270 lines
8.7 KiB
C
270 lines
8.7 KiB
C
/****************************************************************************
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* libc/wqueue/work_process.c
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*
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* Copyright (C) 2009-2014, 2016 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <unistd.h>
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#include <signal.h>
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#include <assert.h>
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#include <queue.h>
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#include <nuttx/irq.h>
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#include <nuttx/clock.h>
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#include <nuttx/wqueue.h>
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#include "wqueue/wqueue.h"
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#ifdef CONFIG_SCHED_WORKQUEUE
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* Use CLOCK_MONOTONIC if it is available. CLOCK_REALTIME can cause bad
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* delays if the time is changed.
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*/
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#ifdef CONFIG_CLOCK_MONOTONIC
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# define WORK_CLOCK CLOCK_MONOTONIC
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#else
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# define WORK_CLOCK CLOCK_REALTIME
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#endif
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#ifndef MIN
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# define MIN(a,b) ((a) < (b) ? (a) : (b))
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#endif
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: work_process
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*
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* Description:
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* This is the logic that performs actions placed on any work list. This
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* logic is the common underlying logic to all work queues. This logic is
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* part of the internal implementation of each work queue; it should not
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* be called from application level logic.
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*
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* Input parameters:
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* wqueue - Describes the work queue to be processed
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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void work_process(FAR struct kwork_wqueue_s *wqueue, systime_t period, int wndx)
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{
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volatile FAR struct work_s *work;
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worker_t worker;
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irqstate_t flags;
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FAR void *arg;
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systime_t elapsed;
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systime_t remaining;
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systime_t stick;
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systime_t ctick;
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systime_t next;
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/* Then process queued work. We need to keep interrupts disabled while
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* we process items in the work list.
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*/
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next = period;
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flags = enter_critical_section();
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/* Get the time that we started this polling cycle in clock ticks. */
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stick = clock_systimer();
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/* And check each entry in the work queue. Since we have disabled
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* interrupts we know: (1) we will not be suspended unless we do
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* so ourselves, and (2) there will be no changes to the work queue
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*/
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work = (FAR struct work_s *)wqueue->q.head;
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while (work)
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{
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/* Is this work ready? It is ready if there is no delay or if
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* the delay has elapsed. qtime is the time that the work was added
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* to the work queue. It will always be greater than or equal to
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* zero. Therefore a delay of zero will always execute immediately.
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*/
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ctick = clock_systimer();
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elapsed = ctick - work->qtime;
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if (elapsed >= work->delay)
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{
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/* Remove the ready-to-execute work from the list */
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(void)dq_rem((struct dq_entry_s *)work, &wqueue->q);
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/* Extract the work description from the entry (in case the work
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* instance by the re-used after it has been de-queued).
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*/
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worker = work->worker;
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/* Check for a race condition where the work may be nullified
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* before it is removed from the queue.
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*/
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if (worker != NULL)
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{
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/* Extract the work argument (before re-enabling interrupts) */
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arg = work->arg;
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/* Mark the work as no longer being queued */
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work->worker = NULL;
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/* Do the work. Re-enable interrupts while the work is being
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* performed... we don't have any idea how long this will take!
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*/
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leave_critical_section(flags);
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worker(arg);
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/* Now, unfortunately, since we re-enabled interrupts we don't
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* know the state of the work list and we will have to start
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* back at the head of the list.
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*/
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flags = enter_critical_section();
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work = (FAR struct work_s *)wqueue->q.head;
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}
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else
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{
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/* Cancelled.. Just move to the next work in the list with
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* interrupts still disabled.
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*/
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work = (FAR struct work_s *)work->dq.flink;
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}
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}
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else /* elapsed < work->delay */
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{
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/* This one is not ready.
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*
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* NOTE that elapsed is relative to the the current time,
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* not the time of beginning of this queue processing pass.
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* So it may need an adjustment.
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*/
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elapsed += (ctick - stick);
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if (elapsed > work->delay)
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{
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/* The delay has expired while we are processing */
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elapsed = work->delay;
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}
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/* Will it be ready before the next scheduled wakeup interval? */
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remaining = work->delay - elapsed;
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if (remaining < next)
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{
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/* Yes.. Then schedule to wake up when the work is ready */
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next = remaining;
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}
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/* Then try the next in the list. */
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work = (FAR struct work_s *)work->dq.flink;
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}
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}
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#if defined(CONFIG_SCHED_LPWORK) && CONFIG_SCHED_LPNTHREADS > 0
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/* Value of zero for period means that we should wait indefinitely until
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* signalled. This option is used only for the case where there are
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* multiple, low-priority worker threads. In that case, only one of
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* the threads does the poll... the others simple. In all other cases
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* period will be non-zero and equal to wqueue->delay.
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*/
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if (period == 0)
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{
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sigset_t set;
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/* Wait indefinitely until signalled with SIGWORK */
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sigemptyset(&set);
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sigaddset(&set, SIGWORK);
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wqueue->worker[wndx].busy = false;
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DEBUGVERIFY(sigwaitinfo(&set, NULL));
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wqueue->worker[wndx].busy = true;
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}
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else
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#endif
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{
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/* Get the delay (in clock ticks) since we started the sampling */
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elapsed = clock_systimer() - stick;
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if (elapsed < period && next > 0)
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{
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/* How much time would we need to delay to get to the end of the
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* sampling period? The amount of time we delay should be the smaller
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* of the time to the end of the sampling period and the time to the
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* next work expiry.
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*/
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remaining = period - elapsed;
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next = MIN(next, remaining);
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/* Wait awhile to check the work list. We will wait here until
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* either the time elapses or until we are awakened by a signal.
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* Interrupts will be re-enabled while we wait.
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*/
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wqueue->worker[wndx].busy = false;
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usleep(next * USEC_PER_TICK);
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wqueue->worker[wndx].busy = true;
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}
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}
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leave_critical_section(flags);
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}
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#endif /* CONFIG_SCHED_WORKQUEUE */
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