incubator-nuttx/sched/wqueue/kwork_process.c

247 lines
7.5 KiB
C

/****************************************************************************
* sched/wqueue/kwork_process.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <unistd.h>
#include <signal.h>
#include <assert.h>
#include <queue.h>
#include <nuttx/irq.h>
#include <nuttx/clock.h>
#include <nuttx/signal.h>
#include <nuttx/wqueue.h>
#include "wqueue/wqueue.h"
#ifdef CONFIG_SCHED_WORKQUEUE
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Use CLOCK_MONOTONIC if it is available. CLOCK_REALTIME can cause bad
* delays if the time is changed.
*/
#ifdef CONFIG_CLOCK_MONOTONIC
# define WORK_CLOCK CLOCK_MONOTONIC
#else
# define WORK_CLOCK CLOCK_REALTIME
#endif
#ifdef CONFIG_SYSTEM_TIME64
# define WORK_DELAY_MAX UINT64_MAX
#else
# define WORK_DELAY_MAX UINT32_MAX
#endif
#ifndef MIN
# define MIN(a,b) ((a) < (b) ? (a) : (b))
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: work_process
*
* Description:
* This is the logic that performs actions placed on any work list. This
* logic is the common underlying logic to all work queues. This logic is
* part of the internal implementation of each work queue; it should not
* be called from application level logic.
*
* Input Parameters:
* wqueue - Describes the work queue to be processed
*
* Returned Value:
* None
*
****************************************************************************/
void work_process(FAR struct kwork_wqueue_s *wqueue, int wndx)
{
volatile FAR struct work_s *work;
worker_t worker;
irqstate_t flags;
FAR void *arg;
clock_t elapsed;
clock_t remaining;
clock_t stick;
clock_t ctick;
clock_t next;
/* Then process queued work. We need to keep interrupts disabled while
* we process items in the work list.
*/
next = WORK_DELAY_MAX;
flags = enter_critical_section();
/* Get the time that we started processing the queue in clock ticks. */
stick = clock_systime_ticks();
/* And check each entry in the work queue. Since we have disabled
* interrupts we know: (1) we will not be suspended unless we do
* so ourselves, and (2) there will be no changes to the work queue
*/
work = (FAR struct work_s *)wqueue->q.head;
while (work != NULL)
{
/* Is this work ready? It is ready if there is no delay or if
* the delay has elapsed. qtime is the time that the work was added
* to the work queue. It will always be greater than or equal to
* zero. Therefore a delay of zero will always execute immediately.
*/
ctick = clock_systime_ticks();
elapsed = ctick - work->qtime;
if (elapsed >= work->delay)
{
/* Remove the ready-to-execute work from the list */
dq_rem((struct dq_entry_s *)work, &wqueue->q);
/* Extract the work description from the entry (in case the work
* instance by the re-used after it has been de-queued).
*/
worker = work->worker;
/* Check for a race condition where the work may be nullified
* before it is removed from the queue.
*/
if (worker != NULL)
{
/* Extract the work argument (before re-enabling interrupts) */
arg = work->arg;
/* Mark the work as no longer being queued */
work->worker = NULL;
/* Do the work. Re-enable interrupts while the work is being
* performed... we don't have any idea how long this will take!
*/
leave_critical_section(flags);
worker(arg);
/* Now, unfortunately, since we re-enabled interrupts we don't
* know the state of the work list and we will have to start
* back at the head of the list.
*/
flags = enter_critical_section();
work = (FAR struct work_s *)wqueue->q.head;
}
else
{
/* Cancelled.. Just move to the next work in the list with
* interrupts still disabled.
*/
work = (FAR struct work_s *)work->dq.flink;
}
}
else /* elapsed < work->delay */
{
/* This one is not ready.
*
* NOTE that elapsed is relative to the current time,
* not the time of beginning of this queue processing pass.
* So it may need an adjustment.
*/
elapsed += (ctick - stick);
if (elapsed > work->delay)
{
/* The delay has expired while we are processing */
elapsed = work->delay;
}
/* Will it be ready before the next scheduled wakeup interval? */
remaining = work->delay - elapsed;
if (remaining < next)
{
/* Yes.. Then schedule to wake up when the work is ready */
next = remaining;
}
/* Then try the next in the list. */
work = (FAR struct work_s *)work->dq.flink;
}
}
/* When multiple worker threads are created for this work queue, only
* thread 0 (wndx = 0) will monitor the unexpired works.
*
* Other worker threads (wndx > 0) just process no-delay or expired
* works, then sleep. The unexpired works are left in the queue. They
* will be handled by thread 0 when it finishes current work and iterate
* over the queue again.
*/
if (wndx > 0 || next == WORK_DELAY_MAX)
{
sigset_t set;
/* Wait indefinitely until signalled with SIGWORK */
sigemptyset(&set);
nxsig_addset(&set, SIGWORK);
wqueue->worker[wndx].busy = false;
DEBUGVERIFY(nxsig_waitinfo(&set, NULL));
wqueue->worker[wndx].busy = true;
}
else
{
/* Wait a while to check the work list. We will wait here until
* either the time elapses or until we are awakened by a signal.
* Interrupts will be re-enabled while we wait.
*/
wqueue->worker[wndx].busy = false;
nxsig_usleep(next * USEC_PER_TICK);
wqueue->worker[wndx].busy = true;
}
leave_critical_section(flags);
}
#endif /* CONFIG_SCHED_WORKQUEUE */