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

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

 struct pool_head *pool2_task;

 /* This is the memory pool containing all the signal structs. These
  * struct are used to store each requiered signal between two tasks.
  */
 struct pool_head *pool2_notification;

 unsigned int nb_tasks = 0;
 unsigned int tasks_run_queue = 0;
 unsigned int tasks_run_queue_cur = 0;    /* copy of the run queue size */
 unsigned int nb_tasks_cur = 0;     /* copy of the tasks count */
 unsigned int niced_tasks = 0;      /* number of niced tasks in the run queue */


 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 -tasks_run_queue*32, while a nice value
  * of 1024 sets the task to tasks_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)
 {
 	tasks_run_queue++;
 	t->rq.key = ++rqueue_ticks;

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

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

 	/* reset flag to pending ones
 	 * Note: __task_wakeup must not be called
 	 * if task is running
 	 */
 	t->state = t->pending_state;
 	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

 	eb32_insert(&timers, &task->wq);

 	return;
 }

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

 	while (1) {
 		eb = eb32_lookup_ge(&timers, now_ms - TIMER_LOOK_BACK);
 		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 */
 			return eb->key;
 		}

 		/* timer looks expired, detach it from the queue */
 		task = eb32_entry(eb, struct task, wq);
 		__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. Note that we might occasionally requeue it at
 		 * the same place, before <eb>, so we have to check if this happens,
 		 * and adjust <eb>, otherwise we may skip it which is not what we want.
 		 * We may also not requeue the task (and not point eb at it) if its
 		 * expiration time is not set.
 		 */
 		if (!tick_is_expired(task->expire, now_ms)) {
 			if (!tick_isset(task->expire))
 				continue;
 			__task_queue(task);
 			continue;
 		}
 		task_wakeup(task, TASK_WOKEN_TIMER);
 	}

 	/* No task is expired */
 	return TICK_ETERNITY;
 }

 /* 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()
 {
 	struct task *t;
 	int i;
 	int max_processed;
 	struct eb32_node *rq_next;
 	int rewind;
 	struct task *local_tasks[16];
 	int local_tasks_count;
 	tasks_run_queue_cur = tasks_run_queue; /* keep a copy for reporting */
 	nb_tasks_cur = nb_tasks;
 	max_processed = tasks_run_queue;
 	if (!tasks_run_queue)
 		return;

 	if (max_processed > 200)
 		max_processed = 200;

 	if (likely(niced_tasks))
 		max_processed = (max_processed + 3) / 4;

 	while (max_processed > 0) {
 		/* Note: this loop is one of the fastest code path in
 		 * the whole program. It should not be re-arranged
 		 * without a good reason.
 		 */

 		rewind = 0;
 		rq_next = eb32_lookup_ge(&rqueue, rqueue_ticks - TIMER_LOOK_BACK);
 		if (!rq_next) {
 			/* 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.
 			 */
 			rq_next = eb32_first(&rqueue);
 			if (!rq_next) {
 				break;
 			}
 			rewind = 1;
 		}

 		local_tasks_count = 0;
 		while (local_tasks_count < 16) {
 			t = eb32_entry(rq_next, struct task, rq);
 			rq_next = eb32_next(rq_next);
 			/* detach the task from the queue */
 			__task_unlink_rq(t);
 			t->state |= TASK_RUNNING;
 			t->pending_state = 0;
 			t->calls++;
 			local_tasks[local_tasks_count++] = t;
 			if (!rq_next) {
 				if (rewind || !(rq_next = eb32_first(&rqueue))) {
 					break;
 				}
 				rewind = 1;
 			}
 		}

 		if (!local_tasks_count)
 			break;


 		for (i = 0; i < local_tasks_count ; i++) {
 			t = local_tasks[i];
 			/* This is an optimisation to help the processor's branch
 			 * predictor take this most common call.
 			 */
 			if (likely(t->process == process_stream))
 				t = process_stream(t);
 			else
 				t = t->process(t);
 			local_tasks[i] = t;
 		}

 		max_processed -= local_tasks_count;
 		for (i = 0; i < local_tasks_count ; i++) {
 			t = local_tasks[i];
 			if (likely(t != NULL)) {
 				t->state &= ~TASK_RUNNING;
 				/* If there is a pending state
 				 * we have to wake up the task
 				 * immediatly, else we defer
 				 * it into wait queue
 				 */
 				if (t->pending_state)
 					__task_wakeup(t);
 				else
 					task_queue(t);
 			}
 		}
 	}
 }

 /* 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);
 	if (!pool2_task)
 		return 0;
 	pool2_notification = create_pool("notification", sizeof(struct notification), MEM_F_SHARED);
 	if (!pool2_notification)
 		return 0;
 	return 1;
 }

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

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

	struct pool_head *pool2_task;

	/* This is the memory pool containing all the signal structs. These
	* struct are used to store each requiered signal between two tasks.
	*/
	struct pool_head *pool2_notification;

	unsigned int nb_tasks = 0;
	unsigned int tasks_run_queue = 0;
	unsigned int tasks_run_queue_cur = 0; /* copy of the run queue size */
	unsigned int nb_tasks_cur = 0; /* copy of the tasks count */
	unsigned int niced_tasks = 0; /* number of niced tasks in the run queue */


	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 -tasks_run_queue*32, while a nice value
	* of 1024 sets the task to tasks_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)
	{
	tasks_run_queue++;
	t->rq.key = ++rqueue_ticks;

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

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

	/* reset flag to pending ones
	* Note: __task_wakeup must not be called
	* if task is running
	*/
	t->state = t->pending_state;
	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

	eb32_insert(&timers, &task->wq);

	return;
	}

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

	while (1) {
	eb = eb32_lookup_ge(&timers, now_ms - TIMER_LOOK_BACK);
	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 */
	return eb->key;
	}

	/* timer looks expired, detach it from the queue */
	task = eb32_entry(eb, struct task, wq);
	__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. Note that we might occasionally requeue it at
	* the same place, before <eb>, so we have to check if this happens,
	* and adjust <eb>, otherwise we may skip it which is not what we want.
	* We may also not requeue the task (and not point eb at it) if its
	* expiration time is not set.
	*/
	if (!tick_is_expired(task->expire, now_ms)) {
	if (!tick_isset(task->expire))
	continue;
	__task_queue(task);
	continue;
	}
	task_wakeup(task, TASK_WOKEN_TIMER);
	}

	/* No task is expired */
	return TICK_ETERNITY;
	}

	/* 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()
	{
	struct task *t;
	int i;
	int max_processed;
	struct eb32_node *rq_next;
	int rewind;
	struct task *local_tasks[16];
	int local_tasks_count;
	tasks_run_queue_cur = tasks_run_queue; /* keep a copy for reporting */
	nb_tasks_cur = nb_tasks;
	max_processed = tasks_run_queue;
	if (!tasks_run_queue)
	return;

	if (max_processed > 200)
	max_processed = 200;

	if (likely(niced_tasks))
	max_processed = (max_processed + 3) / 4;

	while (max_processed > 0) {
	/* Note: this loop is one of the fastest code path in
	* the whole program. It should not be re-arranged
	* without a good reason.
	*/

	rewind = 0;
	rq_next = eb32_lookup_ge(&rqueue, rqueue_ticks - TIMER_LOOK_BACK);
	if (!rq_next) {
	/* 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.
	*/
	rq_next = eb32_first(&rqueue);
	if (!rq_next) {
	break;
	}
	rewind = 1;
	}

	local_tasks_count = 0;
	while (local_tasks_count < 16) {
	t = eb32_entry(rq_next, struct task, rq);
	rq_next = eb32_next(rq_next);
	/* detach the task from the queue */
	__task_unlink_rq(t);
	t->state \|= TASK_RUNNING;
	t->pending_state = 0;
	t->calls++;
	local_tasks[local_tasks_count++] = t;
	if (!rq_next) {
	if (rewind \|\| !(rq_next = eb32_first(&rqueue))) {
	break;
	}
	rewind = 1;
	}
	}

	if (!local_tasks_count)
	break;


	for (i = 0; i < local_tasks_count ; i++) {
	t = local_tasks[i];
	/* This is an optimisation to help the processor's branch
	* predictor take this most common call.
	*/
	if (likely(t->process == process_stream))
	t = process_stream(t);
	else
	t = t->process(t);
	local_tasks[i] = t;
	}

	max_processed -= local_tasks_count;
	for (i = 0; i < local_tasks_count ; i++) {
	t = local_tasks[i];
	if (likely(t != NULL)) {
	t->state &= ~TASK_RUNNING;
	/* If there is a pending state
	* we have to wake up the task
	* immediatly, else we defer
	* it into wait queue
	*/
	if (t->pending_state)
	__task_wakeup(t);
	else
	task_queue(t);
	}
	}
	}
	}

	/* 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);
	if (!pool2_task)
	return 0;
	pool2_notification = create_pool("notification", sizeof(struct notification), MEM_F_SHARED);
	if (!pool2_notification)
	return 0;
	return 1;
	}

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