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Subject: Re: Interrupting a search

Author: Robert Hyatt

Date: 14:32:56 01/31/99

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On January 30, 1999 at 15:22:50, James Long wrote:

>On January 30, 1999 at 14:13:55, James Robertson wrote:
>
>>On January 30, 1999 at 13:50:22, Will Singleton wrote:
>>
>>>On January 30, 1999 at 11:54:18, James Robertson wrote:
>>>
>>>>I am trying to add compatibility with Winboard to allow it to interrupt a
>>>>search. I am looking at EXchess and Crafty's interrupt stuff, but it goes over
>>>>my head. Could somebody explain what is happening? Thanks!
>>>>
>>>>James
>>>
>>>Do you mean that you can't stop a search when you receive a message from
>>>winboard, or that you can't receive the msg while searching?
>>>
>>>Will
>>
>>I can't recieve a message from Winboard when I'm searching.
>>
>>James
>
>One solution is to spool off a thread to check for input.
>If a (valid) user move is received, switch a global variable
>to stop the pondering session (or set time_left if the
>user made the predicted move and you haven't been pondering
>long enough).
>
>Same goes for the regular search - when a valid command
>is received that requires the program to stop searching,
>switch that global variable (something like BOOL stop_search).
>At every node, check for stop_search == TRUE.  If the
>condition is true, return 0 to back down through the root.
>
>The trick to using threads is setting the proper
>"priority," so that the input thread doesn't get any
>more processor time than it needs.  This also renders
>any same machine matches useless, but they're pretty
>meaningless anyway. :-)
>
>
>---
>James


'priority' ought not matter.  the 'input' thread should be blocked on a read,
so that it can't execute anyway.  And in reality, you want the input thread to
have a higher priority than the search thread or you would _never_ get it to
execute and read a move... :)



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