/*
- * Copyright (C) 2006-2013 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2014 Andre Noll <maan@systemlinux.org>
*
* Licensed under the GPL v2. For licencing details see COPYING.
*/
/**
* Paraslash's scheduler.
*
- * Designed with KISS in mind. It manages two lists of tasks. The pre_select
- * list contains pointers to functions that are called before calling select()
- * from the main loop. Similarly, \a post_select_list is a list of function
- * pointers each of which is called after the select call. Tasks add hooks to
- * these lists by registering themselves to the scheduler.
+ * Designed with KISS in mind. It maintains a list of task structures which is
+ * extended when a new task is registered. Each task may define a pre_select
+ * function which is called from the scheduler main loop before it calls
+ * select(). Similarly, each task must define a post_select function which is
+ * called after the select call.
*/
struct sched {
/** Initial value before any pre_select call. */
int max_fileno;
/** If non-NULL, use this function instead of para_select. */
int (*select_function)(int, fd_set *, fd_set *, struct timeval *);
- /** Currently active pre_select functions. */
- struct list_head pre_select_list;
- /** Currently active post_select functions. */
- struct list_head post_select_list;
+ /** Tasks which have been registered to the scheduler. */
+ struct list_head task_list;
};
/**
* Before registering a task to the scheduler, the task structure must be
* filled in properly by the caller.
*
- * If one of these functions sets \a t->error to a negative value, the
- * task gets unregistered automatically.
- *
- * \sa struct sched.
+ * \sa \ref sched.
*/
struct task {
/**
- * The pre select hook of \a t.
+ * The optional pre select hook of \a t.
*
* Its purpose is to add file descriptors to the fd sets of the
* scheduler and to decrease the select timeout if necessary.
*/
void (*pre_select)(struct sched *s, struct task *t);
/**
- * The post select hook of \a t.
+ * The mandatory post select hook of \a t.
*
* Its purpose is to evaluate and act upon the results of the previous
* select call. If this function returns a negative value, the
* scheduler unregisters the task.
*/
int (*post_select)(struct sched *s, struct task *t);
- /** Whether this task is in error state. */
+ /** Whether this task is active (>=0) or in error state (<0). */
int error;
- /** Position of the task in the pre_select list of the scheduler. */
- struct list_head pre_select_node;
- /** Position of the task in the post_select list of the scheduler. */
- struct list_head post_select_node;
+ /** Position of the task in the task list of the scheduler. */
+ struct list_head node;
/** Descriptive text and current status of the task. */
char status[255];
/** If less than zero, the task was notified by another task. */
char *get_task_list(struct sched *s);
void task_notify(struct task *t, int err);
void task_notify_all(struct sched *s, int err);
-int task_get_notification(struct task *t);
+int task_get_notification(const struct task *t);
void sched_min_delay(struct sched *s);
void sched_request_timeout(struct timeval *to, struct sched *s);
void sched_request_timeout_ms(long unsigned ms, struct sched *s);