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[paraslash.git] / sched.h

diff --git a/sched.h b/sched.h
index bd1ad796dfb4fa015e0053c05d83eeb5f5150704..ada1cc106c068706fc175cc883450c17a237f4b7 100644 (file)
--- a/sched.h
+++ b/sched.h
@@ -1,27 +1,86 @@
+/*
+ * Copyright (C) 2006 Andre Noll <maan@tuebingen.mpg.de>
+ *
+ * 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;
 };
 
-struct task {
-       void *private_data;
-       int ret;
-       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];
+struct task;
+
+/** 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, void *context);
+       /**
+        * 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, void *context);
+       /**
+        * This pointer is saved when the task is registered. It is passed to
+        * ->pre_select() and ->post_select(). Usually this is a pointer to the
+        * struct owned by the caller which contains the task pointer.
+        */
+       void *context;
 };
 
-extern struct timeval *now;
+/**
+ * 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 const struct timeval *now;
 
-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);
+struct task *task_register(struct task_info *info, struct sched *s);
+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_status(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);