path: root/04_exercise/slotmap.c

//
// Created by stefan on 18.06.20.
//

#include "slotmap.h"
#include <stdio.h>
smHeader smInit(smEntry * slab, size_t size) {
    for (int i = 0; i < size; ++i) {
        slab[i].value = (intptr_t)NULL;
    }
    return (smHeader){.slab = slab, .size=size, .count = 0};
}
int smInsert(smHeader * header, void * value) {
    for (size_t i = 0; i< header->size; ++i ) {
        intptr_t ptr = atomic_load(&header->slab[i].value);
        if((void *)ptr == NULL) {
            intptr_t expected = (intptr_t) NULL;
            if(atomic_compare_exchange_strong(&header->slab[i].value, &expected, (intptr_t) value)){
                atomic_fetch_add(&header->count, 1);
                return 0;
            }
        }
    }
    return -1;
}
void smDelete(smHeader * header, smEntry * node) {
    intptr_t oldval = atomic_exchange(&node->value, (intptr_t)(NULL));
    if((void *) oldval == NULL) {
        fprintf(stderr, "A Node has been double deleted");
    }
    atomic_fetch_sub(&header->count, 1);
}
void smDeleteValue(smHeader * header, void * value){
    for (size_t i = 0; i< header->size; ++i ) {
        intptr_t ptr = atomic_load(&header->slab[i].value);
        if((void *)ptr == value) {
            smDelete(header, &header->slab[i]);
        }
    }
}
smEntry *smFindEntry(smHeader const * header, SearchFunction func){
    int count = atomic_load(&header->count);
    if (count == 0) {
        return NULL;
    }
    for (size_t i = 0; i< header->size; ++i ) {
        void * value = (void *) atomic_load(&header->slab[i].value);

        if(value != NULL && func(value)) {
            return &header->slab[i];
        }
    }
    return NULL;
}