qhostinfo.cpp

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#include "qhostinfo.h"
#include "qhostinfo_p.h"

#include "QtCore/qscopedpointer.h"
#include <qabstracteventdispatcher.h>
#include <qcoreapplication.h>
#include <qmetaobject.h>
#include <qstringlist.h>
#include <qthread.h>
#include <qurl.h>
#include <private/qnetworksession_p.h>

#ifdef Q_OS_UNIX
#  include <unistd.h>
#endif

QT_BEGIN_NAMESPACE

//#define QHOSTINFO_DEBUG

#ifndef Q_OS_SYMBIAN
Q_GLOBAL_STATIC(QHostInfoLookupManager, theHostInfoLookupManager)
#else
Q_GLOBAL_STATIC(QSymbianHostInfoLookupManager, theHostInfoLookupManager)
#endif

static QBasicAtomicInt theIdCounter = Q_BASIC_ATOMIC_INITIALIZER(1);

int QHostInfo::lookupHost(const QString &name, QObject *receiver,
                          const char *member)
{
#if defined QHOSTINFO_DEBUG
    qDebug("QHostInfo::lookupHost(\"%s\", %p, %s)",
           name.toLatin1().constData(), receiver, member ? member + 1 : 0);
#endif

    if (!QAbstractEventDispatcher::instance(QThread::currentThread())) {
        qWarning("QHostInfo::lookupHost() called with no event dispatcher");
        return -1;
    }

    qRegisterMetaType<QHostInfo>("QHostInfo");

    int id = theIdCounter.fetchAndAddRelaxed(1); // generate unique ID

    if (name.isEmpty()) {
        if (!receiver)
            return -1;

        QHostInfo hostInfo(id);
        hostInfo.setError(QHostInfo::HostNotFound);
        hostInfo.setErrorString(QCoreApplication::translate("QHostInfo", "No host name given"));
        QScopedPointer<QHostInfoResult> result(new QHostInfoResult);
        QObject::connect(result.data(), SIGNAL(resultsReady(QHostInfo)),
                         receiver, member, Qt::QueuedConnection);
        result.data()->emitResultsReady(hostInfo);
        return id;
    }

#ifndef Q_OS_SYMBIAN
    QHostInfoLookupManager *manager = theHostInfoLookupManager();

    if (manager) {
        // the application is still alive
        if (manager->cache.isEnabled()) {
            // check cache first
            bool valid = false;
            QHostInfo info = manager->cache.get(name, &valid);
            if (valid) {
                if (!receiver)
                    return -1;

                info.setLookupId(id);
                QHostInfoResult result;
                QObject::connect(&result, SIGNAL(resultsReady(QHostInfo)), receiver, member, Qt::QueuedConnection);
                result.emitResultsReady(info);
                return id;
            }
        }

        // cache is not enabled or it was not in the cache, do normal lookup
        QHostInfoRunnable* runnable = new QHostInfoRunnable(name, id);
        if (receiver)
            QObject::connect(&runnable->resultEmitter, SIGNAL(resultsReady(QHostInfo)), receiver, member, Qt::QueuedConnection);
        manager->scheduleLookup(runnable);
    }
#else
    QSymbianHostInfoLookupManager *manager = theHostInfoLookupManager();

    if (manager) {
        // the application is still alive
        if (manager->cache.isEnabled()) {
            // check cache first
            bool valid = false;
            QHostInfo info = manager->cache.get(name, &valid);
            if (valid) {
                info.setLookupId(id);
                QHostInfoResult result;
                QObject::connect(&result, SIGNAL(resultsReady(QHostInfo)), receiver, member, Qt::QueuedConnection);
                result.emitResultsReady(info);
                return id;
            }
        }

        // cache is not enabled or it was not in the cache, do normal lookup
#ifndef QT_NO_BEARERMANAGEMENT
        QSharedPointer<QNetworkSession> networkSession;
        QVariant v(receiver->property("_q_networksession"));
        if (v.isValid())
            networkSession = qvariant_cast< QSharedPointer<QNetworkSession> >(v);
#endif

        QSymbianHostResolver *symbianResolver = 0;
        QT_TRAP_THROWING(symbianResolver = new QSymbianHostResolver(name, id, networkSession));
        QObject::connect(&symbianResolver->resultEmitter, SIGNAL(resultsReady(QHostInfo)), receiver, member, Qt::QueuedConnection);
        manager->scheduleLookup(symbianResolver);
    }
#endif

    return id;
}

void QHostInfo::abortHostLookup(int id)
{
    theHostInfoLookupManager()->abortLookup(id);
}

QHostInfo QHostInfo::fromName(const QString &name)
{
#if defined QHOSTINFO_DEBUG
    qDebug("QHostInfo::fromName(\"%s\")",name.toLatin1().constData());
#endif

    QHostInfo hostInfo = QHostInfoAgent::fromName(name);
    QAbstractHostInfoLookupManager* manager = theHostInfoLookupManager();
    manager->cache.put(name, hostInfo);
    return hostInfo;
}

#ifndef QT_NO_BEARERMANAGEMENT
QHostInfo QHostInfoPrivate::fromName(const QString &name, QSharedPointer<QNetworkSession> session)
{
#if defined QHOSTINFO_DEBUG
    qDebug("QHostInfoPrivate::fromName(\"%s\") with session %p",name.toLatin1().constData(), session.data());
#endif

    QHostInfo hostInfo = QHostInfoAgent::fromName(name, session);
    QAbstractHostInfoLookupManager* manager = theHostInfoLookupManager();
    manager->cache.put(name, hostInfo);
    return hostInfo;
}
#endif

#ifndef Q_OS_SYMBIAN
#ifndef QT_NO_BEARERMANAGEMENT
// This function has a special implementation for symbian right now in qhostinfo_symbian.cpp but not on other OS.
QHostInfo QHostInfoAgent::fromName(const QString &hostName, QSharedPointer<QNetworkSession>)
{
    return QHostInfoAgent::fromName(hostName);
}
#endif
#endif


QHostInfo::QHostInfo(int id)
    : d(new QHostInfoPrivate)
{
    d->lookupId = id;
}

QHostInfo::QHostInfo(const QHostInfo &other)
    : d(new QHostInfoPrivate(*other.d.data()))
{
}

QHostInfo &QHostInfo::operator=(const QHostInfo &other)
{
    *d.data() = *other.d.data();
    return *this;
}

QHostInfo::~QHostInfo()
{
}

QList<QHostAddress> QHostInfo::addresses() const
{
    return d->addrs;
}

void QHostInfo::setAddresses(const QList<QHostAddress> &addresses)
{
    d->addrs = addresses;
}

QString QHostInfo::hostName() const
{
    return d->hostName;
}

void QHostInfo::setHostName(const QString &hostName)
{
    d->hostName = hostName;
}

QHostInfo::HostInfoError QHostInfo::error() const
{
    return d->err;
}

void QHostInfo::setError(HostInfoError error)
{
    d->err = error;
}

int QHostInfo::lookupId() const
{
    return d->lookupId;
}

void QHostInfo::setLookupId(int id)
{
    d->lookupId = id;
}

QString QHostInfo::errorString() const
{
    return d->errorStr;
}

void QHostInfo::setErrorString(const QString &str)
{
    d->errorStr = str;
}

#ifndef Q_OS_SYMBIAN
QHostInfoRunnable::QHostInfoRunnable(QString hn, int i) : toBeLookedUp(hn), id(i)
{
    setAutoDelete(true);
}

// the QHostInfoLookupManager will at some point call this via a QThreadPool
void QHostInfoRunnable::run()
{
    QHostInfoLookupManager *manager = theHostInfoLookupManager();
    // check aborted
    if (manager->wasAborted(id)) {
        manager->lookupFinished(this);
        return;
    }

    QHostInfo hostInfo;

    // QHostInfo::lookupHost already checks the cache. However we need to check
    // it here too because it might have been cache saved by another QHostInfoRunnable
    // in the meanwhile while this QHostInfoRunnable was scheduled but not running
    if (manager->cache.isEnabled()) {
        // check the cache first
        bool valid = false;
        hostInfo = manager->cache.get(toBeLookedUp, &valid);
        if (!valid) {
            // not in cache, we need to do the lookup and store the result in the cache
            hostInfo = QHostInfoAgent::fromName(toBeLookedUp);
            manager->cache.put(toBeLookedUp, hostInfo);
        }
    } else {
        // cache is not enabled, just do the lookup and continue
        hostInfo = QHostInfoAgent::fromName(toBeLookedUp);
    }

    // check aborted again
    if (manager->wasAborted(id)) {
        manager->lookupFinished(this);
        return;
    }

    // signal emission
    hostInfo.setLookupId(id);
    resultEmitter.emitResultsReady(hostInfo);

    // now also iterate through the postponed ones
    {
        QMutexLocker locker(&manager->mutex);
        QMutableListIterator<QHostInfoRunnable*> iterator(manager->postponedLookups);
        while (iterator.hasNext()) {
            QHostInfoRunnable* postponed = iterator.next();
            if (toBeLookedUp == postponed->toBeLookedUp) {
                // we can now emit
                iterator.remove();
                hostInfo.setLookupId(postponed->id);
                postponed->resultEmitter.emitResultsReady(hostInfo);
                delete postponed;
            }
        }
    }

    manager->lookupFinished(this);

    // thread goes back to QThreadPool
}

QHostInfoLookupManager::QHostInfoLookupManager() : mutex(QMutex::Recursive), wasDeleted(false)
{
    moveToThread(QCoreApplicationPrivate::mainThread());
    connect(QCoreApplication::instance(), SIGNAL(destroyed()), SLOT(waitForThreadPoolDone()), Qt::DirectConnection);
    threadPool.setMaxThreadCount(5); // do 5 DNS lookups in parallel
}

QHostInfoLookupManager::~QHostInfoLookupManager()
{
    wasDeleted = true;

    // don't qDeleteAll currentLookups, the QThreadPool has ownership
    clear();
}

void QHostInfoLookupManager::clear()
{
    {
        QMutexLocker locker(&mutex);
        qDeleteAll(postponedLookups);
        qDeleteAll(scheduledLookups);
        qDeleteAll(finishedLookups);
        postponedLookups.clear();
        scheduledLookups.clear();
        finishedLookups.clear();
    }

    threadPool.waitForDone();
    cache.clear();
}

void QHostInfoLookupManager::work()
{
    if (wasDeleted)
        return;

    // goals of this function:
    //  - launch new lookups via the thread pool
    //  - make sure only one lookup per host/IP is in progress

    QMutexLocker locker(&mutex);

    if (!finishedLookups.isEmpty()) {
        // remove ID from aborted if it is in there
        for (int i = 0; i < finishedLookups.length(); i++) {
           abortedLookups.removeAll(finishedLookups.at(i)->id);
        }

        finishedLookups.clear();
    }

    if (!postponedLookups.isEmpty()) {
        // try to start the postponed ones

        QMutableListIterator<QHostInfoRunnable*> iterator(postponedLookups);
        while (iterator.hasNext()) {
            QHostInfoRunnable* postponed = iterator.next();

            // check if none of the postponed hostnames is currently running
            bool alreadyRunning = false;
            for (int i = 0; i < currentLookups.length(); i++) {
                if (currentLookups.at(i)->toBeLookedUp == postponed->toBeLookedUp) {
                    alreadyRunning = true;
                    break;
                }
            }
            if (!alreadyRunning) {
                iterator.remove();
                scheduledLookups.prepend(postponed); // prepend! we want to finish it ASAP
            }
        }
    }

    if (!scheduledLookups.isEmpty()) {
        // try to start the new ones
        QMutableListIterator<QHostInfoRunnable*> iterator(scheduledLookups);
        while (iterator.hasNext()) {
            QHostInfoRunnable *scheduled = iterator.next();

            // check if a lookup for this host is already running, then postpone
            for (int i = 0; i < currentLookups.size(); i++) {
                if (currentLookups.at(i)->toBeLookedUp == scheduled->toBeLookedUp) {
                    iterator.remove();
                    postponedLookups.append(scheduled);
                    scheduled = 0;
                    break;
                }
            }

            if (scheduled && currentLookups.size() < threadPool.maxThreadCount()) {
                // runnable now running in new thread, track this in currentLookups
                threadPool.start(scheduled);
                iterator.remove();
                currentLookups.append(scheduled);
            } else {
                // was postponed, continue iterating
                continue;
            }
        };
    }
}

// called by QHostInfo
void QHostInfoLookupManager::scheduleLookup(QHostInfoRunnable *r)
{
    if (wasDeleted)
        return;

    QMutexLocker locker(&this->mutex);
    scheduledLookups.enqueue(r);
    work();
}

// called by QHostInfo
void QHostInfoLookupManager::abortLookup(int id)
{
    if (wasDeleted)
        return;

    QMutexLocker locker(&this->mutex);

    // is postponed? delete and return
    for (int i = 0; i < postponedLookups.length(); i++) {
        if (postponedLookups.at(i)->id == id) {
            delete postponedLookups.takeAt(i);
            return;
        }
    }

    // is scheduled? delete and return
    for (int i = 0; i < scheduledLookups.length(); i++) {
        if (scheduledLookups.at(i)->id == id) {
            delete scheduledLookups.takeAt(i);
            return;
        }
    }

    if (!abortedLookups.contains(id))
        abortedLookups.append(id);
}

// called from QHostInfoRunnable
bool QHostInfoLookupManager::wasAborted(int id)
{
    if (wasDeleted)
        return true;

    QMutexLocker locker(&this->mutex);
    return abortedLookups.contains(id);
}

// called from QHostInfoRunnable
void QHostInfoLookupManager::lookupFinished(QHostInfoRunnable *r)
{
    if (wasDeleted)
        return;

    QMutexLocker locker(&this->mutex);
    currentLookups.removeOne(r);
    finishedLookups.append(r);
    work();
}
#endif

// This function returns immediately when we had a result in the cache, else it will later emit a signal
QHostInfo qt_qhostinfo_lookup(const QString &name, QObject *receiver, const char *member, bool *valid, int *id)
{
    *valid = false;
    *id = -1;

    // check cache
    QAbstractHostInfoLookupManager* manager = theHostInfoLookupManager();
    if (manager && manager->cache.isEnabled()) {
        QHostInfo info = manager->cache.get(name, valid);
        if (*valid) {
            return info;
        }
    }

    // was not in cache, trigger lookup
    *id = QHostInfo::lookupHost(name, receiver, member);

    // return empty response, valid==false
    return QHostInfo();
}

void qt_qhostinfo_clear_cache()
{
    QAbstractHostInfoLookupManager* manager = theHostInfoLookupManager();
    if (manager) {
        manager->clear();
    }
}

void Q_AUTOTEST_EXPORT qt_qhostinfo_enable_cache(bool e)
{
    QAbstractHostInfoLookupManager* manager = theHostInfoLookupManager();
    if (manager) {
        manager->cache.setEnabled(e);
    }
}

// cache for 60 seconds
// cache 128 items
QHostInfoCache::QHostInfoCache() : max_age(60), enabled(true), cache(128)
{
#ifdef QT_QHOSTINFO_CACHE_DISABLED_BY_DEFAULT
    enabled = false;
#endif
}

bool QHostInfoCache::isEnabled()
{
    return enabled;
}

// this function is currently only used for the auto tests
// and not usable by public API
void QHostInfoCache::setEnabled(bool e)
{
    enabled = e;
}


QHostInfo QHostInfoCache::get(const QString &name, bool *valid)
{
    QMutexLocker locker(&this->mutex);

    *valid = false;
    if (cache.contains(name)) {
        QHostInfoCacheElement *element = cache.object(name);
        if (element->age.elapsed() < max_age*1000)
            *valid = true;
        return element->info;

        // FIXME idea:
        // if too old but not expired, trigger a new lookup
        // to freshen our cache
    }

    return QHostInfo();
}

void QHostInfoCache::put(const QString &name, const QHostInfo &info)
{
    // if the lookup failed, don't cache
    if (info.error() != QHostInfo::NoError)
        return;

    QHostInfoCacheElement* element = new QHostInfoCacheElement();
    element->info = info;
    element->age = QElapsedTimer();
    element->age.start();

    QMutexLocker locker(&this->mutex);
    cache.insert(name, element); // cache will take ownership
}

void QHostInfoCache::clear()
{
    QMutexLocker locker(&this->mutex);
    cache.clear();
}

QAbstractHostInfoLookupManager* QAbstractHostInfoLookupManager::globalInstance()
{
    return theHostInfoLookupManager();
}

QT_END_NAMESPACE