source: examples/hashtable.cfa @ d2b5d2d

#include <containers/list.hfa>

#include <exception.hfa>
TRIVIAL_EXCEPTION(ht_fill_limit_crossed);



void defaultResumptionHandler(ht_fill_limit_crossed &) {
    printf("default resumption ht_fill_limit_crossed\n");
}

void defaultTerminationHandler(ht_fill_limit_crossed &) = void;


trait has_hash( otype K ) {
    size_t hash(K);
    int ?==?( K, K );
};

trait hkey( otype K, dtype tN | has_hash(K) ) {
    K key(tN &);
};

forall( otype K, dtype tN, dtype tE | $dlistable(tN, tE) | hkey(K, tN) ) {

    struct hashtable {

        size_t n_buckets;
        dlist(tN, tE) *buckets;
        
        size_t item_count;
        float ff_next_warn_up;

        void (*defaultResumptionHandler) (ht_fill_limit_crossed &);
    };

    void ?{}( hashtable(K, tN, tE) & this ) = void;
}

forall( otype K, dtype tN, dtype tE | $dlistable(tN, tE) | hkey(K, tN) | { void defaultResumptionHandler(ht_fill_limit_crossed &); } ) {

    void ?{}( hashtable(K, tN, tE) & this, size_t n_buckets, dlist(tN, tE) *buckets ) {

        this.n_buckets = n_buckets;
        this.buckets = buckets;

        this.item_count = 0;
        this.ff_next_warn_up = 0.5;

        this.defaultResumptionHandler = defaultResumptionHandler;

        for ( i; n_buckets ) {
            ?{}( this.buckets[i] );
        }
    }
}

forall( otype K, dtype tN, dtype tE | $dlistable(tN, tE) | hkey(K, tN) ) {

    float fill_frac( hashtable(K, tN, tE) & this ) with(this) {
        return ((float)item_count) / n_buckets;
    }

    size_t bucket_of( hashtable(K, tN, tE) & this, K k ) {
        return hash(k) % this.n_buckets;
    }

    tE & get( hashtable(K, tN, tE) & this, K k ) with (this) {

        dlist(tN, tE) & bucket = buckets[ bucket_of(this, k) ];

        for ( tN * item = & $tempcv_e2n(bucket`first);  item != 0p;  item = & $tempcv_e2n((*item)`next) ) {
            if ( key(*item) == k ) {
                return *item;
            }
        }

        return *0p;
    }

    void check_ff_warning( hashtable(K, tN, tE) & this ) with (this) {
        if (fill_frac(this) > ff_next_warn_up) {
            throwResume (ht_fill_limit_crossed){};
            ff_next_warn_up *= 2;
        }
    }

    void put( hashtable(K, tN, tE) & this, tE & v ) with (this) {

        check_ff_warning(this);

        K k = key( $tempcv_e2n(v) );
        dlist(tN, tE) & bucket = buckets[ bucket_of(this, k) ];

        for ( tN * item = & $tempcv_e2n(bucket`first);  item != 0p;  item = & $tempcv_e2n((*item)`next) ) {
            if ( key(*item) == k ) {
                remove(*item);
                break;
            }
        }

        insert_first(bucket, v);
        this.item_count ++;
    }

}

// tactical usage:
// HASHTABLE_STATIC(int, item_by_prority, item, n, ht)
//
// intended equivalent:
// hashtable_static(int, item_by_prority, item, Z(n)) ht;
#define HASHTABLE_STATIC(K, tN, tE, n_buckets, obj) \
    struct __hashtable_static_ ## obj { \
        inline hashtable(K, tN, tE); \
        dlist(tN, tE) $items[n_buckets]; \
    }; \
    void ?{}( __hashtable_static_ ## obj & this )  { \
        ((hashtable(K, tN, tE) &)this){ n_buckets, this.$items }; \
    } \
    __hashtable_static_ ## obj obj;



trait heaped(dtype T) {
    T * alloc( size_t );
    void free( void * ); 
};

void __dynamic_defaultResumptionHandler(ht_fill_limit_crossed & ex) {
    printf("dynamic limit crossed\n");
}

forall( otype K, dtype tN, dtype tE | $dlistable(tN, tE) | hkey(K, tN) | heaped( dlist(tN, tE) ) ) {

    struct hashtable_dynamic { 
        inline hashtable(K, tN, tE); 
    };
    void ?{}( hashtable_dynamic(K, tN, tE) & this, size_t n_buckets )  {
        void (*defaultResumptionHandler) (ht_fill_limit_crossed &) = __dynamic_defaultResumptionHandler;
        dlist(tN, tE) *buckets = alloc(n_buckets);
        ((hashtable(K, tN, tE) &)this){ n_buckets, buckets };
    }
    void ^?{}( hashtable_dynamic(K, tN, tE) & this ) {
        free(this.buckets);
    }
}




struct request {

    unsigned int src_id;
    unsigned int tgt_id;

    DLISTED_MGD_EXPL_IN(request, ht_by_src)
    DLISTED_MGD_EXPL_IN(request, ht_by_tgt)
};
DLISTED_MGD_EXPL_OUT(request, ht_by_src)
DLISTED_MGD_EXPL_OUT(request, ht_by_tgt)

size_t hash( unsigned int k ) {
    // not really a hash function, not really the point
    return k;
}

unsigned int key( request_in_ht_by_src & v ) {
    return v.src_id;
}


#include <stdlib.hfa>

int main() {


    HASHTABLE_STATIC(unsigned int, request_in_ht_by_src, request, 67, h_src)

    request & wasnt_found = get(h_src, 17);
    assert( &wasnt_found == 0p );

    request r;
    r.src_id = 117;
    r.tgt_id = 998;

    put(h_src, r);

    request & found = get(h_src, 117);
    assert( &found == &r );

    & wasnt_found = & get(h_src, 998);
    assert( &wasnt_found == 0p );

    printf( "%f\n", fill_frac(h_src) );


    request rs[500];
    try {
        for (i; 500) {
            rs[i].src_id = 8000 * i;
            put(h_src, rs[i]);
        }
    } catchResume(ht_fill_limit_crossed*) {
        printf("fill limit tripped with h_src filled at %f\n", fill_frac(h_src));
        throwResume;
    }

    assert(  & get(h_src, 117      ) );
    assert(  & get(h_src, 8000*25  ) );
    assert(! & get(h_src, 8000*25+1) );



    dlist(request_in_ht_by_src, request) * (*old_alloc)( size_t ) = alloc;
    dlist(request_in_ht_by_src, request) * alloc( size_t n ) {
        dlist(request_in_ht_by_src, request) * ret = old_alloc(n);
        printf("alloc'ed at %p\n", ret);
        return ret;
    }

    void (*old_free)( void * ) = free;
    void free( void * o ) {
        printf("free'ing at %p\n", o);
        old_free(o);
    }

    hashtable_dynamic(unsigned int, request_in_ht_by_src, request) ht2 = { 113 };
    request rs2[500];
    try {
        for (i; 500) {
            if (i % 10 == 0) {printf("%d(%f),", i, fill_frac(ht2));}
            rs2[i].src_id = 8000 * i;
            put(ht2, rs2[i]);
        }
    } catchResume(ht_fill_limit_crossed*) {
        printf("fill limit tripped with ht2 filled at %f\n", fill_frac(ht2));
        throwResume;
    }


}