X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=sched.h;h=7ab830861a940bff99c3085d3e07be055eb5c513;hp=632fddde19c62782aa89b5db9cc68e1f7c3b8e41;hb=5b972aabaf27931cae6ac318c9b920d33593f07b;hpb=704605b466aca3ae6ca6d1e03b6af55e3d245502

diff --git a/sched.h b/sched.h
index 632fddde..7ab83086 100644
--- a/sched.h
+++ b/sched.h
@@ -1,25 +1,88 @@
+/*
+ * Copyright (C) 2006 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;
+	/** 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;
-	fd_set rfds, wfds;
+	/** the return value of the previous select call */
 	int select_ret;
-	struct timeval default_timeout;
 };
 
+/**
+ * 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 {
+	/** pointer to the struct this task is embedded in */
 	void *private_data;
-	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);
+	/** 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 *register_task(struct task *t);
+/**
+ * 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);
+int schedule(struct sched *s);
 char *get_task_list(void);
 int kill_task(char *id);