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 <eb32sctree.h>
 #include <eb32tree.h>

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

 DECLARE_POOL(pool_head_task,    "task",    sizeof(struct task));
 DECLARE_POOL(pool_head_tasklet, "tasklet", sizeof(struct tasklet));

 /* This is the memory pool containing all the signal structs. These
  * struct are used to store each required signal between two tasks.
  */
 DECLARE_POOL(pool_head_notification, "notification", sizeof(struct notification));

 unsigned int nb_tasks = 0;
 volatile unsigned long active_tasks_mask = 0; /* Mask of threads with active tasks */
 volatile unsigned long global_tasks_mask = 0; /* Mask of threads with tasks in the global runqueue */
 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 */

 THREAD_LOCAL struct task *curr_task = NULL; /* task currently running or NULL */
 THREAD_LOCAL struct eb32sc_node *rq_next = NULL; /* Next task to be potentially run */

 __decl_aligned_spinlock(rq_lock); /* spin lock related to run queue */
 __decl_aligned_spinlock(wq_lock); /* spin lock related to wait queue */

 #ifdef USE_THREAD
 struct eb_root timers;      /* sorted timers tree, global */
 struct eb_root rqueue;      /* tree constituting the run queue */
 int global_rqueue_size; /* Number of element sin the global runqueue */
 #endif

 static unsigned int rqueue_ticks;  /* insertion count */

 struct task_per_thread task_per_thread[MAX_THREADS];

 /* 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.
  */
 void __task_wakeup(struct task *t, struct eb_root *root)
 {
 	void *expected = NULL;
 	int *rq_size;

 #ifdef USE_THREAD
 	if (root == &rqueue) {
 		rq_size = &global_rqueue_size;
 		HA_SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
 	} else
 #endif
 	{
 		int nb = ((void *)root - (void *)&task_per_thread[0].rqueue) / sizeof(task_per_thread[0]);
 		rq_size = &task_per_thread[nb].rqueue_size;
 	}
 	/* Make sure if the task isn't in the runqueue, nobody inserts it
 	 * in the meanwhile.
 	 */
 redo:
 	if (unlikely(!_HA_ATOMIC_CAS(&t->rq.node.leaf_p, &expected, (void *)0x1))) {
 #ifdef USE_THREAD
 		if (root == &rqueue)
 			HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
 #endif
 		return;
 	}
 	/* There's a small race condition, when running a task, the thread
 	 * first sets TASK_RUNNING, and then unlink the task.
 	 * If an another thread calls task_wakeup() for the same task,
 	 * it may set t->state before TASK_RUNNING was set, and then try
 	 * to set t->rq.nod.leaf_p after it was unlinked.
 	 * To make sure it is not a problem, we check if TASK_RUNNING is set
 	 * again. If it is, we unset t->rq.node.leaf_p.
 	 * We then check for TASK_RUNNING a third time. If it is still there,
 	 * then we can give up, the task will be re-queued later if it needs
 	 * to be. If it's not there, and there is still something in t->state,
 	 * then we have to requeue.
 	 */
 	if (((volatile unsigned short)(t->state)) & TASK_RUNNING) {
 		unsigned short state;
 		t->rq.node.leaf_p = NULL;
 		__ha_barrier_full();

 		state = (volatile unsigned short)(t->state);
 		if (unlikely(state != 0 && !(state & TASK_RUNNING)))
 			goto redo;
 #ifdef USE_THREAD
 		if (root == &rqueue)
 			HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
 #endif
 		return;
 	}
 	_HA_ATOMIC_ADD(&tasks_run_queue, 1);
 #ifdef USE_THREAD
 	if (root == &rqueue) {
 		_HA_ATOMIC_OR(&global_tasks_mask, t->thread_mask);
 		__ha_barrier_atomic_store();
 	}
 #endif
 	_HA_ATOMIC_OR(&active_tasks_mask, t->thread_mask);
 	t->rq.key = _HA_ATOMIC_ADD(&rqueue_ticks, 1);

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

 		_HA_ATOMIC_ADD(&niced_tasks, 1);
 		if (likely(t->nice > 0))
 			offset = (unsigned)((*rq_size * (unsigned int)t->nice) / 32U);
 		else
 			offset = -(unsigned)((*rq_size * (unsigned int)-t->nice) / 32U);
 		t->rq.key += offset;
 	}

 	if (profiling & HA_PROF_TASKS)
 		t->call_date = now_mono_time();

 	eb32sc_insert(root, &t->rq, t->thread_mask);
 #ifdef USE_THREAD
 	if (root == &rqueue) {
 		global_rqueue_size++;
 		_HA_ATOMIC_OR(&t->state, TASK_GLOBAL);
 		HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
 	} else
 #endif
 	{
 		int nb = ((void *)root - (void *)&task_per_thread[0].rqueue) / sizeof(task_per_thread[0]);
 		task_per_thread[nb].rqueue_size++;
 	}
 #ifdef USE_THREAD
 	/* If all threads that are supposed to handle this task are sleeping,
 	 * wake one.
 	 */
 	if ((((t->thread_mask & all_threads_mask) & sleeping_thread_mask) ==
 	     (t->thread_mask & all_threads_mask))) {
 		unsigned long m = (t->thread_mask & all_threads_mask) &~ tid_bit;

 		m = (m & (m - 1)) ^ m; // keep lowest bit set
 		_HA_ATOMIC_AND(&sleeping_thread_mask, ~m);
 		wake_thread(my_ffsl(m) - 1);
 	}
 #endif
 	return;
 }

 /*
  * __task_queue()
  *
  * Inserts a task into wait queue <wq> 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(). Moreover this function doesn't care
  * at all about locking so the caller must be careful when deciding whether to
  * lock or not around this call.
  */
 void __task_queue(struct task *task, struct eb_root *wq)
 {
 	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(wq, &task->wq);
 }

 /*
  * 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;
 	int ret = TICK_ETERNITY;

 	while (1) {
   lookup_next_local:
 		eb = eb32_lookup_ge(&task_per_thread[tid].timers, now_ms - TIMER_LOOK_BACK);
 		if (!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(&task_per_thread[tid].timers);
 			if (likely(!eb))
 				break;
 		}

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

 		/* 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))
 				__task_queue(task, &task_per_thread[tid].timers);
 			goto lookup_next_local;
 		}
 		task_wakeup(task, TASK_WOKEN_TIMER);
 	}

 #ifdef USE_THREAD
 	while (1) {
 		HA_SPIN_LOCK(TASK_WQ_LOCK, &wq_lock);
   lookup_next:
 		eb = eb32_lookup_ge(&timers, now_ms - TIMER_LOOK_BACK);
 		if (!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 (tick_is_lt(now_ms, eb->key)) {
 			/* timer not expired yet, revisit it later */
 			ret = tick_first(ret, eb->key);
 			break;
 		}

 		/* 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))
 				__task_queue(task, &timers);
 			goto lookup_next;
 		}
 		task_wakeup(task, TASK_WOKEN_TIMER);
 		HA_SPIN_UNLOCK(TASK_WQ_LOCK, &wq_lock);
 	}

 	HA_SPIN_UNLOCK(TASK_WQ_LOCK, &wq_lock);
 #endif
 	return ret;
 }

 /* 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 to 200 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 max_processed;

 	tasks_run_queue_cur = tasks_run_queue; /* keep a copy for reporting */
 	nb_tasks_cur = nb_tasks;
 	max_processed = global.tune.runqueue_depth;

 	if (likely(global_tasks_mask & tid_bit)) {
 		HA_SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
 		if (!(active_tasks_mask & tid_bit)) {
 			HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
 			activity[tid].empty_rq++;
 			return;
 		}

 #ifdef USE_THREAD
 		/* Get some elements from the global run queue and put it in the
 		 * local run queue. To try to keep a bit of fairness, just get as
 		 * much elements from the global list as to have a bigger local queue
 		 * than the average.
 		 */
 		rq_next = eb32sc_lookup_ge(&rqueue, rqueue_ticks - TIMER_LOOK_BACK, tid_bit);
 		while ((task_per_thread[tid].task_list_size + task_per_thread[tid].rqueue_size) * global.nbthread <= tasks_run_queue) {
 			if (unlikely(!rq_next)) {
 				/* either we just started or we 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 = eb32sc_first(&rqueue, tid_bit);
 				if (!rq_next) {
 					_HA_ATOMIC_AND(&global_tasks_mask, ~tid_bit);
 					break;
 				}
 			}

 			t = eb32sc_entry(rq_next, struct task, rq);
 			rq_next = eb32sc_next(rq_next, tid_bit);

 			/* detach the task from the queue */
 			__task_unlink_rq(t);
 			__task_wakeup(t, &task_per_thread[tid].rqueue);
 		}
 #endif

 		HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
 	} else {
 		if (!(active_tasks_mask & tid_bit)) {
 			activity[tid].empty_rq++;
 			return;
 		}
 	}
 	/* Get some tasks from the run queue, make sure we don't
 	 * get too much in the task list, but put a bit more than
 	 * the max that will be run, to give a bit more fairness
 	 */
 	rq_next = eb32sc_lookup_ge(&task_per_thread[tid].rqueue, rqueue_ticks - TIMER_LOOK_BACK, tid_bit);
 	while (max_processed + (max_processed / 10) > task_per_thread[tid].task_list_size) {
 		/* 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(!rq_next)) {
 			/* either we just started or we 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 = eb32sc_first(&task_per_thread[tid].rqueue, tid_bit);
 			if (!rq_next)
 				break;
 		}
 		t = eb32sc_entry(rq_next, struct task, rq);
 		rq_next = eb32sc_next(rq_next, tid_bit);
 		/* Make sure nobody re-adds the task in the runqueue */
 		_HA_ATOMIC_OR(&t->state, TASK_RUNNING);

 		/* detach the task from the queue */
 		__task_unlink_rq(t);
 		/* And add it to the local task list */
 		task_insert_into_tasklet_list(t);
 	}
 	if (!(global_tasks_mask & tid_bit) && task_per_thread[tid].rqueue_size == 0) {
 		_HA_ATOMIC_AND(&active_tasks_mask, ~tid_bit);
 		__ha_barrier_atomic_load();
 		if (global_tasks_mask & tid_bit)
 			_HA_ATOMIC_OR(&active_tasks_mask, tid_bit);
 	}
 	while (max_processed > 0 && !LIST_ISEMPTY(&task_per_thread[tid].task_list)) {
 		struct task *t;
 		unsigned short state;
 		void *ctx;
 		struct task *(*process)(struct task *t, void *ctx, unsigned short state);

 		t = (struct task *)LIST_ELEM(task_per_thread[tid].task_list.n, struct tasklet *, list);
 		state = _HA_ATOMIC_XCHG(&t->state, TASK_RUNNING);
 		__ha_barrier_atomic_store();
 		__task_remove_from_tasklet_list(t);

 		ctx = t->context;
 		process = t->process;
 		t->calls++;

 		if (unlikely(!TASK_IS_TASKLET(t) && t->call_date)) {
 			uint64_t now_ns = now_mono_time();

 			t->lat_time += now_ns - t->call_date;
 			t->call_date = now_ns;
 		}

 		curr_task = (struct task *)t;
 		if (likely(process == process_stream))
 			t = process_stream(t, ctx, state);
 		else {
 			if (t->process != NULL)
 				t = process(TASK_IS_TASKLET(t) ? NULL : t, ctx, state);
 			else {
 				__task_free(t);
 				t = NULL;
 			}
 		}
 		curr_task = NULL;
 		/* If there is a pending state  we have to wake up the task
 		 * immediately, else we defer it into wait queue
 		 */
 		if (t != NULL) {
 			if (unlikely(!TASK_IS_TASKLET(t) && t->call_date)) {
 				t->cpu_time += now_mono_time() - t->call_date;
 				t->call_date = 0;
 			}

 			state = _HA_ATOMIC_AND(&t->state, ~TASK_RUNNING);
 			if (state)
 #ifdef USE_THREAD
 				__task_wakeup(t, ((t->thread_mask & all_threads_mask) == tid_bit) ?
 				    &task_per_thread[tid].rqueue : &rqueue);
 #else
 				__task_wakeup(t, &task_per_thread[tid].rqueue);
 #endif
 			else
 				task_queue(t);
 		}

 		max_processed--;
 		if (max_processed <= 0) {
 			_HA_ATOMIC_OR(&active_tasks_mask, tid_bit);
 			activity[tid].long_rq++;
 			break;
 		}
 	}
 }

 /*
  * Delete every tasks before running the master polling loop
  */
 void mworker_cleantasks()
 {
 	struct task *t;
 	int i;
 	struct eb32_node *tmp_wq = NULL;
 	struct eb32sc_node *tmp_rq = NULL;

 #ifdef USE_THREAD
 	/* cleanup the global run queue */
 	tmp_rq = eb32sc_first(&rqueue, MAX_THREADS_MASK);
 	while (tmp_rq) {
 		t = eb32sc_entry(tmp_rq, struct task, rq);
 		tmp_rq = eb32sc_next(tmp_rq, MAX_THREADS_MASK);
 		task_delete(t);
 		task_free(t);
 	}
 	/* cleanup the timers queue */
 	tmp_wq = eb32_first(&timers);
 	while (tmp_wq) {
 		t = eb32_entry(tmp_wq, struct task, wq);
 		tmp_wq = eb32_next(tmp_wq);
 		task_delete(t);
 		task_free(t);
 	}
 #endif
 	/* clean the per thread run queue */
 	for (i = 0; i < global.nbthread; i++) {
 		tmp_rq = eb32sc_first(&task_per_thread[i].rqueue, MAX_THREADS_MASK);
 		while (tmp_rq) {
 			t = eb32sc_entry(tmp_rq, struct task, rq);
 			tmp_rq = eb32sc_next(tmp_rq, MAX_THREADS_MASK);
 			task_delete(t);
 			task_free(t);
 		}
 		/* cleanup the per thread timers queue */
 		tmp_wq = eb32_first(&task_per_thread[i].timers);
 		while (tmp_wq) {
 			t = eb32_entry(tmp_wq, struct task, wq);
 			tmp_wq = eb32_next(tmp_wq);
 			task_delete(t);
 			task_free(t);
 		}
 	}
 }

 /* perform minimal intializations */
 static void init_task()
 {
 	int i;

 #ifdef USE_THREAD
 	memset(&timers, 0, sizeof(timers));
 	memset(&rqueue, 0, sizeof(rqueue));
 #endif
 	memset(&task_per_thread, 0, sizeof(task_per_thread));
 	for (i = 0; i < MAX_THREADS; i++) {
 		LIST_INIT(&task_per_thread[i].task_list);
 	}
 }

 INITCALL0(STG_PREPARE, init_task);

 /*
  * 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 <eb32sctree.h>
	#include <eb32tree.h>

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

	DECLARE_POOL(pool_head_task, "task", sizeof(struct task));
	DECLARE_POOL(pool_head_tasklet, "tasklet", sizeof(struct tasklet));

	/* This is the memory pool containing all the signal structs. These
	* struct are used to store each required signal between two tasks.
	*/
	DECLARE_POOL(pool_head_notification, "notification", sizeof(struct notification));

	unsigned int nb_tasks = 0;
	volatile unsigned long active_tasks_mask = 0; /* Mask of threads with active tasks */
	volatile unsigned long global_tasks_mask = 0; /* Mask of threads with tasks in the global runqueue */
	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 */

	THREAD_LOCAL struct task curr_task = NULL; / task currently running or NULL */
	THREAD_LOCAL struct eb32sc_node rq_next = NULL; / Next task to be potentially run */

	__decl_aligned_spinlock(rq_lock); /* spin lock related to run queue */
	__decl_aligned_spinlock(wq_lock); /* spin lock related to wait queue */

	#ifdef USE_THREAD
	struct eb_root timers; /* sorted timers tree, global */
	struct eb_root rqueue; /* tree constituting the run queue */
	int global_rqueue_size; /* Number of element sin the global runqueue */
	#endif

	static unsigned int rqueue_ticks; /* insertion count */

	struct task_per_thread task_per_thread[MAX_THREADS];

	/* 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.
	*/
	void __task_wakeup(struct task t, struct eb_root root)
	{
	void *expected = NULL;
	int *rq_size;

	#ifdef USE_THREAD
	if (root == &rqueue) {
	rq_size = &global_rqueue_size;
	HA_SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
	} else
	#endif
	{
	int nb = ((void )root - (void )&task_per_thread[0].rqueue) / sizeof(task_per_thread[0]);
	rq_size = &task_per_thread[nb].rqueue_size;
	}
	/* Make sure if the task isn't in the runqueue, nobody inserts it
	* in the meanwhile.
	*/
	redo:
	if (unlikely(!_HA_ATOMIC_CAS(&t->rq.node.leaf_p, &expected, (void *)0x1))) {
	#ifdef USE_THREAD
	if (root == &rqueue)
	HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
	#endif
	return;
	}
	/* There's a small race condition, when running a task, the thread
	* first sets TASK_RUNNING, and then unlink the task.
	* If an another thread calls task_wakeup() for the same task,
	* it may set t->state before TASK_RUNNING was set, and then try
	* to set t->rq.nod.leaf_p after it was unlinked.
	* To make sure it is not a problem, we check if TASK_RUNNING is set
	* again. If it is, we unset t->rq.node.leaf_p.
	* We then check for TASK_RUNNING a third time. If it is still there,
	* then we can give up, the task will be re-queued later if it needs
	* to be. If it's not there, and there is still something in t->state,
	* then we have to requeue.
	*/
	if (((volatile unsigned short)(t->state)) & TASK_RUNNING) {
	unsigned short state;
	t->rq.node.leaf_p = NULL;
	__ha_barrier_full();

	state = (volatile unsigned short)(t->state);
	if (unlikely(state != 0 && !(state & TASK_RUNNING)))
	goto redo;
	#ifdef USE_THREAD
	if (root == &rqueue)
	HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
	#endif
	return;
	}
	_HA_ATOMIC_ADD(&tasks_run_queue, 1);
	#ifdef USE_THREAD
	if (root == &rqueue) {
	_HA_ATOMIC_OR(&global_tasks_mask, t->thread_mask);
	__ha_barrier_atomic_store();
	}
	#endif
	_HA_ATOMIC_OR(&active_tasks_mask, t->thread_mask);
	t->rq.key = _HA_ATOMIC_ADD(&rqueue_ticks, 1);

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

	_HA_ATOMIC_ADD(&niced_tasks, 1);
	if (likely(t->nice > 0))
	offset = (unsigned)((rq_size (unsigned int)t->nice) / 32U);
	else
	offset = -(unsigned)((rq_size (unsigned int)-t->nice) / 32U);
	t->rq.key += offset;
	}

	if (profiling & HA_PROF_TASKS)
	t->call_date = now_mono_time();

	eb32sc_insert(root, &t->rq, t->thread_mask);
	#ifdef USE_THREAD
	if (root == &rqueue) {
	global_rqueue_size++;
	_HA_ATOMIC_OR(&t->state, TASK_GLOBAL);
	HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
	} else
	#endif
	{
	int nb = ((void )root - (void )&task_per_thread[0].rqueue) / sizeof(task_per_thread[0]);
	task_per_thread[nb].rqueue_size++;
	}
	#ifdef USE_THREAD
	/* If all threads that are supposed to handle this task are sleeping,
	* wake one.
	*/
	if ((((t->thread_mask & all_threads_mask) & sleeping_thread_mask) ==
	(t->thread_mask & all_threads_mask))) {
	unsigned long m = (t->thread_mask & all_threads_mask) &~ tid_bit;

	m = (m & (m - 1)) ^ m; // keep lowest bit set
	_HA_ATOMIC_AND(&sleeping_thread_mask, ~m);
	wake_thread(my_ffsl(m) - 1);
	}
	#endif
	return;
	}

	/*
	* __task_queue()
	*
	* Inserts a task into wait queue <wq> 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(). Moreover this function doesn't care
	* at all about locking so the caller must be careful when deciding whether to
	* lock or not around this call.
	*/
	void __task_queue(struct task task, struct eb_root wq)
	{
	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(wq, &task->wq);
	}

	/*
	* 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;
	int ret = TICK_ETERNITY;

	while (1) {
	lookup_next_local:
	eb = eb32_lookup_ge(&task_per_thread[tid].timers, now_ms - TIMER_LOOK_BACK);
	if (!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(&task_per_thread[tid].timers);
	if (likely(!eb))
	break;
	}

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

	/* 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))
	__task_queue(task, &task_per_thread[tid].timers);
	goto lookup_next_local;
	}
	task_wakeup(task, TASK_WOKEN_TIMER);
	}

	#ifdef USE_THREAD
	while (1) {
	HA_SPIN_LOCK(TASK_WQ_LOCK, &wq_lock);
	lookup_next:
	eb = eb32_lookup_ge(&timers, now_ms - TIMER_LOOK_BACK);
	if (!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 (tick_is_lt(now_ms, eb->key)) {
	/* timer not expired yet, revisit it later */
	ret = tick_first(ret, eb->key);
	break;
	}

	/* 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))
	__task_queue(task, &timers);
	goto lookup_next;
	}
	task_wakeup(task, TASK_WOKEN_TIMER);
	HA_SPIN_UNLOCK(TASK_WQ_LOCK, &wq_lock);
	}

	HA_SPIN_UNLOCK(TASK_WQ_LOCK, &wq_lock);
	#endif
	return ret;
	}

	/* 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 to 200 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 max_processed;

	tasks_run_queue_cur = tasks_run_queue; /* keep a copy for reporting */
	nb_tasks_cur = nb_tasks;
	max_processed = global.tune.runqueue_depth;

	if (likely(global_tasks_mask & tid_bit)) {
	HA_SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
	if (!(active_tasks_mask & tid_bit)) {
	HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
	activity[tid].empty_rq++;
	return;
	}

	#ifdef USE_THREAD
	/* Get some elements from the global run queue and put it in the
	* local run queue. To try to keep a bit of fairness, just get as
	* much elements from the global list as to have a bigger local queue
	* than the average.
	*/
	rq_next = eb32sc_lookup_ge(&rqueue, rqueue_ticks - TIMER_LOOK_BACK, tid_bit);
	while ((task_per_thread[tid].task_list_size + task_per_thread[tid].rqueue_size) * global.nbthread <= tasks_run_queue) {
	if (unlikely(!rq_next)) {
	/* either we just started or we 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 = eb32sc_first(&rqueue, tid_bit);
	if (!rq_next) {
	_HA_ATOMIC_AND(&global_tasks_mask, ~tid_bit);
	break;
	}
	}

	t = eb32sc_entry(rq_next, struct task, rq);
	rq_next = eb32sc_next(rq_next, tid_bit);

	/* detach the task from the queue */
	__task_unlink_rq(t);
	__task_wakeup(t, &task_per_thread[tid].rqueue);
	}
	#endif

	HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
	} else {
	if (!(active_tasks_mask & tid_bit)) {
	activity[tid].empty_rq++;
	return;
	}
	}
	/* Get some tasks from the run queue, make sure we don't
	* get too much in the task list, but put a bit more than
	* the max that will be run, to give a bit more fairness
	*/
	rq_next = eb32sc_lookup_ge(&task_per_thread[tid].rqueue, rqueue_ticks - TIMER_LOOK_BACK, tid_bit);
	while (max_processed + (max_processed / 10) > task_per_thread[tid].task_list_size) {
	/* 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(!rq_next)) {
	/* either we just started or we 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 = eb32sc_first(&task_per_thread[tid].rqueue, tid_bit);
	if (!rq_next)
	break;
	}
	t = eb32sc_entry(rq_next, struct task, rq);
	rq_next = eb32sc_next(rq_next, tid_bit);
	/* Make sure nobody re-adds the task in the runqueue */
	_HA_ATOMIC_OR(&t->state, TASK_RUNNING);

	/* detach the task from the queue */
	__task_unlink_rq(t);
	/* And add it to the local task list */
	task_insert_into_tasklet_list(t);
	}
	if (!(global_tasks_mask & tid_bit) && task_per_thread[tid].rqueue_size == 0) {
	_HA_ATOMIC_AND(&active_tasks_mask, ~tid_bit);
	__ha_barrier_atomic_load();
	if (global_tasks_mask & tid_bit)
	_HA_ATOMIC_OR(&active_tasks_mask, tid_bit);
	}
	while (max_processed > 0 && !LIST_ISEMPTY(&task_per_thread[tid].task_list)) {
	struct task *t;
	unsigned short state;
	void *ctx;
	struct task (process)(struct task t, void ctx, unsigned short state);

	t = (struct task )LIST_ELEM(task_per_thread[tid].task_list.n, struct tasklet , list);
	state = _HA_ATOMIC_XCHG(&t->state, TASK_RUNNING);
	__ha_barrier_atomic_store();
	__task_remove_from_tasklet_list(t);

	ctx = t->context;
	process = t->process;
	t->calls++;

	if (unlikely(!TASK_IS_TASKLET(t) && t->call_date)) {
	uint64_t now_ns = now_mono_time();

	t->lat_time += now_ns - t->call_date;
	t->call_date = now_ns;
	}

	curr_task = (struct task *)t;
	if (likely(process == process_stream))
	t = process_stream(t, ctx, state);
	else {
	if (t->process != NULL)
	t = process(TASK_IS_TASKLET(t) ? NULL : t, ctx, state);
	else {
	__task_free(t);
	t = NULL;
	}
	}
	curr_task = NULL;
	/* If there is a pending state we have to wake up the task
	* immediately, else we defer it into wait queue
	*/
	if (t != NULL) {
	if (unlikely(!TASK_IS_TASKLET(t) && t->call_date)) {
	t->cpu_time += now_mono_time() - t->call_date;
	t->call_date = 0;
	}

	state = _HA_ATOMIC_AND(&t->state, ~TASK_RUNNING);
	if (state)
	#ifdef USE_THREAD
	__task_wakeup(t, ((t->thread_mask & all_threads_mask) == tid_bit) ?
	&task_per_thread[tid].rqueue : &rqueue);
	#else
	__task_wakeup(t, &task_per_thread[tid].rqueue);
	#endif
	else
	task_queue(t);
	}

	max_processed--;
	if (max_processed <= 0) {
	_HA_ATOMIC_OR(&active_tasks_mask, tid_bit);
	activity[tid].long_rq++;
	break;
	}
	}
	}

	/*
	* Delete every tasks before running the master polling loop
	*/
	void mworker_cleantasks()
	{
	struct task *t;
	int i;
	struct eb32_node *tmp_wq = NULL;
	struct eb32sc_node *tmp_rq = NULL;

	#ifdef USE_THREAD
	/* cleanup the global run queue */
	tmp_rq = eb32sc_first(&rqueue, MAX_THREADS_MASK);
	while (tmp_rq) {
	t = eb32sc_entry(tmp_rq, struct task, rq);
	tmp_rq = eb32sc_next(tmp_rq, MAX_THREADS_MASK);
	task_delete(t);
	task_free(t);
	}
	/* cleanup the timers queue */
	tmp_wq = eb32_first(&timers);
	while (tmp_wq) {
	t = eb32_entry(tmp_wq, struct task, wq);
	tmp_wq = eb32_next(tmp_wq);
	task_delete(t);
	task_free(t);
	}
	#endif
	/* clean the per thread run queue */
	for (i = 0; i < global.nbthread; i++) {
	tmp_rq = eb32sc_first(&task_per_thread[i].rqueue, MAX_THREADS_MASK);
	while (tmp_rq) {
	t = eb32sc_entry(tmp_rq, struct task, rq);
	tmp_rq = eb32sc_next(tmp_rq, MAX_THREADS_MASK);
	task_delete(t);
	task_free(t);
	}
	/* cleanup the per thread timers queue */
	tmp_wq = eb32_first(&task_per_thread[i].timers);
	while (tmp_wq) {
	t = eb32_entry(tmp_wq, struct task, wq);
	tmp_wq = eb32_next(tmp_wq);
	task_delete(t);
	task_free(t);
	}
	}
	}

	/* perform minimal intializations */
	static void init_task()
	{
	int i;

	#ifdef USE_THREAD
	memset(&timers, 0, sizeof(timers));
	memset(&rqueue, 0, sizeof(rqueue));
	#endif
	memset(&task_per_thread, 0, sizeof(task_per_thread));
	for (i = 0; i < MAX_THREADS; i++) {
	LIST_INIT(&task_per_thread[i].task_list);
	}
	}

	INITCALL0(STG_PREPARE, init_task);

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