path: root/cacheserver/friend.cpp

#define NDEBUG
#include <algorithm>
#include <cassert>

// for some constant and type
#include "bbs.h"

/* for each login of user, 
 * input: my index, friend[MAX_FRIEND] of uid, reject[MAX_REJECT] of uid,
 * for all my relation,
 * output: his index, his uid, relation to me, relation to him
 */
/* 支 user  utmp 銋憭, 券函 ref index 賣舫, 蝣箔 insert & delete O(1) */
/* 嗆鈭 refer  resource recycle */

typedef int Uid;
typedef int Idx;


struct Relation {
    Uid him;
    short him_offset;

    Relation(Uid _him, short _him_offset=-1) :him(_him),him_offset(_him_offset) {}
};

template<class T>
struct freelist {
    static const int KEEP = 64;
    static T* list[8][KEEP]; // 2^0~2^7
    static int tail[8];

#define IS_2xxN(a)      (a && (a&(a-1))==0)
    static T* alloc(int n) {
    assert(n>0);
    if(n<256 && IS_2xxN(n) && sizeof(T)*n<65536) {
        int t=n;
        int slot;
        for(slot=0; t>1; t/=2)
        slot++;
        assert(0<=slot && slot<8);
        if(tail[slot]) {
        return list[slot][--tail[slot]];
        }
    }
    return (T*)malloc(sizeof(T)*n);
    }
    static void free(T* p, int n) {
    assert(n>0);
    if(n<256 && IS_2xxN(n) && sizeof(T)*n<65536) {
        int t=n;
        int slot;
        for(slot=0; t>1; t/=2)
        slot++;
        assert(0<=slot && slot<8);
        if(tail[slot]<KEEP) {
        list[slot][tail[slot]++]=p;
        return;
        }
    }
    ::free(p);
    }
};

template<class T> T*  freelist<T>::list[8][KEEP];
template<class T> int freelist<T>::tail[8]={0};

template<class T,int MIN_ROOM = 8, class S = int>
struct myvector {
    // 憭扯港唾 STL vector, 雿 STL  capacity 芣憓銝蝮桀
    // (敺靘潛, 隞 online friend 靘隤, capacity 銝蝮桀嗅祕瘝隞€暻澆蔣)
    // 甇文, pointer  64bit 璈其閬 8bytes, basic overhead 8*3 bytes,
    // 雿鞈瘝獐憭, 寧 S(int or short) 摮 size & capacity 瘥頛
    T *base;
    S room, n;

    myvector() :base(0),room(0),n(0) {}
    ~myvector() {
    clear();
    }
    S append(T data) {
    if(room<n+1)
        resizefor(n+1);
    base[n++]=data;
    return n-1;
    }
    void pop_back() {
    assert(n>0);
    n--;
    resizefor(n);
    }
    void clear() {
    n=0;
    resizefor(n);
    }
    /*
    T& operator[](int idx) {
    return base[idx];
    }
    */

    void resizefor(S size) {
    assert(size>=n);
    if(size==0) {
        if(base) freelist<T>::free(base, room);
        base=0;
        room=0;
    } else {
        S origroom=room;
        if(room==0)
        room=MIN_ROOM;
        while(room<size) room=S(room*2);
        if(size<MIN_ROOM) size=MIN_ROOM;
        while(room/2>size) room=S(room/2);
        if(room!=origroom || base==0) {
        //base=(T*)realloc(base, sizeof(T)*room);
        T* tmp=freelist<T>::alloc(room);
        assert(tmp);
        if(n>0)
            memcpy(tmp, base, sizeof(T)*n);
        if(base!=0)
            freelist<T>::free(base, origroom);
        base=tmp;
        }
        assert(base);
    }
    }
};

template<class R,class B>
struct RelationList: public myvector<Relation, 8, short> {
    RelationList() :myvector<Relation, 8, short>() {}
    void add(Uid me, Uid him) {
    RelationList<B,R>& bl=R::backlist(him);
    short me_offset=append(Relation(him));
        short him_offset=bl.append(Relation(me,me_offset));

    setbackoffset(me_offset,him_offset);
    assert(bl.base[him_offset].him==me);
    assert(bl.base[him_offset].him_offset==me_offset);
    }
    void deleteall(Uid me) {
    for(int i=0; i<n; i++) {
        RelationList<B,R>& bl=R::backlist(base[i].him);
        assert(bl.base[base[i].him_offset].him==me);
        assert(bl.base[base[i].him_offset].him_offset==i);
        bl.delete_half(base[i].him_offset);
        //try_recycle(base[i].him); // dirty
    }
    clear();
    }
    private:
    void setbackoffset(short which,short offset) {
    assert(0<=which && which<n);
    base[which].him_offset=offset;
    }
    void delete_half(short offset) {
    assert(0<=offset && offset<n);
    if(offset<n-1) {
        base[offset]=base[n-1];
        R::backlist(base[offset].him).setbackoffset(base[offset].him_offset,offset);
    }
    pop_back();
    }
    friend class RelationList<B,R>;
};

struct Like;
struct Likeby;
struct Hate;
struct Hateby;
struct Like: public Relation {
    Like(Uid _him, short _him_offset=-1) :Relation(_him,_him_offset) {}
    static RelationList<Likeby,Like>& backlist(Uid him);
};
struct Likeby: public Relation {
    Likeby(Uid _him, short _him_offset=-1) :Relation(_him,_him_offset) {}
    static RelationList<Like,Likeby>& backlist(Uid him);
};
struct Hate: public Relation {
    Hate(Uid _him, short _him_offset=-1) :Relation(_him,_him_offset) {}
    static RelationList<Hateby,Hate>& backlist(Uid him);
};
struct Hateby: public Relation {
    Hateby(Uid _him, short _him_offset=-1) :Relation(_him,_him_offset) {}
    static RelationList<Hate,Hateby>& backlist(Uid him);
};


struct Utmp {
    Utmp() {
    for(int i=0; i<USHM_SIZE; i++)
        utmp[i]=-1;
    }
    /*
    Uid& operator[](int idx) {
    return utmp[idx];
    }
    */
    public:
    Uid utmp[USHM_SIZE];
};
static Utmp utmp;

struct BBSUser {
    Uid me;
    int online;
    /* assume utmplist is short, so just use plain vector and linear search */
    myvector<int,2> utmplist;

    RelationList<Like,Likeby> like;
    RelationList<Hate,Hateby> hate;
    RelationList<Likeby,Like> likeby;
    RelationList<Hateby,Hate> hateby;

    BBSUser() :me(-1),online(0),utmplist(),like(),hate(),likeby(),hateby() {}
    BBSUser(Uid uid) :me(uid),online(0),utmplist(),like(),hate(),likeby(),hateby() {}

    void login(int utmpidx, const Uid likehim[MAX_FRIEND], const Uid hatehim[MAX_REJECT]) {
    if(online>0) {
        /* multiple login 閰, 隞交€敺銝€甈∠ like/hate 箸 */
        like.deleteall(me);
        hate.deleteall(me);
    }
    utmp.utmp[utmpidx]=me;
    utmplist.append(utmpidx);
    online++;
    assert(online==utmplist.n);
    for(int i=0; i<MAX_FRIEND && likehim[i]; i++)
        like.add(me, likehim[i]);
    for(int i=0; i<MAX_REJECT && hatehim[i]; i++)
        hate.add(me, hatehim[i]);
    }

    void logout(int utmpidx) {
    assert(utmp.utmp[utmpidx]==me);
    assert(online==utmplist.n);
    for(int i=0; i<utmplist.n; i++)
        if(utmplist.base[i]==utmpidx) {
        utmplist.base[i]=utmplist.base[utmplist.n-1];
        utmplist.pop_back();
        break;
        }
    utmp.utmp[utmpidx]=-1;
    online--;
    assert(online==utmplist.n);
    if(online==0) {
        like.deleteall(me);
        hate.deleteall(me);
    }
    }
    bool isfree() const {
    return online==0 && like.n==0 && hate.n==0 && likeby.n==0 && hateby.n==0;
    }
};

struct UserList {
    BBSUser users[MAX_USERS];

    UserList() {
    for(int i=0; i<MAX_USERS; i++)
        users[i].me=i;
    }
    void login(Uid uid, Idx idx, const Uid likehim[MAX_FRIEND], const Uid hatehim[MAX_REJECT]) {
    assert(uid<MAX_USERS);
    assert(idx<USHM_SIZE);
    /* 望潔嗅 logout event, 甇 logout 芰潛 utmp override */
    if(utmp.utmp[idx]!=-1) users[utmp.utmp[idx]].logout(idx);
    users[uid].login(idx, likehim, hatehim);
    }
};

struct UserList userlist;
RelationList<Likeby,Like>& Like::backlist(Uid him) { return userlist.users[him].likeby; }
RelationList<Like,Likeby>& Likeby::backlist(Uid him) { return userlist.users[him].like; }
RelationList<Hateby,Hate>& Hate::backlist(Uid him) { return userlist.users[him].hateby; }
RelationList<Hate,Hateby>& Hateby::backlist(Uid him) { return userlist.users[him].hate; }

struct Result {
    Uid who;
    int bits;
    Result(Uid _who, int _bits) :who(_who),bits(_bits) {}
    bool operator<(const Result& b) const {
    return who<b.who;
    }
};

int reverse_friend_stat(int stat)
{
    int             stat1 = 0;
    if (stat & IFH) stat1 |= HFM;
    if (stat & IRH) stat1 |= HRM;
    if (stat & HFM) stat1 |= IFH;
    if (stat & HRM) stat1 |= IRH;
    return stat1;
}

extern "C" void utmplogin(int uid, int index, const int like[MAX_FRIEND], const int hate[MAX_REJECT])
{
    /* login */
    userlist.login(uid, index, like, hate);
}

extern "C" int genfriendlist(int uid, int index, ocfs_t *fs, int maxfs)
{
    /* collect data */
    BBSUser& u=userlist.users[uid];
    myvector<Result,64,short> work;
    for(int i=0; i<u.like.n; i++) work.append(Result(u.like.base[i].him, IFH));
    for(int i=0; i<u.hate.n; i++) work.append(Result(u.hate.base[i].him, IRH));
    for(int i=0; i<u.likeby.n; i++) work.append(Result(u.likeby.base[i].him, HFM));
    for(int i=0; i<u.hateby.n; i++) work.append(Result(u.hateby.base[i].him, HRM));

    /* sort */
    std::sort(work.base, work.base+work.n);
    /* merge */
    if(work.n>0) {
    int newn=1;
    for(int i=1; i<work.n; i++)
        if(work.base[i].who==work.base[newn-1].who) {
        work.base[newn-1].bits|=work.base[i].bits;
        } else {
        work.base[newn++]=work.base[i];
        }
    work.n=newn;
    }
    /* fill */
    int nfs=0;
    for(int i=0; i<work.n && nfs<maxfs; i++) {
    BBSUser& h=userlist.users[work.base[i].who];
    for(int j=0; j<h.utmplist.n && nfs<maxfs; j++) {
        int rstat=reverse_friend_stat(work.base[i].bits);
        if(h.utmplist.base[j]==index) continue;
        fs[nfs].index=h.utmplist.base[j];
        fs[nfs].uid=h.me;
        fs[nfs].friendstat=(work.base[i].bits<<24)|h.utmplist.base[j];
        fs[nfs].rfriendstat=(rstat<<24)|index;
        nfs++;
    }
    }
    return nfs;
}

extern "C" void utmplogoutall(void)
{
    for(int i=0; i<USHM_SIZE; i++)
    if(utmp.utmp[i]!=-1)
        userlist.users[utmp.utmp[i]].logout(i);
}