/* * 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; void lock() { 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; } void unlock() { if (--m_recursionCount) return; m_owner = nullptr; m_lock.unlock(); } bool tryLock() { 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(); } 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;