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Fix #1366, addresses #1350 and reverts a part of #1221 - from commit 6406d8e, the wrong usage of dispatch_apply

This commit is contained in:
Bogdan Poplauschi 2016-01-08 16:50:35 +02:00
parent ee49d49d35
commit cac21e106d
1 changed files with 3 additions and 18 deletions
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21
SDWebImage/SDWebImagePrefetcher.m
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@ -112,29 +112,14 @@
self.completionBlock = completionBlock; self.completionBlock = completionBlock;
self.progressBlock = progressBlock; self.progressBlock = progressBlock;
__weak SDWebImagePrefetcher *weakSelf = self;
if (urls.count == 0) { if (urls.count == 0) {
if (completionBlock) { if (completionBlock) {
completionBlock(0,0); completionBlock(0,0);
} }
} else { } else {
// http://oleb.net/blog/2013/07/parallelize-for-loops-gcd-dispatch_apply/ // Starts prefetching from the very first image on the list with the max allowed concurrency
// Optimize the maxConcurrentdownloads for effeciency. Since caching operations are involved that are non-trivial using NSUInteger listCount = self.prefetchURLs.count;
// dispatch_apply might be helpful. for (NSUInteger i = 0; i < self.maxConcurrentDownloads && self.requestedCount < listCount; i++) {
NSInteger maxNumberOfImages = self.prefetchURLs.count;
dispatch_apply(maxNumberOfImages/self.maxConcurrentDownloads, self.prefetcherQueue, ^(size_t index) {
size_t i = index * self.maxConcurrentDownloads;
size_t stop = i + self.maxConcurrentDownloads;
do {
[weakSelf startPrefetchingAtIndex:i++];
} while (i < stop);
});
// Download remaining images.
for (size_t i = maxNumberOfImages - (maxNumberOfImages % self.maxConcurrentDownloads); i < (size_t)maxNumberOfImages; i++) {
[self startPrefetchingAtIndex:i]; [self startPrefetchingAtIndex:i];
} }
} }