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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 DEBIAN

nullmailer-queue

nullmailer-queue(8)					      System Manager's Manual					       nullmailer-queue(8)

NAME

       nullmailer-queue - insert mail messages into the queue

SYNOPSIS

       nullmailer-queue

DESCRIPTION

       This program reads a formatted mail message from standard input and safely injects it into the outgoing mail queue.

       The data sent into standard input is expected to have the following format: one line containing the envelope sender, one or more lines con-
       taining the recipients, a single blank line, and then the contents of the message exactly as it is to be transmitted  to  the  destination.
       All lines are terminated with a single line-feed character.  All addresses must contain a fully-qualified domain name.

RETURN VALUE

       Exits 0 if it successfully queues the message.  If it failed to queue the message, it exits 1 and prints an error message to stdandard out-
       put.

CONTROL FILES

       adminaddr
	      If this file is not empty, all recipients to users at either "localhost" (the literal string)  or  the  canonical  host  name  (from
	      /etc/mailname)  are  remapped to this address.  This is provided to allow local daemons to be able to send email to "somebody@local-
	      host" and have it go somewhere sensible instead of being bounced by your relay host.

OTHER FILES

       /var/spool/nullmailer/queue
	      The directory into which the completed messages are moved.

       /var/spool/nullmailer/tmp
	      The directory in which messages are formed temporarily.

       /var/spool/nullmailer/trigger
	      A pipe used to trigger nullmailer-send to immediately start sending the message from the queue.

SEE ALSO

       nullmailer-inject(1), nullmailer-send(8)

LIMITATIONS

       This program should enforce system-wide configurable message length limits.

															       nullmailer-queue(8)
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