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 "Database.h"
37#include "SQLTransaction.h"
38#include <wtf/Deque.h>
39#include <wtf/HashMap.h>
40#include <wtf/HashSet.h>
41#include <wtf/RefPtr.h>
42
43namespace WebCore {
44
45static String getDatabaseIdentifier(SQLTransaction* transaction)
46{
47    Database* database = transaction->database();
48    ASSERT(database);
49    return database->stringIdentifier();
50}
51
52void SQLTransactionCoordinator::processPendingTransactions(CoordinationInfo& info)
53{
54    if (info.activeWriteTransaction || info.pendingTransactions.isEmpty())
55        return;
56
57    RefPtr<SQLTransaction> firstPendingTransaction = info.pendingTransactions.first();
58    if (firstPendingTransaction->isReadOnly()) {
59        do {
60            firstPendingTransaction = info.pendingTransactions.takeFirst();
61            info.activeReadTransactions.add(firstPendingTransaction);
62            firstPendingTransaction->lockAcquired();
63        } while (!info.pendingTransactions.isEmpty() && info.pendingTransactions.first()->isReadOnly());
64    } else if (info.activeReadTransactions.isEmpty()) {
65        info.pendingTransactions.removeFirst();
66        info.activeWriteTransaction = firstPendingTransaction;
67        firstPendingTransaction->lockAcquired();
68    }
69}
70
71void SQLTransactionCoordinator::acquireLock(SQLTransaction* transaction)
72{
73    String dbIdentifier = getDatabaseIdentifier(transaction);
74
75    CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
76    if (coordinationInfoIterator == m_coordinationInfoMap.end()) {
77        // No pending transactions for this DB
78        coordinationInfoIterator = m_coordinationInfoMap.add(dbIdentifier, CoordinationInfo()).first;
79    }
80
81    CoordinationInfo& info = coordinationInfoIterator->second;
82    info.pendingTransactions.append(transaction);
83    processPendingTransactions(info);
84}
85
86void SQLTransactionCoordinator::releaseLock(SQLTransaction* transaction)
87{
88    if (m_coordinationInfoMap.isEmpty())
89        return;
90
91    String dbIdentifier = getDatabaseIdentifier(transaction);
92
93    CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
94    ASSERT(coordinationInfoIterator != m_coordinationInfoMap.end());
95    CoordinationInfo& info = coordinationInfoIterator->second;
96
97    if (transaction->isReadOnly()) {
98        ASSERT(info.activeReadTransactions.contains(transaction));
99        info.activeReadTransactions.remove(transaction);
100    } else {
101        ASSERT(info.activeWriteTransaction == transaction);
102        info.activeWriteTransaction = 0;
103    }
104
105    processPendingTransactions(info);
106}
107
108void SQLTransactionCoordinator::shutdown()
109{
110    // Notify all transactions in progress that the database thread is shutting down
111    for (CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.begin();
112         coordinationInfoIterator != m_coordinationInfoMap.end(); ++coordinationInfoIterator) {
113        CoordinationInfo& info = coordinationInfoIterator->second;
114        if (info.activeWriteTransaction)
115            info.activeWriteTransaction->notifyDatabaseThreadIsShuttingDown();
116        for (HashSet<RefPtr<SQLTransaction> >::iterator activeReadTransactionsIterator =
117                     info.activeReadTransactions.begin();
118             activeReadTransactionsIterator != info.activeReadTransactions.end();
119             ++activeReadTransactionsIterator) {
120            (*activeReadTransactionsIterator)->notifyDatabaseThreadIsShuttingDown();
121        }
122    }
123
124    // Clean up all pending transactions for all databases
125    m_coordinationInfoMap.clear();
126}
127
128} // namespace WebCore
129
130#endif // ENABLE(DATABASE)
131