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/* Copyright (C) 2011 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program 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.
This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*!
* \file evsched.h
*
* \author Marek Vavrusa <marek.vavrusa@nic.cz>
*
* \brief Event scheduler.
*
* Scheduler works with the same event_t type as event queue.
* It is also thread-safe so the scheduler can run in a separate thread
* while events can be enqueued from different threads.
*
* Guideline is, that the scheduler run loop should exit with
* a special event type EVSCHED_TERM.
*
* Example usage:
* \code
* evsched_t *s = evsched_new();
*
* // Schedule myfunc() after 1000ms
* evsched_schedule_cb(s, myfunc, data, 1000)
*
* // Schedule termination event after 1500ms
* evsched_schedule_term(s, 1500);
*
* // Event scheduler main loop
* while (1) {
* // Wait for next scheduled event
* event_t *ev = evsched_next();
*
* // Break on termination event
* if (ev->type == EVSCHED_TERM) {
* evsched_event_free(s, ev);
* break;
* }
*
* // Execute and discard event
* if (ev->cb) {
* ev->cb(ev);
* }
* evsched_event_free(s, ev); // Free executed event
* }
*
* // Delete event scheduler
* evsched_delete(s);
* \endcode
*
* \addtogroup common_lib
* @{
*/
#ifndef _KNOTD_COMMON_EVSCHED_H_
#define _KNOTD_COMMON_EVSCHED_H_
#include <pthread.h>
#include "common/slab/slab.h"
#include "common/lists.h"
#include "common/evqueue.h"
/*!
* \brief Scheduler event types.
*/
typedef enum evsched_ev_t {
EVSCHED_NOOP = 0, /*!< No-op action, skip. */
EVSCHED_CB, /*!< Callback action. */
EVSCHED_TERM /*!< Terminal action, stop event scheduler. */
} evsched_ev_t;
/*!
* \brief Event scheduler structure.
*
* Keeps list of scheduled events. Events are executed in their scheduled
* time and kept in an ordered list (queue).
* Scheduler is terminated with a special EVSCHED_TERM event type.
*/
typedef struct {
pthread_mutex_t rl; /*!< Event running lock. */
event_t *current; /*!< Current running event. */
pthread_mutex_t mx; /*!< Event queue locking. */
pthread_cond_t notify; /*!< Event queue notification. */
list calendar; /*!< Event calendar. */
struct {
slab_cache_t alloc; /*!< Events SLAB cache. */
pthread_mutex_t lock; /*!< Events cache spin lock. */
} cache;
} evsched_t;
/*!
* \brief Create new event scheduler instance.
*
* \retval New instance on success.
* \retval NULL on error.
*/
evsched_t *evsched_new();
/*!
* \brief Deinitialize and free event scheduler instance.
*
* \param s Pointer to event scheduler instance.
* \note *sched is set to 0.
*/
void evsched_delete(evsched_t **s);
/*!
* \brief Create an empty event.
*
* \param s Pointer to event scheduler instance.
* \param type Event type.
* \retval New instance on success.
* \retval NULL on error.
*/
event_t *evsched_event_new(evsched_t *s, int type);
/*!
* \brief Dispose event instance.
*
* \param s Pointer to event scheduler instance.
* \param ev Event instance.
*/
void evsched_event_free(evsched_t *s, event_t *ev);
/*!
* \brief Fetch next-event.
*
* Scheduler may block until a next event is available.
* Send scheduler an EVSCHED_NOOP or EVSCHED_TERM event to unblock it.
*
* \warning Returned event must be marked as finished, or deadlock occurs.
*
* \param s Event scheduler.
*
* \retval Scheduled event.
* \retval NULL on error.
*/
event_t* evsched_next(evsched_t *s);
/*!
* \brief Mark running event as finished.
*
* Need to call this after each event returned by evsched_next() is finished.
*
* \param s Event scheduler.
*
* \retval 0 if successful.
* \retval -1 on errors.
*/
int evsched_event_finished(evsched_t *s);
/*!
* \brief Schedule an event.
*
* \param s Event scheduler.
* \param ev Prepared event.
* \param dt Time difference in milliseconds from now (dt is relative).
*
* \retval 0 on success.
* \retval <0 on error.
*/
int evsched_schedule(evsched_t *s, event_t *ev, uint32_t dt);
/*!
* \brief Schedule callback event.
*
* Execute callback after dt miliseconds has passed.
*
* \param s Event scheduler.
* \param cb Callback handler.
* \param data Data for callback.
* \param dt Time difference in milliseconds from now (dt is relative).
*
* \retval Event instance on success.
* \retval NULL on error.
*/
event_t* evsched_schedule_cb(evsched_t *s, event_cb_t cb, void *data, uint32_t dt);
/*!
* \brief Schedule termination event.
*
* Special action for scheduler termination.
*
* \param s Event scheduler.
* \param dt Time difference in milliseconds from now (dt is relative).
*
* \retval Event instance on success.
* \retval NULL on error.
*/
event_t* evsched_schedule_term(evsched_t *s, uint32_t dt);
/*!
* \brief Cancel a scheduled event.
*
* \warning May block until current running event is finished (as it cannot
* interrupt running event).
*
* \warning Never cancel event in it's callback. As it never finishes,
* it deadlocks.
*
* \param s Event scheduler.
* \param ev Scheduled event.
*
* \retval 0 on success.
* \retval <0 on error.
*/
int evsched_cancel(evsched_t *s, event_t *ev);
/* Singleton event scheduler pointer. */
extern evsched_t *s_evsched;
/*!
* \brief Event scheduler singleton.
*/
static inline evsched_t *evsched() {
return s_evsched;
}
/*!
* \brief Set event scheduler singleton.
*/
static inline void evsched_set(evsched_t *s) {
s_evsched = s;
}
#endif /* _KNOTD_COMMON_EVSCHED_H_ */
/*! @} */
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