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/* timer.h
*
* Timing subsystem. Provides deadline timers.
* All times are aliased to a second for efficiency.
*
* Timer Guarantees:
* - The callback will not be called before the timer expires.
* - The callback will be called sometime after the timer expires,
* on a best effort basis.
* - If timer_poll is called at least once a second, the callback
* will be called at most one second after it expires.
*
* Copyright (C) 2013 Tox project All Rights Reserved.
*
* This file is part of Tox.
*
* Tox is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Tox is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Tox. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef TIMER_H
#define TIMER_H
#include <stdint.h>
#include <stdbool.h>
#define US_PER_SECOND 1000000 /* 1 s = 10^6 us */
struct timer;
typedef struct timer timer;
/* If time_callback returns a non-zero value, timer t is deleted.
* You may call any of the timer functions within the callback:
* For example, you may call timer_start to restart the timer from
* within a callback. */
typedef int (*timer_callback)(timer *t, void *userarg);
/* Initisalise timer subsystem */
void timer_init(void);
/* Poll. (I will eventually replace all polling in Tox with an async system.) */
void timer_poll(void);
/* Creates a new timer. Does not enqueue/start it. */
timer *new_timer(void);
/* Destroys a timer instance. */
void delete_timer(timer *t);
/* Sets up the timer callback. */
void timer_setup(timer *t, timer_callback cb, void *userarg);
/* Accessor Function. */
void *timer_get_userdata(timer *t);
/* Starts the timer so that it's called in sec seconds in the future from now.
* A non-positive value of sec results in the callback being called immediately.
* This function may be called again after a timer has been started to adjust
* the expiry time. */
void timer_start(timer *t, int sec);
/* Stops the timer. Returns -1 if the timer was not active. */
int timer_stop(timer *t);
/* Adds additionalsec seconds to the timer.
* Returns -1 and does nothing if the timer was not active. */
int timer_delay(timer *t, int additonalsec);
/* Returns the time remaining on a timer in seconds.
* Returns -1 if the timer is not active.
* Returns 0 if the timer has expired and the callback hasn't been called yet. */
int timer_time_remaining(timer *t);
/* Determines if timer is active. Returns TRUE if it is active */
bool timer_is_active(timer *t);
/* Single-use timer.
* Creates a new timer, preforms setup and starts it.
* Callback must return a non-zero value to prevent memory leak. */
void timer_single(timer_callback cb, void *userarg, int sec);
/* Single-use microsecond timer.
* Creates a new timer, preforms setup and starts it.
* Please do not use this when accuracy is not absolutely required.
* Use when one needs to time a period < 1 s.
* Use the more coarse timers above for periods > 5 s.
* WARNING: the callback will be called with NULL as the first argument */
void timer_us(timer_callback cb, void *userarg, int us);
/* Internal Testing */
void timer_internal_tests(bool( *)(bool, char *));
#endif
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