/*
 * iperf, Copyright (c) 2014, The Regents of the University of
 * California, through Lawrence Berkeley National Laboratory (subject
 * to receipt of any required approvals from the U.S. Dept. of
 * Energy).  All rights reserved.
 *
 * If you have questions about your rights to use or distribute this
 * software, please contact Berkeley Lab's Technology Transfer
 * Department at TTD@lbl.gov.
 *
 * NOTICE.  This software is owned by the U.S. Department of Energy.
 * As such, the U.S. Government has been granted for itself and others
 * acting on its behalf a paid-up, nonexclusive, irrevocable,
 * worldwide license in the Software to reproduce, prepare derivative
 * works, and perform publicly and display publicly.  Beginning five
 * (5) years after the date permission to assert copyright is obtained
 * from the U.S. Department of Energy, and subject to any subsequent
 * five (5) year renewals, the U.S. Government is granted for itself
 * and others acting on its behalf a paid-up, nonexclusive,
 * irrevocable, worldwide license in the Software to reproduce,
 * prepare derivative works, distribute copies to the public, perform
 * publicly and display publicly, and to permit others to do so.
 *
 * This code is distributed under a BSD style license, see the LICENSE
 * file for complete information.
 *
 * Based on timers.c by Jef Poskanzer. Used with permission.
 */

#include <sys/types.h>
#include <stdlib.h>

#include "timer.h"
#include "iperf_time.h"

static Timer *timers = NULL;
static Timer *free_timers = NULL;

TimerClientData JunkClientData;



/* This is an efficiency tweak.  All the routines that need to know the
** current time get passed a pointer to a struct iperf_time.  If it's non-NULL
** it gets used, otherwise we do our own iperf_time_now() to fill it in.
** This lets the caller avoid extraneous iperf_time_now()s when efficiency
** is needed, and not bother with the extra code when efficiency doesn't
** matter too much.
*/
static void
getnow(struct iperf_time *nowP, struct iperf_time *nowP2) {
    if (nowP != NULL)
        *nowP2 = *nowP;
    else
        iperf_time_now(nowP2);
}


static void
list_add(Timer *t) {
    Timer *t2;
    Timer *t2prev;

    if (timers == NULL) {
        /* The list is empty. */
        timers = t;
        t->prev = t->next = NULL;
    } else {
        if (iperf_time_compare(&t->time, &timers->time) < 0) {
            /* The new timer goes at the head of the list. */
            t->prev = NULL;
            t->next = timers;
            timers->prev = t;
            timers = t;
        } else {
            /* Walk the list to find the insertion point. */
            for (t2prev = timers, t2 = timers->next; t2 != NULL;
                 t2prev = t2, t2 = t2->next) {
                if (iperf_time_compare(&t->time, &t2->time) < 0) {
                    /* Found it. */
                    t2prev->next = t;
                    t->prev = t2prev;
                    t->next = t2;
                    t2->prev = t;
                    return;
                }
            }
            /* Oops, got to the end of the list.  Add to tail. */
            t2prev->next = t;
            t->prev = t2prev;
            t->next = NULL;
        }
    }
}


static void
list_remove(Timer *t) {
    if (t->prev == NULL)
        timers = t->next;
    else
        t->prev->next = t->next;
    if (t->next != NULL)
        t->next->prev = t->prev;
}


static void
list_resort(Timer *t) {
    /* Remove the timer from the list. */
    list_remove(t);
    /* And add it back in, sorted correctly. */
    list_add(t);
}


Timer *
tmr_create(
        struct iperf_time *nowP, TimerProc *timer_proc, TimerClientData client_data,
        int64_t usecs, int periodic) {
    struct iperf_time now;
    Timer *t;

    getnow(nowP, &now);

    if (free_timers != NULL) {
        t = free_timers;
        free_timers = t->next;
    } else {
        t = (Timer *) malloc(sizeof(Timer));
        if (t == NULL)
            return NULL;
    }

    t->timer_proc = timer_proc;
    t->client_data = client_data;
    t->usecs = usecs;
    t->periodic = periodic;
    t->time = now;
    iperf_time_add_usecs(&t->time, usecs);
    /* Add the new timer to the active list. */
    list_add(t);

    return t;
}


struct timeval *
tmr_timeout(struct iperf_time *nowP) {
    struct iperf_time now, diff;
    int64_t usecs;
    int past;
    static struct timeval timeout;

    getnow(nowP, &now);
    /* Since the list is sorted, we only need to look at the first timer. */
    if (timers == NULL)
        return NULL;
    past = iperf_time_diff(&timers->time, &now, &diff);
    if (past)
        usecs = 0;
    else
        usecs = iperf_time_in_usecs(&diff);
    timeout.tv_sec = usecs / 1000000LL;
    timeout.tv_usec = usecs % 1000000LL;
    return &timeout;
}


void
tmr_run(struct iperf_time *nowP) {
    struct iperf_time now;
    Timer *t;
    Timer *next;

    getnow(nowP, &now);
    for (t = timers; t != NULL; t = next) {
        next = t->next;
        /* Since the list is sorted, as soon as we find a timer
        ** that isn't ready yet, we are done.
        */
        if (iperf_time_compare(&t->time, &now) > 0)
            break;
        (t->timer_proc)(t->client_data, &now);
        if (t->periodic) {
            /* Reschedule. */
            iperf_time_add_usecs(&t->time, t->usecs);
            list_resort(t);
        } else
            tmr_cancel(t);
    }
}


void
tmr_reset(struct iperf_time *nowP, Timer *t) {
    struct iperf_time now;

    getnow(nowP, &now);
    t->time = now;
    iperf_time_add_usecs(&t->time, t->usecs);
    list_resort(t);
}


void
tmr_cancel(Timer *t) {
    /* Remove it from the active list. */
    list_remove(t);
    /* And put it on the free list. */
    t->next = free_timers;
    free_timers = t;
    t->prev = NULL;
}


void
tmr_cleanup(void) {
    Timer *t;

    while (free_timers != NULL) {
        t = free_timers;
        free_timers = t->next;
        free((void *) t);
    }
}


void
tmr_destroy(void) {
    while (timers != NULL)
        tmr_cancel(timers);
    tmr_cleanup();
}
