/*
* 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
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
#include "config.h"
#include "modules/webdatabase/DatabaseContext.h"
#include "core/dom/Document.h"
#include "core/dom/ExecutionContext.h"
#include "modules/webdatabase/Database.h"
#include "modules/webdatabase/DatabaseManager.h"
#include "modules/webdatabase/DatabaseTask.h"
#include "modules/webdatabase/DatabaseThread.h"
#include "platform/weborigin/SchemeRegistry.h"
#include "platform/weborigin/SecurityOrigin.h"
#include "wtf/Assertions.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. ExecutionContext
// 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 ref(). This lets DatabaseContext keep itself alive.
// Note that paired deref() is called from contextDestroyed().
//
// Once a DatabaseContext is associated with a ExecutionContext, it will
// live until after the ExecutionContext 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 ExecutionContext, the Database
// will re-use the same DatabaseContext.
//
// At Shutdown:
// ===========
// During shutdown, the DatabaseContext needs to:
// 1. "outlive" the ExecutionContext.
// - This is needed because the DatabaseContext needs to remove itself from the
// ExecutionContext's ActiveDOMObject list and ContextLifecycleObserver
// list. This removal needs to be executed on the script's thread. Hence, we
// rely on the ExecutionContext'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 ExecutionContext 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 ExecutionContext or the Databases
// destruct first.
//
// The RefPtrs in the Databases and ExecutionContext will ensure that the
// DatabaseContext will outlive both regardless of which of the 2 destructs first.
PassRefPtrWillBeRawPtr<DatabaseContext> DatabaseContext::create(ExecutionContext* context)
{
RefPtrWillBeRawPtr<DatabaseContext> self = adoptRefWillBeNoop(new DatabaseContext(context));
DatabaseManager::manager().registerDatabaseContext(self.get());
return self.release();
}
DatabaseContext::DatabaseContext(ExecutionContext* context)
: ActiveDOMObject(context)
, m_hasOpenDatabases(false)
, m_hasRequestedTermination(false)
{
// ActiveDOMObject expects this to be called to set internal flags.
suspendIfNeeded();
// For debug accounting only. We must do this before we register the
// instance. The assertions assume this.
DatabaseManager::manager().didConstructDatabaseContext();
}
DatabaseContext::~DatabaseContext()
{
// For debug accounting only. We must call this last. The assertions assume
// this.
DatabaseManager::manager().didDestructDatabaseContext();
}
void DatabaseContext::trace(Visitor* visitor)
{
visitor->trace(m_databaseThread);
visitor->trace(m_openSyncDatabases);
}
// This is called if the associated ExecutionContext 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()
{
RefPtrWillBeRawPtr<DatabaseContext> protector(this);
stopDatabases();
DatabaseManager::manager().unregisterDatabaseContext(this);
ActiveDOMObject::contextDestroyed();
}
void DatabaseContext::willStop()
{
DatabaseManager::manager().interruptAllDatabasesForContext(this);
}
// stop() is from stopActiveDOMObjects() which indicates that the owner LocalFrame
// or WorkerThread is shutting down. Initiate the orderly shutdown by stopping
// the associated databases.
void DatabaseContext::stop()
{
stopDatabases();
}
DatabaseContext* DatabaseContext::backend()
{
return this;
}
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();
m_databaseThread->start();
}
return m_databaseThread.get();
}
void DatabaseContext::didOpenDatabase(DatabaseBackendBase& database)
{
if (!database.isSyncDatabase())
return;
ASSERT(isContextThread());
#if ENABLE(OILPAN)
m_openSyncDatabases.add(&database, adoptPtr(new DatabaseCloser(database)));
#else
m_openSyncDatabases.add(&database);
#endif
}
void DatabaseContext::didCloseDatabase(DatabaseBackendBase& database)
{
#if !ENABLE(OILPAN)
if (!database.isSyncDatabase())
return;
ASSERT(isContextThread());
m_openSyncDatabases.remove(&database);
#endif
}
#if ENABLE(OILPAN)
DatabaseContext::DatabaseCloser::~DatabaseCloser()
{
m_database.closeImmediately();
}
#endif
void DatabaseContext::stopSyncDatabases()
{
// SQLite is "multi-thread safe", but each database handle can only be used
// on a single thread at a time.
//
// For DatabaseBackendSync, we open the SQLite database on the script
// context thread. And hence we should also close it on that same
// thread. This means that the SQLite database need to be closed here in the
// destructor.
ASSERT(isContextThread());
#if ENABLE(OILPAN)
m_openSyncDatabases.clear();
#else
Vector<DatabaseBackendBase*> syncDatabases;
copyToVector(m_openSyncDatabases, syncDatabases);
m_openSyncDatabases.clear();
for (size_t i = 0; i < syncDatabases.size(); ++i)
syncDatabases[i]->closeImmediately();
#endif
}
void DatabaseContext::stopDatabases()
{
stopSyncDatabases();
// 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) {
TaskSynchronizer sync;
m_databaseThread->requestTermination(&sync);
m_hasRequestedTermination = true;
sync.waitForTaskCompletion();
}
}
bool DatabaseContext::allowDatabaseAccess() const
{
if (executionContext()->isDocument())
return toDocument(executionContext())->isActive();
ASSERT(executionContext()->isWorkerGlobalScope());
// allowDatabaseAccess is not yet implemented for workers.
return true;
}
SecurityOrigin* DatabaseContext::securityOrigin() const
{
return executionContext()->securityOrigin();
}
bool DatabaseContext::isContextThread() const
{
return executionContext()->isContextThread();
}
} // namespace WebCore