summaryrefslogtreecommitdiffstats
path: root/src/network/access/qnetworkdiskcache.cpp
blob: 596beb6b58336223fbc37310bc7b75e76681af3a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtNetwork module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

//#define QNETWORKDISKCACHE_DEBUG

#ifndef QT_NO_NETWORKDISKCACHE

#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();
    while (i != cacheItems.constEnd()) {
        if (totalSize < goal)
            break;
        QString name = i.value();
        QFile file(name);
        qint64 size = file.size();
        file.remove();
        totalSize -= size;
        ++removedFiles;
        ++i;
    }
#if defined(QNETWORKDISKCACHE_DEBUG)
    if (removedFiles > 0) {
        qDebug() << "QNetworkDiskCache::expire()"
                << "Removed:" << removedFiles
                << "Kept:" << cacheItems.count() - removedFiles;
    }
#endif
    if (removedFiles > 0)
        d->lastItem.reset();
    return totalSize;
}

/*!
    \reimp
*/
void QNetworkDiskCache::clear()
{
#if defined(QNETWORKDISKCACHE_DEBUG)
    qDebug() << "QNetworkDiskCache::clear()";
#endif
    Q_D(QNetworkDiskCache);
    qint64 size = d->maximumCacheSize;
    d->maximumCacheSize = 0;
    d->currentCacheSize = expire();
    d->maximumCacheSize = size;
}

QByteArray QNetworkDiskCachePrivate::generateId(const QUrl &url) const
{
    QUrl cleanUrl = url;
    cleanUrl.setPassword(QString());
    cleanUrl.setFragment(QString());

    QCryptographicHash hash(QCryptographicHash::Sha1);
    hash.addData(cleanUrl.toEncoded());
    return hash.result().toHex();
}

QString QNetworkDiskCachePrivate::tmpCacheFileName() const
{
    QDir dir;
    dir.mkpath(cacheDirectory + QLatin1String("prepared/"));
    return cacheDirectory + QLatin1String("prepared/") + CACHE_PREFIX + QLatin1String("XXXXXX") + CACHE_POSTFIX;
}

QString QNetworkDiskCachePrivate::cacheFileName(const QUrl &url) const
{
    if (!url.isValid())
        return QString();
    QString directory = cacheDirectory + url.scheme() + QLatin1Char('/');
    if (!QFile::exists(directory)) {
        // ### make a static QDir function for this...
        QDir dir;
        dir.mkpath(directory);
    }

    QString fileName = CACHE_PREFIX + QLatin1String(generateId(url)) + CACHE_POSTFIX;
    return  directory + fileName;
}

/*!
    We compress small text and JavaScript files.
 */
bool QCacheItem::canCompress() const
{
    bool sizeOk = false;
    bool typeOk = false;
    foreach (QNetworkCacheMetaData::RawHeader header, metaData.rawHeaders()) {
        if (header.first.toLower() == "content-length") {
            qint64 size = header.second.toLongLong();
            if (size > MAX_COMPRESSION_SIZE)
                return false;
            else
                sizeOk = true;
        }

        if (header.first.toLower() == "content-type") {
            QByteArray type = header.second;
            if (type.startsWith("text/")
                    || (type.startsWith("application/")
                        && (type.endsWith("javascript") || type.endsWith("ecmascript"))))
                typeOk = true;
            else
                return false;
        }
        if (sizeOk && typeOk)
            return true;
    }
    return false;
}

enum
{
    CacheMagic = 0xe8,
    CurrentCacheVersion = 7
};

void QCacheItem::writeHeader(QFile *device) const
{
    QDataStream out(device);

    out << qint32(CacheMagic);
    out << qint32(CurrentCacheVersion);
    out << metaData;
    bool compressed = canCompress();
    out << compressed;
}

void QCacheItem::writeCompressedData(QFile *device) const
{
    QDataStream out(device);

    out << qCompress(data.data());
}

/*!
    Returns false if the file is a cache file,
    but is an older version and should be removed otherwise true.
 */
bool QCacheItem::read(QFile *device, bool readData)
{
    reset();

    QDataStream in(device);

    qint32 marker;
    qint32 v;
    in >> marker;
    in >> v;
    if (marker != CacheMagic)
        return true;

    // If the cache magic is correct, but the version is not we should remove it
    if (v != CurrentCacheVersion)
        return false;

    bool compressed;
    QByteArray dataBA;
    in >> metaData;
    in >> compressed;
    if (readData && compressed) {
        in >> dataBA;
        data.setData(qUncompress(dataBA));
        data.open(QBuffer::ReadOnly);
    }
    return metaData.isValid();
}

QT_END_NAMESPACE

#endif // QT_NO_NETWORKDISKCACHE