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****************************************************************************/

//#define QNETWORKDISKCACHE_DEBUG

#include "qnetworkdiskcache.h"

#include "qnetworkdiskcache_p.h"

#include "QtCore/qscopedpointer.h"

#include <qfile.h>

#include <qdir.h>

#include <qdatetime.h>

#include <qdiriterator.h>

#include <qcryptographichash.h>

#include <qurl.h>

#include <qdebug.h>

#define CACHE_PREFIX  QLatin1String("cache_")

#define CACHE_POSTFIX QLatin1String(".cache")

#define MAX_COMPRESSION_SIZE (1024 * 1024 * 3)

QT_BEGIN_NAMESPACE

/*!

    \class QNetworkDiskCache

    \since 4.5

    \inmodule QtNetwork

    \brief The QNetworkDiskCache class provides a very basic disk cache.

    QNetworkDiskCache stores each url in its own file inside of the

    cacheDirectory using QDataStream.  Files with a text MimeType

    are compressed using qCompress.  Each cache file starts with "cache_"

    and ends in ".cache".  Data is written to disk only in insert()

    and updateMetaData().

    Currently you can not share the same cache files with more then

    one disk cache.

    QNetworkDiskCache by default limits the amount of space that the cache will

    use on the system to 50MB.

    Note you have to set the cache directory before it will work.

    A network disk cache can be enabled by:

    \snippet doc/src/snippets/code/src_network_access_qnetworkdiskcache.cpp 0

    When sending requests, to control the preference of when to use the cache

    and when to use the network, consider the following:

    \snippet doc/src/snippets/code/src_network_access_qnetworkdiskcache.cpp 1

    To check whether the response came from the cache or from the network, the

    following can be applied:

    \snippet doc/src/snippets/code/src_network_access_qnetworkdiskcache.cpp 2

*/

/*!

    Creates a new disk cache. The \a parent argument is passed to

    QAbstractNetworkCache's constructor.

 */

QNetworkDiskCache::QNetworkDiskCache(QObject *parent)

    : QAbstractNetworkCache(*new QNetworkDiskCachePrivate, parent)

{

}

/*!

    Destroys the cache object.  This does not clear the disk cache.

 */

QNetworkDiskCache::~QNetworkDiskCache()

{

    Q_D(QNetworkDiskCache);

    QHashIterator<QIODevice*, QCacheItem*> it(d->inserting);

    while (it.hasNext()) {

        it.next();

        delete it.value();

    }

}

/*!

    Returns the location where cached files will be stored.

*/

QString QNetworkDiskCache::cacheDirectory() const

{

    Q_D(const QNetworkDiskCache);

    return d->cacheDirectory;

}

/*!

    Sets the directory where cached files will be stored to \a cacheDir

    QNetworkDiskCache will create this directory if it does not exists.

    Prepared cache items will be stored in the new cache directory when

    they are inserted.

    \sa QDesktopServices::CacheLocation

*/

void QNetworkDiskCache::setCacheDirectory(const QString &cacheDir)

{

#if defined(QNETWORKDISKCACHE_DEBUG)

    qDebug() << "QNetworkDiskCache::setCacheDirectory()" << cacheDir;

#endif

    Q_D(QNetworkDiskCache);

    if (cacheDir.isEmpty())

        return;

    d->cacheDirectory = cacheDir;

    QDir dir(d->cacheDirectory);

    d->cacheDirectory = dir.absolutePath();

    if (!d->cacheDirectory.endsWith(QLatin1Char('/')))

        d->cacheDirectory += QLatin1Char('/');

}

/*!

    \reimp

*/

qint64 QNetworkDiskCache::cacheSize() const

{

#if defined(QNETWORKDISKCACHE_DEBUG)

    qDebug() << "QNetworkDiskCache::cacheSize()";

#endif

    Q_D(const QNetworkDiskCache);

    if (d->cacheDirectory.isEmpty())

        return 0;

    if (d->currentCacheSize < 0) {

        QNetworkDiskCache *that = const_cast<QNetworkDiskCache*>(this);

        that->d_func()->currentCacheSize = that->expire();

    }

    return d->currentCacheSize;

}

/*!

    \reimp

*/

QIODevice *QNetworkDiskCache::prepare(const QNetworkCacheMetaData &metaData)

{

#if defined(QNETWORKDISKCACHE_DEBUG)

    qDebug() << "QNetworkDiskCache::prepare()" << metaData.url();

#endif

    Q_D(QNetworkDiskCache);

    if (!metaData.isValid() || !metaData.url().isValid() || !metaData.saveToDisk())

        return 0;

    if (d->cacheDirectory.isEmpty()) {

        qWarning() << "QNetworkDiskCache::prepare() The cache directory is not set";

        return 0;

    }

    foreach (QNetworkCacheMetaData::RawHeader header, metaData.rawHeaders()) {

        if (header.first.toLower() == "content-length") {

            qint64 size = header.second.toInt();

            if (size > (maximumCacheSize() * 3)/4)

                return 0;

            break;

        }

    }

    QScopedPointer<QCacheItem> cacheItem(new QCacheItem);

    cacheItem->metaData = metaData;

    QIODevice *device = 0;

    if (cacheItem->canCompress()) {

        cacheItem->data.open(QBuffer::ReadWrite);

        device = &(cacheItem->data);

    } else {

        QString templateName = d->tmpCacheFileName();

        QT_TRY {

            cacheItem->file = new QTemporaryFile(templateName, &cacheItem->data);

        } QT_CATCH(...) {

            cacheItem->file = 0;

        }

        if (!cacheItem->file || !cacheItem->file->open()) {

            qWarning() << "QNetworkDiskCache::prepare() unable to open temporary file";

            cacheItem.reset();

            return 0;

        }

        cacheItem->writeHeader(cacheItem->file);

        device = cacheItem->file;

    }

    d->inserting[device] = cacheItem.take();

    return device;

}

/*!

    \reimp

*/

void QNetworkDiskCache::insert(QIODevice *device)

{

#if defined(QNETWORKDISKCACHE_DEBUG)

    qDebug() << "QNetworkDiskCache::insert()" << device;

#endif

    Q_D(QNetworkDiskCache);

    QHash<QIODevice*, QCacheItem*>::iterator it = d->inserting.find(device);

    if (it == d->inserting.end()) {

        qWarning() << "QNetworkDiskCache::insert() called on a device we don't know about" << device;

        return;

    }

    d->storeItem(it.value());

    delete it.value();

    d->inserting.erase(it);

}

void QNetworkDiskCachePrivate::storeItem(QCacheItem *cacheItem)

{

    Q_Q(QNetworkDiskCache);

    Q_ASSERT(cacheItem->metaData.saveToDisk());

    QString fileName = cacheFileName(cacheItem->metaData.url());

    Q_ASSERT(!fileName.isEmpty());

    if (QFile::exists(fileName)) {

        if (!QFile::remove(fileName)) {

            qWarning() << "QNetworkDiskCache: couldn't remove the cache file " << fileName;

            return;

        }

    }

    if (currentCacheSize > 0)

        currentCacheSize += 1024 + cacheItem->size();

    currentCacheSize = q->expire();

    if (!cacheItem->file) {

        QString templateName = tmpCacheFileName();

        cacheItem->file = new QTemporaryFile(templateName, &cacheItem->data);

        if (cacheItem->file->open()) {

            cacheItem->writeHeader(cacheItem->file);

            cacheItem->writeCompressedData(cacheItem->file);

        }

    }

    if (cacheItem->file

        && cacheItem->file->isOpen()

        && cacheItem->file->error() == QFile::NoError) {

        cacheItem->file->setAutoRemove(false);

        // ### use atomic rename rather then remove & rename

        if (cacheItem->file->rename(fileName))

            currentCacheSize += cacheItem->file->size();

        else

            cacheItem->file->setAutoRemove(true);

    }

    if (cacheItem->metaData.url() == lastItem.metaData.url())

        lastItem.reset();

}

/*!

    \reimp

*/

bool QNetworkDiskCache::remove(const QUrl &url)

{

#if defined(QNETWORKDISKCACHE_DEBUG)

    qDebug() << "QNetworkDiskCache::remove()" << url;

#endif

    Q_D(QNetworkDiskCache);

    // remove is also used to cancel insertions, not a common operation

    QHashIterator<QIODevice*, QCacheItem*> it(d->inserting);

    while (it.hasNext()) {

        it.next();

        QCacheItem *item = it.value();

        if (item && item->metaData.url() == url) {

            delete item;

            d->inserting.remove(it.key());

            return true;

        }

    }

    if (d->lastItem.metaData.url() == url)

        d->lastItem.reset();

    return d->removeFile(d->cacheFileName(url));

}

/*!

    Put all of the misc file removing into one function to be extra safe

 */

bool QNetworkDiskCachePrivate::removeFile(const QString &file)

{

#if defined(QNETWORKDISKCACHE_DEBUG)

    qDebug() << "QNetworkDiskCache::removFile()" << file;

#endif

    if (file.isEmpty())

        return false;

    QFileInfo info(file);

    QString fileName = info.fileName();

    if (!fileName.endsWith(CACHE_POSTFIX) || !fileName.startsWith(CACHE_PREFIX))

        return false;

    qint64 size = info.size();

    if (QFile::remove(file)) {

        currentCacheSize -= size;

        return true;

    }

    return false;

}

/*!

    \reimp

*/

QNetworkCacheMetaData QNetworkDiskCache::metaData(const QUrl &url)

{

#if defined(QNETWORKDISKCACHE_DEBUG)

    qDebug() << "QNetworkDiskCache::metaData()" << url;

#endif

    Q_D(QNetworkDiskCache);

    if (d->lastItem.metaData.url() == url)

        return d->lastItem.metaData;

    return fileMetaData(d->cacheFileName(url));

}

/*!

    Returns the QNetworkCacheMetaData for the cache file \a fileName.

    If \a fileName is not a cache file QNetworkCacheMetaData will be invalid.

 */

QNetworkCacheMetaData QNetworkDiskCache::fileMetaData(const QString &fileName) const

{

#if defined(QNETWORKDISKCACHE_DEBUG)

    qDebug() << "QNetworkDiskCache::fileMetaData()" << fileName;

#endif

    Q_D(const QNetworkDiskCache);

    QFile file(fileName);

    if (!file.open(QFile::ReadOnly))

        return QNetworkCacheMetaData();

    if (!d->lastItem.read(&file, false)) {

        file.close();

        QNetworkDiskCachePrivate *that = const_cast<QNetworkDiskCachePrivate*>(d);

        that->removeFile(fileName);

    }

    return d->lastItem.metaData;

}

/*!

    \reimp

*/

QIODevice *QNetworkDiskCache::data(const QUrl &url)

{

#if defined(QNETWORKDISKCACHE_DEBUG)

    qDebug() << "QNetworkDiskCache::data()" << url;

#endif

    Q_D(QNetworkDiskCache);

    QScopedPointer<QBuffer> buffer;

    if (!url.isValid())

        return 0;

    if (d->lastItem.metaData.url() == url && d->lastItem.data.isOpen()) {

        buffer.reset(new QBuffer);

        buffer->setData(d->lastItem.data.data());

    } else {

        QScopedPointer<QFile> file(new QFile(d->cacheFileName(url)));

        if (!file->open(QFile::ReadOnly | QIODevice::Unbuffered))

            return 0;

        if (!d->lastItem.read(file.data(), true)) {

            file->close();

            remove(url);

            return 0;

        }

        if (d->lastItem.data.isOpen()) {

            // compressed

            buffer.reset(new QBuffer);

            buffer->setData(d->lastItem.data.data());

        } else {

            buffer.reset(new QBuffer);

            // ### verify that QFile uses the fd size and not the file name

            qint64 size = file->size() - file->pos();

            const uchar *p = 0;

#ifndef Q_OS_WINCE

            p = file->map(file->pos(), size);

#endif

            if (p) {

                buffer->setData((const char *)p, size);

                file.take()->setParent(buffer.data());

            } else {

                buffer->setData(file->readAll());

            }

        }

    }

    buffer->open(QBuffer::ReadOnly);

    return buffer.take();

}

/*!

    \reimp

*/

void QNetworkDiskCache::updateMetaData(const QNetworkCacheMetaData &metaData)

{

#if defined(QNETWORKDISKCACHE_DEBUG)

    qDebug() << "QNetworkDiskCache::updateMetaData()" << metaData.url();

#endif

    QUrl url = metaData.url();

    QIODevice *oldDevice = data(url);

    if (!oldDevice) {

#if defined(QNETWORKDISKCACHE_DEBUG)

        qDebug() << "QNetworkDiskCache::updateMetaData(), no device!";

#endif

        return;

    }

    QIODevice *newDevice = prepare(metaData);

    if (!newDevice) {

#if defined(QNETWORKDISKCACHE_DEBUG)

        qDebug() << "QNetworkDiskCache::updateMetaData(), no new device!" << url;

#endif

        return;

    }

    char data[1024];

    while (!oldDevice->atEnd()) {

        qint64 s = oldDevice->read(data, 1024);

        newDevice->write(data, s);

    }

    delete oldDevice;

    insert(newDevice);

}

/*!

    Returns the current maximum size for the disk cache.

    \sa setMaximumCacheSize()

 */

qint64 QNetworkDiskCache::maximumCacheSize() const

{

    Q_D(const QNetworkDiskCache);

    return d->maximumCacheSize;

}

/*!

    Sets the maximum size of the disk cache to be \a size.

    If the new size is smaller then the current cache size then the cache will call expire().

    \sa maximumCacheSize()

 */

void QNetworkDiskCache::setMaximumCacheSize(qint64 size)

{

    Q_D(QNetworkDiskCache);

    bool expireCache = (size < d->maximumCacheSize);

    d->maximumCacheSize = size;

    if (expireCache)

        d->currentCacheSize = expire();

}

/*!

    Cleans the cache so that its size is under the maximum cache size.

    Returns the current size of the cache.

    When the current size of the cache is greater than the maximumCacheSize()

    older cache files are removed until the total size is less then 90% of

    maximumCacheSize() starting with the oldest ones first using the file

    creation date to determine how old a cache file is.

    Subclasses can reimplement this function to change the order that cache

    files are removed taking into account information in the application

    knows about that QNetworkDiskCache does not, for example the number of times

    a cache is accessed.

    Note: cacheSize() calls expire if the current cache size is unknown.

    \sa maximumCacheSize(), fileMetaData()

 */

qint64 QNetworkDiskCache::expire()

{

    Q_D(QNetworkDiskCache);

    if (d->currentCacheSize >= 0 && d->currentCacheSize < maximumCacheSize())

        return d->currentCacheSize;

    if (cacheDirectory().isEmpty()) {

        qWarning() << "QNetworkDiskCache::expire() The cache directory is not set";

        return 0;

    }

    QDir::Filters filters = QDir::AllDirs | QDir:: Files | QDir::NoDotAndDotDot;

    QDirIterator it(cacheDirectory(), filters, QDirIterator::Subdirectories);

    QMultiMap<QDateTime, QString> cacheItems;

    qint64 totalSize = 0;

    while (it.hasNext()) {

        QString path = it.next();

        QFileInfo info = it.fileInfo();

        QString fileName = info.fileName();

        if (fileName.endsWith(CACHE_POSTFIX) && fileName.startsWith(CACHE_PREFIX)) {

            cacheItems.insert(info.created(), path);

            totalSize += info.size();

        }

    }

    int removedFiles = 0;

    qint64 goal = (maximumCacheSize() * 9) / 10;

    QMultiMap<QDateTime, QString>::const_iterator i = cacheItems.constBegin();