RestKit/Code/Network/RKObjectRequestOperation.m

//
//  RKObjectRequestOperation.m
//  RestKit
//
//  Created by Blake Watters on 8/9/12.
//  Copyright (c) 2012 RestKit. All rights reserved.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.
//

#import "RKObjectRequestOperation.h"
#import "RKResponseMapperOperation.h"
#import "RKResponseDescriptor.h"
#import "RKMIMETypeSerialization.h"
#import "RKHTTPUtilities.h"
#import "RKLog.h"
#import "RKMappingErrors.h"

#import <Availability.h>

#if __IPHONE_OS_VERSION_MIN_REQUIRED
#import "AFNetworkActivityIndicatorManager.h"
#endif

// Set Logging Component
#undef RKLogComponent
#define RKLogComponent RKlcl_cRestKitNetwork

NSString * const RKObjectRequestOperationDidStartNotification = @"RKObjectRequestOperationDidStartNotification";
NSString * const RKObjectRequestOperationDidFinishNotification = @"RKObjectRequestOperationDidFinishNotification";
NSString * const RKResponseHasBeenMappedCacheUserInfoKey = @"RKResponseHasBeenMapped";

static void RKIncrementNetworkActivityIndicator()
{
    #if __IPHONE_OS_VERSION_MIN_REQUIRED
        [[AFNetworkActivityIndicatorManager sharedManager] incrementActivityCount];
    #endif
}

static void RKDecrementNetworkAcitivityIndicator()
{
    #if __IPHONE_OS_VERSION_MIN_REQUIRED
        [[AFNetworkActivityIndicatorManager sharedManager] decrementActivityCount];
    #endif
}

static inline NSString *RKDescriptionForRequest(NSURLRequest *request)
{
    return [NSString stringWithFormat:@"%@ '%@'", request.HTTPMethod, [request.URL absoluteString]];
}

static NSIndexSet *RKAcceptableStatusCodesFromResponseDescriptors(NSArray *responseDescriptors)
{
    // If there are no response descriptors or any descriptor matches any status code (expressed by `statusCodes` == `nil`) then we want to accept anything
    if ([responseDescriptors count] == 0 || [[responseDescriptors valueForKey:@"statusCodes"] containsObject:[NSNull null]]) return nil;
    
    NSMutableIndexSet *acceptableStatusCodes = [NSMutableIndexSet indexSet];
    [responseDescriptors enumerateObjectsUsingBlock:^(RKResponseDescriptor *responseDescriptor, NSUInteger idx, BOOL *stop) {
        [acceptableStatusCodes addIndexes:responseDescriptor.statusCodes];
    }];
    return acceptableStatusCodes;
}

static NSString *RKStringForStateOfObjectRequestOperation(RKObjectRequestOperation *operation)
{
    if ([operation isExecuting]) {
        return @"Executing";
    } else if ([operation isFinished]) {
        if (operation.error) {
            return @"Failed";
        } else {
            return @"Successful";
        }
    } else {
        return @"Ready";
    }
}

static NSString *RKStringDescribingURLResponseWithData(NSURLResponse *response, NSData *data)
{
    if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
        NSHTTPURLResponse *HTTPResponse = (NSHTTPURLResponse *)response;
        return [NSString stringWithFormat:@"<%@: %p statusCode=%ld MIMEType=%@ length=%ld>", [response class], response, (long) [HTTPResponse statusCode], [HTTPResponse MIMEType], (long) [data length]];
    } else {
        return [response description];
    }
}

@interface RKObjectRequestOperation ()
@property (nonatomic, strong, readwrite) RKHTTPRequestOperation *HTTPRequestOperation;
@property (nonatomic, strong, readwrite) NSArray *responseDescriptors;
@property (nonatomic, strong, readwrite) RKMappingResult *mappingResult;
@property (nonatomic, strong, readwrite) NSError *error;
@property (nonatomic, strong) RKObjectResponseMapperOperation *responseMapperOperation;
@property (nonatomic, copy) id (^willMapDeserializedResponseBlock)(id deserializedResponseBody);
@end

@implementation RKObjectRequestOperation

+ (NSOperationQueue *)responseMappingQueue
{
    static NSOperationQueue *responseMappingQueue = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        responseMappingQueue = [NSOperationQueue new];
        [responseMappingQueue setName:@"RKObjectRequestOperation Response Mapping Queue" ];
        [responseMappingQueue setMaxConcurrentOperationCount:1];
    });
    
    return responseMappingQueue;
}

+ (BOOL)canProcessRequest:(NSURLRequest *)request
{
    return YES;
}

- (void)dealloc
{
#if !OS_OBJECT_USE_OBJC
    if (_failureCallbackQueue) dispatch_release(_failureCallbackQueue);
    if (_successCallbackQueue) dispatch_release(_successCallbackQueue);
#endif
    _failureCallbackQueue = NULL;
    _successCallbackQueue = NULL;
}

// Designated initializer
- (id)initWithHTTPRequestOperation:(RKHTTPRequestOperation *)requestOperation responseDescriptors:(NSArray *)responseDescriptors
{
    NSParameterAssert(requestOperation);
    NSParameterAssert(responseDescriptors);
    
    self = [self init];
    if (self) {
        self.responseDescriptors = responseDescriptors;
        self.HTTPRequestOperation = requestOperation;
        self.HTTPRequestOperation.acceptableContentTypes = [RKMIMETypeSerialization registeredMIMETypes];
        self.HTTPRequestOperation.acceptableStatusCodes = RKAcceptableStatusCodesFromResponseDescriptors(responseDescriptors);
    }
    
    return self;
}

- (id)initWithRequest:(NSURLRequest *)request responseDescriptors:(NSArray *)responseDescriptors
{
    NSParameterAssert(request);
    NSParameterAssert(responseDescriptors);    
    return [self initWithHTTPRequestOperation:[[RKHTTPRequestOperation alloc] initWithRequest:request] responseDescriptors:responseDescriptors];
}

- (void)setSuccessCallbackQueue:(dispatch_queue_t)successCallbackQueue
{
   if (successCallbackQueue != _successCallbackQueue) {
       if (_successCallbackQueue) {
#if !OS_OBJECT_USE_OBJC
           dispatch_release(_successCallbackQueue);
#endif
           _successCallbackQueue = NULL;
       }

       if (successCallbackQueue) {
#if !OS_OBJECT_USE_OBJC
           dispatch_retain(successCallbackQueue);
#endif
           _successCallbackQueue = successCallbackQueue;
       }
   }
}

- (void)setFailureCallbackQueue:(dispatch_queue_t)failureCallbackQueue
{
   if (failureCallbackQueue != _failureCallbackQueue) {
       if (_failureCallbackQueue) {
#if !OS_OBJECT_USE_OBJC
           dispatch_release(_failureCallbackQueue);
#endif
           _failureCallbackQueue = NULL;
       }

       if (failureCallbackQueue) {
#if !OS_OBJECT_USE_OBJC
           dispatch_retain(failureCallbackQueue);
#endif
           _failureCallbackQueue = failureCallbackQueue;
       }
   }
}

// Adopted fix for "The Deallocation Problem" from AFN
- (void)setCompletionBlock:(void (^)(void))block
{
    if (!block) {
        [super setCompletionBlock:nil];
    } else {
        __unsafe_unretained id weakSelf = self;
        [super setCompletionBlock:^ {
            block();
            [weakSelf setCompletionBlock:nil];
        }];
    }
}

- (void)setWillMapDeserializedResponseBlock:(id (^)(id))block
{
    if (!block) {
        _willMapDeserializedResponseBlock = nil;
    } else {
        __unsafe_unretained id weakSelf = self;
        _willMapDeserializedResponseBlock = ^id (id deserializedResponse) {
            id result = block(deserializedResponse);
            [weakSelf setWillMapDeserializedResponseBlock:nil];
            return result;
        };
    }
}

- (void)setCompletionBlockWithSuccess:(void (^)(RKObjectRequestOperation *operation, RKMappingResult *mappingResult))success
                              failure:(void (^)(RKObjectRequestOperation *operation, NSError *error))failure
{
// See above setCompletionBlock:
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-retain-cycles"
    self.completionBlock = ^ {
        if ([self isCancelled]) {
            return;
        }

        if (self.error) {
            if (failure) {
                dispatch_async(self.failureCallbackQueue ? self.failureCallbackQueue : dispatch_get_main_queue(), ^{
                    failure(self, self.error);
                });
            }
        } else {
            if (success) {
                dispatch_async(self.successCallbackQueue ? self.successCallbackQueue : dispatch_get_main_queue(), ^{
                    success(self, self.mappingResult);
                });
            }
        }
    };
#pragma clang diagnostic pop
}

- (RKMappingResult *)performMappingOnResponse:(NSError **)error
{
    // Spin up an RKObjectResponseMapperOperation
    self.responseMapperOperation = [[RKObjectResponseMapperOperation alloc] initWithRequest:self.HTTPRequestOperation.request
                                                                                   response:self.HTTPRequestOperation.response
                                                                                       data:self.HTTPRequestOperation.responseData
                                                                        responseDescriptors:self.responseDescriptors];
    self.responseMapperOperation.targetObject = self.targetObject;
    self.responseMapperOperation.mappingMetadata = self.mappingMetadata;
    self.responseMapperOperation.mapperDelegate = self;
    [self.responseMapperOperation setQueuePriority:[self queuePriority]];
    [self.responseMapperOperation setWillMapDeserializedResponseBlock:self.willMapDeserializedResponseBlock];
    [[RKObjectRequestOperation responseMappingQueue] addOperation:self.responseMapperOperation];
    [self.responseMapperOperation waitUntilFinished];
    if ([self isCancelled]) return nil;
    if (self.responseMapperOperation.error) {
        if (error) *error = self.responseMapperOperation.error;
        return nil;
    }
    return self.responseMapperOperation.mappingResult;
}

- (void)willFinish
{
    // Default implementation does nothing
}

- (void)cancel
{
    [super cancel];
    [self.HTTPRequestOperation cancel];
    [self.responseMapperOperation cancel];
}

- (void)execute
{
    // Send the request
    [self.HTTPRequestOperation start];
    [self.HTTPRequestOperation waitUntilFinished];
    
    if (self.HTTPRequestOperation.error) {
        RKLogError(@"Object request failed: Underlying HTTP request operation failed with error: %@", self.HTTPRequestOperation.error);
        self.error = self.HTTPRequestOperation.error;
        return;
    }
    
    if (self.isCancelled) return;
    
    // Map the response
    NSError *error = nil;
    RKMappingResult *mappingResult = [self performMappingOnResponse:&error];
    if (self.isCancelled) {
        return;
    }
    
    // If there is no mapping result but no error, there was no mapping to be performed,
    // which we do not treat as an error condition
    if (! mappingResult && error && !([self.HTTPRequestOperation.request.HTTPMethod isEqualToString:@"DELETE"] && error.code == RKMappingErrorNotFound)) {
        self.error = error;
        return;
    }
    self.mappingResult = mappingResult;
    [self willFinish];
        
    if (self.error) {
        self.mappingResult = nil;
    } else {
        NSCachedURLResponse *cachedResponse = [[NSURLCache sharedURLCache] cachedResponseForRequest:self.HTTPRequestOperation.request];
        if (cachedResponse) {
            // We're all done mapping this request. Now we set a flag on the cache entry's userInfo dictionary to indicate that the request
            // corresponding to the cache entry completed successfully, and we can reliably skip mapping if a subsequent request results
            // in the use of this cachedResponse.
            NSMutableDictionary *userInfo = cachedResponse.userInfo ? [cachedResponse.userInfo mutableCopy] : [NSMutableDictionary dictionary];
            [userInfo setObject:@YES forKey:RKResponseHasBeenMappedCacheUserInfoKey];
            NSCachedURLResponse *newCachedResponse = [[NSCachedURLResponse alloc] initWithResponse:cachedResponse.response data:cachedResponse.data userInfo:userInfo storagePolicy:cachedResponse.storagePolicy];
            [[NSURLCache sharedURLCache] storeCachedResponse:newCachedResponse forRequest:self.HTTPRequestOperation.request];
        }
    }
}

- (void)main
{
    if (self.isCancelled) return;
    
    [[NSNotificationCenter defaultCenter] postNotificationName:RKObjectRequestOperationDidStartNotification object:self];
    RKIncrementNetworkActivityIndicator();
    [self execute];
    RKDecrementNetworkAcitivityIndicator();
    [[NSNotificationCenter defaultCenter] postNotificationName:RKObjectRequestOperationDidFinishNotification object:self];
}

- (NSString *)description {
    return [NSString stringWithFormat:@"<%@: %p, state: %@, isCancelled=%@, request: %@, response: %@>",
            NSStringFromClass([self class]), self, RKStringForStateOfObjectRequestOperation(self), [self isCancelled] ? @"YES" : @"NO",
            self.HTTPRequestOperation.request, RKStringDescribingURLResponseWithData(self.HTTPRequestOperation.response, self.HTTPRequestOperation.responseData)];
}

#pragma mark - NSCopying

- (id)copyWithZone:(NSZone *)zone {
    RKObjectRequestOperation *operation = [(RKObjectRequestOperation *)[[self class] allocWithZone:zone] initWithHTTPRequestOperation:[self.HTTPRequestOperation copyWithZone:zone] responseDescriptors:self.responseDescriptors];
    operation.targetObject = self.targetObject;
    operation.mappingMetadata = self.mappingMetadata;
    operation.successCallbackQueue = self.successCallbackQueue;
    operation.failureCallbackQueue = self.failureCallbackQueue;
    operation.willMapDeserializedResponseBlock = self.willMapDeserializedResponseBlock;
    operation.completionBlock = self.completionBlock;
    
    return operation;
}

@end