CachedResource.cpp revision 2fc2651226baac27029e38c9d6ef883fa32084db 
1/*
2    Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
3    Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
4    Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
5    Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
6    Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
7
8    This library is free software; you can redistribute it and/or
9    modify it under the terms of the GNU Library General Public
10    License as published by the Free Software Foundation; either
11    version 2 of the License, or (at your option) any later version.
12
13    This library is distributed in the hope that it will be useful,
14    but WITHOUT ANY WARRANTY; without even the implied warranty of
15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16    Library General Public License for more details.
17
18    You should have received a copy of the GNU Library General Public License
19    along with this library; see the file COPYING.LIB.  If not, write to
20    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
21    Boston, MA 02110-1301, USA.
22*/
23
24#include "config.h"
25#include "CachedResource.h"
26
27#include "MemoryCache.h"
28#include "CachedMetadata.h"
29#include "CachedResourceClient.h"
30#include "CachedResourceClientWalker.h"
31#include "CachedResourceHandle.h"
32#include "CachedResourceLoader.h"
33#include "CachedResourceRequest.h"
34#include "Frame.h"
35#include "FrameLoaderClient.h"
36#include "KURL.h"
37#include "Logging.h"
38#include "PurgeableBuffer.h"
39#include "ResourceHandle.h"
40#include "SharedBuffer.h"
41#include <wtf/CurrentTime.h>
42#include <wtf/MathExtras.h>
43#include <wtf/RefCountedLeakCounter.h>
44#include <wtf/StdLibExtras.h>
45#include <wtf/Vector.h>
46
47using namespace WTF;
48
49namespace WebCore {
50
51static ResourceLoadPriority defaultPriorityForResourceType(CachedResource::Type type)
52{
53    switch (type) {
54        case CachedResource::CSSStyleSheet:
55#if ENABLE(XSLT)
56        case CachedResource::XSLStyleSheet:
57#endif
58            return ResourceLoadPriorityHigh;
59        case CachedResource::Script:
60        case CachedResource::FontResource:
61            return ResourceLoadPriorityMedium;
62        case CachedResource::ImageResource:
63            return ResourceLoadPriorityLow;
64#if ENABLE(LINK_PREFETCH)
65        case CachedResource::LinkPrefetch:
66            return ResourceLoadPriorityVeryLow;
67#endif
68    }
69    ASSERT_NOT_REACHED();
70    return ResourceLoadPriorityLow;
71}
72
73#ifndef NDEBUG
74static RefCountedLeakCounter cachedResourceLeakCounter("CachedResource");
75#endif
76
77CachedResource::CachedResource(const String& url, Type type)
78    : m_url(url)
79    , m_request(0)
80    , m_loadPriority(defaultPriorityForResourceType(type))
81    , m_responseTimestamp(currentTime())
82    , m_lastDecodedAccessTime(0)
83    , m_encodedSize(0)
84    , m_decodedSize(0)
85    , m_accessCount(0)
86    , m_handleCount(0)
87    , m_preloadCount(0)
88    , m_preloadResult(PreloadNotReferenced)
89    , m_inLiveDecodedResourcesList(false)
90    , m_requestedFromNetworkingLayer(false)
91    , m_sendResourceLoadCallbacks(true)
92    , m_inCache(false)
93    , m_loading(false)
94    , m_type(type)
95    , m_status(Pending)
96    , m_deleted(false)
97#ifndef NDEBUG
98    , m_lruIndex(0)
99#endif
100    , m_nextInAllResourcesList(0)
101    , m_prevInAllResourcesList(0)
102    , m_nextInLiveResourcesList(0)
103    , m_prevInLiveResourcesList(0)
104    , m_owningCachedResourceLoader(0)
105    , m_resourceToRevalidate(0)
106    , m_proxyResource(0)
107{
108#ifndef NDEBUG
109    cachedResourceLeakCounter.increment();
110#endif
111}
112
113CachedResource::~CachedResource()
114{
115    ASSERT(!m_resourceToRevalidate); // Should be true because canDelete() checks this.
116    ASSERT(canDelete());
117    ASSERT(!inCache());
118    ASSERT(!m_deleted);
119    ASSERT(url().isNull() || memoryCache()->resourceForURL(KURL(ParsedURLString, url())) != this);
120
121    if (m_deleted) {
122        // FIXME: Remove when http://webkit.org/b/53045 is fixed.
123        CRASH();
124    }
125
126    m_deleted = true;
127#ifndef NDEBUG
128    cachedResourceLeakCounter.decrement();
129#endif
130
131    if (m_owningCachedResourceLoader)
132        m_owningCachedResourceLoader->removeCachedResource(this);
133}
134
135void CachedResource::load(CachedResourceLoader* cachedResourceLoader, bool incremental, SecurityCheckPolicy securityCheck, bool sendResourceLoadCallbacks)
136{
137    m_sendResourceLoadCallbacks = sendResourceLoadCallbacks;
138    cachedResourceLoader->load(this, incremental, securityCheck, sendResourceLoadCallbacks);
139    m_loading = true;
140}
141
142void CachedResource::data(PassRefPtr<SharedBuffer>, bool allDataReceived)
143{
144    if (!allDataReceived)
145        return;
146
147    setLoading(false);
148    CachedResourceClientWalker w(m_clients);
149    while (CachedResourceClient* c = w.next())
150        c->notifyFinished(this);
151}
152
153void CachedResource::finish()
154{
155    m_status = Cached;
156}
157
158bool CachedResource::isExpired() const
159{
160    if (m_response.isNull())
161        return false;
162
163    return currentAge() > freshnessLifetime();
164}
165
166double CachedResource::currentAge() const
167{
168    // RFC2616 13.2.3
169    // No compensation for latency as that is not terribly important in practice
170    double dateValue = m_response.date();
171    double apparentAge = isfinite(dateValue) ? max(0., m_responseTimestamp - dateValue) : 0;
172    double ageValue = m_response.age();
173    double correctedReceivedAge = isfinite(ageValue) ? max(apparentAge, ageValue) : apparentAge;
174    double residentTime = currentTime() - m_responseTimestamp;
175    return correctedReceivedAge + residentTime;
176}
177
178double CachedResource::freshnessLifetime() const
179{
180    // Cache non-http resources liberally
181    if (!m_response.url().protocolInHTTPFamily())
182        return std::numeric_limits<double>::max();
183
184    // RFC2616 13.2.4
185    double maxAgeValue = m_response.cacheControlMaxAge();
186    if (isfinite(maxAgeValue))
187        return maxAgeValue;
188    double expiresValue = m_response.expires();
189    double dateValue = m_response.date();
190    double creationTime = isfinite(dateValue) ? dateValue : m_responseTimestamp;
191    if (isfinite(expiresValue))
192        return expiresValue - creationTime;
193    double lastModifiedValue = m_response.lastModified();
194    if (isfinite(lastModifiedValue))
195        return (creationTime - lastModifiedValue) * 0.1;
196    // If no cache headers are present, the specification leaves the decision to the UA. Other browsers seem to opt for 0.
197    return 0;
198}
199
200void CachedResource::setResponse(const ResourceResponse& response)
201{
202    m_response = response;
203    m_responseTimestamp = currentTime();
204}
205
206void CachedResource::setSerializedCachedMetadata(const char* data, size_t size)
207{
208    // We only expect to receive cached metadata from the platform once.
209    // If this triggers, it indicates an efficiency problem which is most
210    // likely unexpected in code designed to improve performance.
211    ASSERT(!m_cachedMetadata);
212
213    m_cachedMetadata = CachedMetadata::deserialize(data, size);
214}
215
216void CachedResource::setCachedMetadata(unsigned dataTypeID, const char* data, size_t size)
217{
218    // Currently, only one type of cached metadata per resource is supported.
219    // If the need arises for multiple types of metadata per resource this could
220    // be enhanced to store types of metadata in a map.
221    ASSERT(!m_cachedMetadata);
222
223    m_cachedMetadata = CachedMetadata::create(dataTypeID, data, size);
224    ResourceHandle::cacheMetadata(m_response, m_cachedMetadata->serialize());
225}
226
227CachedMetadata* CachedResource::cachedMetadata(unsigned dataTypeID) const
228{
229    if (!m_cachedMetadata || m_cachedMetadata->dataTypeID() != dataTypeID)
230        return 0;
231    return m_cachedMetadata.get();
232}
233
234void CachedResource::setRequest(CachedResourceRequest* request)
235{
236    if (request && !m_request)
237        m_status = Pending;
238    m_request = request;
239    if (canDelete() && !inCache())
240        delete this;
241}
242
243void CachedResource::addClient(CachedResourceClient* client)
244{
245    addClientToSet(client);
246    didAddClient(client);
247}
248
249void CachedResource::didAddClient(CachedResourceClient* c)
250{
251    if (!isLoading())
252        c->notifyFinished(this);
253}
254
255void CachedResource::addClientToSet(CachedResourceClient* client)
256{
257    ASSERT(!isPurgeable());
258
259    if (m_preloadResult == PreloadNotReferenced) {
260        if (isLoaded())
261            m_preloadResult = PreloadReferencedWhileComplete;
262        else if (m_requestedFromNetworkingLayer)
263            m_preloadResult = PreloadReferencedWhileLoading;
264        else
265            m_preloadResult = PreloadReferenced;
266    }
267    if (!hasClients() && inCache())
268        memoryCache()->addToLiveResourcesSize(this);
269    m_clients.add(client);
270}
271
272void CachedResource::removeClient(CachedResourceClient* client)
273{
274    ASSERT(m_clients.contains(client));
275    m_clients.remove(client);
276
277    if (canDelete() && !inCache())
278        delete this;
279    else if (!hasClients() && inCache()) {
280        memoryCache()->removeFromLiveResourcesSize(this);
281        memoryCache()->removeFromLiveDecodedResourcesList(this);
282        allClientsRemoved();
283        if (response().cacheControlContainsNoStore()) {
284            // RFC2616 14.9.2:
285            // "no-store: ... MUST make a best-effort attempt to remove the information from volatile storage as promptly as possible"
286            // "... History buffers MAY store such responses as part of their normal operation."
287            // We allow non-secure content to be reused in history, but we do not allow secure content to be reused.
288            if (protocolIs(url(), "https"))
289                memoryCache()->remove(this);
290        } else
291            memoryCache()->prune();
292    }
293    // This object may be dead here.
294}
295
296void CachedResource::deleteIfPossible()
297{
298    if (canDelete() && !inCache())
299        delete this;
300}
301
302void CachedResource::setDecodedSize(unsigned size)
303{
304    if (size == m_decodedSize)
305        return;
306
307    int delta = size - m_decodedSize;
308
309    // The object must now be moved to a different queue, since its size has been changed.
310    // We have to remove explicitly before updating m_decodedSize, so that we find the correct previous
311    // queue.
312    if (inCache())
313        memoryCache()->removeFromLRUList(this);
314
315    m_decodedSize = size;
316
317    if (inCache()) {
318        // Now insert into the new LRU list.
319        memoryCache()->insertInLRUList(this);
320
321        // Insert into or remove from the live decoded list if necessary.
322        // When inserting into the LiveDecodedResourcesList it is possible
323        // that the m_lastDecodedAccessTime is still zero or smaller than
324        // the m_lastDecodedAccessTime of the current list head. This is a
325        // violation of the invariant that the list is to be kept sorted
326        // by access time. The weakening of the invariant does not pose
327        // a problem. For more details please see: https://bugs.webkit.org/show_bug.cgi?id=30209
328        if (m_decodedSize && !m_inLiveDecodedResourcesList && hasClients())
329            memoryCache()->insertInLiveDecodedResourcesList(this);
330        else if (!m_decodedSize && m_inLiveDecodedResourcesList)
331            memoryCache()->removeFromLiveDecodedResourcesList(this);
332
333        // Update the cache's size totals.
334        memoryCache()->adjustSize(hasClients(), delta);
335    }
336}
337
338void CachedResource::setEncodedSize(unsigned size)
339{
340    if (size == m_encodedSize)
341        return;
342
343    // The size cannot ever shrink (unless it is being nulled out because of an error).  If it ever does, assert.
344    ASSERT(size == 0 || size >= m_encodedSize);
345
346    int delta = size - m_encodedSize;
347
348    // The object must now be moved to a different queue, since its size has been changed.
349    // We have to remove explicitly before updating m_encodedSize, so that we find the correct previous
350    // queue.
351    if (inCache())
352        memoryCache()->removeFromLRUList(this);
353
354    m_encodedSize = size;
355
356    if (inCache()) {
357        // Now insert into the new LRU list.
358        memoryCache()->insertInLRUList(this);
359
360        // Update the cache's size totals.
361        memoryCache()->adjustSize(hasClients(), delta);
362    }
363}
364
365void CachedResource::didAccessDecodedData(double timeStamp)
366{
367    m_lastDecodedAccessTime = timeStamp;
368
369    if (inCache()) {
370        if (m_inLiveDecodedResourcesList) {
371            memoryCache()->removeFromLiveDecodedResourcesList(this);
372            memoryCache()->insertInLiveDecodedResourcesList(this);
373        }
374        memoryCache()->prune();
375    }
376}
377
378void CachedResource::setResourceToRevalidate(CachedResource* resource)
379{
380    ASSERT(resource);
381    ASSERT(!m_resourceToRevalidate);
382    ASSERT(resource != this);
383    ASSERT(m_handlesToRevalidate.isEmpty());
384    ASSERT(resource->type() == type());
385
386    LOG(ResourceLoading, "CachedResource %p setResourceToRevalidate %p", this, resource);
387
388    // The following assert should be investigated whenever it occurs. Although it should never fire, it currently does in rare circumstances.
389    // https://bugs.webkit.org/show_bug.cgi?id=28604.
390    // So the code needs to be robust to this assert failing thus the "if (m_resourceToRevalidate->m_proxyResource == this)" in CachedResource::clearResourceToRevalidate.
391    ASSERT(!resource->m_proxyResource);
392
393    resource->m_proxyResource = this;
394    m_resourceToRevalidate = resource;
395}
396
397void CachedResource::clearResourceToRevalidate()
398{
399    ASSERT(m_resourceToRevalidate);
400    // A resource may start revalidation before this method has been called, so check that this resource is still the proxy resource before clearing it out.
401    if (m_resourceToRevalidate->m_proxyResource == this) {
402        m_resourceToRevalidate->m_proxyResource = 0;
403        m_resourceToRevalidate->deleteIfPossible();
404    }
405    m_handlesToRevalidate.clear();
406    m_resourceToRevalidate = 0;
407    deleteIfPossible();
408}
409
410void CachedResource::switchClientsToRevalidatedResource()
411{
412    ASSERT(m_resourceToRevalidate);
413    ASSERT(m_resourceToRevalidate->inCache());
414    ASSERT(!inCache());
415
416    LOG(ResourceLoading, "CachedResource %p switchClientsToRevalidatedResource %p", this, m_resourceToRevalidate);
417
418    HashSet<CachedResourceHandleBase*>::iterator end = m_handlesToRevalidate.end();
419    for (HashSet<CachedResourceHandleBase*>::iterator it = m_handlesToRevalidate.begin(); it != end; ++it) {
420        CachedResourceHandleBase* handle = *it;
421        handle->m_resource = m_resourceToRevalidate;
422        m_resourceToRevalidate->registerHandle(handle);
423        --m_handleCount;
424    }
425    ASSERT(!m_handleCount);
426    m_handlesToRevalidate.clear();
427
428    Vector<CachedResourceClient*> clientsToMove;
429    HashCountedSet<CachedResourceClient*>::iterator end2 = m_clients.end();
430    for (HashCountedSet<CachedResourceClient*>::iterator it = m_clients.begin(); it != end2; ++it) {
431        CachedResourceClient* client = it->first;
432        unsigned count = it->second;
433        while (count) {
434            clientsToMove.append(client);
435            --count;
436        }
437    }
438    // Equivalent of calling removeClient() for all clients
439    m_clients.clear();
440
441    unsigned moveCount = clientsToMove.size();
442    for (unsigned n = 0; n < moveCount; ++n)
443        m_resourceToRevalidate->addClientToSet(clientsToMove[n]);
444    for (unsigned n = 0; n < moveCount; ++n) {
445        // Calling didAddClient for a client may end up removing another client. In that case it won't be in the set anymore.
446        if (m_resourceToRevalidate->m_clients.contains(clientsToMove[n]))
447            m_resourceToRevalidate->didAddClient(clientsToMove[n]);
448    }
449}
450
451void CachedResource::updateResponseAfterRevalidation(const ResourceResponse& validatingResponse)
452{
453    m_responseTimestamp = currentTime();
454
455    DEFINE_STATIC_LOCAL(const AtomicString, contentHeaderPrefix, ("content-"));
456    // RFC2616 10.3.5
457    // Update cached headers from the 304 response
458    const HTTPHeaderMap& newHeaders = validatingResponse.httpHeaderFields();
459    HTTPHeaderMap::const_iterator end = newHeaders.end();
460    for (HTTPHeaderMap::const_iterator it = newHeaders.begin(); it != end; ++it) {
461        // Don't allow 304 response to update content headers, these can't change but some servers send wrong values.
462        if (it->first.startsWith(contentHeaderPrefix, false))
463            continue;
464        m_response.setHTTPHeaderField(it->first, it->second);
465    }
466}
467
468void CachedResource::registerHandle(CachedResourceHandleBase* h)
469{
470    ++m_handleCount;
471    if (m_resourceToRevalidate)
472        m_handlesToRevalidate.add(h);
473}
474
475void CachedResource::unregisterHandle(CachedResourceHandleBase* h)
476{
477    ASSERT(m_handleCount > 0);
478    --m_handleCount;
479
480    if (m_resourceToRevalidate)
481         m_handlesToRevalidate.remove(h);
482
483    if (!m_handleCount)
484        deleteIfPossible();
485}
486
487bool CachedResource::canUseCacheValidator() const
488{
489    if (m_loading || errorOccurred())
490        return false;
491
492    if (m_response.cacheControlContainsNoStore())
493        return false;
494
495    DEFINE_STATIC_LOCAL(const AtomicString, lastModifiedHeader, ("last-modified"));
496    DEFINE_STATIC_LOCAL(const AtomicString, eTagHeader, ("etag"));
497    return !m_response.httpHeaderField(lastModifiedHeader).isEmpty() || !m_response.httpHeaderField(eTagHeader).isEmpty();
498}
499
500bool CachedResource::mustRevalidateDueToCacheHeaders(CachePolicy cachePolicy) const
501{
502    ASSERT(cachePolicy == CachePolicyRevalidate || cachePolicy == CachePolicyCache || cachePolicy == CachePolicyVerify);
503
504    if (cachePolicy == CachePolicyRevalidate)
505        return true;
506
507    if (m_response.cacheControlContainsNoCache() || m_response.cacheControlContainsNoStore()) {
508        LOG(ResourceLoading, "CachedResource %p mustRevalidate because of m_response.cacheControlContainsNoCache() || m_response.cacheControlContainsNoStore()\n", this);
509        return true;
510    }
511
512    if (cachePolicy == CachePolicyCache) {
513        if (m_response.cacheControlContainsMustRevalidate() && isExpired()) {
514            LOG(ResourceLoading, "CachedResource %p mustRevalidate because of cachePolicy == CachePolicyCache and m_response.cacheControlContainsMustRevalidate() && isExpired()\n", this);
515            return true;
516        }
517        return false;
518    }
519
520    // CachePolicyVerify
521    if (isExpired()) {
522        LOG(ResourceLoading, "CachedResource %p mustRevalidate because of isExpired()\n", this);
523        return true;
524    }
525
526    return false;
527}
528
529bool CachedResource::isSafeToMakePurgeable() const
530{
531    return !hasClients() && !m_proxyResource && !m_resourceToRevalidate;
532}
533
534bool CachedResource::makePurgeable(bool purgeable)
535{
536    if (purgeable) {
537        ASSERT(isSafeToMakePurgeable());
538
539        if (m_purgeableData) {
540            ASSERT(!m_data);
541            return true;
542        }
543        if (!m_data)
544            return false;
545
546        // Should not make buffer purgeable if it has refs other than this since we don't want two copies.
547        if (!m_data->hasOneRef())
548            return false;
549
550        if (m_data->hasPurgeableBuffer()) {
551            m_purgeableData = m_data->releasePurgeableBuffer();
552        } else {
553            m_purgeableData = PurgeableBuffer::create(m_data->data(), m_data->size());
554            if (!m_purgeableData)
555                return false;
556            m_purgeableData->setPurgePriority(purgePriority());
557        }
558
559        m_purgeableData->makePurgeable(true);
560        m_data.clear();
561        return true;
562    }
563
564    if (!m_purgeableData)
565        return true;
566    ASSERT(!m_data);
567    ASSERT(!hasClients());
568
569    if (!m_purgeableData->makePurgeable(false))
570        return false;
571
572    m_data = SharedBuffer::adoptPurgeableBuffer(m_purgeableData.release());
573    return true;
574}
575
576bool CachedResource::isPurgeable() const
577{
578    return m_purgeableData && m_purgeableData->isPurgeable();
579}
580
581bool CachedResource::wasPurged() const
582{
583    return m_purgeableData && m_purgeableData->wasPurged();
584}
585
586unsigned CachedResource::overheadSize() const
587{
588    return sizeof(CachedResource) + m_response.memoryUsage() + 576;
589    /*
590        576 = 192 +                   // average size of m_url
591              384;                    // average size of m_clients hash map
592    */
593}
594
595void CachedResource::setLoadPriority(ResourceLoadPriority loadPriority)
596{
597    if (loadPriority == ResourceLoadPriorityUnresolved)
598        return;
599    m_loadPriority = loadPriority;
600}
601
602}
603