/**************************************************************************** * sched/work_thread.c * * Copyright (C) 2009-2011 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include #include #include #include #include #include #include #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 */