src/third_party/WebKit/Source/modules/webdatabase/SQLTransactionCoordinator.cpp

   1 /*
   2  * Copyright (C) 2009 Google Inc. All rights reserved.
   3  * Copyright (C) 2013 Apple Inc. All rights reserved.
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   7  * met:
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  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.
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  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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  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/Database.h"
  36 #include "modules/webdatabase/SQLTransactionBackend.h"
  37
  38 namespace blink {
  39
  40 static String getDatabaseIdentifier(SQLTransactionBackend* transaction)
  41 {
  42     Database* database = transaction->database();
  43     ASSERT(database);
  44     return database->stringIdentifier();
  45 }
  46
  47 SQLTransactionCoordinator::SQLTransactionCoordinator()
  48     : m_isShuttingDown(false)
  49 {
  50 }
  51
  52 void SQLTransactionCoordinator::trace(Visitor* visitor)
  53 {
  54     visitor->trace(m_coordinationInfoMap);
  55 }
  56
  57 void SQLTransactionCoordinator::processPendingTransactions(CoordinationInfo& info)
  58 {
  59     if (info.activeWriteTransaction || info.pendingTransactions.isEmpty())
  60         return;
  61
  62     SQLTransactionBackend* firstPendingTransaction = info.pendingTransactions.first();
  63     if (firstPendingTransaction->isReadOnly()) {
  64         do {
  65             firstPendingTransaction = info.pendingTransactions.takeFirst();
  66             info.activeReadTransactions.add(firstPendingTransaction);
  67             firstPendingTransaction->lockAcquired();
  68         } while (!info.pendingTransactions.isEmpty() && info.pendingTransactions.first()->isReadOnly());
  69     } else if (info.activeReadTransactions.isEmpty()) {
  70         info.pendingTransactions.removeFirst();
  71         info.activeWriteTransaction = firstPendingTransaction;
  72         firstPendingTransaction->lockAcquired();
  73     }
  74 }
  75
  76 void SQLTransactionCoordinator::acquireLock(SQLTransactionBackend* transaction)
  77 {
  78     ASSERT(!m_isShuttingDown);
  79
  80     String dbIdentifier = getDatabaseIdentifier(transaction);
  81
  82     CoordinationInfoHeapMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
  83     if (coordinationInfoIterator == m_coordinationInfoMap.end()) {
  84         // No pending transactions for this DB
  85         CoordinationInfo& info = m_coordinationInfoMap.add(dbIdentifier, CoordinationInfo()).storedValue->value;
  86         info.pendingTransactions.append(transaction);
  87         processPendingTransactions(info);
  88     } else {
  89         CoordinationInfo& info = coordinationInfoIterator->value;
  90         info.pendingTransactions.append(transaction);
  91         processPendingTransactions(info);
  92     }
  93
  94 }
  95
  96 void SQLTransactionCoordinator::releaseLock(SQLTransactionBackend* transaction)
  97 {
  98     if (m_isShuttingDown)
  99         return;
 100
 101     String dbIdentifier = getDatabaseIdentifier(transaction);
 102
 103     CoordinationInfoHeapMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
 104     ASSERT_WITH_SECURITY_IMPLICATION(coordinationInfoIterator != m_coordinationInfoMap.end());
 105     CoordinationInfo& info = coordinationInfoIterator->value;
 106
 107     if (transaction->isReadOnly()) {
 108         ASSERT(info.activeReadTransactions.contains(transaction));
 109         info.activeReadTransactions.remove(transaction);
 110     } else {
 111         ASSERT(info.activeWriteTransaction == transaction);
 112         info.activeWriteTransaction = nullptr;
 113     }
 114
 115     processPendingTransactions(info);
 116 }
 117
 118 void SQLTransactionCoordinator::shutdown()
 119 {
 120     // Prevent releaseLock() from accessing / changing the coordinationInfo
 121     // while we're shutting down.
 122     m_isShuttingDown = true;
 123
 124     // Notify all transactions in progress that the database thread is shutting down
 125     for (CoordinationInfoHeapMap::iterator coordinationInfoIterator = m_coordinationInfoMap.begin();
 126          coordinationInfoIterator != m_coordinationInfoMap.end(); ++coordinationInfoIterator) {
 127         CoordinationInfo& info = coordinationInfoIterator->value;
 128
 129         // Clean up transactions that have reached "lockAcquired":
 130         // Transaction phase 4 cleanup. See comment on "What happens if a
 131         // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
 132         if (info.activeWriteTransaction)
 133             info.activeWriteTransaction->notifyDatabaseThreadIsShuttingDown();
 134         for (HeapHashSet<Member<SQLTransactionBackend>>::iterator activeReadTransactionsIterator =
 135                      info.activeReadTransactions.begin();
 136              activeReadTransactionsIterator != info.activeReadTransactions.end();
 137              ++activeReadTransactionsIterator) {
 138             (*activeReadTransactionsIterator)->notifyDatabaseThreadIsShuttingDown();
 139         }
 140
 141         // Clean up transactions that have NOT reached "lockAcquired":
 142         // Transaction phase 3 cleanup. See comment on "What happens if a
 143         // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
 144         while (!info.pendingTransactions.isEmpty()) {
 145             SQLTransactionBackend* transaction = info.pendingTransactions.takeFirst();
 146             transaction->notifyDatabaseThreadIsShuttingDown();
 147         }
 148     }
 149
 150     // Clean up all pending transactions for all databases
 151     m_coordinationInfoMap.clear();
 152 }
 153
 154 } // namespace blink