/*
- * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2014 Andre Noll <maan@systemlinux.org>
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
+ * 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.
*
- * desinged 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;
- /** the return value of the previous select call */
- int select_ret;
+ /** 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
+ * Paraslash's task structure.
*
- * before registering a task to the scheduler, the task structure must be
- * filled in properly by the caller.
+ * This is considered an internal structure and will eventually be made private.
*
- * 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 happend). 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
+ * \sa \ref sched.
*/
struct task {
- /** pointer to the struct this task is embedded in */
- void *private_data;
+ /** Copied from the task_info struct during task_register(). */
+ void (*pre_select)(struct sched *s, struct task *t);
+ /** Copied from the task_info struct during task_register(). */
+ int (*post_select)(struct sched *s, struct task *t);
+ /** Whether this task is active (>=0) or in error state (<0). */
+ int error;
+ /** Position of the task in the task list of the scheduler. */
+ struct list_head node;
+ /** The task name supplied when the task was registered(). */
+ char status[255];
+ /** If less than zero, the task was notified by another task. */
+ int notification;
+ /** Whether the task structure should be freed in sched_shutdown(). */
+ bool owned_by_sched;
+ /** True if task is in error state and exit status has been queried. */
+ bool dead;
+ /** Usually a pointer to the struct containing this task. */
+ void *context;
+};
+
+/** 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 neccessary.
+ * scheduler and to decrease the select timeout if necessary.
*/
void (*pre_select)(struct sched *s, struct task *t);
/**
- * 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, struct task *t);
+ /**
+ * This pointer is saved when the task is register(ed). It may be
+ * queried from ->pre_select() and ->post_select() via \ref
+ * task_context(). Usually this is a pointer to the struct owned by the
+ * caller which contains the task pointer as one member.
*/
- void (*post_select)(struct sched *s, struct task *t);
- /** gets called if pre_select or post_select returned an error */
- void (*event_handler)(struct task *t);
- /** pre_select() and post_select store their return value here */
- int ret;
- /** 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;
-void register_task(struct task *t);
-void unregister_task(struct task *t);
-int sched(struct sched *s);
-char *get_task_list(void);
-int kill_task(char *id);
+struct task *task_register(struct task_info *info, struct sched *s);
+void *task_context(struct task *t);
+int schedule(struct sched *s);
+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_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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