On Thu, Jan 29, 2026 at 10:47 PM Jordan Peck via dev < [email protected]> wrote:
> Hi all, > > I'd like to propose a patch that optimises svnsync when synchronizing to > local filesystem repositories (file:// URLs). Currently, svnsync performs > a two-step process for each revision: > > 1. Commit the revision content (author/date are set to the current > user and current time) > 2. Update svn:author and svn:date revision properties to match the > source repository > > This works but is inefficient for file:// URLs where we have direct > repository access and can set these properties correctly during the > initial commit. > > > THE PROBLEM > ----------- > > When svnsync replays a revision from a source repository, the commit > is created with the local user as the author and the current time as > the date. After the commit completes, svnsync then makes separate > svn_ra_change_rev_prop2() calls to update svn:author and svn:date to > match the source repository. > > For remote servers (svn://, http://), this two-step process is necessary > because the server enforces its own author/date policies. However, for > file:// URLs via ra_local, we have direct access to the repository and > can bypass this limitation. > > We have an SVN server acting as the slave via the Apache module proxy, > the slave server is kept in sync with the master using svnsync. This > two-step approach has caused issues with various tools that monitor the > slave SVN server for new revisions, they will occasionally get the data > for a synced revision that hasn't yet had the revision properties > copied. Having the sync be a single atomic operation means this can > never happen. > > > THE SOLUTION > ------------ > > This patch introduces a new RA capability "commit-allow-rev-props" that > ra_local advertises. When svnsync detects this capability on the > destination repository, it: > > 1. Includes svn:author and svn:date in the initial commit's revprop > table (instead of filtering them out) > > 2. ra_local now conditionally preserves these properties: > - svn:author is only set to the session user if not already provided > - If svn:date is provided, the SVN_FS_TXN_CLIENT_DATE flag is passed > to svn_fs_begin_txn2() so the filesystem uses that date > > 3. Skips the post-commit revprop update step since author/date are > already correct > > > CHANGES OVERVIEW > ---------------- > > subversion/include/svn_ra.h: > - Added SVN_RA_CAPABILITY_COMMIT_ALLOW_REV_PROPS capability definition > > subversion/include/svn_repos.h: > - Added svn_repos_fs_begin_txn_for_commit3() with flags parameter > - Added svn_repos_get_commit_editor6() with txn_flags parameter > > subversion/libsvn_repos/fs-wrap.c: > - Implemented svn_repos_fs_begin_txn_for_commit3() which passes flags > (including SVN_FS_TXN_CLIENT_DATE) to svn_fs_begin_txn2() > > subversion/libsvn_repos/commit.c: > - Added txn_flags to edit_baton structure > - Implemented svn_repos_get_commit_editor6() to support txn_flags > - Updated open_root() to use the new begin_txn function > > subversion/libsvn_ra_local/ra_plugin.c: > - Advertises SVN_RA_CAPABILITY_COMMIT_ALLOW_REV_PROPS > - Modified get_commit_editor to preserve caller-provided author/date > - Sets SVN_FS_TXN_CLIENT_DATE when date is provided in revprops > > subversion/svnsync/svnsync.c: > - Detects the new capability on the destination > - When capability is present, includes author/date in commit revprops > - Skips post-commit revprop sync when capability is present > - Updated user-facing messages to reflect the optimization > > > USER-VISIBLE CHANGES > -------------------- > > When synchronizing to a file:// URL, svnsync now displays: > > Destination supports commit-time author and date; no post-commit > revprop sync needed. > Committed revision 1. > Committed revision 2. > ... > > Instead of the previous: > > Committed revision 1. > Copied properties for revision 1. > Committed revision 2. > Copied properties for revision 2. > ... > > > BENEFITS > -------- > > 1. Atomicity: Author and date are set in the same transaction as the > commit, rather than being updated afterward. > > 2. No behavioral change for remote servers: The optimization only > applies when the destination advertises the capability, so svn:// > and http:// synchronization continues to work as before. > > 3. Reduced I/O: Eliminates separate revprop change operations for each > revision synced to a file:// destination. > > COMPATIBILITY > ------------- > > - The new capability is only advertised by ra_local, so this is a > client-side optimization with no server protocol changes. > > - Existing svnsync mirrors continue to work unchanged. > > - The new API functions (svn_repos_fs_begin_txn_for_commit3 and > svn_repos_get_commit_editor6) maintain backward compatibility > through wrapper functions. > > > TESTING > ------- > > I have tested this with svnsync to file:// URLs and verified that: > - Revision properties (author, date, log) match the source repository > - The new optimization message appears at sync start > - No "Copied properties" messages appear > - Subsequent incremental syncs work correctly > > > Please review and let me know if you have any questions or suggestions. > > Thanks, > Jordan Peck > Hi, +1 I didn't look into the patch in detail, but the idea sounds good to me. -- Timofei Zhakov
