reusing_requests.mm

//
//  SWFHTTPClient
//  RACCancelTest
//
//  Created by Nikolay Kasyanov on 29.03.13.
//  Copyright (c) 2013 Softwear Finance. All rights reserved.
//
#import "SWFHTTPClient.h"

@implementation SWFHTTPClient {
    NSMutableDictionary *_activeSignals;

    NSRecursiveLock *_lock;
}

- (instancetype)initWithBaseURL:(NSURL *)url
{
    self = [super initWithBaseURL:url];
    if (self != nil) {
        _activeSignals = [NSMutableDictionary dictionary];
        _lock = [NSRecursiveLock new];
    }
    return self;
}

- (RACSignal *)feedAtPath:(NSString *)path
{
    NSParameterAssert(path != nil);
    
    RACSignal *existingSignal;
    [_lock lock];

    existingSignal = _activeSignals[path];
    if (existingSignal == nil) {
        RACSignal *networkSignal = [[RACSignal createSignal:^RACDisposable *(id <RACSubscriber> subscriber) {

            NSURLRequest *request = [self requestWithMethod:@"GET"
                                                       path:path
                                                 parameters:nil];

            void (^success)(AFHTTPRequestOperation *, id) =
                    ^(AFHTTPRequestOperation *operation, id responseObject) {
                        [subscriber sendNext:responseObject];
                        [subscriber sendCompleted];
                    };


            void (^failure)(AFHTTPRequestOperation *, NSError *) =
                    ^(AFHTTPRequestOperation *operation, NSError *error) {
                        [subscriber sendError:error];
                    };

            AFHTTPRequestOperation *operation = [[AFJSONRequestOperation alloc] initWithRequest:request];
            [operation setCompletionBlockWithSuccess:success
                                             failure:failure];

            [self enqueueHTTPRequestOperation:operation];

            return [RACDisposable disposableWithBlock:^{
                [operation cancel];
            }];
        }] finally:^{
            [self removeSignalForPath:path];
        }];

        existingSignal = [[networkSignal multicast:[RACSubject subject]] autoconnect];

        _activeSignals[path] = existingSignal;
    }

    [_lock unlock];

    return existingSignal;
}

- (void)removeSignalForPath:(NSString *)path
{
    NSParameterAssert(path != nil);
    [_lock lock];
    [_activeSignals removeObjectForKey:path];
    [_lock unlock];
}

@end