db_stat.c

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#include <stdlib.h>
#include <stdio.h>

#include "odb.h"
#include "op_types.h"

struct odb_hash_stat_t {
    odb_node_nr_t node_nr;          
    odb_node_nr_t used_node_nr;     
    count_type    total_count;      
    odb_index_t   hash_table_size;      
    odb_node_nr_t max_list_length;      
    double       average_list_length;   
    /* do we need variance ? */
};

odb_hash_stat_t * odb_hash_stat(odb_t const * odb)
{
    size_t max_length = 0;
    double total_length = 0.0;
    size_t nr_non_empty_list = 0;
    size_t pos;
    odb_data_t * data = odb->data;

    odb_hash_stat_t * result = calloc(1, sizeof(odb_hash_stat_t));
    if (!result) {
        fprintf(stderr, "not enough memory\n");
        exit(EXIT_FAILURE);
    }

    result->node_nr = data->descr->size;
    result->used_node_nr = data->descr->current_size;
    result->hash_table_size = data->descr->size * BUCKET_FACTOR;

    /* FIXME: I'm dubious if this do right statistics for hash table
     * efficiency check */

    for (pos = 0 ; pos < result->hash_table_size ; ++pos) {
        size_t cur_length = 0;
        size_t index = data->hash_base[pos];
        while (index) {
            result->total_count += data->node_base[index].value;
            index = data->node_base[index].next;
            ++cur_length;
        }

        if (cur_length > max_length)
            max_length = cur_length;

        if (cur_length) {
            total_length += cur_length;
            ++nr_non_empty_list;
        }
    }

    result->max_list_length = max_length;
    result->average_list_length = total_length / nr_non_empty_list;

    return result;
}


void odb_hash_display_stat(odb_hash_stat_t const * stat)
{
    printf("total node number:   %d\n", stat->node_nr);
    printf("total used node:     %d\n", stat->used_node_nr);
    printf("total count:         %llu\n", stat->total_count);
    printf("hash table size:     %d\n", stat->hash_table_size);
    printf("greater list length: %d\n", stat->max_list_length);
    printf("average non empty list length: %2.4f\n", stat->average_list_length);
}


void odb_hash_free_stat(odb_hash_stat_t * stat)
{
    free(stat);
}