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;
37 * Paraslash's task structure.
39 * Before registering a task to the scheduler, the task structure must be
40 * filled in properly by the caller.
46 * The optional pre select hook of \a t.
48 * Its purpose is to add file descriptors to the fd sets of the
49 * scheduler and to decrease the select timeout if necessary.
51 void (*pre_select)(struct sched *s, struct task *t);
53 * The mandatory post select hook of \a t.
55 * Its purpose is to evaluate and act upon the results of the previous
56 * select call. If this function returns a negative value, the
57 * scheduler unregisters the task.
59 int (*post_select)(struct sched *s, struct task *t);
60 /** Whether this task is active (>=0) or in error state (<0). */
62 /** Position of the task in the task list of the scheduler. */
63 struct list_head node;
64 /** Descriptive text and current status of the task. */
66 /** If less than zero, the task was notified by another task. */
71 * This is set by the scheduler at the beginning of its main loop. It may be
72 * used (read-only) from everywhere. As none of the functions called by the
73 * scheduler are allowed to block, this value should be accurate enough so that
74 * there is no need to call clock_gettime() directly.
76 extern struct timeval *now;
78 void register_task(struct sched *s, struct task *t);
79 int schedule(struct sched *s);
80 char *get_task_list(struct sched *s);
81 void task_notify(struct task *t, int err);
82 void task_notify_all(struct sched *s, int err);
83 int task_get_notification(struct task *t);
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);