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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pckt(7) Miscellaneous Information Manual pckt(7)
NAME
pckt - Packet Mode module for STREAMS pty (pseudo-terminal)
SYNOPSIS
DESCRIPTION
The feature for STREAMS pty devices allows the user process on the master side of the pty device to be informed of state changes in the
pty. To enable in the STREAMS pty device, the user process must push the module onto the master side of the pty with a call to the STREAMS
ioctl(2) system call. When the module is pushed onto a STREAMS pty master, certain STREAMS messages going upstream on the master side will
get packetized so they can be subsequently retrieved by the master side with a function.
When the user process writes data, the module passes the message unchanged downstream on to the next module or driver. When the user
process reads data or when the module receives certain STREAMS message types, it constructs a packet out of the message for forwarding
upstream. To construct a message packet, the module creates an message. This message contains the original message type in the first data
block and the original message in as many data blocks as needed. The user process can then retrieve the message with a call to the func-
tion.
The module packetizes the following STREAMS message types:
All other messages are passed unchanged upstream.
If the message is an message, the module looks at the flag and takes the following actions:
o If the flag is the module changes it to before creating the message and passing the message upstream. This prevents the stream
head's read queue from being flushed by the original
o If the flag is the module changes it to before creating the message and passing it upstream. To flush the write queues properly,
the module also sends an message with the flag set.
o If the flag is the module changes it to before creating the message and passing it upstream. To flush the write queues properly,
the module also sends an message with the flag set.
AUTHOR
was developed by HP and OSF.
SEE ALSO
getmsg(2), ioctl(2), ptm(7), pts(7), ldterm(7), ptem(7), streamio(7).
pckt(7)