/* timers.c - simple timer routines
**
** (c) 1995,1998,2000 by Jef Poskanzer <jef@mail.acme.com>.
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
** 1. Redistributions of source code must retain the above copyright
**    notice, this list of conditions and the following disclaimer.
** 2. 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.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/

#include <sys/types.h>

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

#include "main.h"
#include "timers.h"


#define HASH_SIZE 67
static Timer *timers[HASH_SIZE];
static Timer *free_timers;
static int alloc_count, active_count, free_count;

ClientData JunkClientData;



static unsigned int hash(Timer * t)
{
	/* We can hash on the trigger time, even though it can change over
	 ** the life of a timer via either the periodic bit or the tmr_reset()
	 ** call.  This is because both of those guys call l_resort(), which
	 ** recomputes the hash and moves the timer to the appropriate list.
	 */
	return ((unsigned int) t->time.tv_sec ^
					(unsigned int) t->time.tv_usec) % HASH_SIZE;
}


static void l_add(Timer * t)
{
	int h = t->hash;
	Timer *t2;
	Timer *t2prev;

	t2 = timers[h];
	if (t2 == (Timer *) 0)
	{
		/* The list is empty. */
		timers[h] = t;
		t->prev = t->next = (Timer *) 0;
	}
	else
	{
		if (t->time.tv_sec < t2->time.tv_sec ||
				(t->time.tv_sec == t2->time.tv_sec &&
				 t->time.tv_usec <= t2->time.tv_usec))
		{
			/* The new timer goes at the head of the list. */
			timers[h] = t;
			t->prev = (Timer *) 0;
			t->next = t2;
			t2->prev = t;
		}
		else
		{
			/* Walk the list to find the insertion point. */
			for (t2prev = t2, t2 = t2->next; t2 != (Timer *) 0;
					 t2prev = t2, t2 = t2->next)
			{
				if (t->time.tv_sec < t2->time.tv_sec ||
						(t->time.tv_sec == t2->time.tv_sec &&
						 t->time.tv_usec <= t2->time.tv_usec))
				{
					/* 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 = (Timer *) 0;
		}
	}
}


static void l_remove(Timer * t)
{
	int h = t->hash;

	if (t->prev == (Timer *) 0)
		timers[h] = t->next;
	else
		t->prev->next = t->next;
	if (t->next != (Timer *) 0)
		t->next->prev = t->prev;
}


static void l_resort(Timer * t)
{
	/* Remove the timer from its old list. */
	l_remove(t);
	/* Recompute the hash. */
	t->hash = hash(t);
	/* And add it back in to its new list, sorted correctly. */
	l_add(t);
}


void tmr_init(void)
{
	int h;

	for (h = 0; h < HASH_SIZE; ++h)
		timers[h] = (Timer *) 0;
	free_timers = (Timer *) 0;
	alloc_count = active_count = free_count = 0;
}


Timer *tmr_create(struct timeval *nowP, TimerProc * timer_proc,
									ClientData client_data, long msecs, int periodic)
{
	Timer *t;

	if (free_timers != (Timer *) 0)
	{
		t = free_timers;
		free_timers = t->next;
		--free_count;
	}
	else
	{
		t = (Timer *) malloc(sizeof(Timer));
		if (t == (Timer *) 0)
			return (Timer *) 0;
		++alloc_count;
	}

	t->timer_proc = timer_proc;
	t->client_data = client_data;
	t->msecs = msecs;
	t->periodic = periodic;
	if (nowP != (struct timeval *) 0)
		t->time = *nowP;
	else
		(void) gettimeofday(&t->time, (struct timezone *) 0);
	t->time.tv_sec += msecs / 1000L;
	t->time.tv_usec += (msecs % 1000L) * 1000L;
	if (t->time.tv_usec >= 1000000L)
	{
		t->time.tv_sec += t->time.tv_usec / 1000000L;
		t->time.tv_usec %= 1000000L;
	}
	t->hash = hash(t);
	/* Add the new timer to the proper active list. */
	l_add(t);
	++active_count;

	return t;
}


struct timeval *tmr_timeout(struct timeval *nowP)
{
	long msecs;
	static struct timeval timeout;

	msecs = tmr_mstimeout(nowP);
	if (msecs == INFTIM)
		return (struct timeval *) 0;
	timeout.tv_sec = msecs / 1000L;
	timeout.tv_usec = (msecs % 1000L) * 1000L;
	return &timeout;
}


long tmr_mstimeout(struct timeval *nowP)
{
	int h;
	int gotone;
	long msecs, m;
	Timer *t;

	gotone = 0;
	msecs = 0;										/* make lint happy */
	/* Since the lists are sorted, we only need to look at the
	 ** first timer on each one.
	 */
	for (h = 0; h < HASH_SIZE; ++h)
	{
		t = timers[h];
		if (t != (Timer *) 0)
		{
			m = (t->time.tv_sec - nowP->tv_sec) * 1000L +
				(t->time.tv_usec - nowP->tv_usec) / 1000L;
			if (!gotone)
			{
				msecs = m;
				gotone = 1;
			}
			else if (m < msecs)
				msecs = m;
		}
	}
	if (!gotone)
		return INFTIM;
	if (msecs <= 0)
		msecs = 0;
	return msecs;
}


void tmr_run(struct timeval *nowP)
{
	int h;
	Timer *t;
	Timer *next;

	for (h = 0; h < HASH_SIZE; ++h)
		for (t = timers[h]; t != (Timer *) 0; t = next)
		{
			next = t->next;
			/* Since the lists are sorted, as soon as we find a timer
			 ** that isn't ready yet, we can go on to the next list.
			 */
			if (t->time.tv_sec > nowP->tv_sec ||
					(t->time.tv_sec == nowP->tv_sec && t->time.tv_usec > nowP->tv_usec))
				break;
			(t->timer_proc) (t->client_data, nowP);
			if (t->periodic)
			{
				/* Reschedule. */
				t->time.tv_sec += t->msecs / 1000L;
				t->time.tv_usec += (t->msecs % 1000L) * 1000L;
				if (t->time.tv_usec >= 1000000L)
				{
					t->time.tv_sec += t->time.tv_usec / 1000000L;
					t->time.tv_usec %= 1000000L;
				}
				l_resort(t);
			}
			else
				tmr_cancel(t);
		}
}


void tmr_reset(struct timeval *nowP, Timer * t)
{
	t->time = *nowP;
	t->time.tv_sec += t->msecs / 1000L;
	t->time.tv_usec += (t->msecs % 1000L) * 1000L;
	if (t->time.tv_usec >= 1000000L)
	{
		t->time.tv_sec += t->time.tv_usec / 1000000L;
		t->time.tv_usec %= 1000000L;
	}
	l_resort(t);
}


void tmr_cancel(Timer * t)
{
	/* Remove it from its active list. */
	l_remove(t);
	--active_count;
	/* And put it on the free list. */
	t->next = free_timers;
	free_timers = t;
	++free_count;
	t->prev = (Timer *) 0;
}


void tmr_cleanup(void)
{
	Timer *t;

	while (free_timers != (Timer *) 0)
	{
		t = free_timers;
		free_timers = t->next;
		--free_count;
		free((void *) t);
		--alloc_count;
	}
}


void tmr_destroy(void)
{
	int h;

	for (h = 0; h < HASH_SIZE; ++h)
		while (timers[h] != (Timer *) 0)
			tmr_cancel(timers[h]);
	tmr_cleanup();
}


/* Generate debugging statistics syslog message. */
void tmr_logstats(long secs)
{
	syslog(LOG_INFO, "  timers - %d allocated, %d active, %d free",
				 alloc_count, active_count, free_count);
	if (active_count + free_count != alloc_count)
		syslog(LOG_ERR, "timer counts don't add up!");
}