mozglue/misc/PlatformConditionVariable.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_ConditionVariable_h
   8 #define mozilla_ConditionVariable_h
   9
  10 #include <stdint.h>
  11
  12 #include <utility>
  13
  14 #include "mozilla/Attributes.h"
  15 #include "mozilla/PlatformMutex.h"
  16 #include "mozilla/TimeStamp.h"
  17 #if !defined(XP_WIN) && !defined(__wasi__)
  18 #  include <pthread.h>
  19 #endif
  20
  21 namespace mozilla {
  22
  23 enum class CVStatus { NoTimeout, Timeout };
  24
  25 namespace detail {
  26
  27 class ConditionVariableImpl {
  28  public:
  29   struct PlatformData;
  30
  31   MFBT_API ConditionVariableImpl();
  32   MFBT_API ~ConditionVariableImpl();
  33
  34   // Wake one thread that is waiting on this condition.
  35   MFBT_API void notify_one();
  36
  37   // Wake all threads that are waiting on this condition.
  38   MFBT_API void notify_all();
  39
  40   // Atomically release |lock| and sleep the current thread of execution on
  41   // this condition variable.
  42   // |lock| will be re-acquired before this function returns.
  43   // The thread may be woken from sleep from another thread via notify_one()
  44   // or notify_all(), but may also wake spuriously.  The caller should recheck
  45   // its predicate after this function returns, typically in a while loop.
  46   MFBT_API void wait(MutexImpl& lock);
  47
  48   MFBT_API CVStatus wait_for(MutexImpl& lock,
  49                              const mozilla::TimeDuration& rel_time);
  50
  51  private:
  52   ConditionVariableImpl(const ConditionVariableImpl&) = delete;
  53   ConditionVariableImpl& operator=(const ConditionVariableImpl&) = delete;
  54
  55   PlatformData* platformData();
  56
  57 #if !defined(XP_WIN) && !defined(__wasi__)
  58   void* platformData_[sizeof(pthread_cond_t) / sizeof(void*)];
  59   static_assert(sizeof(pthread_cond_t) / sizeof(void*) != 0 &&
  60                     sizeof(pthread_cond_t) % sizeof(void*) == 0,
  61                 "pthread_cond_t must have pointer alignment");
  62 #else
  63   void* platformData_[4];
  64 #endif
  65 };
  66
  67 }  // namespace detail
  68
  69 }  // namespace mozilla
  70
  71 #endif  // mozilla_ConditionVariable_h