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From William A Rowe Jr <wr...@rowe-clan.net>
Subject Re: svn commit: r1778004 - /httpd/httpd/branches/2.4.x/STATUS
Date Thu, 12 Jan 2017 16:32:43 GMT
On Mon, Jan 9, 2017 at 10:12 AM,  <wrowe@apache.org> wrote:
> Author: wrowe
> Date: Mon Jan  9 16:12:53 2017
> New Revision: 1778004
>
>  PATCHES/ISSUES THAT ARE BEING WORKED
>    [ New entried should be added at the START of the list ]
> @@ -275,6 +273,27 @@ PATCHES/ISSUES THAT ARE BEING WORKED
>           (& also, making the structure change with apr-util version
>           means it breaks binary compat across an apr-util upgrade?)
>
> +   * Support PCRE2 (10.x) in place of PCRE (8.x).
> +     Submitted by: wrowe, Petr Pisar [ppisar redhat.com]
> +     trunk patches:
> +         http://svn.apache.org/r1773454
> +         http://svn.apache.org/r1773741
> +         http://svn.apache.org/r1773742
> +         http://svn.apache.org/r1773839
> +         http://svn.apache.org/r1773870
> +         http://svn.apache.org/r1773882
> +     wrowe notes that the current code is too inefficient, owing to the fact
> +     that the ovector is a required allocation and is no longer allocated on
> +     the stack, by design. The correct fix is an apr userdata allocation on
> +     the appropriate pool, which would be thread-safe, but the actual API of
> +     ap_regexec[_len]() offers us no pool. We cannot associate that pool with
> +     the ap_regex_t, because a single regex may be used by many threads in
> +     parallel and is not thread-safe beyond initialization.
> +     So the only fix allowing us to use PCRE 10 in httpd 2.4 would be to write
> +     this as a thread safe storage buffer for the majority of cases (<10 $args)
> +     and we don't have a portable tls mechanism to do so.

Does anyone have a good suggestion on this that would be back-portable
and threadsafe for 2.4, before I surrender and make the trunk-only change
to include the worker's/thread's pool for this reusable buffer tagged with a
pooldata(m) in a new apr_pool_t * passed to the ap_regexec[_len] functions?

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