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
44namespace WebCore {
45
46static String getDatabaseIdentifier(SQLTransaction* transaction)
47{
48    Database* database = transaction->database();
49    ASSERT(database);
50    return database->stringIdentifier();
51}
52
53void 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
73void 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
88void 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
110void 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