WebCore/CachedResource.h

   1 /*
   2     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
   3     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
   4     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
   5     Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
   6
   7     This library is free software; you can redistribute it and/or
   8     modify it under the terms of the GNU Library General Public
   9     License as published by the Free Software Foundation; either
  10     version 2 of the License, or (at your option) any later version.
  11
  12     This library is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15     Library General Public License for more details.
  16
  17     You should have received a copy of the GNU Library General Public License
  18     along with this library; see the file COPYING.LIB.  If not, write to
  19     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  20     Boston, MA 02110-1301, USA.
  21 */
  22
  23 #ifndef CachedResource_h
  24 #define CachedResource_h
  25
  26 #include "CachePolicy.h"
  27 #include "PlatformString.h"
  28 #include "ResourceResponse.h"
  29 #include "SharedBuffer.h"
  30 #include <wtf/HashCountedSet.h>
  31 #include <wtf/HashSet.h>
  32 #include <wtf/OwnPtr.h>
  33 #include <wtf/Vector.h>
  34 #include <time.h>
  35
  36 namespace WebCore {
  37
  38 class Cache;
  39 class CachedResourceClient;
  40 class CachedResourceHandleBase;
  41 class DocLoader;
  42 class InspectorResource;
  43 class Request;
  44 class PurgeableBuffer;
  45
  46 // A resource that is held in the cache. Classes who want to use this object should derive
  47 // from CachedResourceClient, to get the function calls in case the requested data has arrived.
  48 // This class also does the actual communication with the loader to obtain the resource from the network.
  49 class CachedResource {
  50     friend class Cache;
  51     friend class InspectorResource;
  52
  53 public:
  54     enum Type {
  55         ImageResource,
  56         CSSStyleSheet,
  57         Script,
  58         FontResource
  59 #if ENABLE(XSLT)
  60         , XSLStyleSheet
  61 #endif
  62 #if ENABLE(XBL)
  63         , XBL
  64 #endif
  65     };
  66
  67     enum Status {
  68         NotCached,    // this URL is not cached
  69         Unknown,      // let cache decide what to do with it
  70         New,          // inserting new item
  71         Pending,      // only partially loaded
  72         Cached        // regular case
  73     };
  74
  75     CachedResource(const String& url, Type);
  76     virtual ~CachedResource();
  77
  78     virtual void load(DocLoader* docLoader)  { load(docLoader, false, false, true); }
  79     void load(DocLoader*, bool incremental, bool skipCanLoadCheck, bool sendResourceLoadCallbacks);
  80
  81     virtual void setEncoding(const String&) { }
  82     virtual String encoding() const { return String(); }
  83     virtual void data(PassRefPtr<SharedBuffer> data, bool allDataReceived) = 0;
  84     virtual void error() = 0;
  85
  86     const String &url() const { return m_url; }
  87     Type type() const { return m_type; }
  88
  89     virtual void addClient(CachedResourceClient*);
  90     void removeClient(CachedResourceClient*);
  91     bool hasClients() const { return !m_clients.isEmpty(); }
  92     void deleteIfPossible();
  93
  94     enum PreloadResult {
  95         PreloadNotReferenced,
  96         PreloadReferenced,
  97         PreloadReferencedWhileLoading,
  98         PreloadReferencedWhileComplete
  99     };
 100     PreloadResult preloadResult() const { return m_preloadResult; }
 101     void setRequestedFromNetworkingLayer() { m_requestedFromNetworkingLayer = true; }
 102
 103     virtual void allClientsRemoved() { }
 104
 105     unsigned count() const { return m_clients.size(); }
 106
 107     Status status() const { return m_status; }
 108
 109     unsigned size() const { return encodedSize() + decodedSize() + overheadSize(); }
 110     unsigned encodedSize() const { return m_encodedSize; }
 111     unsigned decodedSize() const { return m_decodedSize; }
 112     unsigned overheadSize() const;
 113
 114     bool isLoaded() const { return !m_loading; }
 115     void setLoading(bool b) { m_loading = b; }
 116
 117     virtual bool isImage() const { return false; }
 118
 119     unsigned accessCount() const { return m_accessCount; }
 120     void increaseAccessCount() { m_accessCount++; }
 121
 122     // Computes the status of an object after loading.
 123     // Updates the expire date on the cache entry file
 124     void finish();
 125
 126     // Called by the cache if the object has been removed from the cache
 127     // while still being referenced. This means the object should delete itself
 128     // if the number of clients observing it ever drops to 0.
 129     void setInCache(bool b) { m_inCache = b; }
 130     bool inCache() const { return m_inCache; }
 131
 132     void setInLiveDecodedResourcesList(bool b) { m_inLiveDecodedResourcesList = b; }
 133     bool inLiveDecodedResourcesList() { return m_inLiveDecodedResourcesList; }
 134
 135     void setRequest(Request*);
 136
 137     SharedBuffer* data() const { ASSERT(!m_purgeableData); return m_data.get(); }
 138
 139     void setResponse(const ResourceResponse&);
 140     const ResourceResponse& response() const { return m_response; }
 141
 142     bool canDelete() const { return !hasClients() && !m_request && !m_preloadCount && !m_handleCount && !m_resourceToRevalidate && !m_isBeingRevalidated; }
 143
 144     bool isExpired() const;
 145
 146     virtual bool schedule() const { return false; }
 147
 148     // List of acceptable MIME types seperated by ",".
 149     // A MIME type may contain a wildcard, e.g. "text/*".
 150     String accept() const { return m_accept; }
 151     void setAccept(const String& accept) { m_accept = accept; }
 152
 153     bool errorOccurred() const { return m_errorOccurred; }
 154     bool sendResourceLoadCallbacks() const { return m_sendResourceLoadCallbacks; }
 155
 156     virtual void destroyDecodedData() { }
 157
 158     void setDocLoader(DocLoader* docLoader) { m_docLoader = docLoader; }
 159
 160     bool isPreloaded() const { return m_preloadCount; }
 161     void increasePreloadCount() { ++m_preloadCount; }
 162     void decreasePreloadCount() { ASSERT(m_preloadCount); --m_preloadCount; }
 163
 164     void registerHandle(CachedResourceHandleBase* h) { ++m_handleCount; if (m_resourceToRevalidate) m_handlesToRevalidate.add(h); }
 165     void unregisterHandle(CachedResourceHandleBase* h) { --m_handleCount; if (m_resourceToRevalidate) m_handlesToRevalidate.remove(h); if (!m_handleCount) deleteIfPossible(); }
 166
 167     bool canUseCacheValidator() const;
 168     bool mustRevalidate(CachePolicy) const;
 169     bool isCacheValidator() const { return m_resourceToRevalidate; }
 170     CachedResource* resourceToRevalidate() const { return m_resourceToRevalidate; }
 171
 172     bool isPurgeable() const;
 173     bool wasPurged() const;
 174
 175 protected:
 176     void setEncodedSize(unsigned);
 177     void setDecodedSize(unsigned);
 178     void didAccessDecodedData(double timeStamp);
 179
 180     bool makePurgeable(bool purgeable);
 181     bool isSafeToMakePurgeable() const;
 182
 183     DocLoader* docLoader() const { return m_docLoader; }
 184
 185     HashCountedSet<CachedResourceClient*> m_clients;
 186
 187     String m_url;
 188     String m_accept;
 189     Request* m_request;
 190
 191     ResourceResponse m_response;
 192     RefPtr<SharedBuffer> m_data;
 193     OwnPtr<PurgeableBuffer> m_purgeableData;
 194
 195     Type m_type;
 196     Status m_status;
 197
 198     bool m_errorOccurred;
 199
 200 private:
 201     // These are called by the friendly Cache only
 202     void setResourceToRevalidate(CachedResource*);
 203     void switchClientsToRevalidatedResource();
 204     void clearResourceToRevalidate();
 205     void setExpirationDate(time_t expirationDate) { m_expirationDate = expirationDate; }
 206
 207     unsigned m_encodedSize;
 208     unsigned m_decodedSize;
 209     unsigned m_accessCount;
 210     unsigned m_inLiveDecodedResourcesList;
 211     double m_lastDecodedAccessTime; // Used as a "thrash guard" in the cache
 212
 213     bool m_sendResourceLoadCallbacks;
 214
 215     unsigned m_preloadCount;
 216     PreloadResult m_preloadResult;
 217     bool m_requestedFromNetworkingLayer;
 218
 219 protected:
 220     bool m_inCache;
 221     bool m_loading;
 222     bool m_expireDateChanged;
 223 #ifndef NDEBUG
 224     bool m_deleted;
 225     unsigned m_lruIndex;
 226 #endif
 227
 228 private:
 229     CachedResource* m_nextInAllResourcesList;
 230     CachedResource* m_prevInAllResourcesList;
 231
 232     CachedResource* m_nextInLiveResourcesList;
 233     CachedResource* m_prevInLiveResourcesList;
 234
 235     DocLoader* m_docLoader; // only non-0 for resources that are not in the cache
 236
 237     unsigned m_handleCount;
 238     // If this field is non-null we are using the resource as a proxy for checking whether an existing resource is still up to date
 239     // using HTTP If-Modified-Since/If-None-Match headers. If the response is 304 all clients of this resource are moved
 240     // to to be clients of m_resourceToRevalidate and the resource is deleted. If not, the field is zeroed and this
 241     // resources becomes normal resource load.
 242     CachedResource* m_resourceToRevalidate;
 243     bool m_isBeingRevalidated;
 244     // These handles will need to be updated to point to the m_resourceToRevalidate in case we get 304 response.
 245     HashSet<CachedResourceHandleBase*> m_handlesToRevalidate;
 246
 247     time_t m_expirationDate;
 248 };
 249
 250 }
 251
 252 #endif