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Full Discussion: message queues and multi-process
Top Forums Programming message queues and multi-process Post 302133329 by rvan on Thursday 23rd of August 2007 02:26:27 AM
Old 08-23-2007
Hi blowtorch n Neo
Thank you for the reply...



typedef struct cond
{
/* framework mutex structure for condition variable */
mutex_rs * mutexp ;
pthread_cond_t cond;
} cond_var;


typedef struct mutex_r
{
pthread_mutex_t mutex;
} mutex_rs;



typedef struct msg_q
{
int max_num_of_msgs;
int msg_size;
char name[MSGQ_NAME_SIZE];
cond_var rcv_cond_var; /*condition variable */
cond_var snd_cond_var; /*send condition variable*/
mutex_rs rcv_mutex; ; /*Mutex to block for receive*/
mutex_rs snd_mutex; /*Mutex to block for send*/
int msgq_curr_msgs;
}msg_q

P.S. name[MSGQ_NAME_SIZE]; field will be useful to while mq_unlik();

cond_var rcv_cond_var; /*condition variable */
cond_var snd_cond_var; /*send condition variable*/
mutex_rs rcv_mutex; ; /*Mutex to block for receive*/
mutex_rs snd_mutex; /*Mutex to block for send*/

Condition variables am planning to use to wait for specific time interval on read n write for certain conditions like message queue empty ( for read ) or message queue full (for write).... mutex am using to lock and unlock while accessing the condition variables.


so according to blowtorch if i have to maintain the common data for the queue in the file then i have to write the msg_q details in file and whichever process has to access the message queue has to first open the file and read the details and can act on further.....
sounds good...

my doubt but why not shared memory???? is it complicated compared to files??


Thanks
 

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LEARN ABOUT SUNOS

mqueue.h

mqueue.h(3HEAD) 						      Headers							   mqueue.h(3HEAD)

NAME

       mqueue.h, mqueue - message queues

SYNOPSIS

       #include <mqueue.h>

DESCRIPTION

       The  <mqueue.h>	header	defines  the  mqd_t type, which is used for message queue descriptors.	This will not be an array type.  A message
       queue descriptor may be implemented using a file descriptor, in which case applications can open up to at least OPEN_MAX file  and  message
       queues.

       The <mqueue.h> header defines the sigevent structure (as described in <signal.h>, see signal.h(3HEAD)) and the  mq_attr structure, which is
       used in getting and setting the attributes of a message queue.  Attributes are initially set when the message queue is created.	A  mq_attr
       structure has the following members:

       long    mq_flags       message queue flags
       long    mq_maxmsg      maximum number of messages
       long    mq_msgsize     maximum message size
       long    mq_curmsgs     number of messages currently queued

       Inclusion of the <mqueue.h> header may make visible symbols defined in the headers <fcntl.h>, <signal.h>, <sys/types.h>, and <time.h>.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       fcntl.h(3HEAD), signal.h(3HEAD), time.h(3HEAD), types.h(3HEAD), attributes(5), standards(5)

SunOS 5.10							    30 Aug 2002 						   mqueue.h(3HEAD)
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