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Ship ASExperimentalDispatchApply #1924

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merged 1 commit into from
Oct 6, 2020
Merged

Ship ASExperimentalDispatchApply #1924

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2 changes: 1 addition & 1 deletion Source/Private/ASDispatch.h
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@
#import <AsyncDisplayKit/ASBaseDefines.h>

/**
* Like dispatch_apply, but you can set the thread count. 0 means 2*active CPUs.
* Like dispatch_apply, but you can set the thread count. 0 means letting dispatch_apply determine it.
*
* Note: The actual number of threads may be lower than threadCount, if libdispatch
* decides the system can't handle it. In reality this rarely happens.
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40 changes: 12 additions & 28 deletions Source/Private/ASDispatch.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -9,43 +9,27 @@
#import <AsyncDisplayKit/ASDispatch.h>
#import <AsyncDisplayKit/ASConfigurationInternal.h>


// Prefer C atomics in this file because ObjC blocks can't capture C++ atomics well.
#import <stdatomic.h>

/**
* Like dispatch_apply, but you can set the thread count. 0 means 2*active CPUs.
*
* Note: The actual number of threads may be lower than threadCount, if libdispatch
* decides the system can't handle it. In reality this rarely happens.
*/
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These comments are exactly the same as the ones in the header file, so no point in keeping them.

void ASDispatchApply(size_t iterationCount, dispatch_queue_t queue, NSUInteger threadCount, NS_NOESCAPE void(^work)(size_t i)) {
if (threadCount == 0) {
if (ASActivateExperimentalFeature(ASExperimentalDispatchApply)) {
dispatch_apply(iterationCount, queue, work);
return;
dispatch_apply(iterationCount, queue, work);
} else {
dispatch_group_t group = dispatch_group_create();
__block atomic_size_t counter = ATOMIC_VAR_INIT(0);
for (NSUInteger t = 0; t < threadCount; t++) {
dispatch_group_async(group, queue, ^{
size_t i;
while ((i = atomic_fetch_add(&counter, 1)) < iterationCount) {
work(i);
}
});
}
threadCount = NSProcessInfo.processInfo.activeProcessorCount * 2;
}
dispatch_group_t group = dispatch_group_create();
__block atomic_size_t counter = ATOMIC_VAR_INIT(0);
for (NSUInteger t = 0; t < threadCount; t++) {
dispatch_group_async(group, queue, ^{
size_t i;
while ((i = atomic_fetch_add(&counter, 1)) < iterationCount) {
work(i);
}
});
dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
}
dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
};

/**
* Like dispatch_async, but you can set the thread count. 0 means 2*active CPUs.
*
* Note: The actual number of threads may be lower than threadCount, if libdispatch
* decides the system can't handle it. In reality this rarely happens.
*/
void ASDispatchAsync(size_t iterationCount, dispatch_queue_t queue, NSUInteger threadCount, NS_NOESCAPE void(^work)(size_t i)) {
if (threadCount == 0) {
threadCount = NSProcessInfo.processInfo.activeProcessorCount * 2;
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