2 * Copyright (C) 2006-2014 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file sched.h Sched and task structures and exported symbols from sched.c. */
11 * Paraslash's scheduler.
13 * Designed with KISS in mind. It maintains a list of task structures which is
14 * extended when a new task is registered. Each task may define a pre_select
15 * function which is called from the scheduler main loop before it calls
16 * select(). Similarly, each task must define a post_select function which is
17 * called after the select call.
20 /** Initial value before any pre_select call. */
21 struct timeval default_timeout;
22 /** The current timeout for the upcoming select call. */
23 struct timeval select_timeout;
24 /** fds that should be watched for readability. */
26 /** fds that should be watched for writability. */
28 /** Highest numbered file descriptor in any of the above fd sets. */
30 /** If non-NULL, use this function instead of para_select. */
31 int (*select_function)(int, fd_set *, fd_set *, struct timeval *);
32 /** Tasks which have been registered to the scheduler. */
33 struct list_head task_list;
38 /** Information that must be supplied by callers of \ref task_register(). */
40 /** Used for log messages and by \ref get_task_list(). */
43 * The optional pre select method.
45 * Its purpose is to add file descriptors to the fd sets of the
46 * scheduler and to decrease the select timeout if necessary.
48 void (*pre_select)(struct sched *s, struct task *t);
50 * The mandatory post select method.
52 * Its purpose is to evaluate and act upon the results of the previous
53 * select call. If this function returns a negative value, the
54 * scheduler unregisters the task.
56 int (*post_select)(struct sched *s, struct task *t);
58 * This pointer is saved when the task is register(ed). It may be
59 * queried from ->pre_select() and ->post_select() via \ref
60 * task_context(). Usually this is a pointer to the struct owned by the
61 * caller which contains the task pointer as one member.
67 * This is set by the scheduler at the beginning of its main loop. It may be
68 * used (read-only) from everywhere. As none of the functions called by the
69 * scheduler are allowed to block, this value should be accurate enough so that
70 * there is no need to call clock_gettime() directly.
72 extern struct timeval *now;
74 struct task *task_register(struct task_info *info, struct sched *s);
75 void *task_context(struct task *t);
76 int schedule(struct sched *s);
77 void sched_shutdown(struct sched *s);
78 char *get_task_list(struct sched *s);
79 void task_notify(struct task *t, int err);
80 void task_notify_all(struct sched *s, int err);
81 int task_get_notification(const struct task *t);
82 int task_status(const struct task *t);
83 int task_reap(struct task **tptr);
84 void sched_min_delay(struct sched *s);
85 void sched_request_timeout(struct timeval *to, struct sched *s);
86 void sched_request_timeout_ms(long unsigned ms, struct sched *s);
87 int sched_request_barrier(struct timeval *barrier, struct sched *s);
88 int sched_request_barrier_or_min_delay(struct timeval *barrier, struct sched *s);