X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=sched.h;h=ede5e67ea2ac042c5765a92e6100bc00ab47e103;hb=be5daec66f163725489f42d512659a8af5c3fd59;hp=0363f0d1f4f79b89bc30078e600db4fc3b66898c;hpb=d46fe38dcada4108ed49a0e621376df0f7913fe3;p=paraslash.git

diff --git a/sched.h b/sched.h
index 0363f0d1..ede5e67e 100644
--- a/sched.h
+++ b/sched.h
@@ -1,31 +1,101 @@
+/* Copyright (C) 2006 Andre Noll <maan@tuebingen.mpg.de>, see file 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_monitor
+ * function which is called from the scheduler main loop before it calls
+ * poll(2). Similarly, each task must define a post_monitor function which is
+ * called after poll(2) returns.
+ *
+ * \sa select(2), poll(2).
+ */
 struct sched {
-	struct timeval now, timeout;
-	int max_fileno;
-	fd_set rfds, wfds;
-	int select_ret;
-	struct timeval default_timeout;
+	/** Initial value (in milliseconds) before any pre_monitor call. */
+	int default_timeout;
+	/** The timeout (also in milliseconds) for the next iteration. */
+	int timeout;
+	/** Passed to poll(2). */
+	struct pollfd *pfd;
+	/** Number of elements in the above array, passed to poll(2). */
+	unsigned pfd_array_len;
+	/** Number of fds registered for montitoring so far. */
+	unsigned num_pfds;
+	/** Maps fds to indices of the pfd array. */
+	unsigned *pidx;
+	/** Mumber of elements in the above pidx array. */
+	unsigned pidx_array_len;
+	/** If non-NULL, use this function instead of \ref xpoll(). */
+	int (*poll_function)(struct pollfd *fds, nfds_t nfds, int timeout);
+	/** Tasks which have been registered to the scheduler. */
+	struct list_head task_list;
 };
 
-struct task {
-	void *private_data;
-	unsigned flags;
-	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;
 
-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;
+	/**
+	 * Configure watch fds and impose an upper bound on the I/O timeout.
+	 *
+	 * If this is not NULL, the function is called at each iteration of the
+	 * scheduler's main loop. Its purpose is to tell the scheduler that
+	 * certain file descriptors should be monitored for readiness for I/O.
+	 * The function may also lower the scheduler's timeout value (but shall
+	 * never increase it) to impose an upper bound on the waiting time in
+	 * case no file descriptors happen to be ready.
+	 *
+	 * \sa \ref time.c.
+	 */
+	void (*pre_monitor)(struct sched *s, void *context);
+	/**
+	 * Perform I/O on file descriptors which are ready for I/O.
+	 *
+	 * This mandatory hook is called after the system call which monitors
+	 * file descriptors returns. The function should perform non-blocking
+	 * I/O on those file descriptors which are reported as being ready.
+	 *
+	 * If this function returns a negative value, the scheduler unregisters
+	 * the task.
+	 */
+	int (*post_monitor)(struct sched *s, void *context);
+	/**
+	 * This pointer is saved when the task is registered. It is passed to
+	 * ->pre_monitor() and ->post_monitor(). Usually this is a pointer to the
+	 * struct owned by the caller which contains the task pointer.
+	 */
+	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 const struct timeval *now;
+
+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);
+void sched_monitor_readfd(int fd, struct sched *s);
+void sched_monitor_writefd(int fd, struct sched *s);
+bool sched_read_ok(int fd, const struct sched *s);
+bool sched_write_ok(int fd, const struct sched *s);