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/*
* Copyright (C) 2010 Red Hat, Inc.
*
* Author: Angus Salkeld <asalkeld@redhat.com>
*
* This file is part of libqb.
*
* libqb is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 2.1 of the License, or
* (at your option) any later version.
*
* libqb 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with libqb. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef QB_LOOP_H_DEFINED
#define QB_LOOP_H_DEFINED
/* *INDENT-OFF* */
#ifdef __cplusplus
extern "C" {
#endif
/* *INDENT-ON* */
#include <signal.h>
#include <stdint.h>
#include <poll.h> /* make POLLIN etc. readily available */
/**
* @file qbloop.h
*
* Main loop manages timers, jobs and polling sockets.
*
* Only a weaker sense of priorities is implemented, alluding to distinct
* set of pros and cons compared to the stronger, strict approach to them
* as widely applied in this problem space (since the latter gives the
* application more control as the effect of the former can still be
* achieved with some reductions, whereas it is not straightforward the
* other way around; cf. static priority task scheduling vs. relative
* fine-tuning within a single priority domain with nice(2)):
*
* + implicit mitigation for deadlock-prone priority arrangements
*
* - less predictable (proportional probability based, we can talk
* about an advisory effect of the priorities) responses to the arrival
* of the high-ranked events (i.e. in the process of the picking the next
* event to handle from the priority queue when at least two different
* priorities are eligible at the moment)
*
* One practical application for this module of libqb is in combination with
* IPC servers based on qbipcs.h published one (the #qb_ipcs_poll_handlers
* structure maps fittingly to the control functions published here).
*
* @example tcpserver.c
*/
/**
* Priorites for jobs, timers & poll
*/
enum qb_loop_priority {
QB_LOOP_LOW = 0,
QB_LOOP_MED = 1,
QB_LOOP_HIGH = 2,
};
/**
* An opaque data type representing the main loop.
*/
typedef struct qb_loop qb_loop_t;
typedef uint64_t qb_loop_timer_handle;
typedef void *qb_loop_signal_handle;
typedef int32_t (*qb_loop_poll_dispatch_fn) (int32_t fd, int32_t revents, void *data);
typedef void (*qb_loop_job_dispatch_fn)(void *data);
typedef void (*qb_loop_timer_dispatch_fn)(void *data);
typedef int32_t (*qb_loop_signal_dispatch_fn)(int32_t rsignal, void *data);
typedef void (*qb_loop_poll_low_fds_event_fn) (int32_t not_enough, int32_t fds_available);
/**
* Create a new main loop.
*
* @return loop instance.
*/
qb_loop_t * qb_loop_create(void);
/**
*
*/
void qb_loop_destroy(struct qb_loop * l);
/**
* Stop the main loop.
* @param l pointer to the loop instance
*/
void qb_loop_stop(qb_loop_t *l);
/**
* Run the main loop.
*
* @param l pointer to the loop instance
*/
void qb_loop_run(qb_loop_t *l);
/**
* Add a job to the mainloop.
*
* This is run in the next cycle of the loop.
* @note it is a one-shot job.
*
* @param l pointer to the loop instance
* @param p the priority
* @param data user data passed into the dispatch function
* @param dispatch_fn callback function
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_job_add(qb_loop_t *l,
enum qb_loop_priority p,
void *data,
qb_loop_job_dispatch_fn dispatch_fn);
/**
* Delete a job from the mainloop.
*
* This will try to delete the job if it hasn't run yet.
*
* @note this will remove the first job that matches the
* parameters (priority, data, dispatch_fn).
*
* @param l pointer to the loop instance
* @param p the priority
* @param data user data passed into the dispatch function
* @param dispatch_fn callback function
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_job_del(struct qb_loop *l,
enum qb_loop_priority p,
void *data,
qb_loop_job_dispatch_fn dispatch_fn);
/**
* Add a timer to the mainloop.
* @note it is a one-shot job.
*
* @param l pointer to the loop instance
* @param p the priority
* @param nsec_duration nano-secs in the future to run the dispatch.
* @param data user data passed into the dispatch function
* @param dispatch_fn callback function
* @param timer_handle_out handle to delete the timer if needed.
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_timer_add(qb_loop_t *l,
enum qb_loop_priority p,
uint64_t nsec_duration,
void *data,
qb_loop_timer_dispatch_fn dispatch_fn,
qb_loop_timer_handle * timer_handle_out);
/**
* Delete a timer that is still outstanding.
*
* @param l pointer to the loop instance
* @param th handle to delete the timer if needed.
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_timer_del(qb_loop_t *l, qb_loop_timer_handle th);
/**
* Check to see if a timer that is still outstanding.
*
* @param l pointer to the loop instance
* @param th handle to delete the timer if needed.
* @retval QB_TRUE yes this timer is outstanding
* @retval QB_FALSE this timer does not exist or has expired
*/
int32_t qb_loop_timer_is_running(qb_loop_t *l, qb_loop_timer_handle th);
/**
* Get the time remaining before it expires.
*
* @note if the timer has already expired it will return 0
*
* @param l pointer to the loop instance
* @param th timer handle.
* @return nano seconds left
*/
uint64_t qb_loop_timer_expire_time_get(struct qb_loop *l, qb_loop_timer_handle th);
/**
* Set a callback to receive events on file descriptors
* getting low.
* @param l pointer to the loop instance
* @param fn callback function.
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_poll_low_fds_event_set(qb_loop_t *l,
qb_loop_poll_low_fds_event_fn fn);
/**
* Add a poll job to the mainloop.
* @note it is a re-occurring job.
*
* @param l pointer to the loop instance
* @param p the priority
* @param fd file descriptor.
* @param events (POLLIN|POLLOUT) etc ....
* @param data user data passed into the dispatch function
* @param dispatch_fn callback function
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_poll_add(qb_loop_t *l,
enum qb_loop_priority p,
int32_t fd,
int32_t events,
void *data,
qb_loop_poll_dispatch_fn dispatch_fn);
/**
* Modify a poll job.
*
* @param l pointer to the loop instance
* @param p the priority
* @param fd file descriptor.
* @param events (POLLIN|POLLOUT) etc ....
* @param data user data passed into the dispatch function
* @param dispatch_fn callback function
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_poll_mod(qb_loop_t *l,
enum qb_loop_priority p,
int32_t fd,
int32_t events,
void *data,
qb_loop_poll_dispatch_fn dispatch_fn);
/**
* Delete a poll job.
*
* @param l pointer to the loop instance
* @param fd file descriptor.
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_poll_del(qb_loop_t *l, int32_t fd);
/**
* Add a signal job.
*
* Get a callback on this signal (not in the context of the signal).
*
* @param l pointer to the loop instance
* @param p the priority
* @param sig (SIGHUP or SIGINT) etc ....
* @param data user data passed into the dispatch function
* @param dispatch_fn callback function
* @param handle (out) a reference to the signal job
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_signal_add(qb_loop_t *l,
enum qb_loop_priority p,
int32_t sig,
void *data,
qb_loop_signal_dispatch_fn dispatch_fn,
qb_loop_signal_handle *handle);
/**
* Modify the signal job
*
* @param l pointer to the loop instance
* @param p the priority
* @param sig (SIGHUP or SIGINT) etc ....
* @param data user data passed into the dispatch function
* @param dispatch_fn callback function
* @param handle (in) a reference to the signal job
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_signal_mod(qb_loop_t *l,
enum qb_loop_priority p,
int32_t sig,
void *data,
qb_loop_signal_dispatch_fn dispatch_fn,
qb_loop_signal_handle handle);
/**
* Delete the signal job.
*
* @param l pointer to the loop instance
* @param handle (in) a reference to the signal job
* @return status (0 == ok, -errno == failure)
*/
int32_t qb_loop_signal_del(qb_loop_t *l,
qb_loop_signal_handle handle);
/* *INDENT-OFF* */
#ifdef __cplusplus
}
#endif /* __cplusplus */
/* *INDENT-ON* */
#endif /* QB_LOOP_H_DEFINED */

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