/* Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies) This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with this library; see the file COPYING.LIB. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ #ifndef DNSPREFETCHHELPER_H #define DNSPREFETCHHELPER_H #include <QObject> #include <QCache> #include <QHostInfo> #include <QSet> #include <QString> #include <QTime> #include "qwebsettings.h" namespace WebCore { class DnsPrefetchHelper : public QObject { Q_OBJECT public: DnsPrefetchHelper() : QObject(), currentLookups(0) {}; public slots: void lookup(QString hostname) { if (hostname.isEmpty()) return; // this actually happens if (currentLookups >= 10) return; // do not launch more than 10 lookups at the same time QTime* entryTime = lookupCache.object(hostname); if (entryTime && entryTime->elapsed() > 300*1000) { // delete knowledge about lookup if it is already 300 seconds old lookupCache.remove(hostname); } else if (!entryTime) { // not in cache yet, can look it up QTime *tmpTime = new QTime(); *tmpTime = QTime::currentTime(); lookupCache.insert(hostname, tmpTime); currentLookups++; QHostInfo::lookupHost(hostname, this, SLOT(lookedUp(QHostInfo))); } } void lookedUp(const QHostInfo&) { // we do not cache the result, we throw it away. // we currently rely on the OS to cache the results. If it does not do that // then at least the ISP nameserver did it. currentLookups--; } protected: QCache<QString, QTime> lookupCache; // 100 entries int currentLookups; }; } #endif // DNSPREFETCHHELPER_H