/*
 * Copyright (C) 2007, 2009 Apple Inc. All rights reserved.
 * Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com)
 * Copyright (C) 2011 Research In Motion Limited. 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.
 */

#include "flutter/sky/engine/wtf/Threading.h"

#include <errno.h>
#include "flutter/sky/engine/wtf/HashMap.h"
#include "flutter/sky/engine/wtf/OwnPtr.h"
#include "flutter/sky/engine/wtf/PassOwnPtr.h"
#include "flutter/sky/engine/wtf/StdLibExtras.h"
#include "flutter/sky/engine/wtf/ThreadIdentifierDataPthreads.h"
#include "flutter/sky/engine/wtf/ThreadSpecific.h"
#include "flutter/sky/engine/wtf/ThreadingPrimitives.h"
#include "flutter/sky/engine/wtf/WTFThreadData.h"
#include "flutter/sky/engine/wtf/dtoa.h"
#include "wtf/dtoa/cached-powers.h"

#include <limits.h>
#include <sched.h>
#include <sys/time.h>

#if USE(PTHREADS)

namespace WTF {

class PthreadState {
    WTF_MAKE_FAST_ALLOCATED;
public:
    enum JoinableState {
        Joinable, // The default thread state. The thread can be joined on.

        Joined, // Somebody waited on this thread to exit and this thread finally exited. This state is here because there can be a
                // period of time between when the thread exits (which causes pthread_join to return and the remainder of waitOnThreadCompletion to run)
                // and when threadDidExit is called. We need threadDidExit to take charge and delete the thread data since there's
                // nobody else to pick up the slack in this case (since waitOnThreadCompletion has already returned).

        Detached // The thread has been detached and can no longer be joined on. At this point, the thread must take care of cleaning up after itself.
    };

    // Currently all threads created by WTF start out as joinable.
    PthreadState(pthread_t handle)
        : m_joinableState(Joinable)
        , m_didExit(false)
        , m_pthreadHandle(handle)
    {
    }

    JoinableState joinableState() { return m_joinableState; }
    pthread_t pthreadHandle() { return m_pthreadHandle; }
    void didBecomeDetached() { m_joinableState = Detached; }
    void didExit() { m_didExit = true; }
    void didJoin() { m_joinableState = Joined; }
    bool hasExited() { return m_didExit; }

private:
    JoinableState m_joinableState;
    bool m_didExit;
    pthread_t m_pthreadHandle;
};

typedef HashMap<ThreadIdentifier, OwnPtr<PthreadState> > ThreadMap;

static Mutex* atomicallyInitializedStaticMutex;

void unsafeThreadWasDetached(ThreadIdentifier);
void threadDidExit(ThreadIdentifier);
void threadWasJoined(ThreadIdentifier);

static Mutex& threadMapMutex()
{
    DEFINE_STATIC_LOCAL(Mutex, mutex, ());
    return mutex;
}

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();
    atomicallyInitializedStaticMutex = new Mutex;
    threadMapMutex();
    ThreadIdentifierData::initializeOnce();
    wtfThreadData();
    s_dtoaP5Mutex = new Mutex;
}

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

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

static ThreadMap& threadMap()
{
    DEFINE_STATIC_LOCAL(ThreadMap, map, ());
    return map;
}

static ThreadIdentifier identifierByPthreadHandle(const pthread_t& pthreadHandle)
{
    MutexLocker locker(threadMapMutex());

    ThreadMap::iterator i = threadMap().begin();
    for (; i != threadMap().end(); ++i) {
        if (pthread_equal(i->value->pthreadHandle(), pthreadHandle) && !i->value->hasExited())
            return i->key;
    }

    return 0;
}

static ThreadIdentifier establishIdentifierForPthreadHandle(const pthread_t& pthreadHandle)
{
    ASSERT(!identifierByPthreadHandle(pthreadHandle));
    MutexLocker locker(threadMapMutex());
    static ThreadIdentifier identifierCount = 1;
    threadMap().add(identifierCount, adoptPtr(new PthreadState(pthreadHandle)));
    return identifierCount++;
}

void initializeCurrentThreadInternal(const char* threadName)
{
    ThreadIdentifier id = identifierByPthreadHandle(pthread_self());
    ASSERT(id);
    ThreadIdentifierData::initialize(id);
}

void threadDidExit(ThreadIdentifier threadID)
{
    MutexLocker locker(threadMapMutex());
    PthreadState* state = threadMap().get(threadID);
    ASSERT(state);

    state->didExit();

    if (state->joinableState() != PthreadState::Joinable)
        threadMap().remove(threadID);
}

ThreadIdentifier currentThread()
{
    ThreadIdentifier id = ThreadIdentifierData::identifier();
    if (id)
        return id;

    // Not a WTF-created thread, ThreadIdentifier is not established yet.
    id = establishIdentifierForPthreadHandle(pthread_self());
    ThreadIdentifierData::initialize(id);
    return id;
}

MutexBase::MutexBase(bool recursive)
{
    pthread_mutexattr_t attr;
    pthread_mutexattr_init(&attr);
    pthread_mutexattr_settype(&attr, recursive ? PTHREAD_MUTEX_RECURSIVE : PTHREAD_MUTEX_NORMAL);

    int result = pthread_mutex_init(&m_mutex.m_internalMutex, &attr);
    ASSERT_UNUSED(result, !result);
#if ENABLE(ASSERT)
    m_mutex.m_recursionCount = 0;
#endif

    pthread_mutexattr_destroy(&attr);
}

MutexBase::~MutexBase()
{
    int result = pthread_mutex_destroy(&m_mutex.m_internalMutex);
    ASSERT_UNUSED(result, !result);
}

void MutexBase::lock()
{
    int result = pthread_mutex_lock(&m_mutex.m_internalMutex);
    ASSERT_UNUSED(result, !result);
#if ENABLE(ASSERT)
    ++m_mutex.m_recursionCount;
#endif
}

void MutexBase::unlock()
{
#if ENABLE(ASSERT)
    ASSERT(m_mutex.m_recursionCount);
    --m_mutex.m_recursionCount;
#endif
    int result = pthread_mutex_unlock(&m_mutex.m_internalMutex);
    ASSERT_UNUSED(result, !result);
}

// There is a separate tryLock implementation for the Mutex and the
// RecursiveMutex since on Windows we need to manually check if tryLock should
// succeed or not for the non-recursive mutex. On Linux the two implementations
// are equal except we can assert the recursion count is always zero for the
// non-recursive mutex.
bool Mutex::tryLock()
{
    int result = pthread_mutex_trylock(&m_mutex.m_internalMutex);
    if (result == 0) {
#if ENABLE(ASSERT)
        // The Mutex class is not recursive, so the recursionCount should be
        // zero after getting the lock.
        ASSERT(!m_mutex.m_recursionCount);
        ++m_mutex.m_recursionCount;
#endif
        return true;
    }
    if (result == EBUSY)
        return false;

    ASSERT_NOT_REACHED();
    return false;
}

bool RecursiveMutex::tryLock()
{
    int result = pthread_mutex_trylock(&m_mutex.m_internalMutex);
    if (result == 0) {
#if ENABLE(ASSERT)
        ++m_mutex.m_recursionCount;
#endif
        return true;
    }
    if (result == EBUSY)
        return false;

    ASSERT_NOT_REACHED();
    return false;
}

} // namespace WTF

#endif // USE(PTHREADS)