+/*
+ * Copyright (C) 2006-2014 Andre Noll <maan@systemlinux.org>
+ *
+ * Licensed under the GPL v2. For licencing details see COPYING.
+ */
+
+/** \file sched.h Sched and task structures and exported symbols from sched.c. */
+
+
+/**
+ * Paraslash's 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 {
- struct timeval now, timeout;
- int max_fileno;
- fd_set rfds, wfds;
- int select_ret;
+ /** Initial value before any pre_select call. */
struct timeval default_timeout;
+ /** 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. */
+ fd_set wfds;
+ /** 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.
+ *
+ * This is considered an internal structure and will eventually be made private.
+ *
+ * \sa \ref sched.
+ */
struct task {
- void *private_data;
- unsigned flags;
- int ret;
+ /** Copied from the task_info struct during task_register(). */
void (*pre_select)(struct sched *s, struct task *t);
- void (*post_select)(struct sched *s, struct task *t);
- void (*event_handler)(struct task *t);
- struct list_head pre_select_node;
- struct list_head post_select_node;
- char status[MAXLINE];
+ /** 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;
};
-enum task_flags {
- PRE_ADD_TAIL = 1,
- POST_ADD_TAIL = 2,
+/** 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 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);
+ /**
+ * The mandatory post select method.
+ *
+ * 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 *context;
};
-void *register_task(struct task *t);
-void unregister_task(struct task *t);
-int sched(struct sched *s);
-void init_sched(void);
-char *get_task_list(void);
-int kill_task(char *id);
+/**
+ * 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 clock_gettime() directly.
+ */
+extern struct timeval *now;
+
+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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