/**************************************************************************** * libc/wqueue/work_usrthread.c * * Copyright (C) 2009-2017 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 #include "wqueue/wqueue.h" #if defined(CONFIG_LIB_USRWORK) && !defined(__KERNEL__) /**************************************************************************** * 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 ****************************************************************************/ /* The state of the user mode work queue. */ struct usr_wqueue_s g_usrwork; /* This semaphore supports exclusive access to the user-mode work queue */ #ifdef CONFIG_BUILD_PROTECTED sem_t g_usrsem; #else pthread_mutex_t g_usrmutex; #endif /**************************************************************************** * Private 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 usr_wqueue_s *wqueue) { volatile FAR struct work_s *work; worker_t worker; FAR void *arg; systime_t elapsed; systime_t remaining; systime_t stick; systime_t ctick; systime_t next; int ret; /* Then process queued work. Lock the work queue while we process items * in the work list. */ next = wqueue->delay; ret = work_lock(); if (ret < 0) { /* Break out earlier if we were awakened by a signal */ return; } /* 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 locked the * work queue 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 unlocking the work queue) */ arg = work->arg; /* Mark the work as no longer being queued */ work->worker = NULL; /* Do the work. Unlock the work queue while the work is being * performed... we don't have any idea how long this will take! */ work_unlock(); worker(arg); /* Now, unfortunately, since we unlocked the work queue we don't * know the state of the work list and we will have to start * back at the head of the list. */ ret = work_lock(); if (ret < 0) { /* Break out earlier if we were awakened by a signal */ return; } work = (FAR struct work_s *)wqueue->q.head; } else { /* Cancelled.. Just move to the next work in the list with * the work queue still locked. */ 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; } } /* Get the delay (in clock ticks) since we started the sampling */ elapsed = clock_systimer() - stick; if (elapsed < wqueue->delay && next > 0) { /* How must 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 = wqueue->delay - 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. */ usleep(next * USEC_PER_TICK); } work_unlock(); } /**************************************************************************** * Name: work_usrthread * * Description: * This is the worker thread that performs the actions placed on the user * work queue. * * This is a user mode work queue. It must be used by applications for * miscellaneous operations. The user work thread must be started by * application start-up logic by calling work_usrstart(). * * Input Parameters: * argc, argv (not used) * * Returned Value: * Does not return * ****************************************************************************/ #ifdef CONFIG_BUILD_PROTECTED static int work_usrthread(int argc, char *argv[]) #else static pthread_addr_t work_usrthread(pthread_addr_t arg) #endif { /* Loop forever */ for (; ; ) { /* Then process queued work. We need to keep the work queue locked * while we process items in the work list. */ work_process(&g_usrwork); } #ifdef CONFIG_BUILD_PROTECTED return OK; /* To keep some compilers happy */ #else return NULL; /* To keep some compilers happy */ #endif } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: work_usrstart * * Description: * Start the user mode work queue. * * Input Parameters: * None * * Returned Value: * The task ID of the worker thread is returned on success. A negated * errno value is returned on failure. * ****************************************************************************/ int work_usrstart(void) { /* Initialize work queue data structures */ g_usrwork.delay = CONFIG_LIB_USRWORKPERIOD / USEC_PER_TICK; dq_init(&g_usrwork.q); #ifdef CONFIG_BUILD_PROTECTED { /* Set up the work queue lock */ (void)nxsem_init(&g_usrsem, 0, 1); /* Start a user-mode worker thread for use by applications. */ g_usrwork.pid = task_create("uwork", CONFIG_LIB_USRWORKPRIORITY, CONFIG_LIB_USRWORKSTACKSIZE, (main_t)work_usrthread, (FAR char * const *)NULL); DEBUGASSERT(g_usrwork.pid > 0); if (g_usrwork.pid < 0) { int errcode = get_errno(); DEBUGASSERT(errcode > 0); return -errcode; } return g_usrwork.pid; } #else { pthread_t usrwork; pthread_attr_t attr; struct sched_param param; int ret; /* Set up the work queue lock */ (void)pthread_mutex_init(&g_usrmutex, NULL); /* Start a user-mode worker thread for use by applications. */ (void)pthread_attr_init(&attr); (void)pthread_attr_setstacksize(&attr, CONFIG_LIB_USRWORKSTACKSIZE); #ifdef CONFIG_SCHED_SPORADIC /* Get the current sporadic scheduling parameters. Those will not be * modified. */ ret = set_getparam(pid, ¶m); if (ret < 0) { int erroode = get_errno(); return -errcode; } #endif param.sched_priority = CONFIG_LIB_USRWORKPRIORITY; (void)pthread_attr_setschedparam(&attr, ¶m); ret = pthread_create(&usrwork, &attr, work_usrthread, NULL); if (ret != 0) { return -ret; } /* Detach because the return value and completion status will not be * requested. */ (void)pthread_detach(usrwork); g_usrwork.pid = (pid_t)usrwork; return g_usrwork.pid; } #endif } #endif /* CONFIG_LIB_USRWORK && !__KERNEL__*/