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Merge pull request #2917 from dreampiggy/5.x_fix_local_download_operation_finished_without_callback 

Fix the issue that "There may be no complete callback when download the picture of the local path"
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DreamPiggy 2019-12-26 18:11:44 +08:00 committed by GitHub
parent 69a62ff39d e38388e13f
commit 751d52bbaf
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1 changed files with 2 additions and 1 deletions
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SDWebImage/Core/SDWebImageDownloader.m
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@ -226,10 +226,11 @@ static void * SDWebImageDownloaderContext = &SDWebImageDownloaderContext;
SD_UNLOCK(self.operationsLock); SD_UNLOCK(self.operationsLock);
}; };
self.URLOperations[url] = operation; self.URLOperations[url] = operation;
// Add the handlers before submitting to operation queue, avoid the race condition that operation finished before setting handlers.
downloadOperationCancelToken = [operation addHandlersForProgress:progressBlock completed:completedBlock];
// Add operation to operation queue only after all configuration done according to Apple's doc. // Add operation to operation queue only after all configuration done according to Apple's doc.
// `addOperation:` does not synchronously execute the `operation.completionBlock` so this will not cause deadlock. // `addOperation:` does not synchronously execute the `operation.completionBlock` so this will not cause deadlock.
[self.downloadQueue addOperation:operation]; [self.downloadQueue addOperation:operation];
downloadOperationCancelToken = [operation addHandlersForProgress:progressBlock completed:completedBlock];
} else { } else {
// When we reuse the download operation to attach more callbacks, there may be thread safe issue because the getter of callbacks may in another queue (decoding queue or delegate queue) // When we reuse the download operation to attach more callbacks, there may be thread safe issue because the getter of callbacks may in another queue (decoding queue or delegate queue)
// So we lock the operation here, and in `SDWebImageDownloaderOperation`, we use `@synchonzied (self)`, to ensure the thread safe between these two classes. // So we lock the operation here, and in `SDWebImageDownloaderOperation`, we use `@synchonzied (self)`, to ensure the thread safe between these two classes.