src/time_queue.c

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#ifndef TIME_QUEUE_C
#define TIME_QUEUE_C
#include <stdlib.h>
#include <stdio.h>
#include "time_queue.h"
unsigned long time_queue_hash(unsigned char *str)
{
    unsigned long hash = 5381;
    int c;
    while (c = *str++) hash = ((hash << 5) + hash) + c;
    return hash;
}
time_queue* time_queue_new(unsigned int size, unsigned int quota)
{
    int i;
    time_queue* queue = (time_queue*) malloc(sizeof(time_queue));
    queue->values = (unsigned long*) malloc(size * sizeof(long*));
    queue->hashes = (unsigned long*) malloc(size * sizeof(long*));
    queue->size = size;
    queue->quota = quota;
    queue->i = 0;
    for(i = 0; i < size; i++)
    {
        queue->values[i] = queue->hashes[i] = 0;
    }
    return queue;
}
unsigned long time_queue_time()
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return tv.tv_sec * 1000000 + tv.tv_usec;
}
void time_queue_set(time_queue* queue, char* key)
{
    int i, found;
    unsigned long hash = time_queue_hash(key);
    for(i = found = 0; i < queue->size; i++)
    {
        if(hash == queue->hashes[i])
        {
            found = 1;
            break;
        }
    }
    if(!found)
    {
        queue->i += 1;
        queue->i = queue->i % queue->size;
        i = queue->i;
        queue->hashes[i] = hash;
    }
    queue->values[i] = time_queue_time();
}
unsigned long* time_queue_get(time_queue* queue, char* key)
{
    int i;
    unsigned long hash = time_queue_hash(key);
    for(i = 0; i < queue->size; i++)
    {
        if(hash == queue->hashes[i])
            return queue->values + i;
    }
    return NULL;
}
int time_queue_overflows(time_queue* queue, char* key, unsigned int size)
{
    unsigned long* time = time_queue_get(queue, key);
    if(time == NULL) return 0;
    unsigned long dt = (time_queue_time() - *time);
    if(dt == 0) return 1;
    return (((float) size * 1000000 / dt) > ((float)queue->quota));
}
void time_queue_delete(time_queue* queue)
{
    free(queue->values);
    free(queue->hashes);
    free(queue);
}
/*
 * Example:
int main(int argc, char** argv)
{
    time_queue* queue = time_queue_new(10, 42);
    time_queue_set(queue, "/var/log/lol");
    printf("%lu\n", *time_queue_get(queue, "/var/log/lol"));
    sleep(1);
    printf("%d\n", time_queue_overflows(queue, "/var/log/lol", 880));
    printf("%lu\n", time_queue_hash("hello world"));
    time_queue_delete(queue);
}
*/
#endif