Nagram/TMessagesProj/jni/libtgvoip3/webrtc_dsp/rtc_base/criticalsection.h

/*
 *  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 RTC_BASE_CRITICALSECTION_H_
#define RTC_BASE_CRITICALSECTION_H_

#include "rtc_base/checks.h"
#include "rtc_base/constructormagic.h"
#include "rtc_base/platform_thread_types.h"
#include "rtc_base/thread_annotations.h"

#if defined(WEBRTC_WIN)
// clang-format off
// clang formating would change include order.

// Include winsock2.h before including <windows.h> to maintain consistency with
// win32.h. To include win32.h directly, it must be broken out into its own
// build target.
#include <winsock2.h>
#include <windows.h>
#include <sal.h>  // must come after windows headers.
// clang-format on
#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

#define CS_DEBUG_CHECKS RTC_DCHECK_IS_ON

#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 RTC_LOCKABLE CriticalSection
{
public:
    CriticalSection();
    ~CriticalSection();

    void Enter() const RTC_EXCLUSIVE_LOCK_FUNCTION();
    bool TryEnter() const RTC_EXCLUSIVE_TRYLOCK_FUNCTION(true);
    void Leave() const RTC_UNLOCK_FUNCTION();

private:
    // Use only for RTC_DCHECKing.
    bool CurrentThreadIsOwner() const;

#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
    mutable PlatformThreadRef thread_; // Only used by RTC_DCHECKs.
    mutable int recursion_count_; // Only used by RTC_DCHECKs.
#else // !defined(WEBRTC_WIN) && !defined(WEBRTC_POSIX)
#error Unsupported platform.
#endif
};

// CritScope, for serializing execution through a scope.
class RTC_SCOPED_LOCKABLE CritScope
{
public:
    explicit CritScope(const CriticalSection* cs) RTC_EXCLUSIVE_LOCK_FUNCTION(cs);
    ~CritScope() RTC_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;
#elif defined(WEBRTC_POSIX)
    bool locked() const __attribute__((__warn_unused_result__));
#else // !defined(WEBRTC_WIN) && !defined(WEBRTC_POSIX)
#error Unsupported platform.
#endif
private:
    const CriticalSection* const cs_;
    const bool locked_;
    mutable bool lock_was_called_; // Only used by RTC_DCHECKs.
    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 RTC_LOCKABLE GlobalLockPod
{
public:
    void Lock() RTC_EXCLUSIVE_LOCK_FUNCTION();

    void Unlock() RTC_UNLOCK_FUNCTION();

    volatile int lock_acquired;
};

class GlobalLock : public GlobalLockPod
{
public:
    GlobalLock();
};

// GlobalLockScope, for serializing execution through a scope.
class RTC_SCOPED_LOCKABLE GlobalLockScope
{
public:
    explicit GlobalLockScope(GlobalLockPod* lock)
        RTC_EXCLUSIVE_LOCK_FUNCTION(lock);
    ~GlobalLockScope() RTC_UNLOCK_FUNCTION();

private:
    GlobalLockPod* const lock_;
    RTC_DISALLOW_COPY_AND_ASSIGN(GlobalLockScope);
};

} // namespace rtc

#endif // RTC_BASE_CRITICALSECTION_H_