Subj : Re: concurrent switching between multiple buffers
To   : comp.programming.threads
From : Markus Elfring
Date : Mon Sep 26 2005 09:29 pm

> If you'd rather make it parallel, there are many ways to fix the problem
> with more careful design, depending on your actual intentions for the
> real program of which this might serve as a prototype. At the most
> trivial level, for example, you might switch "buffer" to a
> multi-buffering set, or even a queue, so that your read and write
> threads can operate independently on DIFFERENT buffers at the same time,
> and then coordinate. (That is, the read thread would read a PRIVATE
> buffer of input, and then write the shared "buffer" pointer, signalling
> the write thread that input was ready. The write thread, when it
> finished a write, would wait for a new input buffer, copy the pointer
> and clear the shared pointer, write the data, free the buffer, and wait
> for a new input buffer.) With a little more sophistication the write
> thread can "recycle" the buffer rather than freeing it and making the
> read thread allocate a new one. You can make the read thread add buffers
> to a queue so that it can process input as quickly as it comes even if
> the write thread gets delayed -- if it queues a second input buffer
> while the write thread is working, it'll just catch up later. (Though
> there are certainly applications where that model might not be appropriate.)

Your algorithm description sounds like that a non-blocking (lock-free) technique might
also be applicable.
Example: Document "Asynchronous Data Sharing in Multiprocessor Real-Time Systems Using
Process Consensus" by Jing Chen and Alan Burns
http://citeseer.ist.psu.edu/114960.html
http://www.carrara.ch/fachbeitraege/Consensus.pdf

Regards,
Markus

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