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Re: export, checkout, commit performance

From: <kfogel_at_collab.net>
Date: 2006-03-10 00:09:35 CET

Julian Foad <julianfoad@btopenworld.com> writes:
> Branko ─îibej wrote:
> > How about this one, as a stopgap:
> > Index: subversion/libsvn_subr/io.c
> > ===================================================================
> > --- subversion/libsvn_subr/io.c (revision 18760)
> > +++ subversion/libsvn_subr/io.c (working copy)
> > @@ -988,7 +988,7 @@
> > struct apr_md5_ctx_t context;
> > apr_file_t *f = NULL;
> > svn_error_t *err;
> > - char buf[BUFSIZ]; /* What's a good size for a read chunk? */
> > + char *buf = apr_palloc(pool, SVN__STREAM_CHUNK_SIZE);
> > apr_size_t len;
> > /* ### The apr_md5 functions return apr_status_t, but they only
> > @@ -999,12 +999,12 @@
> > SVN_ERR(svn_io_file_open(&f, file, APR_READ, APR_OS_DEFAULT,
> > pool));
> > - len = sizeof(buf);
> > + len = SVN__STREAM_CHUNK_SIZE;
> > err = svn_io_file_read(f, buf, &len, pool);
> > while (! err)
> > {
> > apr_md5_update(&context, buf, len);
> > - len = sizeof(buf);
> > + len = SVN__STREAM_CHUNK_SIZE;
> > err = svn_io_file_read(f, buf, &len, pool);
> > };
>
> +1, except don't just change this function but also all the other
> places we use it: that's two other functions in io.c, and also:
> subversion/libsvn_wc/entries.c:read_entries(),
> subversion/libsvn_wc/log.c:run_log(),
> subversion/svnlook/main.c:do_cat().

Why would we ever not use sizeof() when calculating len, though? It's
always right. It can never be wrong. To the argument that we would
never change the buffer's size, I point to this patch as
counter-evidence :-).

+1 on moving from BUFSIZ to SVN__STREAM_CHUNK_SIZE, -0.9 on writing
out SVN__STREAM_CHUNK_SIZE instead of just using sizeof().

-K

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Received on Fri Mar 10 01:57:11 2006

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