/*
 * 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 "wtf/Threading.h"

#if OS(WIN)

#include "wtf/CurrentTime.h"
#include "wtf/DateMath.h"
#include "wtf/HashMap.h"
#include "wtf/MathExtras.h"
#include "wtf/ThreadSpecific.h"
#include "wtf/ThreadingPrimitives.h"
#include "wtf/WTFThreadData.h"
#include "wtf/dtoa/double-conversion.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;

namespace internal {

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

}  // namespace internal

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

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

void initializeThreading() {
  // This should only be called once.
  DCHECK(!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();
  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 wtfThreadData().threadId();
}

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() {
  DCHECK(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);
  DCHECK_EQ(res, WAIT_OBJECT_0);
  ++m_waitersBlocked;
  res = ReleaseSemaphore(m_blockLock, 1, 0);
  DCHECK(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);
  DCHECK_EQ(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);
    DCHECK_EQ(res, WAIT_OBJECT_0);
    m_waitersBlocked -= m_waitersGone;
    res = ReleaseSemaphore(m_blockLock, 1, 0);
    DCHECK(res);
    m_waitersGone = 0;
  }

  res = ReleaseMutex(m_unblockLock);
  DCHECK(res);

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

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

  return !timedOut;
}

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

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

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

  res = ReleaseMutex(m_unblockLock);
  DCHECK(res);

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

    m_condition.m_blockLock = nullptr;
    m_condition.m_blockQueue = nullptr;
    m_condition.m_unblockLock = nullptr;
  }
}

ThreadCondition::~ThreadCondition() {
  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);
}

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 DCHECK_IS_ON()
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)