This is a development branch, intended to implement RA context abstraction
layer in libsvn_client.

The branch should be maintained with catch-up merges from trunk.

The branch is going to be merged to trunk with detailed log message describing
all changes made in the branch.

STATUS
======

DONE:
- Initial implementation.
- Separate active and inactive session lists.
- Introduce explicit session reuse and closing.
- Add explicit session reuse throughout libsvn_client.
- Expire and close idle sessions after a given timeout.
- Limit the number of idle open sessions in the cache.
- Add explicit session reuse in the MTCC implementation.
- Find and resolve all 'RA_CACHE TODO' comments.
  The only one RA_CACHE TODO comment remaining, that is
  going to be resolved on trunk by patched posted on dev@ list:
  http://svn.haxx.se/dev/archive-2015-02/0054.shtml

TODO:
- Add new RA method (svn_ra__ping?) to verify that a session
  about to be reused is valid.
- Run performance comparisons between trunk and branch to prove that
  the RA session cache does in fact speed things up.
- Fix JavaHL test failures
  http://svn.haxx.se/dev/archive-2015-09/0237.shtml

PROBLEM
=======

Currently Subversion client layer creates new RA session for every
svn_client_* call. Even more: some operations like svn_client_merge() used
to creates 10-15 RA sessions around the release of 1.8 (the worst cases
were fixed on trunk short after branching). Each session creation takes
significant amount of time: TCP connection, SSL handshake, authentication
and initial handshake. It easily could take several seconds over WAN.

PROPOSED SOLUTION
=================

The idea is introduce RA context abstraction layer for managing set of RA
sessions for different repositories and reuse them if possible. In the first
version it going to be implemented in libsvn_client as private layer, but
we can make it part of ra-loader in future.

LINKS
=====

[1] http://subversion.tigris.org/issues/show_bug.cgi?id=3763
[2] http://svn.haxx.se/dev/archive-2013-06/0164.shtml