/*

 * Copyright (C) 2008 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 COMPUTER, 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 COMPUTER, 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. 

 *

 */

#include "config.h"

#if ENABLE(WORKERS)

#include "WorkerThread.h"

#include "DatabaseTask.h"

#include "DedicatedWorkerContext.h"

#include "KURL.h"

#include "PlatformString.h"

#include "ScriptSourceCode.h"

#include "ScriptValue.h"

#include "ThreadGlobalData.h"

#include <utility>

#include <wtf/Noncopyable.h>

namespace WebCore {

static Mutex& threadCountMutex()

{

    AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);

    return mutex;

}

unsigned WorkerThread::m_threadCount = 0;

unsigned WorkerThread::workerThreadCount()

{

    MutexLocker lock(threadCountMutex());

    return m_threadCount;

}

struct WorkerThreadStartupData : Noncopyable {

public:

    static PassOwnPtr<WorkerThreadStartupData> create(const KURL& scriptURL, const String& userAgent, const String& sourceCode)

    {

        return new WorkerThreadStartupData(scriptURL, userAgent, sourceCode);

    }

    KURL m_scriptURL;

    String m_userAgent;

    String m_sourceCode;

private:

    WorkerThreadStartupData(const KURL& scriptURL, const String& userAgent, const String& sourceCode);

};

WorkerThreadStartupData::WorkerThreadStartupData(const KURL& scriptURL, const String& userAgent, const String& sourceCode)

    : m_scriptURL(scriptURL.copy())

    , m_userAgent(userAgent.crossThreadString())

    , m_sourceCode(sourceCode.crossThreadString())

{

}

WorkerThread::WorkerThread(const KURL& scriptURL, const String& userAgent, const String& sourceCode, WorkerLoaderProxy& workerLoaderProxy, WorkerReportingProxy& workerReportingProxy)

    : m_threadID(0)

    , m_workerLoaderProxy(workerLoaderProxy)

    , m_workerReportingProxy(workerReportingProxy)

    , m_startupData(WorkerThreadStartupData::create(scriptURL, userAgent, sourceCode))

{

    MutexLocker lock(threadCountMutex());

    m_threadCount++;

}

WorkerThread::~WorkerThread()

{

    MutexLocker lock(threadCountMutex());

    ASSERT(m_threadCount > 0);

    m_threadCount--;

}

bool WorkerThread::start()

{

    // Mutex protection is necessary to ensure that m_threadID is initialized when the thread starts.

    MutexLocker lock(m_threadCreationMutex);

    if (m_threadID)

        return true;

    m_threadID = createThread(WorkerThread::workerThreadStart, this, "WebCore: Worker");

    return m_threadID;

}

void* WorkerThread::workerThreadStart(void* thread)

{

    return static_cast<WorkerThread*>(thread)->workerThread();

}

void* WorkerThread::workerThread()

{

    {

        MutexLocker lock(m_threadCreationMutex);

        m_workerContext = createWorkerContext(m_startupData->m_scriptURL, m_startupData->m_userAgent);

        if (m_runLoop.terminated()) {

            // The worker was terminated before the thread had a chance to run. Since the context didn't exist yet,

            // forbidExecution() couldn't be called from stop().

           m_workerContext->script()->forbidExecution(WorkerScriptController::TerminateRunningScript);

        }

    }

    WorkerScriptController* script = m_workerContext->script();

    script->evaluate(ScriptSourceCode(m_startupData->m_sourceCode, m_startupData->m_scriptURL));

    // Free the startup data to cause its member variable deref's happen on the worker's thread (since

    // all ref/derefs of these objects are happening on the thread at this point). Note that

    // WorkerThread::~WorkerThread happens on a different thread where it was created.

    m_startupData.clear();

    runEventLoop();

    ThreadIdentifier threadID = m_threadID;

    ASSERT(m_workerContext->hasOneRef());

    // The below assignment will destroy the context, which will in turn notify messaging proxy.

    // We cannot let any objects survive past thread exit, because no other thread will run GC or otherwise destroy them.

    m_workerContext = 0;

    // Clean up WebCore::ThreadGlobalData before WTF::WTFThreadData goes away!

    threadGlobalData().destroy();

    // The thread object may be already destroyed from notification now, don't try to access "this".

    detachThread(threadID);

    return 0;

}

void WorkerThread::runEventLoop()

{

    // Does not return until terminated.

    m_runLoop.run(m_workerContext.get());

}

class WorkerThreadShutdownFinishTask : public ScriptExecutionContext::Task {

public:

    static PassOwnPtr<WorkerThreadShutdownFinishTask> create()

    {

        return new WorkerThreadShutdownFinishTask();

    }

    virtual void performTask(ScriptExecutionContext *context)

    {

        ASSERT(context->isWorkerContext());

        WorkerContext* workerContext = static_cast<WorkerContext*>(context);

        // It's not safe to call clearScript until all the cleanup tasks posted by functions initiated by WorkerThreadShutdownStartTask have completed.

        workerContext->clearScript();

        workerContext->thread()->runLoop().terminate();

    }

    virtual bool isCleanupTask() const { return true; }

};

class WorkerThreadShutdownStartTask : public ScriptExecutionContext::Task {

public:

    static PassOwnPtr<WorkerThreadShutdownStartTask> create()

    {

        return new WorkerThreadShutdownStartTask();

    }

    virtual void performTask(ScriptExecutionContext *context)

    {

        ASSERT(context->isWorkerContext());

        WorkerContext* workerContext = static_cast<WorkerContext*>(context);

#if ENABLE(DATABASE)

        // We currently ignore any DatabasePolicy used for the document's

        // databases; if it's actually used anywhere, this should be revisited.

        DatabaseTaskSynchronizer cleanupSync;

        workerContext->stopDatabases(&cleanupSync);

#endif

        workerContext->stopActiveDOMObjects();

        // Event listeners would keep DOMWrapperWorld objects alive for too long. Also, they have references to JS objects,

        // which become dangling once Heap is destroyed.

        workerContext->removeAllEventListeners();

#if ENABLE(DATABASE)

        // We wait for the database thread to clean up all its stuff so that we

        // can do more stringent leak checks as we exit.

        cleanupSync.waitForTaskCompletion();

#endif

        // Stick a shutdown command at the end of the queue, so that we deal

        // with all the cleanup tasks the databases post first.

        workerContext->postTask(WorkerThreadShutdownFinishTask::create());

    }

    virtual bool isCleanupTask() const { return true; }

};

void WorkerThread::stop()

{

    // Mutex protection is necessary because stop() can be called before the context is fully created.

    MutexLocker lock(m_threadCreationMutex);

    // Ensure that tasks are being handled by thread event loop. If script execution weren't forbidden, a while(1) loop in JS could keep the thread alive forever.

    if (m_workerContext) {

        m_workerContext->script()->forbidExecution(WorkerScriptController::TerminateRunningScript);

    // FIXME: Rudely killing the thread won't work when we allow nested workers, because they will try to post notifications of their destruction.

    // This can likely use the same mechanism as used for databases above.

        m_runLoop.postTask(WorkerThreadShutdownStartTask::create());

    } else

        m_runLoop.terminate();

}

} // namespace WebCore

#endif // ENABLE(WORKERS)