On Sat, Jun 15, 2013 at 3:34 PM, Ivan Zhakov <i...@visualsvn.com> wrote: > On Tue, Jun 11, 2013 at 3:22 PM, Ivan Zhakov <i...@visualsvn.com> wrote: >> 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. >> > I'll try to summarize concerns that were raised during the Hackathon > and on mailing list: > 1. svn_client_context_t can be used for long time by GUI clients. We > need to deal with somehow. > 2. De-facto ra_svn is stateful protocol and does not support > restarting connection to server if it closed by server due timeout or > restart. > 3. svn+ssh also can be problem (stsp) > 4. Currently serf library has a bug that serf_context_t need manual > connection reset in case of error or cancellation during processing > the request. > > Despite of that idea of reusing ra session considered as step in right > direction. It should also fix issue 3763 [1] (checkout should re-use > ra session for externals if possible). > > Current my current plain is following: > 1. Add function like svn_client_close_all_sessions() to close all > cached ra sessions > 2. Add new RA capability to signal if RA session is reusable and > stateless. Enable it for ra_local and ra_serf. Leave ra_svn not > capable for reusing sessions. > 3. Commit this change and start switching code to explicitly returning > sessions back to cache to reuse them. > 4. Extend ra_svn implementation and protocol to support connection > restart and cheap session reparent. > > Is it makes sense? > > [1] http://subversion.tigris.org/issues/show_bug.cgi?id=3763 > I've created 'reuse-ra-session' branch to finish my patch. I'm going to merge it back to trunk with detailed log message, so branch development should not be big problem.
-- Ivan Zhakov
