src/task.c - haproxy - Gitiles

 /*
  * Task management functions.
  *
  * Copyright 2000-2009 Willy Tarreau <w@1wt.eu>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  *
  */

 #include <string.h>

 #include <common/config.h>
 #include <common/eb32tree.h>
 #include <common/memory.h>
 #include <common/mini-clist.h>
 #include <common/standard.h>
 #include <common/time.h>

 #include <proto/proxy.h>
 #include <proto/session.h>
 #include <proto/task.h>

 struct pool_head *pool2_task;

 unsigned int run_queue = 0;
 unsigned int niced_tasks = 0;      /* number of niced tasks in the run queue */
 struct task *last_timer = NULL;    /* optimization: last queued timer */

 static struct eb_root timers;      /* sorted timers tree */
 static struct eb_root rqueue;      /* tree constituting the run queue */
 static unsigned int rqueue_ticks;  /* insertion count */

 /* Puts the task <t> in run queue at a position depending on t->nice. <t> is
  * returned. The nice value assigns boosts in 32th of the run queue size. A
  * nice value of -1024 sets the task to -run_queue*32, while a nice value of
  * 1024 sets the task to run_queue*32. The state flags are cleared, so the
  * caller will have to set its flags after this call.
  * The task must not already be in the run queue. If unsure, use the safer
  * task_wakeup() function.
  */
 struct task *__task_wakeup(struct task *t)
 {
 	run_queue++;
 	t->rq.key = ++rqueue_ticks;

 	if (likely(t->nice)) {
 		int offset;

 		niced_tasks++;
 		if (likely(t->nice > 0))
 			offset = (unsigned)((run_queue * (unsigned int)t->nice) / 32U);
 		else
 			offset = -(unsigned)((run_queue * (unsigned int)-t->nice) / 32U);
 		t->rq.key += offset;
 	}

 	/* clear state flags at the same time */
 	t->state &= ~TASK_WOKEN_ANY;

 	eb32_insert(&rqueue, &t->rq);
 	return t;
 }

 /*
  * __task_queue()
  *
  * Inserts a task into the wait queue at the position given by its expiration
  * date. It does not matter if the task was already in the wait queue or not,
  * as it will be unlinked. The task must not have an infinite expiration timer.
  * Last, tasks must not be queued further than the end of the tree, which is
  * between <now_ms> and <now_ms> + 2^31 ms (now+24days in 32bit).
  *
  * This function should not be used directly, it is meant to be called by the
  * inline version of task_queue() which performs a few cheap preliminary tests
  * before deciding to call __task_queue().
  */
 void __task_queue(struct task *task)
 {
 	if (likely(task_in_wq(task)))
 		__task_unlink_wq(task);

 	/* the task is not in the queue now */
 	task->wq.key = task->expire;
 #ifdef DEBUG_CHECK_INVALID_EXPIRATION_DATES
 	if (tick_is_lt(task->wq.key, now_ms))
 		/* we're queuing too far away or in the past (most likely) */
 		return;
 #endif

 	if (likely(last_timer &&
 		   last_timer->wq.key == task->wq.key &&
 		   last_timer->wq.node.bit == -1 &&
 		   last_timer->wq.node.node_p)) {
 		/* Most often, last queued timer has the same expiration date, so
 		 * if it's not queued at the root, let's queue a dup directly there.
 		 * Note that we can only use dups at the dup tree's root (bit==-1).
 		 */
 		eb_insert_dup(&last_timer->wq.node, &task->wq.node);
 		return;
 	}
 	eb32_insert(&timers, &task->wq);
 	if (task->wq.node.bit == -1)
 		last_timer = task; /* we only want a dup tree's root */
 	return;
 }

 /*
  * Extract all expired timers from the timer queue, and wakes up all
  * associated tasks. Returns the date of next event (or eternity) in <next>.
  */
 void wake_expired_tasks(int *next)
 {
 	struct task *task;
 	struct eb32_node *eb;

 	eb = eb32_lookup_ge(&timers, now_ms - TIMER_LOOK_BACK);
 	while (1) {
 		if (unlikely(!eb)) {
 			/* we might have reached the end of the tree, typically because
 			* <now_ms> is in the first half and we're first scanning the last
 			* half. Let's loop back to the beginning of the tree now.
 			*/
 			eb = eb32_first(&timers);
 			if (likely(!eb))
 				break;
 		}

 		if (likely(tick_is_lt(now_ms, eb->key))) {
 			/* timer not expired yet, revisit it later */
 			*next = eb->key;
 			return;
 		}

 		/* timer looks expired, detach it from the queue */
 		task = eb32_entry(eb, struct task, wq);
 		eb = eb32_next(eb);
 		__task_unlink_wq(task);

 		/* It is possible that this task was left at an earlier place in the
 		 * tree because a recent call to task_queue() has not moved it. This
 		 * happens when the new expiration date is later than the old one.
 		 * Since it is very unlikely that we reach a timeout anyway, it's a
 		 * lot cheaper to proceed like this because we almost never update
 		 * the tree. We may also find disabled expiration dates there. Since
 		 * we have detached the task from the tree, we simply call task_queue
 		 * to take care of this.
 		 */
 		if (!tick_is_expired(task->expire, now_ms)) {
 			task_queue(task);
 			continue;
 		}
 		task_wakeup(task, TASK_WOKEN_TIMER);
 	}

 	/* We have found no task to expire in any tree */
 	*next = TICK_ETERNITY;
 	return;
 }

 /* The run queue is chronologically sorted in a tree. An insertion counter is
  * used to assign a position to each task. This counter may be combined with
  * other variables (eg: nice value) to set the final position in the tree. The
  * counter may wrap without a problem, of course. We then limit the number of
  * tasks processed at once to 1/4 of the number of tasks in the queue, and to
  * 200 max in any case, so that general latency remains low and so that task
  * positions have a chance to be considered.
  *
  * The function adjusts <next> if a new event is closer.
  */
 void process_runnable_tasks(int *next)
 {
 	struct task *t;
 	struct eb32_node *eb;
 	unsigned int max_processed;
 	int expire;

 	max_processed = run_queue;
 	if (max_processed > 200)
 		max_processed = 200;

 	if (likely(niced_tasks))
 		max_processed /= 4;

 	expire = *next;
 	eb = eb32_lookup_ge(&rqueue, rqueue_ticks - TIMER_LOOK_BACK);
 	while (max_processed--) {
 		/* Note: this loop is one of the fastest code path in
 		 * the whole program. It should not be re-arranged
 		 * without a good reason.
 		 */

 		if (unlikely(!eb)) {
 			/* we might have reached the end of the tree, typically because
 			* <rqueue_ticks> is in the first half and we're first scanning
 			* the last half. Let's loop back to the beginning of the tree now.
 			*/
 			eb = eb32_first(&rqueue);
 			if (likely(!eb))
 				break;
 		}

 		/* detach the task from the queue */
 		t = eb32_entry(eb, struct task, rq);
 		eb = eb32_next(eb);
 		__task_unlink_rq(t);

 		t->state |= TASK_RUNNING;
 		/* This is an optimisation to help the processor's branch
 		 * predictor take this most common call.
 		 */
 		if (likely(t->process == process_session))
 			t = process_session(t);
 		else
 			t = t->process(t);

 		if (likely(t != NULL)) {
 			t->state &= ~TASK_RUNNING;
 			if (t->expire) {
 				task_queue(t);
 				expire = tick_first_2nz(expire, t->expire);
 			}
 		}
 	}
 	*next = expire;
 }

 /* perform minimal intializations, report 0 in case of error, 1 if OK. */
 int init_task()
 {
 	memset(&timers, 0, sizeof(timers));
 	memset(&rqueue, 0, sizeof(rqueue));
 	pool2_task = create_pool("task", sizeof(struct task), MEM_F_SHARED);
 	return pool2_task != NULL;
 }

 /*
  * Local variables:
  *  c-indent-level: 8
  *  c-basic-offset: 8
  * End:
  */
	/*
	* Task management functions.
	*
	* Copyright 2000-2009 Willy Tarreau <w@1wt.eu>
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*
	*/

	#include <string.h>

	#include <common/config.h>
	#include <common/eb32tree.h>
	#include <common/memory.h>
	#include <common/mini-clist.h>
	#include <common/standard.h>
	#include <common/time.h>

	#include <proto/proxy.h>
	#include <proto/session.h>
	#include <proto/task.h>

	struct pool_head *pool2_task;

	unsigned int run_queue = 0;
	unsigned int niced_tasks = 0; /* number of niced tasks in the run queue */
	struct task last_timer = NULL; / optimization: last queued timer */

	static struct eb_root timers; /* sorted timers tree */
	static struct eb_root rqueue; /* tree constituting the run queue */
	static unsigned int rqueue_ticks; /* insertion count */

	/* Puts the task <t> in run queue at a position depending on t->nice. <t> is
	* returned. The nice value assigns boosts in 32th of the run queue size. A
	* nice value of -1024 sets the task to -run_queue*32, while a nice value of
	* 1024 sets the task to run_queue*32. The state flags are cleared, so the
	* caller will have to set its flags after this call.
	* The task must not already be in the run queue. If unsure, use the safer
	* task_wakeup() function.
	*/
	struct task __task_wakeup(struct task t)
	{
	run_queue++;
	t->rq.key = ++rqueue_ticks;

	if (likely(t->nice)) {
	int offset;

	niced_tasks++;
	if (likely(t->nice > 0))
	offset = (unsigned)((run_queue * (unsigned int)t->nice) / 32U);
	else
	offset = -(unsigned)((run_queue * (unsigned int)-t->nice) / 32U);
	t->rq.key += offset;
	}

	/* clear state flags at the same time */
	t->state &= ~TASK_WOKEN_ANY;

	eb32_insert(&rqueue, &t->rq);
	return t;
	}

	/*
	* __task_queue()
	*
	* Inserts a task into the wait queue at the position given by its expiration
	* date. It does not matter if the task was already in the wait queue or not,
	* as it will be unlinked. The task must not have an infinite expiration timer.
	* Last, tasks must not be queued further than the end of the tree, which is
	* between <now_ms> and <now_ms> + 2^31 ms (now+24days in 32bit).
	*
	* This function should not be used directly, it is meant to be called by the
	* inline version of task_queue() which performs a few cheap preliminary tests
	* before deciding to call __task_queue().
	*/
	void __task_queue(struct task *task)
	{
	if (likely(task_in_wq(task)))
	__task_unlink_wq(task);

	/* the task is not in the queue now */
	task->wq.key = task->expire;
	#ifdef DEBUG_CHECK_INVALID_EXPIRATION_DATES
	if (tick_is_lt(task->wq.key, now_ms))
	/* we're queuing too far away or in the past (most likely) */
	return;
	#endif

	if (likely(last_timer &&
	last_timer->wq.key == task->wq.key &&
	last_timer->wq.node.bit == -1 &&
	last_timer->wq.node.node_p)) {
	/* Most often, last queued timer has the same expiration date, so
	* if it's not queued at the root, let's queue a dup directly there.
	* Note that we can only use dups at the dup tree's root (bit==-1).
	*/
	eb_insert_dup(&last_timer->wq.node, &task->wq.node);
	return;
	}
	eb32_insert(&timers, &task->wq);
	if (task->wq.node.bit == -1)
	last_timer = task; /* we only want a dup tree's root */
	return;
	}

	/*
	* Extract all expired timers from the timer queue, and wakes up all
	* associated tasks. Returns the date of next event (or eternity) in <next>.
	*/
	void wake_expired_tasks(int *next)
	{
	struct task *task;
	struct eb32_node *eb;

	eb = eb32_lookup_ge(&timers, now_ms - TIMER_LOOK_BACK);
	while (1) {
	if (unlikely(!eb)) {
	/* we might have reached the end of the tree, typically because
	* <now_ms> is in the first half and we're first scanning the last
	* half. Let's loop back to the beginning of the tree now.
	*/
	eb = eb32_first(&timers);
	if (likely(!eb))
	break;
	}

	if (likely(tick_is_lt(now_ms, eb->key))) {
	/* timer not expired yet, revisit it later */
	*next = eb->key;
	return;
	}

	/* timer looks expired, detach it from the queue */
	task = eb32_entry(eb, struct task, wq);
	eb = eb32_next(eb);
	__task_unlink_wq(task);

	/* It is possible that this task was left at an earlier place in the
	* tree because a recent call to task_queue() has not moved it. This
	* happens when the new expiration date is later than the old one.
	* Since it is very unlikely that we reach a timeout anyway, it's a
	* lot cheaper to proceed like this because we almost never update
	* the tree. We may also find disabled expiration dates there. Since
	* we have detached the task from the tree, we simply call task_queue
	* to take care of this.
	*/
	if (!tick_is_expired(task->expire, now_ms)) {
	task_queue(task);
	continue;
	}
	task_wakeup(task, TASK_WOKEN_TIMER);
	}

	/* We have found no task to expire in any tree */
	*next = TICK_ETERNITY;
	return;
	}

	/* The run queue is chronologically sorted in a tree. An insertion counter is
	* used to assign a position to each task. This counter may be combined with
	* other variables (eg: nice value) to set the final position in the tree. The
	* counter may wrap without a problem, of course. We then limit the number of
	* tasks processed at once to 1/4 of the number of tasks in the queue, and to
	* 200 max in any case, so that general latency remains low and so that task
	* positions have a chance to be considered.
	*
	* The function adjusts <next> if a new event is closer.
	*/
	void process_runnable_tasks(int *next)
	{
	struct task *t;
	struct eb32_node *eb;
	unsigned int max_processed;
	int expire;

	max_processed = run_queue;
	if (max_processed > 200)
	max_processed = 200;

	if (likely(niced_tasks))
	max_processed /= 4;

	expire = *next;
	eb = eb32_lookup_ge(&rqueue, rqueue_ticks - TIMER_LOOK_BACK);
	while (max_processed--) {
	/* Note: this loop is one of the fastest code path in
	* the whole program. It should not be re-arranged
	* without a good reason.
	*/

	if (unlikely(!eb)) {
	/* we might have reached the end of the tree, typically because
	* <rqueue_ticks> is in the first half and we're first scanning
	* the last half. Let's loop back to the beginning of the tree now.
	*/
	eb = eb32_first(&rqueue);
	if (likely(!eb))
	break;
	}

	/* detach the task from the queue */
	t = eb32_entry(eb, struct task, rq);
	eb = eb32_next(eb);
	__task_unlink_rq(t);

	t->state \|= TASK_RUNNING;
	/* This is an optimisation to help the processor's branch
	* predictor take this most common call.
	*/
	if (likely(t->process == process_session))
	t = process_session(t);
	else
	t = t->process(t);

	if (likely(t != NULL)) {
	t->state &= ~TASK_RUNNING;
	if (t->expire) {
	task_queue(t);
	expire = tick_first_2nz(expire, t->expire);
	}
	}
	}
	*next = expire;
	}

	/* perform minimal intializations, report 0 in case of error, 1 if OK. */
	int init_task()
	{
	memset(&timers, 0, sizeof(timers));
	memset(&rqueue, 0, sizeof(rqueue));
	pool2_task = create_pool("task", sizeof(struct task), MEM_F_SHARED);
	return pool2_task != NULL;
	}

	/*
	* Local variables:
	* c-indent-level: 8
	* c-basic-offset: 8
	* End:
	*/