WebCore/loader/CachedResource.h

/*
    This file is part of the KDE libraries

    Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
    Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
    Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
    Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
    Boston, MA 02111-1307, USA.

    This class provides all functionality needed for loading images, style sheets and html
    pages from the web. It has a memory cache for these objects.
*/

#ifndef CachedResource_h
#define CachedResource_h

#include "CachePolicy.h"
#include "PlatformString.h"
#include "ResourceResponse.h"
#include "SharedBuffer.h"
#include <wtf/HashSet.h>
#include <wtf/Vector.h>
#include <time.h>

namespace WebCore {

class Cache;
class CachedResourceClient;
class Request;

// A resource that is held in the cache. Classes who want to use this object should derive
// from CachedResourceClient, to get the function calls in case the requested data has arrived.
// This class also does the actual communication with the loader to obtain the resource from the network.
class CachedResource {
public:
    enum Type {
        ImageResource,
        CSSStyleSheet,
        Script
#if ENABLE(XSLT)
        , XSLStyleSheet
#endif
#if ENABLE(XBL)
        , XBL
#endif
    };

    enum Status {
        NotCached,    // this URL is not cached
        Unknown,      // let cache decide what to do with it
        New,          // inserting new item
        Pending,      // only partially loaded
        Cached       // regular case
    };

    CachedResource(const String& URL, Type type, CachePolicy cachePolicy, unsigned size = 0);
    virtual ~CachedResource();

    virtual void setEncoding(const String&) { }
    virtual Vector<char>& bufferData(const char* bytes, int addedSize, Request*);
    virtual void data(Vector<char>&, bool allDataReceived) = 0;
    virtual void error() = 0;

    const String &url() const { return m_url; }
    Type type() const { return m_type; }

    virtual void ref(CachedResourceClient*);
    void deref(CachedResourceClient*);
    bool referenced() const { return !m_clients.isEmpty(); }

    unsigned count() const { return m_clients.size(); }

    Status status() const { return m_status; }

    unsigned size() const { return m_size; }

    bool isLoaded() const { return !m_loading; }
    void setLoading(bool b) { m_loading = b; }

    virtual bool isImage() const { return false; }

    unsigned accessCount() const { return m_accessCount; }
    void increaseAccessCount() { m_accessCount++; }

    // Computes the status of an object after loading.  
    // Updates the expire date on the cache entry file
    void finish();

    // Called by the cache if the object has been removed from the cache
    // while still being referenced. This means the object should delete itself
    // if the number of clients observing it ever drops to 0.
    void setInCache(bool b) { m_inCache = b; }
    bool inCache() const { return m_inCache; }
    
    CachePolicy cachePolicy() const { return m_cachePolicy; }

    void setRequest(Request*);

    SharedBuffer* allData() const { return m_allData.get(); }
    void setAllData(PassRefPtr<SharedBuffer> allData) { m_allData = allData; }

    void setResponse(const ResourceResponse& response) { m_response = response; }
    const ResourceResponse& response() const { return m_response; }
    
    bool canDelete() const { return !referenced() && !m_request; }

    bool isExpired() const;

    virtual bool schedule() const { return false; }

    // List of acceptable MIME types seperated by ",".
    // A MIME type may contain a wildcard, e.g. "text/*".
    String accept() const { return m_accept; }
    void setAccept(const String& accept) { m_accept = accept; }

protected:
    void setSize(unsigned size);

    HashSet<CachedResourceClient*> m_clients;

    String m_url;
    String m_accept;
    Request* m_request;

    ResourceResponse m_response;
    RefPtr<SharedBuffer> m_allData;

    Type m_type;
    Status m_status;

private:
    unsigned m_size;
    unsigned m_accessCount;

protected:
    CachePolicy m_cachePolicy;
    bool m_inCache;
    bool m_loading;
    bool m_expireDateChanged;
#ifndef NDEBUG
    bool m_deleted;
    unsigned m_lruIndex;
#endif

private:
    CachedResource* m_nextInLRUList;
    CachedResource* m_prevInLRUList;
    friend class Cache;
};

}

#endif