/Users/yzchen/ns/ns-allinone-2.33/ns-2.33/webcache/http-aux.h

/*
 * 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: /cvsroot/nsnam/ns-2/webcache/http-aux.h,v 1.17 2005/08/26 05:05:31 tomh Exp $
 */

//
// Auxiliary classes for HTTP multicast invalidation proxy cache
//

#ifndef ns_http_aux_h
#define ns_http_aux_h

#include <tclcl.h>

#include "random.h"
#include "ns-process.h"
#include "pagepool.h"
#include "timer-handler.h"

const int HTTP_HBEXPIRE_COUNT   = 5; // How many lost HBs mean disconnection?
const int HTTP_HBINTERVAL       = 60;// Heartbeat intervals (seconds)
const int HTTP_UPDATEINTERVAL   = 5; // Delays to push/v1 (seconds)

class HttpMInvalCache;

// Used for caches to keep track of invalidations
class InvalidationRec {
public:
        InvalidationRec(const char *pid, double mtime, char updating = 0) {
                pg_ = new char[strlen(pid) + 1];
                strcpy(pg_, pid);
                mtime_ = mtime;
                scount_ = HTTP_HBEXPIRE_COUNT;
                updating_ = updating;
                next_ = 0, prev_ = 0;
        }
        virtual ~InvalidationRec() {
                delete []pg_;
        }

        const char* pg() const { return pg_; }
        double mtime() const { return mtime_; }
        char updating() const { return updating_; }
        int scount() const { return scount_; }
        InvalidationRec* next() { return next_; } 

        void reset(double mtime) {
                scount_ = HTTP_HBEXPIRE_COUNT;
                mtime_ = mtime;
        }
        int dec_scount() { return --scount_; }
        void set_updating() { updating_ = 1; }
        void clear_updating() { updating_ = 0; }

        void insert(InvalidationRec **head) {
                next_ = *head;
                if (next_ != 0)
                        next_->prev_ = &next_;
                prev_ = head;
                *head = this;
        }
        void detach() {
                if (prev_ != 0)
                        *prev_ = next_;
                if (next_ != 0)
                        next_->prev_ = prev_;
        }

        friend class HttpMInvalCache;

protected:
        char *pg_;
        double mtime_;
        char updating_; // 1 if an update is going to be sent soon
        int scount_;    // Times that an invalidation needs to be multicast
        InvalidationRec *next_;
        InvalidationRec **prev_;
};

class HBTimer : public TimerHandler {
public: 
        HBTimer(HttpMInvalCache *a, double interval) : TimerHandler() { 
                a_ = a, interval_ = interval; 
        }
        void set_interval(double interval) { interval_ = interval; }
        double get_interval() const { return interval_; }
        double next_interval() {
                return interval_ * (1 + Random::uniform(-0.1,0.1));
        }
        void sched() { TimerHandler::sched(interval_); }
        void resched() {
                TimerHandler::resched(next_interval());
        }
protected: 
        virtual void expire(Event *e);
        virtual void handle(Event *e) {
                TimerHandler::handle(e);
                resched();
        }
        HttpMInvalCache *a_;
        double interval_;
};

class PushTimer : public TimerHandler {
public:
        PushTimer(HttpMInvalCache *a, double itv) : 
                TimerHandler(), a_(a), interval_(itv) {}
        void set_interval(double itv) { interval_ = itv; } 
        double get_interval() const { return interval_; }
        void sched() {
                TimerHandler::sched(interval_);
        }
protected:
        virtual void expire(Event *e);
        HttpMInvalCache *a_;
        double interval_;
};

class LivenessTimer : public TimerHandler {
public:
        LivenessTimer(HttpMInvalCache *a, double itv, int nbr) :
                TimerHandler(), a_(a), nbr_(nbr), interval_(itv) {}
        void sched() { TimerHandler::sched(interval_); }
        void resched() { TimerHandler::resched(interval_); }
protected:
        virtual void expire(Event *e);
        HttpMInvalCache *a_;    // The cache to be alerted
        int nbr_;               // Neighbor cache id
        double interval_;
};


// XXX ADU defined in app-connector.h

const int HTTPDATA_COST         = 8;

// User-level packets
class HttpData : public AppData {
private:
        int id_;        // ID of the sender

public:
        HttpData() : AppData(HTTP_DATA) {}
        HttpData(AppDataType t, int d) : AppData(t) { id_ = d; }
        HttpData(HttpData& d) : AppData(d) { id_ = d.id_; }

        inline int& id() { return id_; }
        virtual int size() const { return sizeof(HttpData); }
        virtual int cost() const { return HTTPDATA_COST; }
        virtual AppData* copy() { return (new HttpData(*this)); }
};



// HTTP data during normal request and response: containing a tcl command
class HttpNormalData : public HttpData {
private: 
        char *str_;
        int strlen_;
        int cost_;
public:
        // XXX Whoever sends data should allocate memory to store the string.
        // Whoever receives this object should delete it to free the string.
        HttpNormalData(int id, int cost, const char *str) : 
                HttpData(HTTP_NORMAL, id) {
                if ((str == NULL) || (*str == 0))
                        strlen_ = 0;
                else
                        strlen_ = strlen(str) + 1;
                if (strlen_ > 0) {
                        str_ = new char[strlen_];
                        strcpy(str_, str);
                } else
                        str_ = NULL;
                cost_ = cost;
        }
        HttpNormalData(HttpNormalData& d) : HttpData(d) {
                cost_ = d.cost_;
                strlen_ = d.strlen_;
                if (strlen_ > 0) {
                        str_ = new char[strlen_];
                        strcpy(str_, d.str_);
                } else
                        str_ = NULL;
        }
        virtual ~HttpNormalData() {
                if (str_ != NULL)
                        delete []str_;
        }

        virtual int size() const {
                // Intentially use sizeof(int) instead of 2*sizeof(int)
                return (sizeof(HttpData)+sizeof(int)+strlen_);
        }
        virtual int cost() const { return cost_; }
        char* str() const { return str_; }
        virtual AppData* copy() {
                return (new HttpNormalData(*this));
        }
};



// XXX assign cost to a constant so as to be more portable
const int HTTPHBDATA_COST = 32;
const int HTTP_MAXURLLEN = 20;

// Struct used to pack invalidation records into packets
class HttpHbData : public HttpData {
protected:
        struct InvalRec {
                char pg_[HTTP_MAXURLLEN];       // Maximum page id length
                double mtime_;
                // Used only to mark that this page will be send in the 
                // next multicast update. The updating field in this agent 
                // will only be set after it gets the real update.
                int updating_; 
                void copy(InvalidationRec *v) {
                        strcpy(pg_, v->pg());
                        mtime_ = v->mtime();
                        updating_ = v->updating();
                }
                InvalidationRec* copyto() {
                        return (new InvalidationRec(pg_, mtime_, updating_));
                }
        };

private:
        int num_inv_;
        InvalRec* inv_rec_;
        inline InvalRec* inv_rec() { return inv_rec_; }

public:
        HttpHbData(int id, int n) : 
                HttpData(HTTP_INVALIDATION, id), num_inv_(n) {
                if (num_inv_ > 0)
                        inv_rec_ = new InvalRec[num_inv_];
                else
                        inv_rec_ = NULL;
        }
        HttpHbData(HttpHbData& d) : HttpData(d) {
                num_inv_ = d.num_inv_;
                if (num_inv_ > 0) {
                        inv_rec_ = new InvalRec[num_inv_];
                        memcpy(inv_rec_, d.inv_rec_,num_inv_*sizeof(InvalRec));
                } else
                        inv_rec_ = NULL;
        }
        virtual ~HttpHbData() { 
                if (inv_rec_ != NULL)
                        delete []inv_rec_; 
        }

        virtual int size() const {
                return HttpData::size() + num_inv_*sizeof(InvalRec);
        }
        // XXX byte cost to appear in trace file
        virtual int cost() const { 
                // Minimum size 1 so that TCP will send a packet
                return (num_inv_ == 0) ? 1 : (num_inv_*HTTPHBDATA_COST); 
        }
        virtual AppData* copy() {
                return (new HttpHbData(*this));
        }

        inline int& num_inv() { return num_inv_; }
        inline void add(int i, InvalidationRec *r) {
                inv_rec()[i].copy(r);
        }
        inline char* rec_pg(int i) { return inv_rec()[i].pg_; }
        inline double& rec_mtime(int i) { return inv_rec()[i].mtime_; }
        void extract(InvalidationRec*& ivlist);
};



class HttpUpdateData : public HttpData {
protected:
        // Pack page updates to be pushed to caches
        struct PageRec {
                char pg_[HTTP_MAXURLLEN];
                double mtime_;
                double age_;
                int size_;
                void copy(ClientPage *p) {
                        p->name(pg_);
                        mtime_ = p->mtime();
                        age_ = p->age();
                        size_ = p->size();
                }
        };
private:
        int num_;
        int pgsize_;
        PageRec *rec_;
        inline PageRec* rec() { return rec_; }
public:
        HttpUpdateData(int id, int n) : HttpData(HTTP_UPDATE, id) {
                num_ = n;
                pgsize_ = 0;
                if (num_ > 0)
                        rec_ = new PageRec[num_];
                else
                        rec_ = NULL;
        }
        HttpUpdateData(HttpUpdateData& d) : HttpData(d) {
                num_ = d.num_;
                pgsize_ = d.pgsize_;
                if (num_ > 0) {
                        rec_ = new PageRec[num_];
                        memcpy(rec_, d.rec_, num_*sizeof(PageRec));
                } else
                        rec_ = NULL;
        }
        virtual ~HttpUpdateData() {
                if (rec_ != NULL)
                        delete []rec_;
        }

        virtual int size() const { 
                return HttpData::size() + 2*sizeof(int)+num_*sizeof(PageRec); 
        }
        virtual int cost() const { return pgsize_; }
        virtual AppData* copy() {
                return (new HttpUpdateData(*this));
        }

        inline int num() const { return num_; }
        inline int pgsize() const { return pgsize_; }

        inline void set_pgsize(int s) { pgsize_ = s; }
        inline void add(int i, ClientPage *p) {
                rec()[i].copy(p);
                pgsize_ += p->size();
        }

        inline char* rec_page(int i) { return rec()[i].pg_; }
        inline int& rec_size(int i) { return rec()[i].size_; }
        inline double& rec_age(int i) { return rec()[i].age_; }
        inline double& rec_mtime(int i) { return rec()[i].mtime_; }
};



const int HTTPLEAVE_COST = 4;

// Message: server leave
class HttpLeaveData : public HttpData {
private:
        int num_;
        int* rec_; // array of server ids which are out of contact
        inline int* rec() { return rec_; }
public:
        HttpLeaveData(int id, int n) : HttpData(HTTP_LEAVE, id) {
                num_ = n;
                if (num_ > 0)
                        rec_ = new int[num_];
                else
                        rec_ = NULL;
        }
        HttpLeaveData(HttpLeaveData& d) : HttpData(d) {
                num_ = d.num_;
                if (num_ > 0) {
                        rec_ = new int[num_];
                        memcpy(rec_, d.rec_, num_*sizeof(int));
                } else
                        rec_ = NULL;
        }
        virtual ~HttpLeaveData() { 
                if (rec_ != NULL)
                        delete []rec_; 
        }

        virtual int size() const { 
                return HttpData::size() + (num_+1)*sizeof(int);
        }
        virtual int cost() const { return num_*HTTPLEAVE_COST; }
        virtual AppData* copy() {
                return (new HttpLeaveData(*this));
        }

        inline int num() const { return num_; }
        inline void add(int i, int id) {
                rec()[i] = id;
        }
        inline int rec_id(int i) { return rec()[i]; }
};


// Auxliary class
class NeighborCache {
public:
        NeighborCache(HttpMInvalCache*c, double t, LivenessTimer *timer) : 
                cache_(c), time_(t), down_(0), timer_(timer) {}
        ~NeighborCache();

        double time() { return time_; }
        void reset_timer(double time) { 
                time_ = time, timer_->resched(); 
        }
        int is_down() { return down_; }
        void down() { down_ = 1; }
        void up() { down_ = 0; }
        int num() const { return sl_.num(); }
        HttpMInvalCache* cache() { return cache_; }
        void pack_leave(HttpLeaveData&);
        int is_server_down(int sid);
        void server_down(int sid);
        void server_up(int sid);
        void invalidate(HttpMInvalCache *c);
        void add_server(int sid);

        // Maintaining neighbor cache timeout entries
        struct ServerEntry {
                ServerEntry(int sid) : server_(sid), next_(NULL), down_(0) {}
                int server() { return server_; }
                ServerEntry* next() { return next_; }
                int is_down() { return down_; }
                void down() { down_ = 1; }
                void up() { down_ = 0; }

                int server_;
                ServerEntry *next_;
                int down_;
        };
        // We cannot use template. :(((
        struct ServerList {
                ServerList() : head_(NULL), num_(0) {}
                void insert(ServerEntry *s) {
                        s->next_ = head_;
                        head_ = s;
                        num_++;
                }
                // We don't need a detach()
                ServerEntry* gethead() { return head_; } // For iterations
                int num() const { return num_; }
                ServerEntry *head_;
                int num_;
        };

protected:
        HttpMInvalCache* cache_;
        double time_;
        int down_;
        ServerList sl_;
        LivenessTimer *timer_;
};

#endif // ns_http_aux_h