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/*
* Copyright (C) 2016 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <wtf/Lock.h>
#include <wtf/Threading.h>
namespace WTF {
template<typename LockType>
class RecursiveLockAdapter {
public:
RecursiveLockAdapter() = default;
// Use WTF_IGNORES_THREAD_SAFETY_ANALYSIS because the function does conditional locking, which is
// not supported by analysis. Also RecursiveLockAdapter may wrap a lock type besides WTF::Lock
// which doesn't support analysis.
void lock() WTF_IGNORES_THREAD_SAFETY_ANALYSIS
{
Thread& me = Thread::current();
if (&me == m_owner) {
m_recursionCount++;
return;
}
m_lock.lock();
ASSERT(!m_owner);
ASSERT(!m_recursionCount);
m_owner = &me;
m_recursionCount = 1;
}
// Use WTF_IGNORES_THREAD_SAFETY_ANALYSIS because the function does conditional unlocking, which is
// not supported by analysis. Also RecursiveLockAdapter may wrap a lock type besides WTF::Lock
// which doesn't support analysis.
void unlock() WTF_IGNORES_THREAD_SAFETY_ANALYSIS
{
if (--m_recursionCount)
return;
m_owner = nullptr;
m_lock.unlock();
}
// Use WTF_IGNORES_THREAD_SAFETY_ANALYSIS because the function does conditional locking, which is
// not supported by analysis. Also RecursiveLockAdapter may wrap a lock type besides WTF::Lock
// which doesn't support analysis.
bool tryLock() WTF_IGNORES_THREAD_SAFETY_ANALYSIS
{
Thread& me = Thread::current();
if (&me == m_owner) {
m_recursionCount++;
return true;
}
if (!m_lock.tryLock())
return false;
ASSERT(!m_owner);
ASSERT(!m_recursionCount);
m_owner = &me;
m_recursionCount = 1;
return true;
}
bool isLocked() const
{
return m_lock.isLocked();
}
bool isOwner() const { return m_owner == &Thread::current(); }
private:
Thread* m_owner { nullptr }; // Use Thread* instead of RefPtr<Thread> since m_owner thread is always alive while m_onwer is set.
unsigned m_recursionCount { 0 };
LockType m_lock;
};
using RecursiveLock = RecursiveLockAdapter<Lock>;
} // namespace WTF
using WTF::RecursiveLock;
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