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 "FrameLoaderTypes.h"
28#include "PlatformString.h"
29#include "ResourceResponse.h"
30#include "SharedBuffer.h"
31#include <wtf/HashCountedSet.h>
32#include <wtf/HashSet.h>
33#include <wtf/OwnPtr.h>
34#include <wtf/Vector.h>
35#include <time.h>
36
37namespace WebCore {
38
39class Cache;
40class CachedResourceClient;
41class CachedResourceHandleBase;
42class DocLoader;
43class InspectorResource;
44class Request;
45class PurgeableBuffer;
46
47// A resource that is held in the cache. Classes who want to use this object should derive
48// from CachedResourceClient, to get the function calls in case the requested data has arrived.
49// This class also does the actual communication with the loader to obtain the resource from the network.
50class CachedResource : public Noncopyable {
51    friend class Cache;
52    friend class InspectorResource;
53
54public:
55    enum Type {
56        ImageResource,
57        CSSStyleSheet,
58        Script,
59        FontResource
60#if ENABLE(XSLT)
61        , XSLStyleSheet
62#endif
63#if ENABLE(XBL)
64        , XBL
65#endif
66    };
67
68    enum Status {
69        NotCached,    // this URL is not cached
70        Unknown,      // let cache decide what to do with it
71        New,          // inserting new item
72        Pending,      // only partially loaded
73        Cached        // regular case
74    };
75
76    CachedResource(const String& url, Type);
77    virtual ~CachedResource();
78
79    virtual void load(DocLoader* docLoader)  { load(docLoader, false, DoSecurityCheck, true); }
80    void load(DocLoader*, bool incremental, SecurityCheckPolicy, bool sendResourceLoadCallbacks);
81
82    virtual void setEncoding(const String&) { }
83    virtual String encoding() const { return String(); }
84    virtual void data(PassRefPtr<SharedBuffer> data, bool allDataReceived) = 0;
85    virtual void error() = 0;
86    virtual void httpStatusCodeError() { error(); } // Images keep loading in spite of HTTP errors (for legacy compat with <img>, etc.).
87
88    const String &url() const { return m_url; }
89    Type type() const { return m_type; }
90
91    void addClient(CachedResourceClient*);
92    void removeClient(CachedResourceClient*);
93    bool hasClients() const { return !m_clients.isEmpty(); }
94    void deleteIfPossible();
95
96    enum PreloadResult {
97        PreloadNotReferenced,
98        PreloadReferenced,
99        PreloadReferencedWhileLoading,
100        PreloadReferencedWhileComplete
101    };
102    PreloadResult preloadResult() const { return m_preloadResult; }
103    void setRequestedFromNetworkingLayer() { m_requestedFromNetworkingLayer = true; }
104
105    virtual void didAddClient(CachedResourceClient*) = 0;
106    virtual void allClientsRemoved() { }
107
108    unsigned count() const { return m_clients.size(); }
109
110    Status status() const { return m_status; }
111
112    unsigned size() const { return encodedSize() + decodedSize() + overheadSize(); }
113    unsigned encodedSize() const { return m_encodedSize; }
114    unsigned decodedSize() const { return m_decodedSize; }
115    unsigned overheadSize() const;
116
117    bool isLoaded() const { return !m_loading; }
118    void setLoading(bool b) { m_loading = b; }
119
120    virtual bool isImage() const { return false; }
121
122    unsigned accessCount() const { return m_accessCount; }
123    void increaseAccessCount() { m_accessCount++; }
124
125    // Computes the status of an object after loading.
126    // Updates the expire date on the cache entry file
127    void finish();
128
129    // Called by the cache if the object has been removed from the cache
130    // while still being referenced. This means the object should delete itself
131    // if the number of clients observing it ever drops to 0.
132    // The resource can be brought back to cache after successful revalidation.
133    void setInCache(bool inCache) { m_inCache = inCache; }
134    bool inCache() const { return m_inCache; }
135
136    void setInLiveDecodedResourcesList(bool b) { m_inLiveDecodedResourcesList = b; }
137    bool inLiveDecodedResourcesList() { return m_inLiveDecodedResourcesList; }
138
139    void setRequest(Request*);
140
141    SharedBuffer* data() const { ASSERT(!m_purgeableData); return m_data.get(); }
142
143    void setResponse(const ResourceResponse&);
144    const ResourceResponse& response() const { return m_response; }
145
146    bool canDelete() const { return !hasClients() && !m_request && !m_preloadCount && !m_handleCount && !m_resourceToRevalidate && !m_proxyResource; }
147
148    bool isExpired() const;
149
150    virtual bool schedule() const { return false; }
151
152    // List of acceptable MIME types separated by ",".
153    // A MIME type may contain a wildcard, e.g. "text/*".
154    String accept() const { return m_accept; }
155    void setAccept(const String& accept) { m_accept = accept; }
156
157    bool errorOccurred() const { return m_errorOccurred; }
158    bool sendResourceLoadCallbacks() const { return m_sendResourceLoadCallbacks; }
159
160    virtual void destroyDecodedData() { }
161
162    void setDocLoader(DocLoader* docLoader) { m_docLoader = docLoader; }
163
164    bool isPreloaded() const { return m_preloadCount; }
165    void increasePreloadCount() { ++m_preloadCount; }
166    void decreasePreloadCount() { ASSERT(m_preloadCount); --m_preloadCount; }
167
168    void registerHandle(CachedResourceHandleBase* h) { ++m_handleCount; if (m_resourceToRevalidate) m_handlesToRevalidate.add(h); }
169    void unregisterHandle(CachedResourceHandleBase* h) { ASSERT(m_handleCount > 0); --m_handleCount; if (m_resourceToRevalidate) m_handlesToRevalidate.remove(h); if (!m_handleCount) deleteIfPossible(); }
170
171    bool canUseCacheValidator() const;
172    bool mustRevalidate(CachePolicy) const;
173    bool isCacheValidator() const { return m_resourceToRevalidate; }
174    CachedResource* resourceToRevalidate() const { return m_resourceToRevalidate; }
175
176    bool isPurgeable() const;
177    bool wasPurged() const;
178
179    // This is used by the archive machinery to get at a purged resource without
180    // triggering a load. We should make it protected again if we can find a
181    // better way to handle the archive case.
182    bool makePurgeable(bool purgeable);
183
184protected:
185    void setEncodedSize(unsigned);
186    void setDecodedSize(unsigned);
187    void didAccessDecodedData(double timeStamp);
188
189    bool isSafeToMakePurgeable() const;
190
191    HashCountedSet<CachedResourceClient*> m_clients;
192
193    String m_url;
194    String m_accept;
195    Request* m_request;
196
197    ResourceResponse m_response;
198    double m_responseTimestamp;
199
200    RefPtr<SharedBuffer> m_data;
201    OwnPtr<PurgeableBuffer> m_purgeableData;
202
203    Type m_type;
204    Status m_status;
205
206    bool m_errorOccurred;
207
208private:
209    void addClientToSet(CachedResourceClient*);
210
211    // These are called by the friendly Cache only
212    void setResourceToRevalidate(CachedResource*);
213    void switchClientsToRevalidatedResource();
214    void clearResourceToRevalidate();
215    void updateResponseAfterRevalidation(const ResourceResponse& validatingResponse);
216
217    double currentAge() const;
218    double freshnessLifetime() const;
219
220    unsigned m_encodedSize;
221    unsigned m_decodedSize;
222    unsigned m_accessCount;
223    unsigned m_inLiveDecodedResourcesList;
224    double m_lastDecodedAccessTime; // Used as a "thrash guard" in the cache
225
226    bool m_sendResourceLoadCallbacks;
227
228    unsigned m_preloadCount;
229    PreloadResult m_preloadResult;
230    bool m_requestedFromNetworkingLayer;
231
232protected:
233    bool m_inCache;
234    bool m_loading;
235#ifndef NDEBUG
236    bool m_deleted;
237    unsigned m_lruIndex;
238#endif
239
240private:
241    CachedResource* m_nextInAllResourcesList;
242    CachedResource* m_prevInAllResourcesList;
243
244    CachedResource* m_nextInLiveResourcesList;
245    CachedResource* m_prevInLiveResourcesList;
246
247    DocLoader* m_docLoader; // only non-0 for resources that are not in the cache
248
249    unsigned m_handleCount;
250    // 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
251    // using HTTP If-Modified-Since/If-None-Match headers. If the response is 304 all clients of this resource are moved
252    // to to be clients of m_resourceToRevalidate and the resource is deleted. If not, the field is zeroed and this
253    // resources becomes normal resource load.
254    CachedResource* m_resourceToRevalidate;
255
256    // If this field is non-null, the resource has a proxy for checking whether it is still up to date (see m_resourceToRevalidate).
257    CachedResource* m_proxyResource;
258
259    // These handles will need to be updated to point to the m_resourceToRevalidate in case we get 304 response.
260    HashSet<CachedResourceHandleBase*> m_handlesToRevalidate;
261};
262
263}
264
265#endif
266