Subj : Re: STL Containers w/ Virtually Zero-Overhead Lock-Free Reads...
To   : (Usenet)
From : kanze
Date : Tue Sep 20 2005 08:21 am

Chris Thomasson wrote:

> Should it be done?

I'm not sure exactly what you are asking for.  Currently, the
SGI implementation doesn't require external synchronization if
all accesses are non-modifying.  Globally, I don't think that
they had to do anything special to achieve this.  (It does mean
that std::string cannot be COW.)

If you're asking about lock free read access while someone else
is modifying, and only the modifier having a lock, I'm
sceptical.  A modifying access can generally rearrange memory,
changing the addresses of objects, etc.  Which in turn
invalidates results from read accesses, even in a single thread
environment.

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James Kanze                                           GABI Software
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