Swiftgram/Source/Private/ASDispatch.h
Brandon Kase 554c688eba Workaround clang4.0 <stdatomic.h> initialization (#426)
Texture fails to build with this error on clang 4.0:

```
external/Texture/pod_support/Headers/Public/AsyncDisplayKit/ASDispatch.h:32:35: error: illegal initializer type 'atomic_size_t' (aka '_Atomic(size_t)')
  __block atomic_size_t counter = ATOMIC_VAR_INIT(0);
                                  ^
In module 'std' imported from external/Texture/pod_support/Headers/Public/AsyncDisplayKit/ASStackUnpositionedLayout.h:18:
/private/var/tmp/_bazel_bkase/a00d4cbe29902fb63d5778cc19944cd2/external/clang40/bin/../include/c++/v1/atomic:1839:30: note: expanded from macro 'ATOMIC_VAR_INIT'
                             ^
1 error generated.
```

See
http://techqa.info/programming/question/38233019/Initializing-an--atomic-int--with-a-braced-constant--Is-this-valid-C-code--If-so-why-does-it-not-compile-in-clang-

Replacing the intialization with just 0 (and not the macro fixes the
error). For now this is safe because the macro just expands to the
value.
2017-07-07 16:29:50 -07:00

48 lines
1.9 KiB
Objective-C

//
// ASDispatch.h
// Texture
//
// Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the /ASDK-Licenses directory of this source tree. An additional
// grant of patent rights can be found in the PATENTS file in the same directory.
//
// Modifications to this file made after 4/13/2017 are: Copyright (c) 2017-present,
// Pinterest, Inc. Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
#import <Foundation/Foundation.h>
#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.
*/
static void ASDispatchApply(size_t iterationCount, dispatch_queue_t queue, NSUInteger threadCount, NS_NOESCAPE void(^work)(size_t i)) {
if (threadCount == 0) {
threadCount = NSProcessInfo.processInfo.activeProcessorCount * 2;
}
dispatch_group_t group = dispatch_group_create();
// HACK: This is a workaround for mm files that include this in Clang4.0
// Omitting ATOMIC_VAR_INIT is okay in this case because the current
// expansion of that macro no-ops.
// TODO: Move this implementation into a m file so it's not compiled in C++
// See: https://github.com/TextureGroup/Texture/pull/426
__block atomic_size_t counter = 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);
};