compiler-rt/test/tsan/libdispatch/async_and_wait.c

   1 // RUN: %clang_tsan %s -o %t -undefined dynamic_lookup
   2 // RUN: %run %t 2>&1 | FileCheck %s --implicit-check-not='ThreadSanitizer'
   3
   4 #include "dispatch/dispatch.h"
   5
   6 #include <stdio.h>
   7
   8 // Allow compilation with pre-macOS 10.14 (and aligned) SDKs
   9 API_AVAILABLE(macos(10.14), ios(12.0), tvos(12.0), watchos(5.0))
  10 DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW
  11 void dispatch_async_and_wait(dispatch_queue_t queue,
  12            DISPATCH_NOESCAPE dispatch_block_t block);
  13
  14 long global;
  15
  16 int main() {
  17   // Guard execution on pre-macOS 10.14 (and aligned) platforms
  18   if (dispatch_async_and_wait == NULL) {
  19     fprintf(stderr, "Done.\n");
  20     return 0;
  21   }
  22
  23   dispatch_queue_t q = dispatch_queue_create("my.queue", DISPATCH_QUEUE_SERIAL);
  24   dispatch_semaphore_t s = dispatch_semaphore_create(0);
  25
  26   // Force queue to context switch onto separate thread.
  27   dispatch_async(q, ^{
  28     dispatch_semaphore_wait(s, DISPATCH_TIME_FOREVER);
  29   });
  30   dispatch_semaphore_signal(s);
  31
  32   global++;
  33   dispatch_async_and_wait(q, ^{
  34     // The queue continues to execute on separate thread.  This would cause a
  35     // race if we had used `dispatch_async()` without the `_and_wait` part.
  36     global++;
  37   });
  38   global++;
  39
  40   fprintf(stderr, "Done.\n");
  41   return 0;
  42 }
  43
  44 // CHECK: Done.