[svn.haxx.se] · SVN Dev · SVN Users · SVN Org · TSVN Dev · TSVN Users · Subclipse Dev · Subclipse Users · this month's index

RE: [RFC, PATCH] RA context abstraction layer in libsvn_client

From: Bert Huijben <bert_at_qqmail.nl>
Date: Tue, 11 Jun 2013 15:56:23 +0200

> -----Original Message-----
> From: Ivan Zhakov [mailto:ivan_at_visualsvn.com]
> Sent: dinsdag 11 juni 2013 15:22
> To: Subversion Development
> Subject: [RFC, PATCH] RA context abstraction layer in libsvn_client
>
> Hi,
>
> Currently Subversion client layer creates new RA session for every
> svn_client_* call. Even more: for some operations like
> svn_client_merge() it creates 10-15 RA sessions. Each session creation
> takes significant amount of time: TCP connection, SSL handshake,
> authentication and initial handshake. It easily could take several
> seconds over WAN.
>
> To solve this problem I propose to introduce RA context abstraction
> layer for managing set of RA sessions for different repositories and
> reuse them if possible. In the first version I made this layer
> libsvn_client private, but in we can make it part of ra-loader in
> future.
>
> The patch is attached. It passes all tests of course. I'm very
> interested for feedback. Proposed solution should make our svn merge
> code much easy to maintain and significantly faster.
>
> [[[
> Introduce repository access abstraction layer for managing RA session for
> different repositories.
>
> * subversion/include/private/svn_client_private.h
> (svn_client__ra_session_release): New.
> (svn_client__ra_session_from_path2): Document that created session will
> be
> automatically returned back to RA session cache on pool cleanup.
>
> * subversion/libsvn_client/ra.c
> (): Include ra_ctx.h.
> (svn_client__open_ra_session_internal): Use
> svn_client__ra_session_open().
> (svn_client__ra_session_release): New. Wrapper around
> svn_client__ra_ctx_release_session()
>
> * subversion/include/svn_client.h
> (svn_client_ctx_t): Add RA_CTX member.
>
> * subversion/libsvn_client/ctx.c
> (): Include ra_ctx.h.
> (svn_client_create_context2): Initialize RA_CTX.

I haven't looked at the code yet, but is this going to work for clients that keep a svn_client_context_t instance for hours/days/weeks?
All that time reusing it for different operations every now and then.
(One step further: How would this be affected by configuration and/or authorization baton changes when there are sessions cached)

Existing TCP connections (w/c)ould be broken on the next usage, kerberos cookies could have expired, etc. etc., especially with ra_svn, but maybe also with ra_serf where an existing connection can be reused in some cases.

>
> * subversion/libsvn_client/log.c
> (svn_client_log5): Return RA session back to session cache.
>
> * subversion/libsvn_client/ra_ctx.c
> * subversion/libsvn_client/ra_ctx.h
> (svn_client__ra_ctx_t, svn_client__ra_ctx_create,
> svn_client__ra_session_open, svn_client__ra_ctx_release_session): New.
> ]]]

        Bert
>
> --
> Ivan Zhakov
> CTO | VisualSVN | http://www.visualsvn.com
Received on 2013-06-11 15:57:23 CEST

This is an archived mail posted to the Subversion Dev mailing list.