConstants.h

@@ -51,4 +51,14 @@ extern NSString *const MSErrorDomain;
 extern NSString *const MSErrorTooManyRedirectsFormatString;
 extern NSString *const MSErrorLocationHeaderNotFoundString;
 extern NSString *const MSErrorOperationUnsuccessfulString;
+
+extern NSString *const MSErrorTooManyRetries;
+extern NSString *const MSErrorTooManyRetriesFormatString;
+
+extern NSString *const HTTPMethodGet;
+extern NSString *const HTTPMethodPut;
+extern NSString *const HTTPMethodPatch;
+extern NSString *const HTTPMethodPost;
+extern NSString *const HTTPMethodDelete;
+
 #endif

MSGraphCoreSDK/MSGraphCoreSDK/Common/MSConstants.m

@@ -10,7 +10,18 @@
 
 NSString *const MSErrorDomain = @"com.microsoft.graph.errors";
 
-NSString *const MSErrorTooManyRedirectsFormatString = @"More than %d redirects encountered while sending the request.";
+NSString *const MSErrorTooManyRedirectsFormatString = @"More than %ld redirects encountered while sending the request.";
 
 NSString *const MSErrorLocationHeaderNotFoundString = @"There is no location header in the redirect response.";
 NSString *const MSErrorOperationUnsuccessfulString = @"Operation was unsuccessful.";
+
+NSString *const MSErrorTooManyRetries = @"Too many retries";
+
+NSString *const MSErrorTooManyRetriesFormatString = @"More than %ld retries encountered while sending the request.";
+
+
+ NSString *const HTTPMethodGet = @"GET";
+ NSString *const HTTPMethodPut = @"PUT";
+ NSString *const HTTPMethodPatch = @"PATCH";
+ NSString *const HTTPMethodPost = @"POST";
+ NSString *const HTTPMethodDelete = @"DELETE";

MSGraphCoreSDK/MSGraphCoreSDK/HTTPClient/MSClientFactory.m

@@ -7,6 +7,7 @@
 #import "MSURLSessionManager.h"
 #import "MSMiddlewareFactory.h"
 #import "MSRedirectHandler.h"
+#import "MSRetryHandler.h"
 
 @implementation MSClientFactory
 
@@ -20,10 +21,12 @@ +(MSHTTPClient *)createHTTPClientWithAuthenticationProvider:(id<MSAuthentication
     MSAuthenticationHandler *authenticationHandler = (MSAuthenticationHandler *)[MSMiddlewareFactory createMiddleware:MSMiddlewareTypeAuthentication];
     authenticationHandler.authProvider = authenticationProvider;
     MSRedirectHandler *redirectHandler = (MSRedirectHandler *)[MSMiddlewareFactory createMiddleware:MSMiddlewareTypeRedirect];
+    MSRetryHandler *retryHandler = (MSRetryHandler *)[MSMiddlewareFactory createMiddleware:MSMiddlewareTypeRetry];
     MSURLSessionManager *sessionManager = (MSURLSessionManager *)[MSMiddlewareFactory createMiddleware:MSMiddlewareTypeHTTP];
     //Creating a default chain
     [authenticationHandler setNext:redirectHandler];
-    [redirectHandler setNext:sessionManager];
+    [redirectHandler setNext:retryHandler];
+    [retryHandler setNext:sessionManager];
 
     return [MSClientFactory createHTTPClientWithMiddleware:authenticationHandler];
 }

MSGraphCoreSDK/MSGraphCoreSDK/HTTPClient/MSMiddlewareFactory.h

@@ -13,8 +13,9 @@
 typedef NS_ENUM(NSInteger, MSMiddlewareType)
 {
     MSMiddlewareTypeAuthentication,
+    MSMiddlewareTypeHTTP,
     MSMiddlewareTypeRedirect,
-    MSMiddlewareTypeHTTP
+    MSMiddlewareTypeRetry
 };
 
 /*

MSGraphCoreSDK/MSGraphCoreSDK/HTTPClient/MSMiddlewareFactory.m

@@ -6,6 +6,7 @@
 #import "MSURLSessionManager.h"
 #import "MSAuthenticationHandler.h"
 #import "MSRedirectHandler.h"
+#import "MSRetryHandler.h"
 
 @implementation MSMiddlewareFactory
 
@@ -28,6 +29,11 @@ @implementation MSMiddlewareFactory
             MSAuthenticationHandler *authenticationHandler = [[MSAuthenticationHandler alloc] init];
             return authenticationHandler;
         }
+        case MSMiddlewareTypeRetry:
+        {
+            MSRetryHandler *retryHandler = [[MSRetryHandler alloc] init];
+            return retryHandler;
+        }
         default:
             break;
     }

MSGraphCoreSDK/MSGraphCoreSDK/MSGraphCoreSDK.h

@@ -28,6 +28,7 @@ FOUNDATION_EXPORT const unsigned char MSGraphSDKVersionString[];
 #import "MSGraphCoreSDK/MSURLSessionTaskDelegate.h"
 #import "MSGraphCoreSDK/MSAuthenticationHandler.h"
 #import "MSGraphCoreSDK/MSRedirectHandler.h"
+#import "MSGraphCoreSDK/MSRetryHandler.h"
 
 #import "MSGraphCoreSDK/MSURLSessionTask.h"
 #import "MSGraphCoreSDK/MSURLSessionDataTask.h"

MSGraphCoreSDK/MSGraphCoreSDK/Middleware/Implementations/RetryHandler/MSRetryHandler.h

@@ -0,0 +1,14 @@
+//
+// Copyright (c) Microsoft Corporation. All Rights Reserved. Licensed under the MIT License. See License in the project root for license information.
+//
+
+#import <Foundation/Foundation.h>
+#import "MSGraphMiddleware.h"
+
+/*
+ This class provides the mechanism to handle retry response codes from Graph server. It is implmented as a middleware so it will be called during the execution of network calls.
+ */
+
+@interface MSRetryHandler : NSObject<MSGraphMiddleware>
+
+@end

MSGraphCoreSDK/MSGraphCoreSDK/Middleware/Implementations/RetryHandler/MSRetryHandler.m

@@ -0,0 +1,159 @@
+//
+// Copyright (c) Microsoft Corporation. All Rights Reserved. Licensed under the MIT License. See License in the project root for license information.
+//
+
+#import "MSRetryHandler.h"
+#import "MSURLSessionTask.h"
+#import "MSConstants.h"
+
+NSString * const RETRY_AFTER = @"Retry-After";
+NSString * const RETRY_ATTEMPT = @"Retry-Attempt";
+NSString * const TRANSFER_ENCODING = @"Transfer-Encoding";
+
+#define DELAY_SECONDS 10;
+#define DEFAULT_MAX_RETRIES 10;
+#define DEFAULT_RETRY_POWER 1;
+
+@interface MSURLSessionTask()
+
+-(void)setRequest:(NSMutableURLRequest *)request;
+
+@end
+
+@interface MSRetryHandler()
+
+@property (nonatomic, strong) id<MSGraphMiddleware> nextMiddleware;
+
+@end
+
+@implementation MSRetryHandler
+{
+    NSInteger maxRetries;
+    double retryPower;
+}
+
+- (instancetype)init
+{
+    self = [super init];
+    if(self)
+    {
+        maxRetries = DEFAULT_MAX_RETRIES;
+        retryPower = DEFAULT_RETRY_POWER;
+    }
+    return self;
+}
+
+#pragma mark - MSGraphMiddleware method implmentation
+- (void)execute:(MSURLSessionTask *)task withCompletionHandler:(HTTPRequestCompletionHandler)completionHandler
+{
+    [self execute:task retriesAttempted:0 withCompletionHandler:completionHandler];
+}
+
+- (void)setNext:(id<MSGraphMiddleware>)nextMiddleware
+{
+    if(_nextMiddleware)
+    {
+        [nextMiddleware setNext:_nextMiddleware];
+    }
+    _nextMiddleware = nextMiddleware;
+
+}
+
+#pragma mark - Retry Handler methods
+- (void)execute:(MSURLSessionTask *)task retriesAttempted:(NSInteger)retriesAttempted withCompletionHandler:(HTTPRequestCompletionHandler)completionHandler
+{
+    __block NSInteger localRetriesAttempted = retriesAttempted;
+    NSInteger localMaxRetriesAllowed = maxRetries;
+    __block MSURLSessionTask *blockTask = task;
+    [self.nextMiddleware execute:blockTask withCompletionHandler:^(id data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
+        if(response && [response isKindOfClass:[NSHTTPURLResponse class]])
+        {
+            if([self isRetry:[(NSHTTPURLResponse *)response statusCode]] && [self isBuffered:blockTask.request forResponse:(NSHTTPURLResponse *)response])
+            {
+                //Return an error if maximum retry attempt limit is reached
+                if(localRetriesAttempted==localMaxRetriesAllowed)
+                {
+                    NSDictionary *userInfo = @{
+                                               NSLocalizedDescriptionKey: MSErrorTooManyRetries,
+                                               NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:MSErrorTooManyRetriesFormatString,(long)localRetriesAttempted]
+                                               };
+                    completionHandler(data, response, [NSError errorWithDomain:MSErrorDomain code:[(NSHTTPURLResponse *)response statusCode] userInfo:userInfo]);
+                    return ;
+                }
+
+                //Get the delay before next retry attempt
+                double delay = [self retryDelay:(NSHTTPURLResponse *)response andRetryCount:localRetriesAttempted];
+
+                localRetriesAttempted++;
+
+                //Set Retry-Attempt header on request to track how many requests were made via retry handler
+                [blockTask setRequest:[self updateRetryAttemptHeader:blockTask.request withRetryAttemptCount:localRetriesAttempted]];
+
+                //Dispatch the execution of next retry on Global queue after the delay
+                dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delay * NSEC_PER_SEC);
+                dispatch_after(popTime, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void){
+                    //code to be executed on the global queue after delay
+                    [self execute:blockTask retriesAttempted:localRetriesAttempted withCompletionHandler:completionHandler];
+                });
+            }
+            else
+            {
+                completionHandler(data, response, error);
+            }
+        }
+        else
+        {
+            completionHandler(data, response, error);
+        }
+    }];
+}
+
+- (BOOL)isRetry:(NSInteger)statusCode
+{
+    if (statusCode == MSClientErrorCodeTooManyRequests ||
+        statusCode == MSClientErrorCodeInternalServerError)
+    {
+        return true;
+    }
+    return false;
+}
+
+- (BOOL)isBuffered:(NSURLRequest *)request forResponse:(NSHTTPURLResponse *)response
+{
+    NSData *requestBody = request.HTTPBody;
+
+    BOOL isTransferEncodingChunked = [response.allHeaderFields valueForKey:TRANSFER_ENCODING] && [[response.allHeaderFields valueForKey:TRANSFER_ENCODING] isEqualToString:@"chunked"];
+
+    BOOL isHTTPMethodPutPatchOrPost = ([request.HTTPMethod isEqualToString:HTTPMethodPut] || [request.HTTPMethod isEqualToString:HTTPMethodPatch] || [request.HTTPMethod isEqualToString:HTTPMethodPost]);
+
+    if(isHTTPMethodPutPatchOrPost && requestBody && isTransferEncodingChunked)
+    {
+        return false;
+    }
+    return true;
+}
+
+- (double)retryDelay:(NSHTTPURLResponse *)response andRetryCount:(NSInteger)retryCount
+{
+    double delay = 0;
+
+    NSDictionary *responseHeaders = [response allHeaderFields];
+    if(responseHeaders && [responseHeaders objectForKey:RETRY_AFTER])
+    {
+        delay = [[responseHeaders objectForKey:RETRY_AFTER] doubleValue];
+    }
+    else
+    {
+        retryPower = pow(2, retryCount);
+        delay = retryPower*DELAY_SECONDS;
+    }
+    return delay;
+}
+
+- (NSMutableURLRequest *)updateRetryAttemptHeader:(NSMutableURLRequest *)request withRetryAttemptCount:(NSInteger)retryAttempt
+{
+    [request setValue:[NSString stringWithFormat:@"%ld",(long)retryAttempt] forHTTPHeaderField:RETRY_ATTEMPT];
+    return request;
+}
+
+@end

MSGraphCoreSDK/MSGraphCoreSDKTests/MSGraphWorkloadsTests.m

@@ -40,10 +40,12 @@ - (void)setUp {
 
     MSURLSessionManager *sessionManager = [[MSURLSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
     MSRedirectHandler *redirectHandler = [[MSRedirectHandler alloc] init];
+    MSRetryHandler *retryHandler = [[MSRetryHandler alloc] init];
     MSAuthenticationHandler *authHandler = [[MSAuthenticationHandler alloc] init];
     authHandler.authProvider = self.mockAuthProvider;
     [authHandler setNext:redirectHandler];
-    [redirectHandler setNext:sessionManager];
+    [redirectHandler setNext:retryHandler];
+    [retryHandler setNext:sessionManager];
 
     _httpClient = [MSClientFactory createHTTPClientWithMiddleware:authHandler];