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 "SQLTransactionCoordinator.h"
34
35#if ENABLE(SQL_DATABASE)
36
37#include "DatabaseBackend.h"
38#include "SQLTransactionBackend.h"
39#include "SecurityOrigin.h"
40#include <wtf/Deque.h>
41#include <wtf/HashMap.h>
42#include <wtf/HashSet.h>
43#include <wtf/RefPtr.h>
44
45namespace WebCore {
46
47static String getDatabaseIdentifier(SQLTransactionBackend* transaction)
48{
49    DatabaseBackend* database = transaction->database();
50    ASSERT(database);
51    return database->securityOrigin()->databaseIdentifier();
52}
53
54SQLTransactionCoordinator::SQLTransactionCoordinator()
55    : m_isShuttingDown(false)
56{
57}
58
59void SQLTransactionCoordinator::processPendingTransactions(CoordinationInfo& info)
60{
61    if (info.activeWriteTransaction || info.pendingTransactions.isEmpty())
62        return;
63
64    RefPtr<SQLTransactionBackend> firstPendingTransaction = info.pendingTransactions.first();
65    if (firstPendingTransaction->isReadOnly()) {
66        do {
67            firstPendingTransaction = info.pendingTransactions.takeFirst();
68            info.activeReadTransactions.add(firstPendingTransaction);
69            firstPendingTransaction->lockAcquired();
70        } while (!info.pendingTransactions.isEmpty() && info.pendingTransactions.first()->isReadOnly());
71    } else if (info.activeReadTransactions.isEmpty()) {
72        info.pendingTransactions.removeFirst();
73        info.activeWriteTransaction = firstPendingTransaction;
74        firstPendingTransaction->lockAcquired();
75    }
76}
77
78void SQLTransactionCoordinator::acquireLock(SQLTransactionBackend* transaction)
79{
80    ASSERT(!m_isShuttingDown);
81
82    String dbIdentifier = getDatabaseIdentifier(transaction);
83
84    CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
85    if (coordinationInfoIterator == m_coordinationInfoMap.end()) {
86        // No pending transactions for this DB
87        coordinationInfoIterator = m_coordinationInfoMap.add(dbIdentifier, CoordinationInfo()).iterator;
88    }
89
90    CoordinationInfo& info = coordinationInfoIterator->value;
91    info.pendingTransactions.append(transaction);
92    processPendingTransactions(info);
93}
94
95void SQLTransactionCoordinator::releaseLock(SQLTransactionBackend* transaction)
96{
97    if (m_isShuttingDown)
98        return;
99
100    String dbIdentifier = getDatabaseIdentifier(transaction);
101
102    CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
103    ASSERT(coordinationInfoIterator != m_coordinationInfoMap.end());
104    CoordinationInfo& info = coordinationInfoIterator->value;
105
106    if (transaction->isReadOnly()) {
107        ASSERT(info.activeReadTransactions.contains(transaction));
108        info.activeReadTransactions.remove(transaction);
109    } else {
110        ASSERT(info.activeWriteTransaction == transaction);
111        info.activeWriteTransaction = 0;
112    }
113
114    processPendingTransactions(info);
115}
116
117void SQLTransactionCoordinator::shutdown()
118{
119    // Prevent releaseLock() from accessing / changing the coordinationInfo
120    // while we're shutting down.
121    m_isShuttingDown = true;
122
123    // Notify all transactions in progress that the database thread is shutting down
124    for (CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.begin();
125         coordinationInfoIterator != m_coordinationInfoMap.end(); ++coordinationInfoIterator) {
126        CoordinationInfo& info = coordinationInfoIterator->value;
127
128        // Clean up transactions that have reached "lockAcquired":
129        // Transaction phase 4 cleanup. See comment on "What happens if a
130        // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
131        if (info.activeWriteTransaction)
132            info.activeWriteTransaction->notifyDatabaseThreadIsShuttingDown();
133        for (HashSet<RefPtr<SQLTransactionBackend>>::iterator activeReadTransactionsIterator =
134                     info.activeReadTransactions.begin();
135             activeReadTransactionsIterator != info.activeReadTransactions.end();
136             ++activeReadTransactionsIterator) {
137            (*activeReadTransactionsIterator)->notifyDatabaseThreadIsShuttingDown();
138        }
139
140        // Clean up transactions that have NOT reached "lockAcquired":
141        // Transaction phase 3 cleanup. See comment on "What happens if a
142        // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
143        while (!info.pendingTransactions.isEmpty()) {
144            RefPtr<SQLTransactionBackend> transaction = info.pendingTransactions.first();
145            transaction->notifyDatabaseThreadIsShuttingDown();
146        }
147    }
148
149    // Clean up all pending transactions for all databases
150    m_coordinationInfoMap.clear();
151}
152
153} // namespace WebCore
154
155#endif // ENABLE(SQL_DATABASE)
156