http.h

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// Copyright (c) Xerox Corporation 1998. All rights reserved.
//
// License is granted to copy, to use, and to make and to use derivative
// works for research and evaluation purposes, provided that Xerox is
// acknowledged in all documentation pertaining to any such copy or
// derivative work. Xerox grants no other licenses expressed or
// implied. The Xerox trade name should not be used in any advertising
// without its written permission. 
//
// XEROX CORPORATION MAKES NO REPRESENTATIONS CONCERNING EITHER THE
// MERCHANTABILITY OF THIS SOFTWARE OR THE SUITABILITY OF THIS SOFTWARE
// FOR ANY PARTICULAR PURPOSE.  The software is provided "as is" without
// express or implied warranty of any kind.
//
// These notices must be retained in any copies of any part of this
// software. 
//
// Definition of the HTTP agent
// 
// $Header: /nfs/jade/vint/CVSROOT/ns-2/webcache/http.h,v 1.13 1999/08/24 04:16:24 haoboy Exp $

#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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