Simplify sched: Use only a single task list.

[paraslash.git] / sched.h

diff --git a/sched.h b/sched.h
index da20e3039c3572144486d8c2aefd54815ae314e2..c706b5093fba47f3173cc183daa07f0b77120a48 100644 (file)
--- a/sched.h
+++ b/sched.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006-2013 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2014 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -10,11 +10,11 @@
 /**
  * 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. */
@@ -29,10 +29,8 @@ struct sched {
        int max_fileno;
        /** If non-NULL, use this function instead of para_select. */
        int (*select_function)(int, fd_set *, fd_set *, struct timeval *);
-       /** Currently active pre_select functions. */
-       struct list_head pre_select_list;
-       /** Currently active post_select functions. */
-       struct list_head post_select_list;
+       /** Tasks which have been registered to the scheduler. */
+       struct list_head task_list;
 };
 
 /**
@@ -41,32 +39,28 @@ struct sched {
  * 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.
+ * \sa \ref sched.
  */
 struct task {
        /**
-        * The pre select hook of \a t.
+        * The optional 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 newer variant of the post select hook of \a t.
+        * The mandatory post select hook of \a t.
         *
-        * This hook must return the error code rather than store it in
-        * t->error.
+        * 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 (*new_post_select)(struct sched *s, struct task *t);
-       /** Whether this task is in error state. */
+       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 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;
+       /** Position of the task in the task list of the scheduler. */
+       struct list_head node;
        /** Descriptive text and current status of the task. */
        char status[255];
        /** If less than zero, the task was notified by another task. */