Settling on a relatively stable implementation of pause/resume

AFNetworking/AFHTTPRequestOperation.m

@@ -58,7 +58,6 @@ static void AFSwizzleClassMethodWithClassAndSelectorUsingBlock(Class klass, SEL
     Method originalMethod = class_getClassMethod(klass, selector);
     IMP implementation = imp_implementationWithBlock(block);
     class_replaceMethod(objc_getMetaClass([NSStringFromClass(klass) UTF8String]), selector, implementation, method_getTypeEncoding(originalMethod));
-    
 }
 
 static NSString * AFStringFromIndexSet(NSIndexSet *indexSet) {
@@ -127,6 +126,7 @@ static NSString * AFIncompleteDownloadDirectory() {
 
 @interface AFHTTPRequestOperation ()
 @property (readwrite, nonatomic, retain) NSURLRequest *request;
+@property (readwrite, nonatomic, retain) NSHTTPURLResponse *response;
 @property (readwrite, nonatomic, retain) NSError *HTTPError;
 @property (readwrite, nonatomic, copy) NSString *responseFilePath;
 @property (readonly) NSString *temporaryFilePath;
@@ -180,6 +180,24 @@ static NSString * AFIncompleteDownloadDirectory() {
     }
 }
 
+- (void)pause {
+    unsigned long long offset = 0; 
+    if ([self.outputStream propertyForKey:NSStreamFileCurrentOffsetKey]) {
+        offset = [[self.outputStream propertyForKey:NSStreamFileCurrentOffsetKey] unsignedLongLongValue];
+    } else {
+        offset = [[self.outputStream propertyForKey:NSStreamDataWrittenToMemoryStreamKey] length];
+    }
+        
+    NSMutableURLRequest *mutableURLRequest = [[self.request mutableCopy] autorelease];
+    if ([[self.response allHeaderFields] valueForKey:@"ETag"]) {
+        [mutableURLRequest setValue:[[self.response allHeaderFields] valueForKey:@"ETag"] forHTTPHeaderField:@"If-Range"];
+    }
+    [mutableURLRequest setValue:[NSString stringWithFormat:@"bytes=%llu-", offset] forHTTPHeaderField:@"Range"];
+    self.request = mutableURLRequest;
+    
+    [super pause];
+}
+
 - (BOOL)hasAcceptableStatusCode {
     return ![[self class] acceptableStatusCodes] || [[[self class] acceptableStatusCodes] containsIndex:[self.response statusCode]];
 }
@@ -228,14 +246,14 @@ static NSString * AFIncompleteDownloadDirectory() {
         self.responseFilePath = path;
     }
         
-    if (shouldResume) {
+//    if (shouldResume) {
-        unsigned long long downloadedBytes = AFFileSizeForPath(self.temporaryFilePath);
+//        unsigned long long downloadedBytes = AFFileSizeForPath(self.temporaryFilePath);
-        if (downloadedBytes > 0) {
+//        if (downloadedBytes > 0) {
-            NSMutableURLRequest *mutableURLRequest = [[self.request mutableCopy] autorelease];
+//            NSMutableURLRequest *mutableURLRequest = [[self.request mutableCopy] autorelease];
-            [mutableURLRequest setValue:[NSString stringWithFormat:@"bytes=%llu-", downloadedBytes] forHTTPHeaderField:@"Range"];
+//            [mutableURLRequest setValue:[NSString stringWithFormat:@"bytes=%llu-", downloadedBytes] forHTTPHeaderField:@"Range"];
-            self.request = mutableURLRequest;
+//            self.request = mutableURLRequest;
-        }
+//        }
-    }
+//    }
     
     self.outputStream = [NSOutputStream outputStreamToFileAtPath:self.temporaryFilePath append:!![self.request valueForHTTPHeaderField:@"Range"]];
 }
@@ -311,34 +329,25 @@ static NSString * AFIncompleteDownloadDirectory() {
 - (void)connection:(NSURLConnection *)connection 
 didReceiveResponse:(NSURLResponse *)response 
 {
-    [super connection:connection didReceiveResponse:response];
+    self.response = (NSHTTPURLResponse *)response;
     
-    if (![self.response isKindOfClass:[NSHTTPURLResponse class]]) {
+    if ([self.response statusCode] != 206) {
-        return;
+        if ([self.outputStream propertyForKey:NSStreamFileCurrentOffsetKey]) {
-    }
+            [self.outputStream setProperty:[NSNumber numberWithInteger:0] forKey:NSStreamFileCurrentOffsetKey];
-    
+        } else {
-    // check for valid response to resume the download if possible
+            if ([[self.outputStream propertyForKey:NSStreamDataWrittenToMemoryStreamKey] length] > 0) {
-    long long totalContentLength = self.response.expectedContentLength;
+                self.outputStream = [NSOutputStream outputStreamToMemory];
-    long long fileOffset = 0;
-    if ([self.response statusCode] == 206) {
-        NSString *contentRange = [[self.response allHeaderFields] valueForKey:@"Content-Range"];
-        if ([contentRange hasPrefix:@"bytes"]) {
-            NSArray *bytes = [contentRange componentsSeparatedByCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@" -/"]];
-            if ([bytes count] == 4) {
-                fileOffset = [[bytes objectAtIndex:1] longLongValue];
-                totalContentLength = [[bytes objectAtIndex:2] longLongValue]; // if this is *, it's converted to 0
             }
         }
     }
     
-    unsigned long long offsetContentLength = MAX(fileOffset, 0);
+    [self.outputStream open];
-    [self.outputStream setProperty:[NSNumber numberWithLongLong:offsetContentLength] forKey:NSStreamFileCurrentOffsetKey];
 }
 
 - (void)connectionDidFinishLoading:(NSURLConnection *)connection {
     [super connectionDidFinishLoading:connection];
 
-    if (self.responseFilePath) {
+    if (self.responseFilePath && ![self isCancelled]) {
         @synchronized(self) {
             NSString *temporaryFilePath = [AFIncompleteDownloadDirectory() stringByAppendingPathComponent:[[NSNumber numberWithInteger:[self.responseFilePath hash]] stringValue]];
             NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];

AFNetworking/AFURLConnectionOperation.h

@@ -82,7 +82,7 @@ extern NSString * const kAFNetworkingIncompleteDownloadDirectoryName;
  */
 @interface AFURLConnectionOperation : NSOperation <NSURLConnectionDataDelegate, NSStreamDelegate> {
 @private
-    unsigned short _state;
+    signed short _state;
     BOOL _cancelled;
     NSRecursiveLock *_lock;
     
@@ -156,7 +156,7 @@ extern NSString * const kAFNetworkingIncompleteDownloadDirectoryName;
 /**
  The output stream that is used to write data received until the request is finished.
  
- @discussion By default, data is accumulated into a buffer that is stored into `responseData` upon completion of the request. When `outputStream` is set, the data will not be accumulated into an internal buffer, and as a result, the `responseData` property of the completed request will be `nil`.
+ @discussion By default, data is accumulated into a buffer that is stored into `responseData` upon completion of the request. When `outputStream` is set, the data will not be accumulated into an internal buffer, and as a result, the `responseData` property of the completed request will be `nil`. The output stream will be scheduled in the network thread runloop upon being set.
  */
 @property (nonatomic, retain) NSOutputStream *outputStream;
 
@@ -173,6 +173,11 @@ extern NSString * const kAFNetworkingIncompleteDownloadDirectoryName;
  */
 - (id)initWithRequest:(NSURLRequest *)urlRequest;
 
+- (void)pause;
+- (BOOL)isPaused;
+
+- (void)resume;
+
 ///---------------------------------
 /// @name Setting Progress Callbacks
 ///---------------------------------

AFNetworking/AFURLConnectionOperation.m

@@ -23,12 +23,13 @@
 #import "AFURLConnectionOperation.h"
 
 typedef enum {
+    AFHTTPOperationPausedState      = -1,
     AFHTTPOperationReadyState       = 1,
     AFHTTPOperationExecutingState   = 2,
     AFHTTPOperationFinishedState    = 3,
 } _AFOperationState;
 
-typedef unsigned short AFOperationState;
+typedef signed short AFOperationState;
 
 static NSString * const kAFNetworkingLockName = @"com.alamofire.networking.operation.lock";
 
@@ -50,6 +51,8 @@ static inline NSString * AFKeyPathFromOperationState(AFOperationState state) {
             return @"isExecuting";
         case AFHTTPOperationFinishedState:
             return @"isFinished";
+        case AFHTTPOperationPausedState:
+            return @"isPaused";
         default:
             return @"state";
     }
@@ -59,6 +62,7 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
     switch (fromState) {
         case AFHTTPOperationReadyState:
             switch (toState) {
+                case AFHTTPOperationPausedState:
                 case AFHTTPOperationExecutingState:
                     return YES;
                 case AFHTTPOperationFinishedState:
@@ -68,6 +72,7 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
             }
         case AFHTTPOperationExecutingState:
             switch (toState) {
+                case AFHTTPOperationPausedState:
                 case AFHTTPOperationFinishedState:
                     return YES;
                 default:
@@ -75,6 +80,8 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
             }
         case AFHTTPOperationFinishedState:
             return NO;
+        case AFHTTPOperationPausedState:
+            return toState == AFHTTPOperationReadyState;
         default:
             return YES;
     }
@@ -164,6 +171,8 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
     self.outputStream = [NSOutputStream outputStreamToMemory];
     self.outputStream.delegate = self;
     
+    [self.outputStream setProperty:@"Foo bar" forKey:@"Test"];
+    
     self.state = AFHTTPOperationReadyState;
 	
     return self;
@@ -221,9 +230,24 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
 }
 
 - (void)setInputStream:(NSInputStream *)inputStream {
+    [self willChangeValueForKey:@"inputStream"];
     NSMutableURLRequest *mutableRequest = [[self.request mutableCopy] autorelease];
     mutableRequest.HTTPBodyStream = inputStream;
     self.request = mutableRequest;
+    [self didChangeValueForKey:@"inputStream"];
+}
+
+- (void)setOutputStream:(NSOutputStream *)outputStream {
+    [self willChangeValueForKey:@"outputStream"];
+    [outputStream retain];
+    [_outputStream release];
+    _outputStream = outputStream;
+    [self didChangeValueForKey:@"outputStream"];
+    
+    NSRunLoop *runLoop = [NSRunLoop currentRunLoop];
+    for (NSString *runLoopMode in self.runLoopModes) {
+        [self.outputStream scheduleInRunLoop:runLoop forMode:runLoopMode];
+    }
 }
 
 - (void)setUploadProgressBlock:(void (^)(NSInteger bytesWritten, long long totalBytesWritten, long long totalBytesExpectedToWrite))block {
@@ -287,6 +311,35 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
     return _responseString;
 }
 
+- (void)pause {
+    if ([self isPaused]) {
+        return;
+    }
+    
+    [self.lock lock];
+    self.state = AFHTTPOperationPausedState;
+    
+    [self.connection performSelector:@selector(cancel) onThread:[[self class] networkRequestThread] withObject:nil waitUntilDone:NO modes:[self.runLoopModes allObjects]];
+    [[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingOperationDidFinishNotification object:self];
+    [self.lock unlock];
+}
+
+- (BOOL)isPaused {
+    return self.state == AFHTTPOperationPausedState;
+}
+
+- (void)resume {
+    if (![self isPaused]) {
+        return;
+    }
+    
+    [self.lock lock];
+    self.state = AFHTTPOperationReadyState;
+    
+    [self start];
+    [self.lock unlock];
+}
+
 #pragma mark - NSOperation
 
 - (BOOL)isReady {
@@ -439,11 +492,9 @@ totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite
 - (void)connection:(NSURLConnection *)__unused connection 
 didReceiveResponse:(NSURLResponse *)response 
 {
-    self.response = (NSHTTPURLResponse *)response;
+    self.response = response;
     
-    if (self.outputStream) {
+    [self.outputStream open];
-        [self.outputStream open];
-    }
 }
 
 - (void)connection:(NSURLConnection *)__unused connection