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/*
* include/proto/task.h
* Functions for task management.
*
* Copyright (C) 2000-2010 Willy Tarreau - w@1wt.eu
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, version 2.1
* exclusively.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _PROTO_TASK_H
#define _PROTO_TASK_H
#include <sys/time.h>
#include <common/config.h>
#include <common/memory.h>
#include <common/mini-clist.h>
#include <common/standard.h>
#include <common/ticks.h>
#include <common/hathreads.h>
#include <eb32tree.h>
#include <types/global.h>
#include <types/task.h>
/* Principle of the wait queue.
*
* We want to be able to tell whether an expiration date is before of after the
* current time <now>. We KNOW that expiration dates are never too far apart,
* because they are measured in ticks (milliseconds). We also know that almost
* all dates will be in the future, and that a very small part of them will be
* in the past, they are the ones which have expired since last time we checked
* them. Using ticks, we know if a date is in the future or in the past, but we
* cannot use that to store sorted information because that reference changes
* all the time.
*
* We'll use the fact that the time wraps to sort timers. Timers above <now>
* are in the future, timers below <now> are in the past. Here, "above" and
* "below" are to be considered modulo 2^31.
*
* Timers are stored sorted in an ebtree. We use the new ability for ebtrees to
* lookup values starting from X to only expire tasks between <now> - 2^31 and
* <now>. If the end of the tree is reached while walking over it, we simply
* loop back to the beginning. That way, we have no problem keeping sorted
* wrapping timers in a tree, between (now - 24 days) and (now + 24 days). The
* keys in the tree always reflect their real position, none can be infinite.
* This reduces the number of checks to be performed.
*
* Another nice optimisation is to allow a timer to stay at an old place in the
* queue as long as it's not further than the real expiration date. That way,
* we use the tree as a place holder for a minorant of the real expiration
* date. Since we have a very low chance of hitting a timeout anyway, we can
* bounce the nodes to their right place when we scan the tree if we encounter
* a misplaced node once in a while. This even allows us not to remove the
* infinite timers from the wait queue.
*
* So, to summarize, we have :
* - node->key always defines current position in the wait queue
* - timer is the real expiration date (possibly infinite)
* - node->key is always before or equal to timer
*
* The run queue works similarly to the wait queue except that the current date
* is replaced by an insertion counter which can also wrap without any problem.
*/
/* The farthest we can look back in a timer tree */
#define TIMER_LOOK_BACK (1U << 31)
/* a few exported variables */
extern unsigned int nb_tasks; /* total number of tasks */
extern unsigned int tasks_run_queue; /* run queue size */
extern unsigned int tasks_run_queue_cur;
extern unsigned int nb_tasks_cur;
extern unsigned int niced_tasks; /* number of niced tasks in the run queue */
extern struct pool_head *pool2_task;
extern struct pool_head *pool2_notification;
#ifdef USE_THREAD
extern HA_SPINLOCK_T rq_lock; /* spin lock related to run queue */
extern HA_SPINLOCK_T wq_lock; /* spin lock related to wait queue */
#endif
/* return 0 if task is in run queue, otherwise non-zero */
static inline int task_in_rq(struct task *t)
{
return t->rq.node.leaf_p != NULL;
}
/* return 0 if task is in wait queue, otherwise non-zero */
static inline int task_in_wq(struct task *t)
{
return t->wq.node.leaf_p != NULL;
}
/* puts the task <t> in run queue with reason flags <f>, and returns <t> */
struct task *__task_wakeup(struct task *t);
static inline struct task *task_wakeup(struct task *t, unsigned int f)
{
SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
/* If task is running, we postpone the call
* and backup the state.
*/
if (unlikely(t->state & TASK_RUNNING)) {
t->pending_state |= f;
SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
return t;
}
if (likely(!task_in_rq(t)))
__task_wakeup(t);
t->state |= f;
SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
return t;
}
/* change the thread affinity of a task to <thread_mask> */
static inline void task_set_affinity(struct task *t, unsigned long thread_mask)
{
t->thread_mask = thread_mask;
}
/*
* Unlink the task from the wait queue, and possibly update the last_timer
* pointer. A pointer to the task itself is returned. The task *must* already
* be in the wait queue before calling this function. If unsure, use the safer
* task_unlink_wq() function.
*/
static inline struct task *__task_unlink_wq(struct task *t)
{
eb32_delete(&t->wq);
return t;
}
static inline struct task *task_unlink_wq(struct task *t)
{
SPIN_LOCK(TASK_WQ_LOCK, &wq_lock);
if (likely(task_in_wq(t)))
__task_unlink_wq(t);
SPIN_UNLOCK(TASK_WQ_LOCK, &wq_lock);
return t;
}
/*
* Unlink the task from the run queue. The tasks_run_queue size and number of
* niced tasks are updated too. A pointer to the task itself is returned. The
* task *must* already be in the run queue before calling this function. If
* unsure, use the safer task_unlink_rq() function. Note that the pointer to the
* next run queue entry is neither checked nor updated.
*/
static inline struct task *__task_unlink_rq(struct task *t)
{
eb32_delete(&t->rq);
tasks_run_queue--;
if (likely(t->nice))
niced_tasks--;
return t;
}
/* This function unlinks task <t> from the run queue if it is in it. It also
* takes care of updating the next run queue task if it was this task.
*/
static inline struct task *task_unlink_rq(struct task *t)
{
SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
if (likely(task_in_rq(t)))
__task_unlink_rq(t);
SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
return t;
}
/*
* Unlinks the task and adjusts run queue stats.
* A pointer to the task itself is returned.
*/
static inline struct task *task_delete(struct task *t)
{
task_unlink_wq(t);
task_unlink_rq(t);
return t;
}
/*
* Initialize a new task. The bare minimum is performed (queue pointers and
* state). The task is returned. This function should not be used outside of
* task_new().
*/
static inline struct task *task_init(struct task *t, unsigned long thread_mask)
{
t->wq.node.leaf_p = NULL;
t->rq.node.leaf_p = NULL;
t->pending_state = t->state = TASK_SLEEPING;
t->thread_mask = thread_mask;
t->nice = 0;
t->calls = 0;
t->expire = TICK_ETERNITY;
return t;
}
/*
* Allocate and initialise a new task. The new task is returned, or NULL in
* case of lack of memory. The task count is incremented. Tasks should only
* be allocated this way, and must be freed using task_free().
*/
static inline struct task *task_new(unsigned long thread_mask)
{
struct task *t = pool_alloc2(pool2_task);
if (t) {
HA_ATOMIC_ADD(&nb_tasks, 1);
task_init(t, thread_mask);
}
return t;
}
/*
* Free a task. Its context must have been freed since it will be lost.
* The task count is decremented.
*/
static inline void task_free(struct task *t)
{
pool_free2(pool2_task, t);
if (unlikely(stopping))
pool_flush2(pool2_task);
HA_ATOMIC_SUB(&nb_tasks, 1);
}
/* Place <task> into the wait queue, where it may already be. If the expiration
* timer is infinite, do nothing and rely on wake_expired_task to clean up.
*/
void __task_queue(struct task *task);
static inline void task_queue(struct task *task)
{
/* If we already have a place in the wait queue no later than the
* timeout we're trying to set, we'll stay there, because it is very
* unlikely that we will reach the timeout anyway. If the timeout
* has been disabled, it's useless to leave the queue as well. We'll
* rely on wake_expired_tasks() to catch the node and move it to the
* proper place should it ever happen. Finally we only add the task
* to the queue if it was not there or if it was further than what
* we want.
*/
if (!tick_isset(task->expire))
return;
SPIN_LOCK(TASK_WQ_LOCK, &wq_lock);
if (!task_in_wq(task) || tick_is_lt(task->expire, task->wq.key))
__task_queue(task);
SPIN_UNLOCK(TASK_WQ_LOCK, &wq_lock);
}
/* Ensure <task> will be woken up at most at <when>. If the task is already in
* the run queue (but not running), nothing is done. It may be used that way
* with a delay : task_schedule(task, tick_add(now_ms, delay));
*/
static inline void task_schedule(struct task *task, int when)
{
/* TODO: mthread, check if there is no tisk with this test */
if (task_in_rq(task))
return;
SPIN_LOCK(TASK_WQ_LOCK, &wq_lock);
if (task_in_wq(task))
when = tick_first(when, task->expire);
task->expire = when;
if (!task_in_wq(task) || tick_is_lt(task->expire, task->wq.key))
__task_queue(task);
SPIN_UNLOCK(TASK_WQ_LOCK, &wq_lock);
}
/* This function register a new signal. "lua" is the current lua
* execution context. It contains a pointer to the associated task.
* "link" is a list head attached to an other task that must be wake
* the lua task if an event occurs. This is useful with external
* events like TCP I/O or sleep functions. This funcion allocate
* memory for the signal.
*/
static inline struct notification *notification_new(struct list *purge, struct list *event, struct task *wakeup)
{
struct notification *com = pool_alloc2(pool2_notification);
if (!com)
return NULL;
LIST_ADDQ(purge, &com->purge_me);
LIST_ADDQ(event, &com->wake_me);
SPIN_INIT(&com->lock);
com->task = wakeup;
return com;
}
/* This function purge all the pending signals when the LUA execution
* is finished. This prevent than a coprocess try to wake a deleted
* task. This function remove the memory associated to the signal.
*/
static inline void notification_purge(struct list *purge)
{
struct notification *com, *back;
/* Delete all pending communication signals. */
list_for_each_entry_safe(com, back, purge, purge_me) {
SPIN_LOCK(NOTIF_LOCK, &com->lock);
LIST_DEL(&com->purge_me);
if (!com->task) {
SPIN_UNLOCK(NOTIF_LOCK, &com->lock);
pool_free2(pool2_notification, com);
continue;
}
com->task = NULL;
SPIN_UNLOCK(NOTIF_LOCK, &com->lock);
}
}
/* This function sends signals. It wakes all the tasks attached
* to a list head, and remove the signal, and free the used
* memory.
*/
static inline void notification_wake(struct list *wake)
{
struct notification *com, *back;
/* Wake task and delete all pending communication signals. */
list_for_each_entry_safe(com, back, wake, wake_me) {
SPIN_LOCK(NOTIF_LOCK, &com->lock);
LIST_DEL(&com->wake_me);
if (!com->task) {
SPIN_UNLOCK(NOTIF_LOCK, &com->lock);
pool_free2(pool2_notification, com);
continue;
}
task_wakeup(com->task, TASK_WOKEN_MSG);
com->task = NULL;
SPIN_UNLOCK(NOTIF_LOCK, &com->lock);
}
}
/*
* This does 3 things :
* - wake up all expired tasks
* - call all runnable tasks
* - return the date of next event in <next> or eternity.
*/
void process_runnable_tasks();
/*
* 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();
/* Perform minimal initializations, report 0 in case of error, 1 if OK. */
int init_task();
#endif /* _PROTO_TASK_H */
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/