/*
- * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006 Andre Noll <maan@tuebingen.mpg.de>
*
* Licensed under the GPL v2. For licencing details see COPYING.
*/
-/** \file sched.h sched and task structures and exported symbols from sched.c */
+/** \file sched.h Sched and task structures and exported symbols from sched.c. */
/**
- * paraslash's scheduler
+ * 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 */
+ /** Initial value before any pre_select call. */
struct timeval default_timeout;
- /** the current timeout for the upcoming select call */
- struct timeval timeout;
- /** fds that should be watched for readability */
+ /** The current timeout for the upcoming select call. */
+ struct timeval select_timeout;
+ /** fds that should be watched for readability. */
fd_set rfds;
- /** fds that should be watched for writability */
+ /** fds that should be watched for writability. */
fd_set wfds;
- /** highest numbered file descriptor in any of the above fd sets */
+ /** Highest numbered file descriptor in any of the above fd sets. */
int max_fileno;
+ /** If non-NULL, use this function instead of para_select. */
+ int (*select_function)(int, fd_set *, fd_set *, struct timeval *);
+ /** Tasks which have been registered to the scheduler. */
+ struct list_head task_list;
};
-/**
- * paraslash's task structure
- *
- * before registering a task to the scheduler, the task structure must be
- * filled in properly by the caller.
- *
- * If one of these functions return a negative value via \a t->ret the
- * (optional) event_handler gets called (it may also be called in case another
- * event happened). In many cases the only possible event is an error or an eof
- * condition and the event handler simply unregisters the task from the
- * scheduler.
- *
- * \sa struct sched
- */
-struct task {
+struct task;
+
+/** Information that must be supplied by callers of \ref task_register(). */
+struct task_info {
+ /** Used for log messages and by \ref get_task_list(). */
+ const char *name;
/**
- * the pre select hook of \a t
+ * The optional pre select method.
*
* 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);
+ void (*pre_select)(struct sched *s, void *context);
/**
- * the postselect hook of \a t
+ * The mandatory post select method.
*
- * evaluate and act upon the results of the previous select call.
+ * 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, void *context);
+ /**
+ * This pointer is saved when the task is registered. It is passed to
+ * ->pre_select() and ->post_select(). Usually this is a pointer to the
+ * struct owned by the caller which contains the task pointer.
*/
- void (*post_select)(struct sched *s, struct task *t);
- /** Whether this task is in error state. */
- 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;
- /** descriptive text and current status of the task */
- char status[MAXLINE];
+ void *context;
};
/**
* This is set by the scheduler at the beginning of its main loop. It may be
* used (read-only) from everywhere. As none of the functions called by the
* scheduler are allowed to block, this value should be accurate enough so that
- * there is no need to call gettimeofday() directly.
+ * there is no need to call clock_gettime() directly.
*/
-extern struct timeval *now;
+extern const struct timeval *now;
-void register_task(struct task *t);
-void unregister_task(struct task *t);
+struct task *task_register(struct task_info *info, struct sched *s);
int schedule(struct sched *s);
-char *get_task_list(void);
-int kill_task(char *id);
-void sched_shutdown(void);
+void sched_shutdown(struct sched *s);
+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(const struct task *t);
+int task_status(const struct task *t);
+int task_reap(struct task **tptr);
+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);
+int sched_request_barrier(struct timeval *barrier, struct sched *s);
+int sched_request_barrier_or_min_delay(struct timeval *barrier, struct sched *s);
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