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Use lock instead of barrier queue to keep callbacks block thread-safe

This commit is contained in:
DreamPiggy 2018-02-01 21:20:10 +08:00
parent aeb5194dc4
commit 7eff69685a
2 changed files with 32 additions and 28 deletions
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4
SDWebImage/SDWebImageDownloaderOperation.h
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@ -63,7 +63,7 @@ FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadFinishNotification
@property (nonatomic, assign) BOOL shouldUseCredentialStorage __deprecated_msg("Property deprecated. Does nothing. Kept only for backwards compatibility");
/**
* The credential used for authentication challenges in `-connection:didReceiveAuthenticationChallenge:`.
* The credential used for authentication challenges in `-URLSession:task:didReceiveChallenge:completionHandler:`.
*
* This will be overridden by any shared credentials that exist for the username or password of the request URL, if present.
*/
@ -80,7 +80,7 @@ FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadFinishNotification
@property (assign, nonatomic) NSInteger expectedSize;
/**
* The response returned by the operation's connection.
* The response returned by the operation's task.
*/
@property (strong, nonatomic, nullable) NSURLResponse *response;

56
SDWebImage/SDWebImageDownloaderOperation.m
View File

@ -11,6 +11,9 @@
#import "NSImage+WebCache.h"
#import "SDWebImageCodersManager.h"
#define LOCK(lock) dispatch_semaphore_wait(lock, DISPATCH_TIME_FOREVER);
#define UNLOCK(lock) dispatch_semaphore_signal(lock);
NSString *const SDWebImageDownloadStartNotification = @"SDWebImageDownloadStartNotification";
NSString *const SDWebImageDownloadReceiveResponseNotification = @"SDWebImageDownloadReceiveResponseNotification";
NSString *const SDWebImageDownloadStopNotification = @"SDWebImageDownloadStopNotification";
@ -28,7 +31,7 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
@property (assign, nonatomic, getter = isExecuting) BOOL executing;
@property (assign, nonatomic, getter = isFinished) BOOL finished;
@property (strong, nonatomic, nullable) NSMutableData *imageData;
@property (copy, nonatomic, nullable) NSData *cachedData;
@property (copy, nonatomic, nullable) NSData *cachedData; // for `SDWebImageDownloaderIgnoreCachedResponse`
// This is weak because it is injected by whoever manages this session. If this gets nil-ed out, we won't be able to run
// the task associated with this operation
@ -38,10 +41,9 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
@property (strong, nonatomic, readwrite, nullable) NSURLSessionTask *dataTask;
@property (strong, nonatomic, nonnull) dispatch_queue_t barrierQueue;
@property (strong, nonatomic, nonnull) dispatch_queue_t coderQueue;
@property (strong, nonatomic, nonnull) dispatch_semaphore_t callbacksLock; // a lock to keep the access to `callbackBlocks` thread-safe
@property (strong, nonatomic, nonnull) dispatch_queue_t coderQueue; // the queue to do image decoding
#if SD_UIKIT
@property (assign, nonatomic) UIBackgroundTaskIdentifier backgroundTaskId;
#endif
@ -71,7 +73,7 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
_finished = NO;
_expectedSize = 0;
_unownedSession = session;
_barrierQueue = dispatch_queue_create("com.hackemist.SDWebImageDownloaderOperationBarrierQueue", DISPATCH_QUEUE_CONCURRENT);
_callbacksLock = dispatch_semaphore_create(1);
_coderQueue = dispatch_queue_create("com.hackemist.SDWebImageDownloaderOperationCoderQueue", DISPATCH_QUEUE_SERIAL);
}
return self;
@ -82,30 +84,29 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
SDCallbacksDictionary *callbacks = [NSMutableDictionary new];
if (progressBlock) callbacks[kProgressCallbackKey] = [progressBlock copy];
if (completedBlock) callbacks[kCompletedCallbackKey] = [completedBlock copy];
dispatch_barrier_async(self.barrierQueue, ^{
[self.callbackBlocks addObject:callbacks];
});
LOCK(self.callbacksLock);
[self.callbackBlocks addObject:callbacks];
UNLOCK(self.callbacksLock);
return callbacks;
}
- (nullable NSArray<id> *)callbacksForKey:(NSString *)key {
__block NSMutableArray<id> *callbacks = nil;
dispatch_sync(self.barrierQueue, ^{
// We need to remove [NSNull null] because there might not always be a progress block for each callback
callbacks = [[self.callbackBlocks valueForKey:key] mutableCopy];
[callbacks removeObjectIdenticalTo:[NSNull null]];
});
return [callbacks copy]; // strip mutability here
LOCK(self.callbacksLock);
NSMutableArray<id> *callbacks = [[self.callbackBlocks valueForKey:key] mutableCopy];
UNLOCK(self.callbacksLock);
// We need to remove [NSNull null] because there might not always be a progress block for each callback
[callbacks removeObjectIdenticalTo:[NSNull null]];
return [callbacks copy]; // strip mutability here
}
- (BOOL)cancel:(nullable id)token {
__block BOOL shouldCancel = NO;
dispatch_barrier_sync(self.barrierQueue, ^{
[self.callbackBlocks removeObjectIdenticalTo:token];
if (self.callbackBlocks.count == 0) {
shouldCancel = YES;
}
});
BOOL shouldCancel = NO;
LOCK(self.callbacksLock);
[self.callbackBlocks removeObjectIdenticalTo:token];
if (self.callbackBlocks.count == 0) {
shouldCancel = YES;
}
UNLOCK(self.callbacksLock);
if (shouldCancel) {
[self cancel];
}
@ -245,10 +246,9 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
}
- (void)reset {
__weak typeof(self) weakSelf = self;
dispatch_barrier_async(self.barrierQueue, ^{
[weakSelf.callbackBlocks removeAllObjects];
});
LOCK(self.callbacksLock);
[self.callbackBlocks removeAllObjects];
UNLOCK(self.callbacksLock);
self.dataTask = nil;
if (self.ownedSession) {
@ -336,6 +336,7 @@ didReceiveResponse:(NSURLResponse *)response
}
}
// progressive decode the image in coder queue
dispatch_async(self.coderQueue, ^{
UIImage *image = [self.progressiveCoder incrementallyDecodedImageWithData:imageData finished:finished];
if (image) {
@ -345,6 +346,8 @@ didReceiveResponse:(NSURLResponse *)response
image = [[SDWebImageCodersManager sharedInstance] decompressedImageWithImage:image data:&imageData options:@{SDWebImageCoderScaleDownLargeImagesKey: @(NO)}];
}
// We do not keep the progressive decoding image even when `finished`=YES. Because they are for view rendering but not take full function from downloader options. And some coders implementation may not keep consistent between progressive decoding and normal decoding.
[self callCompletionBlocksWithImage:image imageData:nil error:nil finished:NO];
}
});
@ -404,6 +407,7 @@ didReceiveResponse:(NSURLResponse *)response
[self callCompletionBlocksWithImage:nil imageData:nil error:nil finished:YES];
[self done];
} else {
// decode the image in coder queue
dispatch_async(self.coderQueue, ^{
UIImage *image = [[SDWebImageCodersManager sharedInstance] decodedImageWithData:imageData];
NSString *key = [[SDWebImageManager sharedManager] cacheKeyForURL:self.request.URL];