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incubator-nuttx/sched/mq_timedsend.c

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/****************************************************************************
* sched/mq_timedsend.c
*
* Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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 <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <unistd.h>
#include <mqueue.h>
#include <wdog.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/arch.h>
#include "clock_internal.h"
#include "os_internal.h"
#include "mq_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Function: mq_sndtimeout
*
* Description:
* This function is called if the timeout elapses before the message queue
* becomes non-full.
*
* Parameters:
* argc - the number of arguments (should be 1)
* pid - the task ID of the task to wakeup
*
* Return Value:
* None
*
* Assumptions:
*
****************************************************************************/
static void mq_sndtimeout(int argc, uint32_t pid)
{
FAR _TCB *wtcb;
irqstate_t saved_state;
/* Disable interrupts. This is necessary because an
* interrupt handler may attempt to send a message while we are
* doing this.
*/
saved_state = irqsave();
/* Get the TCB associated with this pid. It is possible that
* task may no longer be active when this watchdog goes off.
*/
wtcb = sched_gettcb((pid_t)pid);
/* It is also possible that an interrupt/context switch beat us to the
* punch and already changed the task's state.
*/
if (wtcb && wtcb->task_state == TSTATE_WAIT_MQNOTFULL)
{
/* Mark the errno value for the thread. */
wtcb->pterrno = ETIMEDOUT;
/* Restart the task. */
up_unblock_task(wtcb);
}
/* Interrupts may now be enabled. */
irqrestore(saved_state);
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Function: mq_send
*
* Description:
* This function adds the specificied message (msg) to the message queue
* (mqdes). The "msglen" parameter specifies the length of the message
* in bytes pointed to by "msg." This length must not exceed the maximum
* message length from the mq_getattr().
*
* If the message queue is not full, mq_timedsend() place the message in the
* message queue at the position indicated by the "prio" argrument.
* Messages with higher priority will be inserted before lower priority
* messages. The value of "prio" must not exceed MQ_PRIO_MAX.
*
* If the specified message queue is full and O_NONBLOCK is not set in the
* message queue, then mq_timedsend() will block until space becomes available
* to the queue the message or a timeout occurs.
*
* mq_timedsend() behaves just like mq_send(), except that if the queue
* is full and the O_NONBLOCK flag is not enabled for the message queue
* description, then abstime points to a structure which specifies a
* ceiling on the time for which the call will block. This ceiling is an
* absolute timeout in seconds and nanoseconds since the Epoch (midnight
* on the morning of 1 January 1970).
*
* If the message queue is full, and the timeout has already expired by
* the time of the call, mq_timedsend() returns immediately.
*
* Parameters:
* mqdes - Message queue descriptor
* msg - Message to send
* msglen - The length of the message in bytes
* prio - The priority of the message
* abstime - the absolute time to wait until a timeout is decleared
*
* Return Value:
* On success, mq_send() returns 0 (OK); on error, -1 (ERROR)
* is returned, with errno set to indicate the error:
*
* EAGAIN The queue was empty, and the O_NONBLOCK flag was set for the
* message queue description referred to by mqdes.
* EINVAL Either msg or mqdes is NULL or the value of prio is invalid.
* EPERM Message queue opened not opened for writing.
* EMSGSIZE 'msglen' was greater than the maxmsgsize attribute of the
* message queue.
* EINTR The call was interrupted by a signal handler.
*
* Assumptions/restrictions:
*
****************************************************************************/
int mq_timedsend(mqd_t mqdes, const char *msg, size_t msglen, int prio,
const struct timespec *abstime)
{
WDOG_ID wdog;
FAR msgq_t *msgq;
FAR mqmsg_t *mqmsg = NULL;
irqstate_t saved_state;
int ret = ERROR;
DEBUGASSERT(up_interrupt_context() == false);
/* Verify the input parameters -- setting errno appropriately
* on any failures to verify.
*/
if (mq_verifysend(mqdes, msg, msglen, prio) != OK)
{
return ERROR;
}
if (!abstime || abstime->tv_sec < 0 || abstime->tv_nsec > 1000000000)
{
*get_errno_ptr() = EINVAL;
return ERROR;
}
/* Get a pointer to the message queue */
msgq = mqdes->msgq;
/* Create a watchdog. We will not actually need this watchdog
* unless the queue is full, but we will reserve it up front
* before we enter the following critical section.
*/
wdog = wd_create();
if (!wdog)
{
*get_errno_ptr() = EINVAL;
return ERROR;
}
/* Allocate a message structure:
* - If we are called from an interrupt handler, or
* - If the message queue is not full, or
*/
sched_lock();
saved_state = irqsave();
if (up_interrupt_context() || /* In an interrupt handler */
msgq->nmsgs < msgq->maxmsgs) /* OR Message queue not full */
{
/* Allocate the message */
irqrestore(saved_state);
mqmsg = mq_msgalloc();
}
else
{
int ticks;
/* We are not in an interupt handler and the message queue is full.
* set up a timed wait for the message queue to become non-full.
*
* Convert the timespec to clock ticks. We must have interrupts
* disabled here so that this time stays valid until the wait begins.
*/
int result = clock_abstime2ticks(CLOCK_REALTIME, abstime, &ticks);
/* If the time has already expired and the message queue is empty,
* return immediately.
*/
if (result == OK && ticks <= 0)
{
result = ETIMEDOUT;
}
/* Handle any time-related errors */
if (result != OK)
{
*get_errno_ptr() = result;
ret = ERROR;
}
/* Start the watchdog and begin the wait for MQ not full */
if (result == OK)
{
/* Start the watchdog */
wd_start(wdog, ticks, (wdentry_t)mq_sndtimeout, 1, getpid());
/* And wait for the message queue to be non-empty */
ret = mq_waitsend(mqdes);
/* This may return with an error and errno set to either EINTR
* or ETIMEOUT. Cancel the watchdog timer in any event.
*/
wd_cancel(wdog);
}
/* That is the end of the atomic operations */
irqrestore(saved_state);
/* If any of the above failed, set the errno. Otherwise, there should
* be space for another message in the message queue. NOW we can allocate
* the message structure.
*/
if (ret == OK)
{
mqmsg = mq_msgalloc();
}
}
/* Check if we were able to get a message structure -- this can fail
* either because we cannot send the message (and didn't bother trying
* to allocate it) or because the allocation failed.
*/
if (mqmsg)
{
/* Yes, peform the message send. */
ret = mq_dosend(mqdes, mqmsg, msg, msglen, prio);
}
sched_unlock();
wd_delete(wdog);
return ret;
}
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