/*
 * util/timehist.c - make histogram of time values.
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file
 *
 * This file contains functions to make a histogram of time values.
 */
#include "config.h"
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#include <sys/time.h>
#include <sys/types.h>
#include "util/timehist.h"
#include "util/log.h"
#include "util/timeval_func.h"

/** special timestwo operation for time values in histogram setup */
static void
timestwo(struct timeval* v)
{
#ifndef S_SPLINT_S
        if(v->tv_sec == 0 && v->tv_usec == 0) {
                v->tv_usec = 1;
                return;
        }
        v->tv_sec *= 2;
        v->tv_usec *= 2;
        if(v->tv_usec == 1024*1024) {
                /* nice values and easy to compute */
                v->tv_sec = 1;
                v->tv_usec = 0;
        }
#endif
}

/** do setup exponentially */
static void
dosetup(struct timehist* hist)
{
        struct timeval last;
        size_t i;
        memset(&last, 0, sizeof(last));
        for(i=0; i<hist->num; i++) {
                hist->buckets[i].lower = last;
                timestwo(&last);
                hist->buckets[i].upper = last;
                hist->buckets[i].count = 0;
        }
}

struct timehist* timehist_setup(void)
{
        struct timehist* hist = (struct timehist*)calloc(1,
                sizeof(struct timehist));
        if(!hist)
                return NULL;
        hist->num = NUM_BUCKETS_HIST;
        hist->buckets = (struct th_buck*)calloc(hist->num,
                sizeof(struct th_buck));
        if(!hist->buckets) {
                free(hist);
                return NULL;
        }
        /* setup the buckets */
        dosetup(hist);
        return hist;
}

void timehist_delete(struct timehist* hist)
{
        if(!hist)
                return;
        free(hist->buckets);
        free(hist);
}

void timehist_clear(struct timehist* hist)
{
        size_t i;
        for(i=0; i<hist->num; i++)
                hist->buckets[i].count = 0;
}

void timehist_insert(struct timehist* hist, struct timeval* tv)
{
        size_t i;
        for(i=0; i<hist->num; i++) {
                if(timeval_smaller(tv, &hist->buckets[i].upper)) {
                        hist->buckets[i].count++;
                        return;
                }
        }
        /* dump in last bucket */
        hist->buckets[hist->num-1].count++;
}

void timehist_print(struct timehist* hist)
{
#ifndef S_SPLINT_S
        size_t i;
        for(i=0; i<hist->num; i++) {
                if(hist->buckets[i].count != 0) {
                        printf("%4d.%6.6d %4d.%6.6d %u\n",
                                (int)hist->buckets[i].lower.tv_sec,
                                (int)hist->buckets[i].lower.tv_usec,
                                (int)hist->buckets[i].upper.tv_sec,
                                (int)hist->buckets[i].upper.tv_usec,
                                (unsigned)hist->buckets[i].count);
                }
        }
#endif
}

void timehist_log(struct timehist* hist, const char* name)
{
#ifndef S_SPLINT_S
        size_t i;
        log_info("[25%%]=%g median[50%%]=%g [75%%]=%g",
                timehist_quartile(hist, 0.25),
                timehist_quartile(hist, 0.50),
                timehist_quartile(hist, 0.75));
        /*        0000.000000 0000.000000 0 */
        log_info("lower(secs) upper(secs) %s", name);
        for(i=0; i<hist->num; i++) {
                if(hist->buckets[i].count != 0) {
                        log_info("%4d.%6.6d %4d.%6.6d %u",
                                (int)hist->buckets[i].lower.tv_sec,
                                (int)hist->buckets[i].lower.tv_usec,
                                (int)hist->buckets[i].upper.tv_sec,
                                (int)hist->buckets[i].upper.tv_usec,
                                (unsigned)hist->buckets[i].count);
                }
        }
#endif
}

/** total number in histogram */
static size_t
timehist_count(struct timehist* hist)
{
        size_t i, res = 0;
        for(i=0; i<hist->num; i++)
                res += hist->buckets[i].count;
        return res;
}

double
timehist_quartile(struct timehist* hist, double q)
{
        double lookfor, passed, res;
        double low = 0, up = 0;
        size_t i;
        if(!hist || hist->num == 0)
                return 0.;
        /* look for i'th element, interpolated */
        lookfor = (double)timehist_count(hist);
        if(lookfor < 4)
                return 0.; /* not enough elements for a good estimate */
        lookfor *= q;
        passed = 0;
        i = 0;
        while(i+1 < hist->num &&
                passed+(double)hist->buckets[i].count < lookfor) {
                passed += (double)hist->buckets[i++].count;
        }
        /* got the right bucket */
#ifndef S_SPLINT_S
        low = (double)hist->buckets[i].lower.tv_sec +
                (double)hist->buckets[i].lower.tv_usec/1000000.;
        up = (double)hist->buckets[i].upper.tv_sec +
                (double)hist->buckets[i].upper.tv_usec/1000000.;
#endif
        res = (lookfor - passed)*(up-low)/((double)hist->buckets[i].count);
        return low+res;
}

void
timehist_export(struct timehist* hist, long long* array, size_t sz)
{
        size_t i;
        if(!hist) return;
        if(sz > hist->num)
                sz = hist->num;
        for(i=0; i<sz; i++)
                array[i] = (long long)hist->buckets[i].count;
}

void
timehist_import(struct timehist* hist, long long* array, size_t sz)
{
        size_t i;
        if(!hist) return;
        if(sz > hist->num)
                sz = hist->num;
        for(i=0; i<sz; i++)
                hist->buckets[i].count = (size_t)array[i];
}