memory/build/Mutex.cpp

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #include "Mutex.h"
   6
   7 #include <errno.h>
   8
   9 #include "mozilla/Assertions.h"
  10
  11 bool Mutex::TryLock() {
  12 #if defined(XP_WIN)
  13   return !!TryEnterCriticalSection(&mMutex);
  14 #elif defined(XP_DARWIN)
  15   return os_unfair_lock_trylock(&mMutex);
  16 #else
  17   switch (pthread_mutex_trylock(&mMutex)) {
  18     case 0:
  19       return true;
  20     case EBUSY:
  21       return false;
  22     default:
  23       MOZ_CRASH("pthread_mutex_trylock error.");
  24   }
  25 #endif
  26 }
  27
  28 #if defined(XP_DARWIN)
  29
  30 // static
  31 bool Mutex::SpinInKernelSpace() {
  32 #  ifdef __aarch64__
  33   return true;
  34 #  else
  35   if (__builtin_available(macOS 10.15, *)) {
  36     return true;
  37   }
  38
  39   return false;
  40 #  endif
  41 }
  42
  43 // static
  44 const bool Mutex::gSpinInKernelSpace = SpinInKernelSpace();
  45
  46 #endif  // defined(XP_DARWIN)