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

   1 /*
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   3  * Copyright (C) 2013 Apple Inc. All rights reserved.
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  10  * notice, this list of conditions and the following disclaimer.
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  13  * in the documentation and/or other materials provided with the
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  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
  40 static String getDatabaseIdentifier(SQLTransactionBackend* transaction)
  41 {
  42     DatabaseBackend* 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::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
  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         CoordinationInfo& info = m_coordinationInfoMap.add(dbIdentifier, CoordinationInfo()).storedValue->value;
  81         info.pendingTransactions.append(transaction);
  82         processPendingTransactions(info);
  83     } else {
  84         CoordinationInfo& info = coordinationInfoIterator->value;
  85         info.pendingTransactions.append(transaction);
  86         processPendingTransactions(info);
  87     }
  88
  89 }
  90
  91 void SQLTransactionCoordinator::releaseLock(SQLTransactionBackend* transaction)
  92 {
  93     if (m_isShuttingDown)
  94         return;
  95
  96     String dbIdentifier = getDatabaseIdentifier(transaction);
  97
  98     CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
  99     ASSERT_WITH_SECURITY_IMPLICATION(coordinationInfoIterator != m_coordinationInfoMap.end());
 100     CoordinationInfo& info = coordinationInfoIterator->value;
 101
 102     if (transaction->isReadOnly()) {
 103         ASSERT(info.activeReadTransactions.contains(transaction));
 104         info.activeReadTransactions.remove(transaction);
 105     } else {
 106         ASSERT(info.activeWriteTransaction == transaction);
 107         info.activeWriteTransaction = 0;
 108     }
 109
 110     processPendingTransactions(info);
 111 }
 112
 113 void SQLTransactionCoordinator::shutdown()
 114 {
 115     // Prevent releaseLock() from accessing / changing the coordinationInfo
 116     // while we're shutting down.
 117     m_isShuttingDown = true;
 118
 119     // Notify all transactions in progress that the database thread is shutting down
 120     for (CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.begin();
 121          coordinationInfoIterator != m_coordinationInfoMap.end(); ++coordinationInfoIterator) {
 122         CoordinationInfo& info = coordinationInfoIterator->value;
 123
 124         // Clean up transactions that have reached "lockAcquired":
 125         // Transaction phase 4 cleanup. See comment on "What happens if a
 126         // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
 127         if (info.activeWriteTransaction)
 128             info.activeWriteTransaction->notifyDatabaseThreadIsShuttingDown();
 129         for (HashSet<RefPtr<SQLTransactionBackend> >::iterator activeReadTransactionsIterator =
 130                      info.activeReadTransactions.begin();
 131              activeReadTransactionsIterator != info.activeReadTransactions.end();
 132              ++activeReadTransactionsIterator) {
 133             (*activeReadTransactionsIterator)->notifyDatabaseThreadIsShuttingDown();
 134         }
 135
 136         // Clean up transactions that have NOT reached "lockAcquired":
 137         // Transaction phase 3 cleanup. See comment on "What happens if a
 138         // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
 139         while (!info.pendingTransactions.isEmpty()) {
 140             RefPtr<SQLTransactionBackend> transaction = info.pendingTransactions.first();
 141             transaction->notifyDatabaseThreadIsShuttingDown();
 142         }
 143     }
 144
 145     // Clean up all pending transactions for all databases
 146     m_coordinationInfoMap.clear();
 147 }
 148
 149 } // namespace WebCore