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/*
* Copyright (C) 2008 Apple Inc. All Rights Reserved.
* Copyright (C) 2011 Google, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include "config.h"
#include "modules/webdatabase/DatabaseContext.h"
#include "core/dom/Document.h"
#include "core/dom/ScriptExecutionContext.h"
#include "core/page/Chrome.h"
#include "core/page/ChromeClient.h"
#include "core/page/Page.h"
#include "core/page/Settings.h"
#include "modules/webdatabase/Database.h"
#include "modules/webdatabase/DatabaseBackendContext.h"
#include "modules/webdatabase/DatabaseManager.h"
#include "modules/webdatabase/DatabaseTask.h"
#include "modules/webdatabase/DatabaseThread.h"
#include "weborigin/SchemeRegistry.h"
#include "weborigin/SecurityOrigin.h"
namespace WebCore {
// How the DatabaseContext Life-Cycle works?
// ========================================
// ... in other words, who's keeping the DatabaseContext alive and how long does
// it need to stay alive?
//
// The DatabaseContext is referenced from RefPtrs in:
// 1. ScriptExecutionContext
// 2. Database
//
// At Birth:
// ========
// We create a DatabaseContext only when there is a need i.e. the script tries to
// open a Database via DatabaseManager::openDatabase().
//
// The DatabaseContext constructor will call setDatabaseContext() on the
// the ScriptExecutionContext. This sets the RefPtr in the ScriptExecutionContext
// for keeping the DatabaseContext alive. Since the DatabaseContext is only
// created from the script thread, it is safe for the constructor to call
// ScriptExecutionContext::setDatabaseContext().
//
// Once a DatabaseContext is associated with a ScriptExecutionContext, it will
// live until after the ScriptExecutionContext destructs. This is true even if
// we don't succeed in opening any Databases for that context. When we do
// succeed in opening Databases for this ScriptExecutionContext, the Database
// will re-use the same DatabaseContext.
//
// At Shutdown:
// ===========
// During shutdown, the DatabaseContext needs to:
// 1. "outlive" the ScriptExecutionContext.
// - This is needed because the DatabaseContext needs to remove itself from the
// ScriptExecutionContext's ActiveDOMObject list and ContextLifecycleObserver
// list. This removal needs to be executed on the script's thread. Hence, we
// rely on the ScriptExecutionContext's shutdown process to call
// stop() and contextDestroyed() to give us a chance to clean these up from
// the script thread.
//
// 2. "outlive" the Databases.
// - This is because they may make use of the DatabaseContext to execute a close
// task and shutdown in an orderly manner. When the Databases are destructed,
// they will deref the DatabaseContext from the DatabaseThread.
//
// During shutdown, the ScriptExecutionContext is shutting down on the script thread
// while the Databases are shutting down on the DatabaseThread. Hence, there can be
// a race condition as to whether the ScriptExecutionContext or the Databases
// destruct first.
//
// The RefPtrs in the Databases and ScriptExecutionContext will ensure that the
// DatabaseContext will outlive both regardless of which of the 2 destructs first.
DatabaseContext::DatabaseContext(ScriptExecutionContext* context)
: ActiveDOMObject(context)
, m_hasOpenDatabases(false)
, m_isRegistered(true) // will register on construction below.
, m_hasRequestedTermination(false)
{
// ActiveDOMObject expects this to be called to set internal flags.
suspendIfNeeded();
context->setDatabaseContext(this);
// For debug accounting only. We must do this before we register the
// instance. The assertions assume this.
DatabaseManager::manager().didConstructDatabaseContext();
DatabaseManager::manager().registerDatabaseContext(this);
}
DatabaseContext::~DatabaseContext()
{
stopDatabases();
ASSERT(!m_databaseThread || m_databaseThread->terminationRequested());
// For debug accounting only. We must call this last. The assertions assume
// this.
DatabaseManager::manager().didDestructDatabaseContext();
}
// This is called if the associated ScriptExecutionContext is destructing while
// we're still associated with it. That's our cue to disassociate and shutdown.
// To do this, we stop the database and let everything shutdown naturally
// because the database closing process may still make use of this context.
// It is not safe to just delete the context here.
void DatabaseContext::contextDestroyed()
{
stopDatabases();
ActiveDOMObject::contextDestroyed();
}
// stop() is from stopActiveDOMObjects() which indicates that the owner Frame
// or WorkerThread is shutting down. Initiate the orderly shutdown by stopping
// the associated databases.
void DatabaseContext::stop()
{
stopDatabases();
}
PassRefPtr<DatabaseBackendContext> DatabaseContext::backend()
{
DatabaseBackendContext* backend = static_cast<DatabaseBackendContext*>(this);
return backend;
}
DatabaseThread* DatabaseContext::databaseThread()
{
if (!m_databaseThread && !m_hasOpenDatabases) {
// It's OK to ask for the m_databaseThread after we've requested
// termination because we're still using it to execute the closing
// of the database. However, it is NOT OK to create a new thread
// after we've requested termination.
ASSERT(!m_hasRequestedTermination);
// Create the database thread on first request - but not if at least one database was already opened,
// because in that case we already had a database thread and terminated it and should not create another.
m_databaseThread = DatabaseThread::create();
if (!m_databaseThread->start())
m_databaseThread = 0;
}
return m_databaseThread.get();
}
bool DatabaseContext::stopDatabases(DatabaseTaskSynchronizer* cleanupSync)
{
if (m_isRegistered) {
DatabaseManager::manager().unregisterDatabaseContext(this);
m_isRegistered = false;
}
// Though we initiate termination of the DatabaseThread here in
// stopDatabases(), we can't clear the m_databaseThread ref till we get to
// the destructor. This is because the Databases that are managed by
// DatabaseThread still rely on this ref between the context and the thread
// to execute the task for closing the database. By the time we get to the
// destructor, we're guaranteed that the databases are destructed (which is
// why our ref count is 0 then and we're destructing). Then, the
// m_databaseThread RefPtr destructor will deref and delete the
// DatabaseThread.
if (m_databaseThread && !m_hasRequestedTermination) {
m_databaseThread->requestTermination(cleanupSync);
m_hasRequestedTermination = true;
return true;
}
return false;
}
bool DatabaseContext::allowDatabaseAccess() const
{
if (m_scriptExecutionContext->isDocument()) {
Document* document = toDocument(m_scriptExecutionContext);
return document->page();
}
ASSERT(m_scriptExecutionContext->isWorkerContext());
// allowDatabaseAccess is not yet implemented for workers.
return true;
}
} // namespace WebCore