guile-user
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: question about atomics


From: joakim
Subject: Re: question about atomics
Date: Fri, 26 May 2017 13:22:50 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/26.0.50 (gnu/linux)

Chris Vine <address@hidden> writes:

> On Fri, 26 May 2017 12:37:47 +0200
> address@hidden wrote:
>> Hello,
>> 
>> I'm making a simple program that processes a lot of mail in separate
>> guile threads.
>> 
>> I would like a counter of how many messages have been processed so I
>> made an attempt with atomics.
>> 
>> first:
>>     (define *msgcount* (make-atomic-box 0))
>> 
>> and later:
>>     (atomic-box-swap! *msgcount* (+ 1 (atomic-box-ref *msgcount*)))
>> 
>> This of course doesn't work very well, and I didnt expect it to
>> either. (usually the count is low by a couple of hundred messages)
>> 
>> So basically, how do I get something similar to the swap! function in
>> clojure? Did I miss something in the documentation for guiles atomics?
>> 
>> I think I expected to be able to do the following:
>>     (atomic-box-swap! *msgcount* (lambda (atom) (+ 1 (atomic-box-ref
>> atom))))
>
> That won't work.  You have to use atomic-box-compare-and-swap!, in order
> to detect interleaving by other threads.  For more on this, google
> "compare and swap".

Thanks!

>
>
>
-- 
Joakim Verona
address@hidden
+46705459454




reply via email to

[Prev in Thread] Current Thread [Next in Thread]