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      1 /*
      2  * Copyright (C) 2009 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #include "config.h"
     32 #include "SQLTransactionCoordinator.h"
     33 
     34 #if ENABLE(DATABASE)
     35 
     36 #include "CString.h"
     37 #include "Database.h"
     38 #include "SQLTransaction.h"
     39 #include <wtf/Deque.h>
     40 #include <wtf/HashMap.h>
     41 #include <wtf/HashSet.h>
     42 #include <wtf/RefPtr.h>
     43 
     44 namespace WebCore {
     45 
     46 static String getDatabaseIdentifier(SQLTransaction* transaction)
     47 {
     48     Database* database = transaction->database();
     49     ASSERT(database);
     50     return database->stringIdentifier();
     51 }
     52 
     53 void SQLTransactionCoordinator::processPendingTransactions(CoordinationInfo& info)
     54 {
     55     if (info.activeWriteTransaction || info.pendingTransactions.isEmpty())
     56         return;
     57 
     58     RefPtr<SQLTransaction> firstPendingTransaction = info.pendingTransactions.first();
     59     if (firstPendingTransaction->isReadOnly()) {
     60         do {
     61             firstPendingTransaction = info.pendingTransactions.first();
     62             info.pendingTransactions.removeFirst();
     63             info.activeReadTransactions.add(firstPendingTransaction);
     64             firstPendingTransaction->lockAcquired();
     65         } while (!info.pendingTransactions.isEmpty() && info.pendingTransactions.first()->isReadOnly());
     66     } else if (info.activeReadTransactions.isEmpty()) {
     67         info.pendingTransactions.removeFirst();
     68         info.activeWriteTransaction = firstPendingTransaction;
     69         firstPendingTransaction->lockAcquired();
     70     }
     71 }
     72 
     73 void SQLTransactionCoordinator::acquireLock(SQLTransaction* transaction)
     74 {
     75     String dbIdentifier = getDatabaseIdentifier(transaction);
     76 
     77     CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
     78     if (coordinationInfoIterator == m_coordinationInfoMap.end()) {
     79         // No pending transactions for this DB
     80         coordinationInfoIterator = m_coordinationInfoMap.add(dbIdentifier, CoordinationInfo()).first;
     81     }
     82 
     83     CoordinationInfo& info = coordinationInfoIterator->second;
     84     info.pendingTransactions.append(transaction);
     85     processPendingTransactions(info);
     86 }
     87 
     88 void SQLTransactionCoordinator::releaseLock(SQLTransaction* transaction)
     89 {
     90     if (m_coordinationInfoMap.isEmpty())
     91         return;
     92 
     93     String dbIdentifier = getDatabaseIdentifier(transaction);
     94 
     95     CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
     96     ASSERT(coordinationInfoIterator != m_coordinationInfoMap.end());
     97     CoordinationInfo& info = coordinationInfoIterator->second;
     98 
     99     if (transaction->isReadOnly()) {
    100         ASSERT(info.activeReadTransactions.contains(transaction));
    101         info.activeReadTransactions.remove(transaction);
    102     } else {
    103         ASSERT(info.activeWriteTransaction == transaction);
    104         info.activeWriteTransaction = 0;
    105     }
    106 
    107     processPendingTransactions(info);
    108 }
    109 
    110 void SQLTransactionCoordinator::shutdown()
    111 {
    112     // Notify all transactions in progress that the database thread is shutting down
    113     for (CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.begin();
    114          coordinationInfoIterator != m_coordinationInfoMap.end(); ++coordinationInfoIterator) {
    115         CoordinationInfo& info = coordinationInfoIterator->second;
    116         if (info.activeWriteTransaction)
    117             info.activeWriteTransaction->notifyDatabaseThreadIsShuttingDown();
    118         for (HashSet<RefPtr<SQLTransaction> >::iterator activeReadTransactionsIterator =
    119                      info.activeReadTransactions.begin();
    120              activeReadTransactionsIterator != info.activeReadTransactions.end();
    121              ++activeReadTransactionsIterator) {
    122             (*activeReadTransactionsIterator)->notifyDatabaseThreadIsShuttingDown();
    123         }
    124     }
    125 
    126     // Clean up all pending transactions for all databases
    127     m_coordinationInfoMap.clear();
    128 }
    129 
    130 } // namespace WebCore
    131 
    132 #endif // ENABLE(DATABASE)
    133