third_party/WebKit/Source/modules/webdatabase/DatabaseThread.cpp

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#include "modules/webdatabase/DatabaseThread.h"

#include "modules/webdatabase/Database.h"
#include "modules/webdatabase/DatabaseTask.h"
#include "modules/webdatabase/SQLTransactionClient.h"
#include "modules/webdatabase/SQLTransactionCoordinator.h"
#include "platform/CrossThreadFunctional.h"
#include "platform/Logging.h"
#include "platform/WebThreadSupportingGC.h"
#include "public/platform/Platform.h"
#include "wtf/PtrUtil.h"
#include <memory>

namespace blink {

DatabaseThread::DatabaseThread()
    : m_transactionClient(wrapUnique(new SQLTransactionClient()))
    , m_cleanupSync(nullptr)
    , m_terminationRequested(false)
{
    DCHECK(isMainThread());
}

DatabaseThread::~DatabaseThread()
{
    ASSERT(m_openDatabaseSet.isEmpty());
    ASSERT(!m_thread);
}

DEFINE_TRACE(DatabaseThread)
{
}

void DatabaseThread::start()
{
    ASSERT(isMainThread());
    if (m_thread)
        return;
    m_thread = WebThreadSupportingGC::create("WebCore: Database", true);
    m_thread->postTask(BLINK_FROM_HERE, crossThreadBind(&DatabaseThread::setupDatabaseThread, wrapCrossThreadPersistent(this)));
}

void DatabaseThread::setupDatabaseThread()
{
    m_thread->initialize();
    m_transactionCoordinator = new SQLTransactionCoordinator();
}

void DatabaseThread::terminate()
{
    ASSERT(isMainThread());
    TaskSynchronizer sync;
    {
        MutexLocker lock(m_terminationRequestedMutex);
        ASSERT(!m_terminationRequested);
        m_terminationRequested = true;
        m_cleanupSync = &sync;
        WTF_LOG(StorageAPI, "DatabaseThread %p was asked to terminate\n", this);
        m_thread->postTask(BLINK_FROM_HERE, crossThreadBind(&DatabaseThread::cleanupDatabaseThread, wrapCrossThreadPersistent(this)));
    }
    sync.waitForTaskCompletion();
    // The WebThread destructor blocks until all the tasks of the database
    // thread are processed. However, it shouldn't block at all because
    // the database thread has already finished processing the cleanup task.
    m_thread.reset();
}

void DatabaseThread::cleanupDatabaseThread()
{
    DCHECK(isDatabaseThread());

    WTF_LOG(StorageAPI, "Cleaning up DatabaseThread %p", this);

    // Clean up the list of all pending transactions on this database thread
    m_transactionCoordinator->shutdown();

    // Close the databases that we ran transactions on. This ensures that if any transactions are still open, they are rolled back and we don't leave the database in an
    // inconsistent or locked state.
    if (m_openDatabaseSet.size() > 0) {
        // As the call to close will modify the original set, we must take a copy to iterate over.
        HashSet<CrossThreadPersistent<Database>> openSetCopy;
        openSetCopy.swap(m_openDatabaseSet);
        HashSet<CrossThreadPersistent<Database>>::iterator end = openSetCopy.end();
        for (HashSet<CrossThreadPersistent<Database>>::iterator it = openSetCopy.begin(); it != end; ++it)
            (*it)->close();
    }
    m_openDatabaseSet.clear();

    m_thread->postTask(BLINK_FROM_HERE, WTF::bind(&DatabaseThread::cleanupDatabaseThreadCompleted, wrapCrossThreadPersistent(this)));
}

void DatabaseThread::cleanupDatabaseThreadCompleted()
{
    m_thread->shutdown();
    if (m_cleanupSync) // Someone wanted to know when we were done cleaning up.
        m_cleanupSync->taskCompleted();
}

void DatabaseThread::recordDatabaseOpen(Database* database)
{
    ASSERT(isDatabaseThread());
    ASSERT(database);
    ASSERT(!m_openDatabaseSet.contains(database));
    MutexLocker lock(m_terminationRequestedMutex);
    if (!m_terminationRequested)
        m_openDatabaseSet.add(database);
}

void DatabaseThread::recordDatabaseClosed(Database* database)
{
    ASSERT(isDatabaseThread());
    ASSERT(database);
#if ENABLE(ASSERT)
    {
        MutexLocker lock(m_terminationRequestedMutex);
        ASSERT(m_terminationRequested || m_openDatabaseSet.contains(database));
    }
#endif
    m_openDatabaseSet.remove(database);
}

bool DatabaseThread::isDatabaseOpen(Database* database)
{
    ASSERT(isDatabaseThread());
    ASSERT(database);
    MutexLocker lock(m_terminationRequestedMutex);
    return !m_terminationRequested && m_openDatabaseSet.contains(database);
}

bool DatabaseThread::isDatabaseThread() const
{
    // This function is called only from the main thread or the database
    // thread. If we are not in the main thread, we are in the database thread.
    return !isMainThread();
}

void DatabaseThread::scheduleTask(std::unique_ptr<DatabaseTask> task)
{
    ASSERT(m_thread);
#if ENABLE(ASSERT)
    {
        MutexLocker lock(m_terminationRequestedMutex);
        ASSERT(!m_terminationRequested);
    }
#endif
    // WebThread takes ownership of the task.
    m_thread->postTask(BLINK_FROM_HERE, crossThreadBind(&DatabaseTask::run, std::move(task)));
}

} // namespace blink