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Diffstat (limited to 'src/knot/common/evsched.h')
| -rw-r--r-- | src/knot/common/evsched.h | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/src/knot/common/evsched.h b/src/knot/common/evsched.h new file mode 100644 index 0000000..13a236f --- /dev/null +++ b/src/knot/common/evsched.h @@ -0,0 +1,153 @@ +/* Copyright (C) 2019 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/>. + */ +/*! + * \brief Event scheduler. + */ + +#pragma once + +#include <pthread.h> +#include <stdbool.h> +#include <stdint.h> +#include <sys/time.h> + +#include "knot/server/dthreads.h" +#include "contrib/ucw/heap.h" + +/* Forward decls. */ +struct evsched; +struct event; + +/*! + * \brief Event callback. + * + * Pointer to whole event structure is passed to the callback. + * Callback should return 0 on success and negative integer on error. + * + * Example callback: + * \code + * void print_callback(event_t *t) { + * printf("Callback: %s\n", t->data); + * } + * \endcode + */ +typedef void (*event_cb_t)(struct event *); + +/*! + * \brief Event structure. + */ +typedef struct event { + struct heap_val hpos; + struct timeval tv; /*!< Event scheduled time. */ + void *data; /*!< Usable data ptr. */ + event_cb_t cb; /*!< Event callback. */ + struct evsched *sched; /*!< Scheduler for this event. */ +} event_t; + +/*! + * \brief Event scheduler structure. + */ +typedef struct evsched { + volatile bool paused; /*!< Temporarily stop processing events. */ + pthread_mutex_t heap_lock; /*!< Event heap locking. */ + pthread_cond_t notify; /*!< Event heap notification. */ + struct heap heap; /*!< Event heap. */ + void *ctx; /*!< Scheduler context. */ + dt_unit_t *thread; +} evsched_t; + +/*! + * \brief Initialize event scheduler instance. + * + * \retval New instance on success. + * \retval NULL on error. + */ +int evsched_init(evsched_t *sched, void *ctx); + +/*! + * \brief Deinitialize and free event scheduler instance. + * + * \param sched Pointer to event scheduler instance. + */ +void evsched_deinit(evsched_t *sched); + +/*! + * \brief Create a callback event. + * + * \note Scheduler takes ownership of scheduled events. Created, but unscheduled + * events are in the ownership of the caller. + * + * \param sched Pointer to event scheduler instance. + * \param cb Callback handler. + * \param data Data for callback. + * + * \retval New instance on success. + * \retval NULL on error. + */ +event_t *evsched_event_create(evsched_t *sched, event_cb_t cb, void *data); + +/*! + * \brief Dispose event instance. + * + * \param ev Event instance. + */ +void evsched_event_free(event_t *ev); + +/*! + * \brief Schedule an event. + * + * \note This function checks if the event was already scheduled, if it was + * then it replaces this timer with the newer value. + * Running events are not canceled or waited for. + * + * \param ev Prepared event. + * \param dt Time difference in milliseconds from now (dt is relative). + * + * \retval KNOT_EOK on success. + * \retval KNOT_EINVAL + */ +int evsched_schedule(event_t *ev, 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 ev Scheduled event. + * + * \retval KNOT_EOK + * \retval KNOT_EINVAL + */ +int evsched_cancel(event_t *ev); + +/*! \brief Start event processing threads. */ +void evsched_start(evsched_t *sched); + +/*! \brief Stop event processing threads. */ +void evsched_stop(evsched_t *sched); + +/*! \brief Join event processing threads. */ +void evsched_join(evsched_t *sched); + +/*! \brief Temporarily stop processing events. */ +void evsched_pause(evsched_t *sched); + +/*! \brief Resume processing events. */ +void evsched_resume(evsched_t *sched); |