Standard C Library Functions mq_send(3C)
NAME
mq_send, mq_timedsend, mq_reltimedsend_np - send a message
to a message queueSYNOPSIS
#include
int mq_send(mqd_t mqdes, const char *msg_ptr, size_t msg_len,
unsigned msg_prio);
#include
#include
int mq_timedsend(mqd_t mqdes, const char *msg_ptr,
size_t msg_len, unsigned msg_prio,
const struct timespec *restrict abs_timeout);
int mq_reltimedsend_np(mqd_t mqdes, const char *msg_ptr,
size_t msg_len, unsigned msg_prio,
const struct timespec *restrict rel_timeout);
DESCRIPTION
The mq_send() function adds the message pointed to by the
argument msg_ptr to the message queue specified by mqdes.
The msg_len argument specifies the length of the message in
bytes pointed to by msg_ptr. The value of msg_len is less
than or equal to the mq_msgsize attribute of the message
queue, or mq_send() fails.
If the specified message queue is not full, mq_send()
behaves as if the message is inserted into the message queueat the position indicated by the msg_prio argument. A mes-
sage with a larger numeric value of msg_prio is inserted
before messages with lower values of msg_prio. A message
will be inserted after other messages in the queue, if any,with equal msg_prio. The value of msg_prio must be greater
than zero and less than or equal to MQ_PRIO_MAX.
If the specified message queue is full and O_NONBLOCK is not
set in the message queue description associated with mqdes(see mq_open(3C) and mq_setattr(3C)), mq_send() blocks until
space becomes available to enqueue the message, or untilmq_send() is interrupted by a signal. If more than one
thread is waiting to send when space becomes available in the message queue, then the thread of the highest priority which has been waiting the longest is unblocked to send its message. Otherwise, it is unspecified which waiting threadSunOS 5.11 Last change: 5 Feb 2008 1
Standard C Library Functions mq_send(3C)
is unblocked. If the specified message queue is full andO_NONBLOCK is set in the message queue description associ-
ated with mqdes, the message is not queued and mq_send()
returns an error.The mq_timedsend() function adds a message to the message
queue specified by mqdes in the manner defined for themq_send() function. However, if the specified message queue
is full and O_NONBLOCK is not set in the message queue
description associated with mqdes, the wait for sufficient room in the queue is terminated when the specified timeoutexpires. If O_NONBLOCK is set in the message queue descrip-
tion, this function is equivalent to mq_send().
The mq_reltimedsend_np() function is identical to the
mq_timedsend() function, except that the timeout is speci-
fied as a relative time interval.For mq_timedsend(), the timeout expires when the absolute
time specified by abs_timeout passes, as measured by the
CLOCK_REALTIME clock (that is, when the value of that clock
equals or exceeds abs_timeout), or if the absolute time
specified by abs_timeout has already been passed at the time
of the call.For mq_reltimedsend_np(), the timeout expires when the time
interval specified by rel_timeout passes, as measured by the
CLOCK_REALTIME clock, or if the time interval specified by
rel_timeout is negative at the time of the call.
The resolution of the timeout is the resolution of theCLOCK_REALTIME clock. The timespec argument is defined in
theheader. Under no circumstance does the operation fail with a timeout if there is sufficient room in the queue to add the message immediately. The validity of the timeout parameter need not be checked when there is sufficient room in the queue. RETURN VALUES
Upon successful completion, mq_send(), mq_timedsend(), and
mq_reltimedsend_np() return 0. Otherwise, no message is
enqueued, the functions return -1, and errno is set to indi-
cate the error.SunOS 5.11 Last change: 5 Feb 2008 2
Standard C Library Functions mq_send(3C)
ERRORS
The mq_send(), mq_timedsend(), and mq_reltimedsend_np()
functions will fail if:EAGAIN The O_NONBLOCK flag is set in the message
queue description associated with mqdes, and the specified message queue is full. EBADF The mqdes argument is not a valid message queue descriptor open for writing. EINTR A signal interrupted the function call.EINVAL The value of msg_prio was outside the valid
range. EINVAL The process or thread would have blocked, and the timeout parameter specified a nanoseconds field value less than zero or greater than or equal to 1,000 million.EMSGSIZE The specified message length, msg_len, exceeds
the message size attribute of the message queue.ETIMEDOUT The O_NONBLOCK flag was not set when the mes-
sage queue was opened, but the timeout expired before the message could be added to the queue.ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:SunOS 5.11 Last change: 5 Feb 2008 3
Standard C Library Functions mq_send(3C)
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| MT-Level | MT-Safe |
|_____________________________|_____________________________|
| Standard | See below. ||_____________________________|_____________________________|
For mq_send() and mq_timedsend(), see standards(5).
SEE ALSO
sysconf(3C), mqueue.h(3HEAD), mq_open(3C), mq_receive(3C),
mq_setattr(3C), attributes(5), standards(5)
SunOS 5.11 Last change: 5 Feb 2008 4