Home | History | Annotate | Download | only in webdatabase 
      1 /*
      2  * Copyright (C) 2009 Google Inc. All rights reserved.
      3  * Copyright (C) 2013 Apple Inc. All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are
      7  * met:
      8  *
      9  *     * Redistributions of source code must retain the above copyright
     10  * notice, this list of conditions and the following disclaimer.
     11  *     * Redistributions in binary form must reproduce the above
     12  * copyright notice, this list of conditions and the following disclaimer
     13  * in the documentation and/or other materials provided with the
     14  * distribution.
     15  *     * Neither the name of Google Inc. nor the names of its
     16  * contributors may be used to endorse or promote products derived from
     17  * this software without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     22  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     23  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include "config.h"
     33 #include "modules/webdatabase/SQLTransactionCoordinator.h"
     34 
     35 #include "modules/webdatabase/DatabaseBackend.h"
     36 #include "modules/webdatabase/SQLTransactionBackend.h"
     37 #include "wtf/Deque.h"
     38 #include "wtf/HashMap.h"
     39 #include "wtf/HashSet.h"
     40 #include "wtf/RefPtr.h"
     41 
     42 namespace WebCore {
     43 
     44 static String getDatabaseIdentifier(SQLTransactionBackend* transaction)
     45 {
     46     DatabaseBackend* database = transaction->database();
     47     ASSERT(database);
     48     return database->stringIdentifier();
     49 }
     50 
     51 SQLTransactionCoordinator::SQLTransactionCoordinator()
     52     : m_isShuttingDown(false)
     53 {
     54 }
     55 
     56 void SQLTransactionCoordinator::processPendingTransactions(CoordinationInfo& info)
     57 {
     58     if (info.activeWriteTransaction || info.pendingTransactions.isEmpty())
     59         return;
     60 
     61     RefPtr<SQLTransactionBackend> firstPendingTransaction = info.pendingTransactions.first();
     62     if (firstPendingTransaction->isReadOnly()) {
     63         do {
     64             firstPendingTransaction = info.pendingTransactions.takeFirst();
     65             info.activeReadTransactions.add(firstPendingTransaction);
     66             firstPendingTransaction->lockAcquired();
     67         } while (!info.pendingTransactions.isEmpty() && info.pendingTransactions.first()->isReadOnly());
     68     } else if (info.activeReadTransactions.isEmpty()) {
     69         info.pendingTransactions.removeFirst();
     70         info.activeWriteTransaction = firstPendingTransaction;
     71         firstPendingTransaction->lockAcquired();
     72     }
     73 }
     74 
     75 void SQLTransactionCoordinator::acquireLock(SQLTransactionBackend* transaction)
     76 {
     77     ASSERT(!m_isShuttingDown);
     78 
     79     String dbIdentifier = getDatabaseIdentifier(transaction);
     80 
     81     CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
     82     if (coordinationInfoIterator == m_coordinationInfoMap.end()) {
     83         // No pending transactions for this DB
     84         coordinationInfoIterator = m_coordinationInfoMap.add(dbIdentifier, CoordinationInfo()).iterator;
     85     }
     86 
     87     CoordinationInfo& info = coordinationInfoIterator->value;
     88     info.pendingTransactions.append(transaction);
     89     processPendingTransactions(info);
     90 }
     91 
     92 void SQLTransactionCoordinator::releaseLock(SQLTransactionBackend* transaction)
     93 {
     94     if (m_isShuttingDown)
     95         return;
     96 
     97     String dbIdentifier = getDatabaseIdentifier(transaction);
     98 
     99     CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
    100     ASSERT(coordinationInfoIterator != m_coordinationInfoMap.end());
    101     CoordinationInfo& info = coordinationInfoIterator->value;
    102 
    103     if (transaction->isReadOnly()) {
    104         ASSERT(info.activeReadTransactions.contains(transaction));
    105         info.activeReadTransactions.remove(transaction);
    106     } else {
    107         ASSERT(info.activeWriteTransaction == transaction);
    108         info.activeWriteTransaction = 0;
    109     }
    110 
    111     processPendingTransactions(info);
    112 }
    113 
    114 void SQLTransactionCoordinator::shutdown()
    115 {
    116     // Prevent releaseLock() from accessing / changing the coordinationInfo
    117     // while we're shutting down.
    118     m_isShuttingDown = true;
    119 
    120     // Notify all transactions in progress that the database thread is shutting down
    121     for (CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.begin();
    122          coordinationInfoIterator != m_coordinationInfoMap.end(); ++coordinationInfoIterator) {
    123         CoordinationInfo& info = coordinationInfoIterator->value;
    124 
    125         // Clean up transactions that have reached "lockAcquired":
    126         // Transaction phase 4 cleanup. See comment on "What happens if a
    127         // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
    128         if (info.activeWriteTransaction)
    129             info.activeWriteTransaction->notifyDatabaseThreadIsShuttingDown();
    130         for (HashSet<RefPtr<SQLTransactionBackend> >::iterator activeReadTransactionsIterator =
    131                      info.activeReadTransactions.begin();
    132              activeReadTransactionsIterator != info.activeReadTransactions.end();
    133              ++activeReadTransactionsIterator) {
    134             (*activeReadTransactionsIterator)->notifyDatabaseThreadIsShuttingDown();
    135         }
    136 
    137         // Clean up transactions that have NOT reached "lockAcquired":
    138         // Transaction phase 3 cleanup. See comment on "What happens if a
    139         // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
    140         while (!info.pendingTransactions.isEmpty()) {
    141             RefPtr<SQLTransactionBackend> transaction = info.pendingTransactions.first();
    142             transaction->notifyDatabaseThreadIsShuttingDown();
    143         }
    144     }
    145 
    146     // Clean up all pending transactions for all databases
    147     m_coordinationInfoMap.clear();
    148 }
    149 
    150 } // namespace WebCore
    151