http.h

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/*
 *
 * Copyright (c) Xerox Corporation 1998. All rights reserved.
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linking this file statically or dynamically with other modules is making
 * a combined work based on this file.  Thus, the terms and conditions of
 * the GNU General Public License cover the whole combination.
 *
 * In addition, as a special exception, the copyright holders of this file
 * give you permission to combine this file with free software programs or
 * libraries that are released under the GNU LGPL and with code included in
 * the standard release of ns-2 under the Apache 2.0 license or under
 * otherwise-compatible licenses with advertising requirements (or modified
 * versions of such code, with unchanged license).  You may copy and
 * distribute such a system following the terms of the GNU GPL for this
 * file and the licenses of the other code concerned, provided that you
 * include the source code of that other code when and as the GNU GPL
 * requires distribution of source code.
 *
 * Note that people who make modified versions of this file are not
 * obligated to grant this special exception for their modified versions;
 * it is their choice whether to do so.  The GNU General Public License
 * gives permission to release a modified version without this exception;
 * this exception also makes it possible to release a modified version
 * which carries forward this exception.
 *
 * $Header: /nfs/jade/vint/CVSROOT/ns-2/webcache/http.h,v 1.14 2005/08/26 05:05:31 tomh Exp $
 *
 */
//
// Definition of the HTTP agent
// 

#ifndef ns_http_h
#define ns_http_h

#include <stdlib.h>
#include <tcl.h>
#include "config.h"
#include "agent.h"
#include "ns-process.h"
#include "app.h"

#include "pagepool.h"
#include "inval-agent.h"
#include "tcpapp.h"
#include "http-aux.h"

class HttpApp : public Process {
public:
    HttpApp();
    virtual ~HttpApp();

    virtual int command(int argc, const char*const* argv);
    void log(const char *fmt, ...);
    int id() const { return id_; }

    virtual void process_data(int size, AppData* d);
    virtual AppData* get_data(int&, AppData*) {
        // Do not support it
        abort();
        return NULL;
    }

protected:
    int add_cnc(HttpApp *client, TcpApp *agt);
    void delete_cnc(HttpApp *client);
    TcpApp* lookup_cnc(HttpApp *client);

    void set_pagepool(ClientPagePool* pp) { pool_ = pp; }

    Tcl_HashTable *tpa_;    // TcpApp hash table
    int id_;        // Node id
    ClientPagePool *pool_;  // Page repository
    Tcl_Channel log_;   // Log file descriptor
};


//----------------------------------------------------------------------
// Servers
//----------------------------------------------------------------------
class HttpServer : public HttpApp {
public: 
    // All methods are in TCL
};

class HttpInvalServer : public HttpServer {
public:
};

// Http server with periodic unicast heartbeat invalidations
class HttpYucInvalServer : public HttpInvalServer {
public:
    HttpYucInvalServer();

    virtual int command(int argc, const char*const* argv);
    void add_inv(const char *name, double mtime);

protected:
    // heartbeat methods
    HttpUInvalAgent *inv_sender_; // Heartbeat/invalidation sender
    InvalidationRec *invlist_; 
    int num_inv_;

    void send_heartbeat();
    HttpHbData* pack_heartbeat();
    virtual void send_hb_helper(int size, AppData *data);
    InvalidationRec* get_invrec(const char *name);

    int Ca_, Cb_, push_thresh_, enable_upd_;
    int push_high_bound_, push_low_bound_;
    double hb_interval_;        // Heartbeat interval (second)
};



//----------------------------------------------------------------------
// Clients
//----------------------------------------------------------------------

// Place holder: everything is in OTcl. We declare it as a split object
// in case that its derived classes need some C++ handling.
class HttpClient : public HttpApp {
};



//----------------------------------------------------------------------
// Caches
//----------------------------------------------------------------------

class HttpCache : public HttpApp {
};

class HttpInvalCache : public HttpCache {
};

// Invalidations embedded in periodic heartbeats
// Used by recv_inv() and recv_inv_filter() to filter invalidations.
const int HTTP_INVALCACHE_FILTERED  = 0;
const int HTTP_INVALCACHE_UNFILTERED    = 1;

// Http cache with periodic multicast heartbeat invalidation
class HttpMInvalCache : public HttpInvalCache {
public:
    HttpMInvalCache();
    virtual ~HttpMInvalCache();

    virtual int command(int argc, const char*const* argv);
    virtual void process_data(int size, AppData* data);
    virtual void timeout(int reason);

    void handle_node_failure(int cid);
    void invalidate_server(int sid);
    void add_inv(const char *name, double mtime);

protected:
    HBTimer hb_timer_;      // Heartbeat/Inval timer
    HttpInvalAgent **inv_sender_;   // Heartbeat/Inval sender agents
    int num_sender_;        // # of heartbeat sender agents
    int size_sender_;       // Maximum size of array inv_sender_
    InvalidationRec *invlist_;  // All invalidations to be sent
    int num_inv_;           // # of invalidations in invlist_

    void send_heartbeat();
    HttpHbData* pack_heartbeat();
    virtual void send_hb_helper(int size, AppData *data);

    int recv_inv(HttpHbData *d);
    virtual void process_inv(int n, InvalidationRec *ivlist, int cache);
    virtual int recv_inv_filter(ClientPage* pg, InvalidationRec *p) {
        return ((pg == NULL) || (pg->mtime() >= p->mtime()) ||
            !pg->is_valid()) ? 
            HTTP_INVALCACHE_FILTERED : HTTP_INVALCACHE_UNFILTERED;
    }
    InvalidationRec* get_invrec(const char *name);

    // Maintaining SState(Server, NextCache)
    // Use the shadow names of server and cache as id
    struct SState {
        SState(NeighborCache* c) : down_(0), cache_(c) {}
        int is_down() { return down_; }
        void down() { down_ = 1; }
        void up() { down_ = 0; }
        NeighborCache* cache() { return cache_; }
        int down_;      // If the server is disconnected
        NeighborCache *cache_;  // NextCache
    };

    Tcl_HashTable sstate_;
    void add_sstate(int sid, SState* sst);
    SState* lookup_sstate(int sid);
    // check & establish sstate
    void check_sstate(int sid, int cid); 

    // Maintaining liveness of neighbor caches
    Tcl_HashTable nbr_;
    void add_nbr(HttpMInvalCache* c);
    NeighborCache* lookup_nbr(int id);

    HttpUInvalAgent *inv_parent_;   // Heartbeat/Inval to parent cache
    
    void recv_heartbeat(int id);
    void recv_leave(HttpLeaveData *d);
    void send_leave(HttpLeaveData *d);

    double hb_interval_;        // Heartbeat interval (second)
    int enable_upd_;        // Whether enable push
    int Ca_, Cb_, push_thresh_;
    int push_high_bound_, push_low_bound_;

    HttpInvalAgent **upd_sender_;   // Agents to push updates to
    int num_updater_;       // # number of update agents
    int size_updater_;      // Size of array upd_sender_

    void add_update(const char *name, double mtime);
    void send_upd(ClientPage *pg);
    int recv_upd(HttpUpdateData *d);
    virtual void send_upd_helper(int pgsize, AppData* data);
    HttpUpdateData* pack_upd(ClientPage *pg);

    // Use a static mapping to convert cache id to cache pointers
    static HttpMInvalCache** CacheRepository_;
    static int NumCache_;
    static void add_cache(HttpMInvalCache* c);
    static HttpMInvalCache* map_cache(int id) {
        return CacheRepository_[id];
    }
};

//----------------------------------------------------------------------
// Multicast invalidation + two way liveness messages + 
// invalidation filtering. 
//----------------------------------------------------------------------
class HttpPercInvalCache : virtual public HttpMInvalCache {
public:
    HttpPercInvalCache();
    int command(int argc, const char*const* argv);

protected: 
    virtual int recv_inv_filter(ClientPage *pg, InvalidationRec *ir) {
        // If we already have an invalid page, don't forward the
        // invalidation any more.
        return ((pg == NULL) || (pg->mtime() >= ir->mtime()) ||
            !pg->is_header_valid()) ? 
            HTTP_INVALCACHE_FILTERED : HTTP_INVALCACHE_UNFILTERED;
    }

    // Flag: if we allow direct request, and hence pro formas
    int direct_request_;
};

#endif // ns_http_h

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