/****************************************************************************
* libc/wqueue/work_process.c
*
* Copyright (C) 2009-2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <unistd.h>
#include <signal.h>
#include <assert.h>
#include <queue.h>
#include <nuttx/clock.h>
#include <nuttx/wqueue.h>
#include <arch/irq.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
#ifndef MIN
# define MIN(a,b) ((a) < (b) ? (a) : (b))
#endif
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* 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, uint32_t period, int wndx)
{
volatile FAR struct work_s *work;
worker_t worker;
irqstate_t flags;
FAR void *arg;
uint32_t elapsed;
uint32_t remaining;
uint32_t stick;
uint32_t ctick;
uint32_t next;
/* Then process queued work. We need to keep interrupts disabled while
* we process items in the work list.
*/
next = period;
flags = irqsave();
/* Get the time that we started this polling cycle in clock ticks. */
stick = clock_systimer();
/* 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)
{
/* 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_systimer();
elapsed = ctick - work->qtime;
if (elapsed >= work->delay)
{
/* Remove the ready-to-execute work from the list */
(void)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!
*/
irqrestore(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 = irqsave();
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 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;
}
}
#if defined(CONFIG_SCHED_LPWORK) && CONFIG_SCHED_LPNTHREADS > 0
/* Value of zero for period means that we should wait indefinitely until
* signalled. This option is used only for the case where there are
* multiple, low-priority worker threads. In that case, only one of
* the threads does the poll... the others simple. In all other cases
* period will be non-zero and equal to wqueue->delay.
*/
if (period == 0)
{
sigset_t set;
/* Wait indefinitely until signalled with SIGWORK */
sigemptyset(&set);
sigaddset(&set, SIGWORK);
wqueue->worker[wndx].busy = false;
DEBUGVERIFY(sigwaitinfo(&set, NULL));
wqueue->worker[wndx].busy = true;
}
else
#endif
{
/* Get the delay (in clock ticks) since we started the sampling */
elapsed = clock_systimer() - stick;
if (elapsed < period && next > 0)
{
/* How much time would we need to delay to get to the end of the
* sampling period? The amount of time we delay should be the smaller
* of the time to the end of the sampling period and the time to the
* next work expiry.
*/
remaining = period - elapsed;
next = MIN(next, remaining);
/* Wait awhile 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;
usleep(next * USEC_PER_TICK);
wqueue->worker[wndx].busy = true;
}
}
irqrestore(flags);
}
#endif /* CONFIG_SCHED_WORKQUEUE */