+/*
+ * Copyright (C) 2006-2009 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 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.
+ */
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 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;
+ /** In non-NULL, use this function instead of para_select. */
+ int (*select_function)(int, fd_set *, fd_set *, struct timeval *);
};
+/**
+ * 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 sets \a t->error to a negative value, the
+ * task gets unregistered automatically.
+ *
+ * \sa struct sched.
+ */
struct task {
- void *private_data;
- unsigned flags;
- int ret;
+ /**
+ * The 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 postselect hook of \a t.
+ *
+ * Evaluate and act upon the results of the previous select call.
+ */
void (*post_select)(struct sched *s, struct task *t);
- void (*event_handler)(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;
- char status[MAXLINE];
+ /** Descriptive text and current status of the task. */
+ char status[255];
};
-enum task_flags {
- PRE_ADD_TAIL = 1,
- POST_ADD_TAIL = 2,
-};
+/**
+ * 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.
+ */
+extern struct timeval *now;
-void *register_task(struct task *t);
-void unregister_task(struct task *t);
-int sched(struct sched *s);
-void init_sched(void);
+void register_task(struct task *t);
+int schedule(struct sched *s);
+char *get_task_list(void);
+int kill_task(char *id);
+void sched_shutdown(void);