rhxk has asked for the wisdom of the Perl Monks concerning the following question:

So now I'm able to utilize the IPC::SysV perl module to read the shared memory and I'm seeking your wisdom.

How can I check to see if the contents in a shared memory has been updated or not...best close to as atomic as possible?

There are several processes writing data once a second to their specified shared memory...and I need to either log it or send it to a host (most likely) via sockets.

Of course, if a process has died & its shm is not cleaned, I should not send or log the same data over and over and over again. 2 scenarios I'm thinking of...If that process has failed before this script is ran, I can compare the previous output with the new one(which I'm not sure if this is the correct way), and the other is if the process has failed after the script( then the previous value would eq to the current value)
...any ideas?... thanx a mil...

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Re: shmread help
by quester (Vicar) on Mar 05, 2007 at 03:26 UTC
    Putting an integer counter in shared memory and incrementing it for each message works on most platforms. You have the overhead of polling the shared memory periodically, though.

    If this is just sending messages to a central log server process you might find msgsnd and msgrcv more efficient without being too difficult to use. For a more general case, you might want to use the semaphore operations in IPC::Semaphore.

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