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
38 namespace WebCore {
39
getDatabaseIdentifier(SQLTransactionBackend * transaction)40 static String getDatabaseIdentifier(SQLTransactionBackend* transaction)
41 {
42 DatabaseBackend* database = transaction->database();
43 ASSERT(database);
44 return database->stringIdentifier();
45 }
46
SQLTransactionCoordinator()47 SQLTransactionCoordinator::SQLTransactionCoordinator()
48 : m_isShuttingDown(false)
49 {
50 }
51
processPendingTransactions(CoordinationInfo & info)52 void SQLTransactionCoordinator::processPendingTransactions(CoordinationInfo& info)
53 {
54 if (info.activeWriteTransaction || info.pendingTransactions.isEmpty())
55 return;
56
57 RefPtr<SQLTransactionBackend> 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
acquireLock(SQLTransactionBackend * transaction)71 void SQLTransactionCoordinator::acquireLock(SQLTransactionBackend* transaction)
72 {
73 ASSERT(!m_isShuttingDown);
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()).iterator;
81 }
82
83 CoordinationInfo& info = coordinationInfoIterator->value;
84 info.pendingTransactions.append(transaction);
85 processPendingTransactions(info);
86 }
87
releaseLock(SQLTransactionBackend * transaction)88 void SQLTransactionCoordinator::releaseLock(SQLTransactionBackend* transaction)
89 {
90 if (m_isShuttingDown)
91 return;
92
93 String dbIdentifier = getDatabaseIdentifier(transaction);
94
95 CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
96 ASSERT_WITH_SECURITY_IMPLICATION(coordinationInfoIterator != m_coordinationInfoMap.end());
97 CoordinationInfo& info = coordinationInfoIterator->value;
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
shutdown()110 void SQLTransactionCoordinator::shutdown()
111 {
112 // Prevent releaseLock() from accessing / changing the coordinationInfo
113 // while we're shutting down.
114 m_isShuttingDown = true;
115
116 // Notify all transactions in progress that the database thread is shutting down
117 for (CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.begin();
118 coordinationInfoIterator != m_coordinationInfoMap.end(); ++coordinationInfoIterator) {
119 CoordinationInfo& info = coordinationInfoIterator->value;
120
121 // Clean up transactions that have reached "lockAcquired":
122 // Transaction phase 4 cleanup. See comment on "What happens if a
123 // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
124 if (info.activeWriteTransaction)
125 info.activeWriteTransaction->notifyDatabaseThreadIsShuttingDown();
126 for (HashSet<RefPtr<SQLTransactionBackend> >::iterator activeReadTransactionsIterator =
127 info.activeReadTransactions.begin();
128 activeReadTransactionsIterator != info.activeReadTransactions.end();
129 ++activeReadTransactionsIterator) {
130 (*activeReadTransactionsIterator)->notifyDatabaseThreadIsShuttingDown();
131 }
132
133 // Clean up transactions that have NOT reached "lockAcquired":
134 // Transaction phase 3 cleanup. See comment on "What happens if a
135 // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
136 while (!info.pendingTransactions.isEmpty()) {
137 RefPtr<SQLTransactionBackend> transaction = info.pendingTransactions.first();
138 transaction->notifyDatabaseThreadIsShuttingDown();
139 }
140 }
141
142 // Clean up all pending transactions for all databases
143 m_coordinationInfoMap.clear();
144 }
145
146 } // namespace WebCore
147