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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt Creator.
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
****************************************************************************/
#include "stringtable.h"
#include <utils/qtcassert.h>
#include <utils/runextensions.h>
#include <QDebug>
#include <QElapsedTimer>
#include <QMutex>
#include <QSet>
#include <QThreadPool>
#include <QTimer>
#ifdef WITH_TESTS
#include <extensionsystem/pluginmanager.h>
#endif
namespace CppEditor::Internal {
enum {
GCTimeOut = 10 * 1000 // 10 seconds
};
enum {
DebugStringTable = 0
};
class StringTablePrivate : public QObject
{
public:
StringTablePrivate();
~StringTablePrivate() override { cancelAndWait(); }
void cancelAndWait();
QString insert(const QString &string);
void startGC();
void GC(QFutureInterface<void> &futureInterface);
QFuture<void> m_future;
QMutex m_lock;
QSet<QString> m_strings;
QTimer m_gcCountDown;
};
static StringTablePrivate *m_instance = nullptr;
StringTablePrivate::StringTablePrivate()
{
m_strings.reserve(1000);
m_gcCountDown.setObjectName(QLatin1String("StringTable::m_gcCountDown"));
m_gcCountDown.setSingleShot(true);
m_gcCountDown.setInterval(GCTimeOut);
connect(&m_gcCountDown, &QTimer::timeout, this, &StringTablePrivate::startGC);
}
QString StringTable::insert(const QString &string)
{
return m_instance->insert(string);
}
void StringTablePrivate::cancelAndWait()
{
if (!m_future.isRunning())
return;
m_future.cancel();
m_future.waitForFinished();
}
QString StringTablePrivate::insert(const QString &string)
{
if (string.isEmpty())
return string;
QMutexLocker locker(&m_lock);
// From this point of time any possible new call to startGC() will be held until
// we finish this function. So we are sure that after canceling the running GC() method now,
// no new call to GC() will be executed until we finish this function.
cancelAndWait();
// A possibly running GC() thread already finished, so it's safe to modify m_strings from
// now until we unlock the mutex.
return *m_strings.insert(string);
}
void StringTablePrivate::startGC()
{
QMutexLocker locker(&m_lock);
cancelAndWait();
m_future = Utils::runAsync(&StringTablePrivate::GC, this);
}
void StringTable::scheduleGC()
{
QMetaObject::invokeMethod(&m_instance->m_gcCountDown, QOverload<>::of(&QTimer::start),
Qt::QueuedConnection);
}
StringTable::StringTable()
{
m_instance = new StringTablePrivate;
}
StringTable::~StringTable()
{
delete m_instance;
m_instance = nullptr;
}
static inline bool isQStringInUse(const QString &string)
{
auto data_ptr = const_cast<QString&>(string).data_ptr();
return data_ptr->isShared() || !data_ptr->isMutable() /* QStringLiteral ? */;
}
void StringTablePrivate::GC(QFutureInterface<void> &futureInterface)
{
#ifdef WITH_TESTS
if (ExtensionSystem::PluginManager::isScenarioRunning("TestStringTable")) {
if (ExtensionSystem::PluginManager::finishScenario())
QThread::currentThread()->sleep(5);
}
#endif
int initialSize = 0;
QElapsedTimer timer;
if (DebugStringTable) {
initialSize = m_strings.size();
timer.start();
}
// Collect all QStrings which have refcount 1. (One reference in m_strings and nowhere else.)
for (QSet<QString>::iterator i = m_strings.begin(); i != m_strings.end();) {
if (futureInterface.isCanceled())
return;
if (!isQStringInUse(*i))
i = m_strings.erase(i);
else
++i;
}
if (DebugStringTable) {
const int currentSize = m_strings.size();
qDebug() << "StringTable::GC removed" << initialSize - currentSize
<< "strings in" << timer.elapsed() << "ms, size is now" << currentSize;
}
}
} // CppEditor::Internal
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