source: examples/hashtable2.cfa @ d1864da

#include <containers/list.hfa>

typedef unsigned int K;

// workaround type for trac#185; used here as the ticket's examples use a spontaneous float
typedef struct {} t_unused;

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 <exception.hfa>

DATA_EXCEPTION(ht_fill_limit_crossed)(
        void * theHashtable;
    bool want_throwResume_ht_auto_resize_pending;
    size_t size_for_ht_auto_resize_pending;
);

void ?{}(ht_fill_limit_crossed & this, void * theHashtable) {
        VTABLE_INIT(this, ht_fill_limit_crossed);
        this.theHashtable = theHashtable;
    this.want_throwResume_ht_auto_resize_pending = false;
    this.size_for_ht_auto_resize_pending = 0;
}

const char * ht_fill_limit_crossed_msg(ht_fill_limit_crossed * this) {
        return "ht_fill_limit_crossed";
}

VTABLE_INSTANCE(ht_fill_limit_crossed)(ht_fill_limit_crossed_msg);


DATA_EXCEPTION(ht_auto_resize_pending)(
        void * theHashtable;
    size_t new_size;
);

void ?{}(ht_auto_resize_pending & this, void * theHashtable, size_t new_size) {
        VTABLE_INIT(this, ht_auto_resize_pending);
        this.theHashtable = theHashtable;
    this.new_size = new_size;
}

const char * ht_auto_resize_pending_msg(ht_auto_resize_pending * this) {
        return "ht_auto_resize_pending";
}

VTABLE_INSTANCE(ht_auto_resize_pending)(ht_auto_resize_pending_msg);



trait pretendsToMatter( dtype TTT ) {
    void actsmart(TTT &);
};

forall( dtype TTTx )
void actsmart(TTTx &) {}

// probable bug, wrt otype Tt_unused...
//   1. changing to dtype Tt_unused crashes GenPoly
//   2. declaring function check_ff_warning as concrete, i.e. operating on type hashtable_rbs(t_unused) makes cfa-cc generate bad C
// in both cases, it's on the throwResume call
// where it implicitly uses this.defaultResumptionHandler as a throwResume argument
// whereas that, of course, has to be surrounded in a cast
// at GenPoly breakpoint, type of said cast appears as CFA generic struct, even as the "this" parameter appears as C struct; casted type ...
//   1. is hashtable_rbs(Tt_unused); assertion complains you don't need a type arg here
//   2. shows up in -CFA output as hashtable_rbs(), which is bad C; expecting hashtable_rbs*

forall( otype Tt_unused | pretendsToMatter(Tt_unused) ) {

    // hashtable of request by source
    struct hashtable_rbs {

        size_t n_buckets;
        dlist(request_in_ht_by_src, request) *buckets;
        
        size_t item_count;
        float ff_next_warn_up;
        float ff_warn_step_factor;

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

    void ?{}( hashtable_rbs(Tt_unused) & this ) = void;
}

forall( otype Tt_unused | pretendsToMatter(Tt_unused) | { void defaultResumptionHandler(ht_fill_limit_crossed &); } ) {

    void ?{}( hashtable_rbs(Tt_unused) & this, size_t n_buckets, dlist(request_in_ht_by_src, request) *buckets,
        float ff_next_warn_up, float ff_warn_step_factor ) {

        printf( "base hashtable ctor with %ld buckets at %p\n", n_buckets, buckets);

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

        this.item_count = 0;
        this.ff_next_warn_up = ff_next_warn_up;
        this.ff_warn_step_factor = ff_warn_step_factor;

        this.defaultResumptionHandler = defaultResumptionHandler;

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

    void ?{}( hashtable_rbs(Tt_unused) & this, size_t n_buckets, dlist(request_in_ht_by_src, request) *buckets ) {
        printf( "base hashtable ctor with default warning steps\n" );
        ( this ) { n_buckets, buckets, 0.5, 2 };
    }

}

// this fwd declaration is artifact of workaround trac#192
void defaultResumptionHandler( ht_auto_resize_pending & ex );

forall( otype Tt_unused | pretendsToMatter(Tt_unused) ) {

    float fill_frac( hashtable_rbs(Tt_unused) & this ) with(this) {
        return ((float)item_count) / n_buckets;
    }

    size_t bucket_of( hashtable_rbs(Tt_unused) & this, K k ) {
        return hash(k) % this.n_buckets;
    }

    request & get( hashtable_rbs(Tt_unused) & this, K k ) with (this) {

        dlist(request_in_ht_by_src, request) & bucket = buckets[ bucket_of(this, k) ];

        for ( request_in_ht_by_src * 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_rbs(Tt_unused) & this ) with (this) {
        if (fill_frac(this) > ff_next_warn_up) {
            ht_fill_limit_crossed ex1 = { &this };
            throwResume ex1;
            // workaround trac#192: want the second throwResume to be in __dynamic_defaultResumptionHandler
            // ... want base hashtable decoupled from resize
            if ( ex1.want_throwResume_ht_auto_resize_pending ) {
                throwResume( (ht_auto_resize_pending) { & this, ex1.size_for_ht_auto_resize_pending } );
            }
        }
    }

    void put( hashtable_rbs(Tt_unused) & this, request & v ) with (this) {

        check_ff_warning(this);

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

        for ( request_in_ht_by_src * 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_RBS_STATIC(n, ht)
//
// intended equivalent:
// hashtable_rbs_static(Z(n)) ht;
#define HASHTABLE_RBS_STATIC(n_buckets, obj) \
    struct __hashtable_static_ ## obj { \
        inline hashtable_rbs(t_unused); \
        dlist(request_in_ht_by_src, request) $items[n_buckets]; \
    }; \
    void ?{}( __hashtable_static_ ## obj & this )  { \
        ((hashtable_rbs(t_unused) &)this){ n_buckets, this.$items }; \
    } \
    __hashtable_static_ ## obj obj;



void defaultResumptionHandler(ht_fill_limit_crossed & ex) {
    hashtable_rbs(t_unused) & ht = *(hashtable_rbs(t_unused) *)ex.theHashtable;
    printf("base default resumption handler ht_fill_limit_crossed with ht filled at %f\n", fill_frac(ht));
    ht.ff_next_warn_up *= ht.ff_warn_step_factor;
}

void defaultTerminationHandler(ht_fill_limit_crossed &) = void;





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

void __dynamic_defaultResumptionHandler(ht_fill_limit_crossed &);

forall( otype Tt_unused ) {

    struct hashtable_rbs_dynamic { 
        inline hashtable_rbs(Tt_unused);

        struct resize_policy {
            // When fill factor exceeds grow limit, grow big enough for
            // resulting fill factor to be lower than grow_target.  Vice versa.
            // Using different grow and shrink limits prevents noisy current
            // size from triggering grow-shrink oscillation.  OK to use same
            // grow and shrink targets.
            float grow_limit, shrink_limit, grow_target, shrink_target;

            // warn with exception but do nothing, this many -1 times, then actually resize
            unsigned short int warns_per_grow, warns_per_shrink;

            // Don't shrink below.
            size_t nbuckets_floor;
        } policy;

        dlist(request_in_ht_by_src, request) * (*alloc)( size_t );
        void (*free)( void * ); 
    };
}

// will be in list api
void splice_all_to_last( dlist(request_in_ht_by_src, request) & src_to_empty, dlist(request_in_ht_by_src, request) & snk_to_fill_at_last ) {

    // will re-implement as an actual splice
    while ( & src_to_empty`first != 0p ) {
        insert_last( snk_to_fill_at_last, pop_first( src_to_empty ) );
    }
}


forall( otype Tt_unused | heaped( dlist(request_in_ht_by_src, request) ) ) {

    void ?{}( hashtable_rbs_dynamic(Tt_unused).resize_policy & this, size_t nbuckets_floor ) {
        printf("default dynamic policy ctor\n");

        (this.grow_limit)      {2.0};
        (this.shrink_limit)    {0.5};
        (this.grow_target)     {1.0};
        (this.shrink_target)   {1.0};
        (this.warns_per_grow)  {4};
        (this.warns_per_shrink){4};
        (this.nbuckets_floor)  {nbuckets_floor};
    }

    void ?{}( hashtable_rbs_dynamic(Tt_unused) & this, size_t n_buckets, hashtable_rbs_dynamic(Tt_unused).resize_policy rp )  {
        printf("ctor hashtable_rbs_dynamic{ size_t, resize_policy }\n");

        float first_first_warn_up = rp.grow_target;
        float ff_warn_step_factor = (rp.grow_limit / rp.grow_target) \ ( 1. / rp.warns_per_grow );

        void (*defaultResumptionHandler) (ht_fill_limit_crossed &) = __dynamic_defaultResumptionHandler;
        dlist(request_in_ht_by_src, request) *buckets = alloc(n_buckets);
        ( ( hashtable_rbs( Tt_unused ) & ) this ){ n_buckets, buckets, first_first_warn_up, ff_warn_step_factor };
        ( this.policy ){ rp };
        this.alloc = alloc;
        this.free = free;
    }
    void ?{}( hashtable_rbs_dynamic(Tt_unused) & this, hashtable_rbs_dynamic(Tt_unused).resize_policy rp )  {
        printf("ctor hashtable_rbs_dynamic{ resize_policy }\n");
        ( this ) { rp.nbuckets_floor, rp };
    }
    void ?{}( hashtable_rbs_dynamic(Tt_unused) & this, size_t n_buckets )  {
        printf("ctor hashtable_rbs_dynamic{ size_t }\n");
        ( this ) { n_buckets, (hashtable_rbs_dynamic(Tt_unused).resize_policy){ n_buckets } };
    }
    void ^?{}( hashtable_rbs_dynamic(Tt_unused) & this ) {
        free(this.buckets);
    }
    void rehashToLarger( hashtable_rbs_dynamic(Tt_unused) & this, size_t new_n_buckets ) with(this) {
        printf("resizing from %ld to %ld, old buckets at %p\n", n_buckets, new_n_buckets, buckets);

        // collect hash items from old buckets
        dlist(request_in_ht_by_src, request) items;
        for (i; n_buckets) {
            splice_all_to_last( buckets[i], items );
        }

        // make empty hash table of new size
        dlist(request_in_ht_by_src, request) *oldBuckets = buckets;
        float oldFfWarnStepFactor = ff_warn_step_factor;
        float newFfNextWarnUp = ((float)item_count) / ((float) new_n_buckets);
        ^?{}( (hashtable_rbs(Tt_unused) &)this );
        free( oldBuckets );
        ?{}( (hashtable_rbs(Tt_unused) &)this, new_n_buckets, alloc(new_n_buckets), newFfNextWarnUp, oldFfWarnStepFactor );

        // fill new table with old items
        while ( & items`first != 0p ) {
            put( this, pop_first( items ) );
        }
    }
}

forall( otype Tt_unused ) {
    void rehashToLarger_STEP( hashtable_rbs_dynamic(Tt_unused) & this, size_t new_n_buckets ) with (this) {
        rehashToLarger( this, new_n_buckets );
    }
}

void defaultResumptionHandler( ht_auto_resize_pending & ex ) {
    hashtable_rbs_dynamic(t_unused) & ht = *(hashtable_rbs_dynamic(t_unused) *)ex.theHashtable;
    printf("auto-resize unhandled: proceeding with resize\n");
    rehashToLarger_STEP( ht, ex.new_size );
}

void __dynamic_defaultResumptionHandler(ht_fill_limit_crossed & ex) {
    hashtable_rbs_dynamic(t_unused) & ht = *(hashtable_rbs_dynamic(t_unused) *)ex.theHashtable;
    printf("dynamic warning received with fill_frac = %f and buckets at %p\n", fill_frac(ht), ht.buckets);
    if ( fill_frac( ht ) >= ht.policy.grow_limit ) {
        float grow_amount =  ht.policy.grow_limit / ht.policy.grow_target;
        ex.want_throwResume_ht_auto_resize_pending = true;
        ex.size_for_ht_auto_resize_pending = ( size_t )( grow_amount * ht.n_buckets );
    } else {
        // base handler, not specialized for dynamic
        defaultResumptionHandler( ex );
    }
}






#include <stdlib.hfa>

void basicFillingTestHelper( hashtable_rbs(t_unused) & ht, size_t n_elems ) {

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

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

    put(ht, r);

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

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

    request rs[n_elems];
    for (i; n_elems) {
        rs[i].src_id = 8000 * i;
        put(ht, rs[i]);
    }

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

void basicFillingTest_static() {

    printf("---start basic fill test static ----\n");

    HASHTABLE_RBS_STATIC(67, ht)

    basicFillingTestHelper(ht, 500);
}

void basicFillingTest_dynamic() {

    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);
    }

    printf("---start basic fill test dynamic ----\n");

    hashtable_rbs_dynamic(t_unused) ht = { 113 };

    basicFillingTestHelper(ht, 500);
}

// Demonstrates user-provided instrumentation monitoring a fixed-size hash table
void logTest() {

    printf("---start log test ----\n");

    HASHTABLE_RBS_STATIC(67, ht)

    try {
        basicFillingTestHelper(ht, 500);
    } catchResume( ht_fill_limit_crossed * ) {
        printf("log test instrumentation runs\n");
        throwResume;
    }
}

// Demonstrates "snoozing" a growing hash table's auto-resize event,
// in that that next call to put will get the resize exception instead.
void snoozeTest() {

    printf("---start snooze test ----\n");

    hashtable_rbs_dynamic(t_unused) ht = { 113 };

    bool lastResizeSnoozed = false;

    try {
        basicFillingTestHelper(ht, 500);
    } catchResume( ht_auto_resize_pending * ) {

        if ( lastResizeSnoozed == false ) {
            lastResizeSnoozed = true;
            printf("snooze test intervention decides to snooze this time\n");
        } else {
            lastResizeSnoozed = false;
            printf("snooze test intervention decides to allow the resize\n");
            throwResume;
        }

    }
}

int main() {

    basicFillingTest_static();
    basicFillingTest_dynamic();

    logTest();
    snoozeTest();
}