155 lines
4.8 KiB
C++
155 lines
4.8 KiB
C++
/*
|
|
* Copyright 2004 The WebRTC Project Authors. All rights reserved.
|
|
*
|
|
* Use of this source code is governed by a BSD-style license
|
|
* that can be found in the LICENSE file in the root of the source
|
|
* tree. An additional intellectual property rights grant can be found
|
|
* in the file PATENTS. All contributing project authors may
|
|
* be found in the AUTHORS file in the root of the source tree.
|
|
*/
|
|
|
|
#ifndef WEBRTC_BASE_CRITICALSECTION_H_
|
|
#define WEBRTC_BASE_CRITICALSECTION_H_
|
|
|
|
#include "webrtc/base/atomicops.h"
|
|
#include "webrtc/base/constructormagic.h"
|
|
#include "webrtc/base/thread_annotations.h"
|
|
#include "webrtc/base/platform_thread_types.h"
|
|
|
|
#if defined(WEBRTC_WIN)
|
|
// Include winsock2.h before including <windows.h> to maintain consistency with
|
|
// win32.h. We can't include win32.h directly here since it pulls in
|
|
// headers such as basictypes.h which causes problems in Chromium where webrtc
|
|
// exists as two separate projects, webrtc and libjingle.
|
|
#include <winsock2.h>
|
|
#include <windows.h>
|
|
#include <sal.h> // must come after windows headers.
|
|
#endif // defined(WEBRTC_WIN)
|
|
|
|
#if defined(WEBRTC_POSIX)
|
|
#include <pthread.h>
|
|
#endif
|
|
|
|
// See notes in the 'Performance' unit test for the effects of this flag.
|
|
#define USE_NATIVE_MUTEX_ON_MAC 0
|
|
|
|
#if defined(WEBRTC_MAC) && !USE_NATIVE_MUTEX_ON_MAC
|
|
#include <dispatch/dispatch.h>
|
|
#endif
|
|
|
|
#if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
|
|
#define CS_DEBUG_CHECKS 1
|
|
#endif
|
|
|
|
#if CS_DEBUG_CHECKS
|
|
#define CS_DEBUG_CODE(x) x
|
|
#else // !CS_DEBUG_CHECKS
|
|
#define CS_DEBUG_CODE(x)
|
|
#endif // !CS_DEBUG_CHECKS
|
|
|
|
namespace rtc {
|
|
|
|
// Locking methods (Enter, TryEnter, Leave)are const to permit protecting
|
|
// members inside a const context without requiring mutable CriticalSections
|
|
// everywhere.
|
|
class LOCKABLE CriticalSection {
|
|
public:
|
|
CriticalSection();
|
|
~CriticalSection();
|
|
|
|
void Enter() const EXCLUSIVE_LOCK_FUNCTION();
|
|
bool TryEnter() const EXCLUSIVE_TRYLOCK_FUNCTION(true);
|
|
void Leave() const UNLOCK_FUNCTION();
|
|
|
|
// Use only for RTC_DCHECKing.
|
|
bool CurrentThreadIsOwner() const;
|
|
// Use only for RTC_DCHECKing.
|
|
bool IsLocked() const;
|
|
|
|
private:
|
|
#if defined(WEBRTC_WIN)
|
|
mutable CRITICAL_SECTION crit_;
|
|
#elif defined(WEBRTC_POSIX)
|
|
#if defined(WEBRTC_MAC) && !USE_NATIVE_MUTEX_ON_MAC
|
|
// Number of times the lock has been locked + number of threads waiting.
|
|
// TODO(tommi): We could use this number and subtract the recursion count
|
|
// to find places where we have multiple threads contending on the same lock.
|
|
mutable volatile int lock_queue_;
|
|
// |recursion_| represents the recursion count + 1 for the thread that owns
|
|
// the lock. Only modified by the thread that owns the lock.
|
|
mutable int recursion_;
|
|
// Used to signal a single waiting thread when the lock becomes available.
|
|
mutable dispatch_semaphore_t semaphore_;
|
|
// The thread that currently holds the lock. Required to handle recursion.
|
|
mutable PlatformThreadRef owning_thread_;
|
|
#else
|
|
mutable pthread_mutex_t mutex_;
|
|
#endif
|
|
CS_DEBUG_CODE(mutable PlatformThreadRef thread_);
|
|
CS_DEBUG_CODE(mutable int recursion_count_);
|
|
#endif
|
|
};
|
|
|
|
// CritScope, for serializing execution through a scope.
|
|
class SCOPED_LOCKABLE CritScope {
|
|
public:
|
|
explicit CritScope(const CriticalSection* cs) EXCLUSIVE_LOCK_FUNCTION(cs);
|
|
~CritScope() UNLOCK_FUNCTION();
|
|
private:
|
|
const CriticalSection* const cs_;
|
|
RTC_DISALLOW_COPY_AND_ASSIGN(CritScope);
|
|
};
|
|
|
|
// Tries to lock a critical section on construction via
|
|
// CriticalSection::TryEnter, and unlocks on destruction if the
|
|
// lock was taken. Never blocks.
|
|
//
|
|
// IMPORTANT: Unlike CritScope, the lock may not be owned by this thread in
|
|
// subsequent code. Users *must* check locked() to determine if the
|
|
// lock was taken. If you're not calling locked(), you're doing it wrong!
|
|
class TryCritScope {
|
|
public:
|
|
explicit TryCritScope(const CriticalSection* cs);
|
|
~TryCritScope();
|
|
#if defined(WEBRTC_WIN)
|
|
_Check_return_ bool locked() const;
|
|
#else
|
|
bool locked() const __attribute__ ((__warn_unused_result__));
|
|
#endif
|
|
private:
|
|
const CriticalSection* const cs_;
|
|
const bool locked_;
|
|
CS_DEBUG_CODE(mutable bool lock_was_called_);
|
|
RTC_DISALLOW_COPY_AND_ASSIGN(TryCritScope);
|
|
};
|
|
|
|
// A POD lock used to protect global variables. Do NOT use for other purposes.
|
|
// No custom constructor or private data member should be added.
|
|
class LOCKABLE GlobalLockPod {
|
|
public:
|
|
void Lock() EXCLUSIVE_LOCK_FUNCTION();
|
|
|
|
void Unlock() UNLOCK_FUNCTION();
|
|
|
|
volatile int lock_acquired;
|
|
};
|
|
|
|
class GlobalLock : public GlobalLockPod {
|
|
public:
|
|
GlobalLock();
|
|
};
|
|
|
|
// GlobalLockScope, for serializing execution through a scope.
|
|
class SCOPED_LOCKABLE GlobalLockScope {
|
|
public:
|
|
explicit GlobalLockScope(GlobalLockPod* lock) EXCLUSIVE_LOCK_FUNCTION(lock);
|
|
~GlobalLockScope() UNLOCK_FUNCTION();
|
|
private:
|
|
GlobalLockPod* const lock_;
|
|
RTC_DISALLOW_COPY_AND_ASSIGN(GlobalLockScope);
|
|
};
|
|
|
|
} // namespace rtc
|
|
|
|
#endif // WEBRTC_BASE_CRITICALSECTION_H_
|