[Spread-users] Receive with timeout

John Schultz jschultz at spreadconcepts.com
Thu Jun 1 09:48:44 EDT 2006

Mark Snelling wrote:

>Is there any chance of adding variants of the receive and poll functions 
>that accept a timeout parameter?
>The combination of the current non-blocking SP_poll() and blocking 
>SP_receive() functions make it quite tricky to have a separate receive 
>thread, which is quite a common approach for distributed applications.
>The problem is that the receive thread blocks while waiting for messages, 
>this means there can be no other processing done if there is nothing pending 
>(also making shutdown difficult). If you were to poll first and then receive 
>if there were messages pending the receive thread would spin as it 
>constantly polled. You may add some form of sleep here but that will just 
>add extra latency in the time it takes to process the message.

Commonly, people will use select or poll system calls to watch for 
activity on the mailbox, which is a file descriptor.  For a receive 
thread, you would simply wait for read activity on the mailbox and then 
call SP_receive, which will then block until all the bytes are received.


John Schultz
Spread Concepts LLC
Phn:  301 498 3233
Cell: 443 838 2200

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