/****************************************************************************
* sched/work_thread.c
*
* Copyright (C) 2009-2011 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 <queue.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/arch.h>
#include <nuttx/wqueue.h>
#include <nuttx/clock.h>
#include "os_internal.h"
#include "work_internal.h"
#ifdef CONFIG_SCHED_WORKQUEUE
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Public Variables
****************************************************************************/
/* The queue of pending work */
struct dq_queue_s g_work;
/* The task ID of the worker thread */
#ifdef CONFIG_SCHED_WORKQUEUE
pid_t g_worker;
#endif
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: work_thread
*
* Description:
* This is the main worker thread that performs actions placed on the work
* list. It also performs periodic garbage collection (that is performed
* by the idle thread if CONFIG_SCHED_WORKQUEUE is not defined).
*
* Input parameters:
* argc, argv (not used)
*
* Returned Value:
* Does not return
*
****************************************************************************/
int work_thread(int argc, char *argv[])
{
volatile FAR struct work_s *work;
worker_t worker;
FAR void *arg;
uint32_t elapsed;
uint32_t remaining;
uint32_t next;
int usec;
irqstate_t flags;
/* Loop forever */
usec = CONFIG_SCHED_WORKPERIOD;
flags = irqsave();
for (;;)
{
/* Wait awhile to check the work list. We will wait here until either
* the time elapses or until we are awakened by a signal.
*/
usleep(usec);
irqrestore(flags);
/* First, perform garbage collection. This cleans-up memory de-allocations
* that were queued because they could not be freed in that execution
* context (for example, if the memory was freed from an interrupt handler).
* NOTE: If the work thread is disabled, this clean-up is performed by
* the IDLE thread (at a very, very lower priority).
*/
sched_garbagecollection();
/* Then process queued work. We need to keep interrupts disabled while
* we process items in the work list.
*/
next = CONFIG_SCHED_WORKPERIOD / USEC_PER_TICK;
flags = irqsave();
work = (FAR struct work_s *)g_work.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.
*/
elapsed = clock_systimer() - work->qtime;
if (elapsed >= work->delay)
{
/* Remove the ready-to-execute work from the list */
(void)dq_rem((struct dq_entry_s *)work, &g_work);
/* 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;
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 that 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 *)g_work.head;
}
else
{
/* This one is not ready.. will it be ready before the next
* scheduled wakeup interval?
*/
remaining = elapsed - work->delay;
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;
}
}
/* Now calculate the microsecond delay we should wait */
usec = next * USEC_PER_TICK;
}
return OK; /* To keep some compilers happy */
}
#endif /* CONFIG_SCHED_WORKQUEUE */
