2 .\" Hey Emacs! This file is -*- nroff -*- source.
4 .\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
6 .\" Permission is granted to make and distribute verbatim copies of this
7 .\" manual provided the copyright notice and this permission notice are
8 .\" preserved on all copies.
10 .\" Permission is granted to copy and distribute modified versions of this
11 .\" manual under the conditions for verbatim copying, provided that the
12 .\" entire resulting derived work is distributed under the terms of a
13 .\" permission notice identical to this one.
15 .\" Since the Linux kernel and libraries are constantly changing, this
16 .\" manual page may be incorrect or out-of-date. The author(s) assume no
17 .\" responsibility for errors or omissions, or for damages resulting from
18 .\" the use of the information contained herein. The author(s) may not
19 .\" have taken the same level of care in the production of this manual,
20 .\" which is licensed free of charge, as they might when working
23 .\" Formatted or processed versions of this manual, if unaccompanied by
24 .\" the source, must acknowledge the copyright and authors of this work.
26 .\" Japanese Version Copyright (c) 2006 Akihiro MOTOKI all rights reserved.
27 .\" Translated 2006-07-31, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
28 .\" Updated 2010-04-18, Akihiro MOTOKI, LDP v3.24
30 .TH MQ_NOTIFY 3 2009-09-15 "Linux" "Linux Programmer's Manual"
33 .\"O mq_notify \- register for notification when a message is available
34 mq_notify \- ¥á¥Ã¥»¡¼¥¸ÅþÃå»þ¤ËÄÌÃΤò¹Ô¤¦¤è¤¦ÅÐÏ¿¤¹¤ë
38 .B #include <mqueue.h>
40 .BI "mqd_t mq_notify(mqd_t " mqdes ", const struct sigevent *" notification );
43 .\"O Link with \fI\-lrt\fP.
44 \fI\-lrt\fP ¤Ç¥ê¥ó¥¯¤¹¤ë¡£
48 .\"O allows the calling process to register or unregister for delivery of
49 .\"O an asynchronous notification when a new message arrives on
50 .\"O the empty message queue referred to by the descriptor
53 ¤ò»È¤¦¤È¡¢¥Ç¥£¥¹¥¯¥ê¥×¥¿
55 ¤Ç»²¾È¤µ¤ì¤ë¶õ¤Î¥á¥Ã¥»¡¼¥¸¥¥å¡¼¤Ë¿·¤·¤¯¥á¥Ã¥»¡¼¥¸¤¬ÅþÃ夷¤¿»þ¤Ë
56 ÈóƱ´ü¤ÎÄÌÃÎ (notification) ¤ÎÇÛÁ÷¤¬¹Ô¤ï¤ì¤ë¤è¤¦¤ËÅÐÏ¿¤·¤¿¤ê¡¢
57 ¤½¤Î²ò½ü¤ò¹Ô¤Ã¤¿¤ê¤Ç¤¤ë¡£
61 .\"O argument is a pointer to a
63 .\"O structure that is defined something like the following:
67 ¹½Â¤ÂΤؤΥݥ¤¥ó¥¿¤Ç¤¢¤ë¡£
69 ¹½Â¤ÂΤϰʲ¼¤Î¤è¤¦¤Ê´¶¤¸¤ÇÄêµÁ¤µ¤ì¤Æ¤¤¤ë:
73 union sigval { /* Data passed with notification */
74 int sival_int; /* Integer value */
75 void *sival_ptr; /* Pointer value */
79 int sigev_notify; /* Notification method */
80 int sigev_signo; /* Notification signal */
81 union sigval sigev_value; /* Data passed with
83 void (*sigev_notify_function) (union sigval);
84 /* Function for thread
86 void *sigev_notify_attributes;
87 /* Thread function attributes */
94 .\"O is a non-NULL pointer, then
96 .\"O registers the calling process to receive message notification.
98 ¤¬ NULL ¤Ç¤Ê¤¤¥Ý¥¤¥ó¥¿¤Ç¤¢¤ì¤Ð¡¢
100 ¤Ï¥á¥Ã¥»¡¼¥¸ÄÌÃΤò¼õ¤±¼è¤ë¤è¤¦¤Ë¸Æ¤Ó½Ð¤·¸µ¤Î¥×¥í¥»¥¹¤òÅÐÏ¿¤¹¤ë¡£
107 .\"O points specifies how notification is to be performed.
108 .\"O This field has one of the following values:
114 ¥Õ¥£¡¼¥ë¥É¤Ï¡¢¤É¤Î¤è¤¦¤ÊÄÌÃΤò¹Ô¤¦¤Î¤«¤ò»ØÄꤹ¤ë¡£
115 ¤³¤Î¥Õ¥£¡¼¥ë¥É¤Ï°Ê²¼¤ÎÃͤΤ¤¤º¤ì¤«¤ò»ý¤Ä¡£
118 .\"O A "null" notification: the calling process is registered as the target
119 .\"O for notification, but when a message arrives, no notification is sent.
120 ¡Ö¶õ¤Î (null)¡×¤ÎÄÌÃÎ: ¸Æ¤Ó½Ð¤·¸µ¤Î¥×¥í¥»¥¹¤òÄÌÃΤΰ¸Àè¤È¤·¤ÆÅÐÏ¿¤¹¤ë¤¬¡¢
121 ¼ÂºÝ¤Ë¤Ï¥á¥Ã¥»¡¼¥¸¤¬ÅþÃ夷¤¿»þ¤ËÄÌÃΤÏÁ÷¤é¤ì¤Ê¤¤¡£
122 .\" When is SIGEV_NONE useful?
125 .\"O Notify the process by sending the signal specified in
126 .\"O .IR sigev_signo .
127 .\"O If the signal is caught with a signal handler that
128 .\"O was registered using the
129 .\"O .BR sigaction (2)
131 .\"O flag, then the following fields are set in the
133 .\"O structure that is passed as the second argument of the handler:
135 ¤Ç»ØÄꤵ¤ì¤¿¥·¥°¥Ê¥ë¤òÁ÷¤Ã¤Æ¡¢¥×¥í¥»¥¹¤ËÄÌÃΤ¹¤ë¡£
139 ¥Õ¥é¥°¤Ç¥·¥°¥Ê¥ë¥Ï¥ó¥É¥é¤òÅÐÏ¿¤·¤Æ¤¤¤ë¾ì¹ç¡¢
140 ¤½¤Î¥·¥°¥Ê¥ë¥Ï¥ó¥É¥é¤Ç¥·¥°¥Ê¥ë¤¬Ê᪤µ¤ì¤¿¾ì¹ç¤Ë¤Ï¡¢
141 ¥·¥°¥Ê¥ë¥Ï¥ó¥É¥é¤ÎÂèÆó°ú¤¿ô¤È¤·¤ÆÅϤµ¤ì¤ë
143 ¹½Â¤ÂΤγƥե£¡¼¥ë¥É¤Ï°Ê²¼¤Î¤è¤¦¤ËÀßÄꤵ¤ì¤ë¡£
148 .\"O is set to the signal number;
150 .\"O is set to the value specified in
151 .\"O .IR notification\->sigev_value ;
160 .I notification\->sigev_value
161 ¤Ç»ØÄꤷ¤¿Ãͤ¬ÀßÄꤵ¤ì¤ë¡£
162 .\" I don't know of other implementations that set
163 .\" si_pid and si_uid -- MTK
165 .\"O is set to the PID of the process that sent the message; and
167 .\"O is set to the real user ID of the sending process.
168 .\"O The same information is available if the signal is accepted using
169 .\"O .BR sigwaitinfo (2).
171 ¤Ë¤Ï¥á¥Ã¥»¡¼¥¸¤òÁ÷¿®¤·¤¿¥×¥í¥»¥¹¤Î PID ¤¬¡¢
173 ¤Ë¤ÏÁ÷¿®¥×¥í¥»¥¹¤Î¼Â¥æ¡¼¥¶ ID ¤¬ÀßÄꤵ¤ì¤ë¡£
175 ¤ò»È¤Ã¤Æ¥·¥°¥Ê¥ë¤ò¼õ¿®¤¹¤ë¾ì¹ç¤â¡¢Æ±¤¸¾ðÊó¤¬ÆÀ¤é¤ì¤ë¡£
178 .\"O Deliver notification by invoking
179 .\"O .I notification\->sigev_notify_function
180 .\"O as the start function of a new thread.
181 .\"O The function is invoked with
182 .\"O .I notification\->sigev_value
183 .\"O as its sole argument.
185 .\"O .I notification\->sigev_notify_attributes
186 .\"O is not NULL, then it should point to a
187 .\"O .I pthread_attr_t
188 .\"O structure that defines attributes for the thread (see
189 .\"O .BR pthread_attr_init (3)).
190 ¿·¤·¤¤¥¹¥ì¥Ã¥É¤Î³«»Ï´Ø¿ô¤È¤·¤Æ
191 .I notification\->sigev_thread_function
192 ¤òµ¯Æ°¤¹¤ë¤³¤È¤ÇÄÌÃΤò¹Ô¤¦¡£
193 µ¯Æ°»þ¤Î´Ø¿ô¤Î°ú¤¿ô¤È¤·¤Æ¤Ï
194 .I notification\->sigev_value
196 .I notification\->sigev_notify_attributes
197 ¤Ï¡¢NULL °Ê³°¤Î¾ì¹ç¡¢
198 ¤½¤Î¥¹¥ì¥Ã¥É¤Î°À¤òÄêµÁ¤¹¤ë
200 ¹½Â¤ÂΤؤΥݥ¤¥ó¥¿¤È¤Ê¤Ã¤Æ¤¤¤ëɬÍפ¬¤¢¤ë
201 .RB ( pthread_attr_init (3)
204 .\"O Only one process can be registered to receive notification
205 .\"O from a message queue.
206 °ì¤Ä¤Î¥á¥Ã¥»¡¼¥¸¥¥å¡¼¤«¤éÄÌÃΤò¼õ¿®¤¹¤ë¤è¤¦¤ËÅÐÏ¿¤Ç¤¤ë¥×¥í¥»¥¹¤Ï
211 .\"O is NULL, and the calling process is currently registered to receive
212 .\"O notifications for this message queue, then the registration is removed;
213 .\"O another process can then register to receive a message notification
216 ¤¬ NULL ¤Ç¡¢¤«¤Ä¸Æ¤Ó½Ð¤·¸µ¤Î¥×¥í¥»¥¹¤¬¤³¤Î¥á¥Ã¥»¡¼¥¸¥¥å¡¼¤«¤é¤Î
217 ÄÌÃΤò¼õ¿®¤¹¤ë¤Ë¸½ºßÅÐÏ¿¤·¤Æ¤¤¤ë¾ì¹ç¡¢ÅÐÏ¿¤òºï½ü¤¹¤ë¡£
218 ¤³¤ì°Ê¹ß¡¢ÊÌ¤Î¥×¥í¥»¥¹¤¬¤³¤Î¥á¥Ã¥»¡¼¥¸¥¥å¡¼¤«¤éÄÌÃΤò¼õ¿®¤¹¤ë¤è¤¦¤Ë
219 ÅÐÏ¿¤Ç¤¤ë¤è¤¦¤Ë¤Ê¤ë¡£
221 .\"O Message notification only occurs when a new message arrives and
222 .\"O the queue was previously empty.
223 .\"O If the queue was not empty at the time
224 .\"O .BR mq_notify ()
225 .\"O was called, then a notification will only occur after
226 .\"O the queue is emptied and a new message arrives.
227 ¥á¥Ã¥»¡¼¥¸ÄÌÃΤϡ¢¤½¤ì¤Þ¤Ç¶õ¤Î¥¥å¡¼¤Ë¿·¤·¤¤¥á¥Ã¥»¡¼¥¸¤¬ÅþÃ夷¤¿
230 ¤¬¸Æ¤Ó½Ð¤µ¤ì¤¿»þ¤Ë¤½¤Î¥¥å¡¼¤¬¶õ¤Ç¤Ê¤¤¾ì¹ç¡¢
231 ¤½¤Î¥¥å¡¼¤¬¶õ¤Ë¤Ê¤ê¡¢¤½¤Î¸å¿·¤·¤¤¥á¥Ã¥»¡¼¥¸¤¬ÅþÃ夷¤¿»þ¤Ë
232 ½é¤á¤ÆÄÌÃΤ¬¹Ô¤ï¤ì¤ë¤³¤È¤Ë¤Ê¤ë¡£
234 .\"O If another process or thread is waiting to read a message
235 .\"O from an empty queue using
236 .\"O .BR mq_receive (3),
237 .\"O then any message notification registration is ignored:
238 .\"O the message is delivered to the process or thread calling
239 .\"O .BR mq_receive (3),
240 .\"O and the message notification registration remains in effect.
241 ÊÌ¤Î¥×¥í¥»¥¹¤ä¥¹¥ì¥Ã¥É¤¬
243 ¤ò»È¤Ã¤Æ¡¢¶õ¤Î¥¥å¡¼¤«¤é¥á¥Ã¥»¡¼¥¸¤ÎÆɤ߽Ф·¤òÂԤäƤ¤¤ë¾ì¹ç¡¢
244 ¥á¥Ã¥»¡¼¥¸ÄÌÃΤÎÅÐÏ¿¤ÏÁ´¤Æ̵»ë¤µ¤ì¤ë¡£
247 ¤ò¸Æ¤Ó½Ð¤·¤Æ¤¤¤ë¥×¥í¥»¥¹¤ä¥¹¥ì¥Ã¥É¤ËÇÛÁ÷¤µ¤ì¡¢
248 ¥á¥Ã¥»¡¼¥¸ÄÌÃΤÎÅÐÏ¿¤Ï¸úÎϤò»ý¤Ã¤¿¤Þ¤Þ¤È¤Ê¤ë¡£
250 .\"O Notification occurs once: after a notification is delivered,
251 .\"O the notification registration is removed,
252 .\"O and another process can register for message notification.
253 .\"O If the notified process wishes to receive the next notification,
255 .\"O .BR mq_notify ()
256 .\"O to request a further notification.
257 .\"O This should be done before emptying all unread messages from the queue.
258 .\"O (Placing the queue in nonblocking mode is useful for emptying
259 .\"O the queue of messages without blocking once it is empty.)
260 ÄÌÃΤϰìÅÙ¤À¤±¹Ô¤ï¤ì¤ë¡£ÄÌÃΤ¬Á÷¤é¤ì¤¿¸å¤Ï¡¢ÄÌÃÎÍ×µá¤ÎÅÐÏ¿¤Ïºï½ü¤µ¤ì¡¢
261 ÊÌ¤Î¥×¥í¥»¥¹¤¬¥á¥Ã¥»¡¼¥¸ÄÌÃΤò¼õ¿®¤¹¤ë¤è¤¦¤ËÅÐÏ¿¤Ç¤¤ë¤è¤¦¤Ë¤Ê¤ë¡£
262 ÄÌÃΤò¼õ¤±¤¿¥×¥í¥»¥¹¤¬¼¡¤ÎÄÌÃΤâ¼õ¿®¤·¤¿¤¤¾ì¹ç¤Ï¡¢
264 ¤ò»È¤Ã¤Æ¤½¤Î¸å¤ÎÄÌÃΤâ¼õ¤±¤ë¤è¤¦¤ËÍ׵᤹¤ë¤³¤È¤¬¤Ç¤¤ë¡£
266 ¤òºÆÅٸƤӽФ¹¤Î¤Ï¡¢Æɤ߽Ф·¤Æ¤¤¤Ê¤¤¥á¥Ã¥»¡¼¥¸¤òÁ´ÉôÆɤ߽Ф·¤Æ
267 ¥¥å¡¼¤¬¶õ¤Ë¤Ê¤ëÁ°¤Ë¤¹¤Ù¤¤Ç¤¢¤ë
268 (¥¥å¡¼¤«¤é¤Î¥á¥Ã¥»¡¼¥¸Æɤ߽Ф·¤ò¥¥å¡¼¤¬¶õ¤Ë¤Ê¤Ã¤¿»þ¤Ë
269 Ää»ß (block) ¤»¤º¤Ë¹Ô¤¦¤Ë¤Ï¡¢¥¥å¡¼¤òÈóÄä»ß¥â¡¼¥É (non-blocking mode)
270 ¤ËÀßÄꤷ¤Æ¤ª¤¯¤È¤è¤¤)¡£
271 .\"O .SH RETURN VALUE
274 .\"O .BR mq_notify ()
275 .\"O returns 0; on error, \-1 is returned, with
277 .\"O set to indicate the error.
280 ¤Ï 0 ¤òÊÖ¤¹¡£¥¨¥é¡¼¤Î¾ì¹ç¡¢\-1 ¤òÊÖ¤·¡¢
282 ¤ò¥¨¥é¡¼¤ò¼¨¤¹ÃͤËÀßÄꤹ¤ë¡£
287 .\"O The descriptor specified in
291 ¤Ë»ØÄꤵ¤ì¤¿¥Ç¥£¥¹¥¯¥ê¥×¥¿¤¬ÉÔÀµ¤Ç¤¢¤ë¡£
294 .\"O Another process has already registered to receive notification
295 .\"O for this message queue.
297 ¤³¤Î¥á¥Ã¥»¡¼¥¸¥¥å¡¼¤ËÂФ¹¤ëÄÌÃΤò¼õ¿®¤¹¤ë¤è¤¦¤ËÅÐÏ¿¤·¤Æ¤¤¤ë¡£
300 .\"O .I notification\->sigev_notify
301 .\"O is not one of the permitted values; or
302 .\"O .I notification\->sigev_notify
306 .\"O .I notification\->sigev_signo
307 .\"O is not a valid signal number.
308 .I notification\->sigev_notify
309 ¤¬µö²Ä¤µ¤ì¤¿ÃͤΤ¤¤º¤ì¤Ç¤â¤Ê¤¤¡£¤â¤·¤¯¤Ï
310 .I notification\->sigev_notify
314 .I notification\->sigev_signo
315 ¤¬Í¸ú¤Ê¥·¥°¥Ê¥ëÈÖ¹æ¤Ç¤Ï¤Ê¤¤¡£
318 .\"O Insufficient memory.
319 ɬÍפʥá¥â¥ê¤¬¤Ê¤«¤Ã¤¿¡£
321 .\"O POSIX.1-2008 says that an implementation
325 .\"O .\" Linux does not do this
328 .\"O is NULL, and the caller is not currently registered to receive
329 .\"O notifications for the queue
333 ¤¬ NULL ¤Ç¡¢¸Æ¤Ó½Ð¤·¸µ¤Î¥×¥í¥»¥¹¤¬¥¥å¡¼
335 ¤Ë´Ø¤¹¤ëÄÌÃΤò¼õ¿®¤¹¤ë¤è¤¦¤ËÅÐÏ¿¤µ¤ì¤Æ¤¤¤Ê¤¤¾ì¹ç¡¢¥¨¥é¡¼
337 ¤òÀ¸À®¤¹¤ë¤è¤¦¤Ê¼ÂÁõ¤ò¹Ô¤Ã¤Æ¤â¡Ö¤è¤¤¡×¤³¤È¤Ë¤Ê¤Ã¤Æ¤¤¤ë¡£
338 .\" Linux ¤Î¼ÂÁõ¤Ç¤Ï EINVAL ¤ÏÀ¸À®¤µ¤ì¤Ê¤¤
339 .\"O .SH CONFORMING TO
344 .\"O The following program registers a notification request for the
345 .\"O message queue named in its command-line argument.
346 .\"O Notification is performed by creating a thread.
347 .\"O The thread executes a function which reads one message from the
348 .\"O queue and then terminates the process.
350 ¥³¥Þ¥ó¥É¥é¥¤¥ó°ú¤¿ô¤Ç»ØÄꤵ¤ì¤¿Ì¾Á°¤Î¥á¥Ã¥»¡¼¥¸¥¥å¡¼¤Ø¤Î
351 ÄÌÃÎÍ×µá¤òÅÐÏ¿¤·¡¢ÄÌÃΤϥ¹¥ì¥Ã¥É¤ÎºîÀ®¤Ë¤è¤Ã¤Æ¹Ô¤ï¤ì¤ë¡£
352 ¤½¤Î¥¹¥ì¥Ã¥É¤Ï¡¢¤½¤Î¥¥å¡¼¤«¤é¥á¥Ã¥»¡¼¥¸¤ò°ì¤ÄÆɤ߽Ф·¤Æ¤«¤é¡¢
353 ¥×¥í¥»¥¹¤ò½ªÎ»¤¹¤ë´Ø¿ô¤ò¼Â¹Ô¤¹¤ë¡£
362 #define handle_error(msg) \\
363 do { perror(msg); exit(EXIT_FAILURE); } while (0)
365 .\"O static void /* Thread start function */
366 static void /* ¥¹¥ì¥Ã¥É³«»Ï´Ø¿ô */
367 tfunc(union sigval sv)
372 mqd_t mqdes = *((mqd_t *) sv.sival_ptr);
374 .\"O /* Determine max. msg size; allocate buffer to receive msg */
375 /* ºÇÂç¥á¥Ã¥»¡¼¥¸¥µ¥¤¥º¤ò·èÄꤷ¡¢
376 ¥á¥Ã¥»¡¼¥¸¼õ¿®ÍѤΥХåե¡¤ò³ÎÊݤ¹¤ë */
378 if (mq_getattr(mqdes, &attr) == \-1)
379 handle_error("mq_getattr");
380 buf = malloc(attr.mq_msgsize);
382 handle_error("malloc");
384 nr = mq_receive(mqdes, buf, attr.mq_msgsize, NULL);
386 handle_error("mq_receive");
388 printf("Read %ld bytes from MQ\\n", (long) nr);
390 .\"O exit(EXIT_SUCCESS); /* Terminate the process */
391 exit(EXIT_SUCCESS); /* ¥×¥í¥»¥¹¤ò½ªÎ»¤¹¤ë */
395 main(int argc, char *argv[])
401 fprintf(stderr, "Usage: %s <mq-name>\\n", argv[0]);
405 mqdes = mq_open(argv[1], O_RDONLY);
406 if (mqdes == (mqd_t) \-1)
407 handle_error("mq_open");
409 not.sigev_notify = SIGEV_THREAD;
410 not.sigev_notify_function = tfunc;
411 not.sigev_notify_attributes = NULL;
412 .\"O not.sigev_value.sival_ptr = &mqdes; /* Arg. to thread func. */
413 not.sigev_value.sival_ptr = &mqdes; /* ¥¹¥ì¥Ã¥É´Ø¿ô¤ËÅϤ¹°ú¤¿ô */
414 if (mq_notify(mqdes, ¬) == \-1)
415 handle_error("mq_notify");
417 .\"O pause(); /* Process will be terminated by thread function */
418 pause(); /* ¥×¥í¥»¥¹¤Ï¥¹¥ì¥Ã¥É´Ø¿ô¤Ë¤è¤ê½ªÎ»¤µ¤ì¤ë */