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[chromium-blink-merge.git] / third_party / WebKit / Source / wtf / ThreadingWin.cpp

/*
 * Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
 * Copyright (C) 2009 Google Inc. All rights reserved.
 * Copyright (C) 2009 Torch Mobile, 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.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "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 OR ITS 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.
 */

/*
 * There are numerous academic and practical works on how to implement pthread_cond_wait/pthread_cond_signal/pthread_cond_broadcast
 * functions on Win32. Here is one example: http://www.cs.wustl.edu/~schmidt/win32-cv-1.html which is widely credited as a 'starting point'
 * of modern attempts. There are several more or less proven implementations, one in Boost C++ library (http://www.boost.org) and another
 * in pthreads-win32 (http://sourceware.org/pthreads-win32/).
 *
 * The number of articles and discussions is the evidence of significant difficulties in implementing these primitives correctly.
 * The brief search of revisions, ChangeLog entries, discussions in comp.programming.threads and other places clearly documents
 * numerous pitfalls and performance problems the authors had to overcome to arrive to the suitable implementations.
 * Optimally, WebKit would use one of those supported/tested libraries directly. To roll out our own implementation is impractical,
 * if even for the lack of sufficient testing. However, a faithful reproduction of the code from one of the popular supported
 * libraries seems to be a good compromise.
 *
 * The early Boost implementation (http://www.boxbackup.org/trac/browser/box/nick/win/lib/win32/boost_1_32_0/libs/thread/src/condition.cpp?rev=30)
 * is identical to pthreads-win32 (http://sourceware.org/cgi-bin/cvsweb.cgi/pthreads/pthread_cond_wait.c?rev=1.10&content-type=text/x-cvsweb-markup&cvsroot=pthreads-win32).
 * Current Boost uses yet another (although seemingly equivalent) algorithm which came from their 'thread rewrite' effort.
 *
 * This file includes timedWait/signal/broadcast implementations translated to WebKit coding style from the latest algorithm by
 * Alexander Terekhov and Louis Thomas, as captured here: http://sourceware.org/cgi-bin/cvsweb.cgi/pthreads/pthread_cond_wait.c?rev=1.10&content-type=text/x-cvsweb-markup&cvsroot=pthreads-win32
 * It replaces the implementation of their previous algorithm, also documented in the same source above.
 * The naming and comments are left very close to original to enable easy cross-check.
 *
 * The corresponding Pthreads-win32 License is included below, and CONTRIBUTORS file which it refers to is added to
 * source directory (as CONTRIBUTORS.pthreads-win32).
 */

/*
 *      Pthreads-win32 - POSIX Threads Library for Win32
 *      Copyright(C) 1998 John E. Bossom
 *      Copyright(C) 1999,2005 Pthreads-win32 contributors
 *
 *      Contact Email: rpj@callisto.canberra.edu.au
 *
 *      The current list of contributors is contained
 *      in the file CONTRIBUTORS included with the source
 *      code distribution. The list can also be seen at the
 *      following World Wide Web location:
 *      http://sources.redhat.com/pthreads-win32/contributors.html
 *
 *      This library is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU Lesser General Public
 *      License as published by the Free Software Foundation; either
 *      version 2 of the License, or (at your option) any later version.
 *
 *      This library is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *      Lesser General Public License for more details.
 *
 *      You should have received a copy of the GNU Lesser General Public
 *      License along with this library in the file COPYING.LIB;
 *      if not, write to the Free Software Foundation, Inc.,
 *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include "config.h"
#include "Threading.h"

#if OS(WIN)

#include "wtf/CurrentTime.h"
#include "wtf/DateMath.h"
#include "wtf/HashMap.h"
#include "wtf/MainThread.h"
#include "wtf/MathExtras.h"
#include "wtf/OwnPtr.h"
#include "wtf/PassOwnPtr.h"
#include "wtf/ThreadSpecific.h"
#include "wtf/ThreadingPrimitives.h"
#include "wtf/WTFThreadData.h"
#include "wtf/dtoa.h"
#include "wtf/dtoa/cached-powers.h"
#include <errno.h>
#include <process.h>
#include <windows.h>

namespace WTF {

// THREADNAME_INFO comes from <http://msdn.microsoft.com/en-us/library/xcb2z8hs.aspx>.
#pragma pack(push, 8)
typedef struct tagTHREADNAME_INFO {
    DWORD dwType; // must be 0x1000
    LPCSTR szName; // pointer to name (in user addr space)
    DWORD dwThreadID; // thread ID (-1=caller thread)
    DWORD dwFlags; // reserved for future use, must be zero
} THREADNAME_INFO;
#pragma pack(pop)

static Mutex* atomicallyInitializedStaticMutex;

void lockAtomicallyInitializedStaticMutex()
{
    ASSERT(atomicallyInitializedStaticMutex);
    atomicallyInitializedStaticMutex->lock();
}

void unlockAtomicallyInitializedStaticMutex()
{
    atomicallyInitializedStaticMutex->unlock();
}

void initializeThreading()
{
    // This should only be called once.
    ASSERT(!atomicallyInitializedStaticMutex);

    // StringImpl::empty() does not construct its static string in a threadsafe fashion,
    // so ensure it has been initialized from here.
    StringImpl::empty();
    StringImpl::empty16Bit();
    atomicallyInitializedStaticMutex = new Mutex;
    wtfThreadData();
    s_dtoaP5Mutex = new Mutex;
    initializeDates();
    // Force initialization of static DoubleToStringConverter converter variable
    // inside EcmaScriptConverter function while we are in single thread mode.
    double_conversion::DoubleToStringConverter::EcmaScriptConverter();
}

ThreadIdentifier currentThread()
{
    return static_cast<ThreadIdentifier>(GetCurrentThreadId());
}

MutexBase::MutexBase(bool recursive)
{
    m_mutex.m_recursionCount = 0;
    InitializeCriticalSection(&m_mutex.m_internalMutex);
}

MutexBase::~MutexBase()
{
    DeleteCriticalSection(&m_mutex.m_internalMutex);
}

void MutexBase::lock()
{
    EnterCriticalSection(&m_mutex.m_internalMutex);
    ++m_mutex.m_recursionCount;
}

void MutexBase::unlock()
{
    ASSERT(m_mutex.m_recursionCount);
    --m_mutex.m_recursionCount;
    LeaveCriticalSection(&m_mutex.m_internalMutex);
}

bool Mutex::tryLock()
{
    // This method is modeled after the behavior of pthread_mutex_trylock,
    // which will return an error if the lock is already owned by the
    // current thread.  Since the primitive Win32 'TryEnterCriticalSection'
    // treats this as a successful case, it changes the behavior of several
    // tests in WebKit that check to see if the current thread already
    // owned this mutex (see e.g., IconDatabase::getOrCreateIconRecord)
    DWORD result = TryEnterCriticalSection(&m_mutex.m_internalMutex);

    if (result != 0) {       // We got the lock
        // If this thread already had the lock, we must unlock and return
        // false since this is a non-recursive mutex. This is to mimic the
        // behavior of POSIX's pthread_mutex_trylock. We don't do this
        // check in the lock method (presumably due to performance?). This
        // means lock() will succeed even if the current thread has already
        // entered the critical section.
        if (m_mutex.m_recursionCount > 0) {
            LeaveCriticalSection(&m_mutex.m_internalMutex);
            return false;
        }
        ++m_mutex.m_recursionCount;
        return true;
    }

    return false;
}

bool RecursiveMutex::tryLock()
{
    // CRITICAL_SECTION is recursive/reentrant so TryEnterCriticalSection will
    // succeed if the current thread is already in the critical section.
    DWORD result = TryEnterCriticalSection(&m_mutex.m_internalMutex);
    if (result == 0) { // We didn't get the lock.
        return false;
    }
    ++m_mutex.m_recursionCount;
    return true;
}

bool PlatformCondition::timedWait(PlatformMutex& mutex, DWORD durationMilliseconds)
{
    // Enter the wait state.
    DWORD res = WaitForSingleObject(m_blockLock, INFINITE);
    ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
    ++m_waitersBlocked;
    res = ReleaseSemaphore(m_blockLock, 1, 0);
    ASSERT_UNUSED(res, res);

    --mutex.m_recursionCount;
    LeaveCriticalSection(&mutex.m_internalMutex);

    // Main wait - use timeout.
    bool timedOut = (WaitForSingleObject(m_blockQueue, durationMilliseconds) == WAIT_TIMEOUT);

    res = WaitForSingleObject(m_unblockLock, INFINITE);
    ASSERT_UNUSED(res, res == WAIT_OBJECT_0);

    int signalsLeft = m_waitersToUnblock;

    if (m_waitersToUnblock)
        --m_waitersToUnblock;
    else if (++m_waitersGone == (INT_MAX / 2)) { // timeout/canceled or spurious semaphore
        // timeout or spurious wakeup occured, normalize the m_waitersGone count
        // this may occur if many calls to wait with a timeout are made and
        // no call to notify_* is made
        res = WaitForSingleObject(m_blockLock, INFINITE);
        ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
        m_waitersBlocked -= m_waitersGone;
        res = ReleaseSemaphore(m_blockLock, 1, 0);
        ASSERT_UNUSED(res, res);
        m_waitersGone = 0;
    }

    res = ReleaseMutex(m_unblockLock);
    ASSERT_UNUSED(res, res);

    if (signalsLeft == 1) {
        res = ReleaseSemaphore(m_blockLock, 1, 0); // Open the gate.
        ASSERT_UNUSED(res, res);
    }

    EnterCriticalSection (&mutex.m_internalMutex);
    ++mutex.m_recursionCount;

    return !timedOut;
}

void PlatformCondition::signal(bool unblockAll)
{
    unsigned signalsToIssue = 0;

    DWORD res = WaitForSingleObject(m_unblockLock, INFINITE);
    ASSERT_UNUSED(res, res == WAIT_OBJECT_0);

    if (m_waitersToUnblock) { // the gate is already closed
        if (!m_waitersBlocked) { // no-op
            res = ReleaseMutex(m_unblockLock);
            ASSERT_UNUSED(res, res);
            return;
        }

        if (unblockAll) {
            signalsToIssue = m_waitersBlocked;
            m_waitersToUnblock += m_waitersBlocked;
            m_waitersBlocked = 0;
        } else {
            signalsToIssue = 1;
            ++m_waitersToUnblock;
            --m_waitersBlocked;
        }
    } else if (m_waitersBlocked > m_waitersGone) {
        res = WaitForSingleObject(m_blockLock, INFINITE); // Close the gate.
        ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
        if (m_waitersGone != 0) {
            m_waitersBlocked -= m_waitersGone;
            m_waitersGone = 0;
        }
        if (unblockAll) {
            signalsToIssue = m_waitersBlocked;
            m_waitersToUnblock = m_waitersBlocked;
            m_waitersBlocked = 0;
        } else {
            signalsToIssue = 1;
            m_waitersToUnblock = 1;
            --m_waitersBlocked;
        }
    } else { // No-op.
        res = ReleaseMutex(m_unblockLock);
        ASSERT_UNUSED(res, res);
        return;
    }

    res = ReleaseMutex(m_unblockLock);
    ASSERT_UNUSED(res, res);

    if (signalsToIssue) {
        res = ReleaseSemaphore(m_blockQueue, signalsToIssue, 0);
        ASSERT_UNUSED(res, res);
    }
}

static const long MaxSemaphoreCount = static_cast<long>(~0UL >> 1);

ThreadCondition::ThreadCondition()
{
    m_condition.m_waitersGone = 0;
    m_condition.m_waitersBlocked = 0;
    m_condition.m_waitersToUnblock = 0;
    m_condition.m_blockLock = CreateSemaphore(0, 1, 1, 0);
    m_condition.m_blockQueue = CreateSemaphore(0, 0, MaxSemaphoreCount, 0);
    m_condition.m_unblockLock = CreateMutex(0, 0, 0);

    if (!m_condition.m_blockLock || !m_condition.m_blockQueue || !m_condition.m_unblockLock) {
        if (m_condition.m_blockLock)
            CloseHandle(m_condition.m_blockLock);
        if (m_condition.m_blockQueue)
            CloseHandle(m_condition.m_blockQueue);
        if (m_condition.m_unblockLock)
            CloseHandle(m_condition.m_unblockLock);
    }
}

ThreadCondition::~ThreadCondition()
{
    CloseHandle(m_condition.m_blockLock);
    CloseHandle(m_condition.m_blockQueue);
    CloseHandle(m_condition.m_unblockLock);
}

void ThreadCondition::wait(MutexBase& mutex)
{
    m_condition.timedWait(mutex.impl(), INFINITE);
}

bool ThreadCondition::timedWait(MutexBase& mutex, double absoluteTime)
{
    DWORD interval = absoluteTimeToWaitTimeoutInterval(absoluteTime);

    if (!interval) {
        // Consider the wait to have timed out, even if our condition has already been signaled, to
        // match the pthreads implementation.
        return false;
    }

    return m_condition.timedWait(mutex.impl(), interval);
}

void ThreadCondition::signal()
{
    m_condition.signal(false); // Unblock only 1 thread.
}

void ThreadCondition::broadcast()
{
    m_condition.signal(true); // Unblock all threads.
}

DWORD absoluteTimeToWaitTimeoutInterval(double absoluteTime)
{
    double currentTime = WTF::currentTime();

    // Time is in the past - return immediately.
    if (absoluteTime < currentTime)
        return 0;

    // Time is too far in the future (and would overflow unsigned long) - wait forever.
    if (absoluteTime - currentTime > static_cast<double>(INT_MAX) / 1000.0)
        return INFINITE;

    return static_cast<DWORD>((absoluteTime - currentTime) * 1000.0);
}

#if ENABLE(ASSERT)
static bool s_threadCreated = false;

bool isAtomicallyInitializedStaticMutexLockHeld()
{
    return atomicallyInitializedStaticMutex && atomicallyInitializedStaticMutex->locked();
}

bool isBeforeThreadCreated()
{
    return !s_threadCreated;
}

void willCreateThread()
{
    s_threadCreated = true;
}
#endif

} // namespace WTF

#endif // OS(WIN)