/*

 * Copyright (C) 2009 Google 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:

 *

 *     * Redistributions of source code must retain the above copyright

 * notice, this list of conditions and the following disclaimer.

 *     * 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.

 *     * Neither the name of Google Inc. 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 THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT

 * OWNER 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

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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "config.h"

#include "SQLTransactionCoordinator.h"

#if ENABLE(DATABASE)

#include "Database.h"

#include "SQLTransaction.h"

#include <wtf/Deque.h>

#include <wtf/HashMap.h>

#include <wtf/HashSet.h>

#include <wtf/RefPtr.h>

namespace WebCore {

static String getDatabaseIdentifier(SQLTransaction* transaction)

{

    Database* database = transaction->database();

    ASSERT(database);

    return database->stringIdentifier();

}

void SQLTransactionCoordinator::processPendingTransactions(CoordinationInfo& info)

{

    if (info.activeWriteTransaction || info.pendingTransactions.isEmpty())

        return;

    RefPtr<SQLTransaction> firstPendingTransaction = info.pendingTransactions.first();

    if (firstPendingTransaction->isReadOnly()) {

        do {

            firstPendingTransaction = info.pendingTransactions.takeFirst();

            info.activeReadTransactions.add(firstPendingTransaction);

            firstPendingTransaction->lockAcquired();

        } while (!info.pendingTransactions.isEmpty() && info.pendingTransactions.first()->isReadOnly());

    } else if (info.activeReadTransactions.isEmpty()) {

        info.pendingTransactions.removeFirst();

        info.activeWriteTransaction = firstPendingTransaction;

        firstPendingTransaction->lockAcquired();

    }

}

void SQLTransactionCoordinator::acquireLock(SQLTransaction* transaction)

{

    String dbIdentifier = getDatabaseIdentifier(transaction);

    CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);

    if (coordinationInfoIterator == m_coordinationInfoMap.end()) {

        // No pending transactions for this DB

        coordinationInfoIterator = m_coordinationInfoMap.add(dbIdentifier, CoordinationInfo()).first;

    }

    CoordinationInfo& info = coordinationInfoIterator->second;

    info.pendingTransactions.append(transaction);

    processPendingTransactions(info);

}

void SQLTransactionCoordinator::releaseLock(SQLTransaction* transaction)

{

    if (m_coordinationInfoMap.isEmpty())

        return;

    String dbIdentifier = getDatabaseIdentifier(transaction);

    CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);

    ASSERT(coordinationInfoIterator != m_coordinationInfoMap.end());

    CoordinationInfo& info = coordinationInfoIterator->second;

    if (transaction->isReadOnly()) {

        ASSERT(info.activeReadTransactions.contains(transaction));

        info.activeReadTransactions.remove(transaction);

    } else {

        ASSERT(info.activeWriteTransaction == transaction);

        info.activeWriteTransaction = 0;

    }

    processPendingTransactions(info);

}

void SQLTransactionCoordinator::shutdown()

{

    // Notify all transactions in progress that the database thread is shutting down

    for (CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.begin();

         coordinationInfoIterator != m_coordinationInfoMap.end(); ++coordinationInfoIterator) {

        CoordinationInfo& info = coordinationInfoIterator->second;

        if (info.activeWriteTransaction)

            info.activeWriteTransaction->notifyDatabaseThreadIsShuttingDown();

        for (HashSet<RefPtr<SQLTransaction> >::iterator activeReadTransactionsIterator =

                     info.activeReadTransactions.begin();

             activeReadTransactionsIterator != info.activeReadTransactions.end();

             ++activeReadTransactionsIterator) {

            (*activeReadTransactionsIterator)->notifyDatabaseThreadIsShuttingDown();

        }

    }

    // Clean up all pending transactions for all databases

    m_coordinationInfoMap.clear();

}

} // namespace WebCore

#endif // ENABLE(DATABASE)