ByteString I/O Performance
Donald Bruce Stewart
dons at cse.unsw.edu.au
Mon Sep 3 00:02:52 EDT 2007
> -----Original Message-----
> From: libraries-bounces at haskell.org [mailto:libraries-bounces at haskell.org] On Behalf Of Bryan O'Sullivan
> Sent: Sunday, September 02, 2007 11:23 PM
> To: Peter Simons
> Cc: libraries at haskell.org
> Subject: Re: ByteString I/O Performance
> Peter Simons wrote:
> > One way to get malloc() out of the picture would be to provide a
> > variant of hGet that takes an existing, pre-allocated buffer as an
> > argument, so that the user can allocate a ByteString once and re-use
> > it for every single hGet and hPut.
> This is already quite easy to do. See unsafeUseAsCStringLen in
> Data.ByteString.Base, and hGetBuf in System.IO.
> Is it possible without resorting to an unsafeXXX function?
They're all 'unsafe' for different reasons :)
The question should be: why is this unsafe?
(It's unsafe because it doesn't copy the C string, so you need to have a
side condition that the string isn't modified by C).
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