git-commit-vandalism

Author SHA1 Message Date

Author	SHA1	Message	Date
Johan Herland	fe191fcaa5	Git 2.0: git svn: Set default --prefix='origin/' if --prefix is not given git-svn by default puts its Subversion-tracking refs directly in refs/remotes/. This runs counter to Git's convention of using refs/remotes/$remote/ for storing remote-tracking branches. Furthermore, combining git-svn with regular git remotes run the risk of clobbering refs under refs/remotes (e.g. if you have a git remote called "tags" with a "v1" branch, it will overlap with the git-svn's tracking branch for the "v1" tag from Subversion. Even though the git-svn refs stored in refs/remotes/* are not "proper" remote-tracking branches (since they are not covered by a proper git remote's refspec), they clearly represent a similar concept, and would benefit from following the same convention. For example, if git-svn tracks Subversion branch "foo" at refs/remotes/foo, and you create a local branch refs/heads/foo to add some commits to be pushed back to Subversion (using "git svn dcommit), then it is clearly unhelpful of Git to throw warning: refname 'foo' is ambiguous. every time you checkout, rebase, or otherwise interact with the branch. The existing workaround for this is to supply the --prefix=quux/ to git svn init/clone, so that git-svn's tracking branches end up in refs/remotes/quux/* instead of refs/remotes/*. However, encouraging users to specify --prefix to work around a design flaw in git-svn is suboptimal, and not a long term solution to the problem. Instead, git-svn should default to use a non-empty prefix that saves unsuspecting users from the inconveniences described above. This patch will only affect newly created git-svn setups, as the --prefix option only applies to git svn init (and git svn clone). Existing git-svn setups will continue with their existing (lack of) prefix. Also, if anyone somehow prefers git-svn's old layout, they can recreate that by explicitly passing an empty prefix (--prefix "") on the git svn init/clone command line. The patch changes the default value for --prefix from "" to "origin/", updates the git-svn manual page, and fixes the fallout in the git-svn testcases. (Note that this patch might be easier to review using the --word-diff and --word-diff-regex=. diff options.) [ew: squashed description of <= 1.9 behavior into manpage] Suggested-by: Thomas Ferris Nicolaisen <tfnico@gmail.com> Signed-off-by: Johan Herland <johan@herland.net> Signed-off-by: Eric Wong <normalperson@yhbt.net>	2014-04-19 11:30:13 +00:00
Peter Baumann	61b472ed8b	git svn: reset invalidates the memoized mergeinfo caches Since v1.7.0-rc2~11 (git-svn: persistent memoization, 2010-01-30), git-svn has maintained some private per-repository caches in .git/svn/.caches to avoid refetching and recalculating some mergeinfo-related information with every 'git svn fetch'. This memoization can cause problems, e.g consider the following case: SVN repo: ... - a - b - c - m <- trunk \ / d - e <- branch1 The Git import of the above repo is at commit 'a' and doesn't know about the branch1. In case of an 'git svn rebase', only the trunk of the SVN repo is imported. During the creation of the git commit 'm', git svn uses the svn:mergeinfo property and tries to find the corresponding git commit 'e' to create 'm' with 'c' and 'e' as parents. But git svn rebase only imports the current branch so commit 'e' is not imported. Therefore git svn fails to create commit 'm' as a merge commit, because one of its parents is not known to git. The imported history looks like this: ... - a - b - c - m <- trunk A later 'git svn fetch' to import all branches can't rewrite the commit 'm' to add 'e' as a parent and to make it a real git merge commit, because it was already imported. That's why the imported history misses the merge and looks like this: ... - a - b - c - m <- trunk \ d - e <- branch1 Right now the only known workaround for importing 'm' as a merge is to force reimporting 'm' again from SVN, e.g. via $ git svn reset --revision $(git find-rev $c) $ git svn fetch Sadly, this is where the behavior has regressed: git svn reset doesn't invalidate the old mergeinfo cache, which is no longer valid for the reimport, which leads to 'm' beeing imprted with only 'c' as parent. As solution to this problem, this commit invalidates the mergeinfo cache to force correct recalculation of the parents. During development of this patch, several ways for invalidating the cache where considered. One of them is to use Memoize::flush_cache, which will call the CLEAR method on the underlying Memoize persistency implementation. Sadly, neither Memoize::Storable nor the newer Memoize::YAML module introduced in `68f532f4ba` could optionally be used implement the CLEAR method, so this is not an option. Reseting the internal hash used to store the memoized values has the same problem, because it calls the non-existing CLEAR method of the underlying persistency layer, too. Considering this and taking into account the different implementations of the memoization modules, where Memoize::Storable is not in our control, implementing the missing CLEAR method is not an option, at least not if Memoize::Storable is still used. Therefore the easiest solution to clear the cache is to delete the files on disk in 'git svn reset'. Normally, deleting the files behind the back of the memoization module would be problematic, because the in-memory representation would still exist and contain wrong data. Fortunately, the memoization is active in memory only for a small portion of the code. Invalidating the cache by deleting the files on disk if it isn't active should be safe. Signed-off-by: Peter Baumann <waste.manager@gmx.de> Signed-off-by: Steven Walter <stevenrwalter@gmail.com> Signed-off-by: Eric Wong <normalperson@yhbt.net>	2012-08-10 19:53:18 +00:00

Johan Herland

fe191fcaa5

Git 2.0: git svn: Set default --prefix='origin/' if --prefix is not given

git-svn by default puts its Subversion-tracking refs directly in
refs/remotes/*. This runs counter to Git's convention of using
refs/remotes/$remote/* for storing remote-tracking branches.

Furthermore, combining git-svn with regular git remotes run the risk of
clobbering refs under refs/remotes (e.g. if you have a git remote
called "tags" with a "v1" branch, it will overlap with the git-svn's
tracking branch for the "v1" tag from Subversion.

Even though the git-svn refs stored in refs/remotes/* are not "proper"
remote-tracking branches (since they are not covered by a proper git
remote's refspec), they clearly represent a similar concept, and would
benefit from following the same convention.

For example, if git-svn tracks Subversion branch "foo" at
refs/remotes/foo, and you create a local branch refs/heads/foo to add
some commits to be pushed back to Subversion (using "git svn dcommit),
then it is clearly unhelpful of Git to throw

  warning: refname 'foo' is ambiguous.

every time you checkout, rebase, or otherwise interact with the branch.

The existing workaround for this is to supply the --prefix=quux/ to
git svn init/clone, so that git-svn's tracking branches end up in
refs/remotes/quux/* instead of refs/remotes/*. However, encouraging
users to specify --prefix to work around a design flaw in git-svn is
suboptimal, and not a long term solution to the problem. Instead,
git-svn should default to use a non-empty prefix that saves
unsuspecting users from the inconveniences described above.

This patch will only affect newly created git-svn setups, as the
--prefix option only applies to git svn init (and git svn clone).
Existing git-svn setups will continue with their existing (lack of)
prefix. Also, if anyone somehow prefers git-svn's old layout, they
can recreate that by explicitly passing an empty prefix (--prefix "")
on the git svn init/clone command line.

The patch changes the default value for --prefix from "" to "origin/",
updates the git-svn manual page, and fixes the fallout in the git-svn
testcases.

(Note that this patch might be easier to review using the --word-diff
and --word-diff-regex=. diff options.)

[ew: squashed description of <= 1.9 behavior into manpage]

Suggested-by: Thomas Ferris Nicolaisen <tfnico@gmail.com>
Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Eric Wong <normalperson@yhbt.net>

2014-04-19 11:30:13 +00:00

Peter Baumann

61b472ed8b

git svn: reset invalidates the memoized mergeinfo caches

Since v1.7.0-rc2~11 (git-svn: persistent memoization, 2010-01-30),
git-svn has maintained some private per-repository caches in
.git/svn/.caches to avoid refetching and recalculating some
mergeinfo-related information with every 'git svn fetch'.

This memoization can cause problems, e.g consider the following case:

SVN repo:

  ... - a - b - c - m  <- trunk
          \        /
            d  -  e    <- branch1

The Git import of the above repo is at commit 'a' and doesn't know about
the branch1. In case of an 'git svn rebase', only the trunk of the
SVN repo is imported. During the creation of the git commit 'm', git svn
uses the svn:mergeinfo property and tries to find the corresponding git
commit 'e' to create 'm' with 'c' and 'e' as parents. But git svn rebase
only imports the current branch so commit 'e' is not imported.
Therefore git svn fails to create commit 'm' as a merge commit, because one
of its parents is not known to git. The imported history looks like this:

  ... - a - b - c - m  <- trunk

A later 'git svn fetch' to import all branches can't rewrite the commit 'm'
to add 'e' as a parent and to make it a real git merge commit, because it
was already imported.

That's why the imported history misses the merge and looks like this:

  ... - a - b - c - m  <- trunk
          \
            d  -  e    <- branch1

Right now the only known workaround for importing 'm' as a merge is to
force reimporting 'm' again from SVN, e.g. via

  $ git svn reset --revision $(git find-rev $c)
  $ git svn fetch

Sadly, this is where the behavior has regressed: git svn reset doesn't
invalidate the old mergeinfo cache, which is no longer valid for the
reimport, which leads to 'm' beeing imprted with only 'c' as parent.

As solution to this problem, this commit invalidates the mergeinfo cache
to force correct recalculation of the parents.

During development of this patch, several ways for invalidating the cache
where considered. One of them is to use Memoize::flush_cache, which will
call the CLEAR method on the underlying Memoize persistency implementation.
Sadly, neither Memoize::Storable nor the newer Memoize::YAML module
introduced in 68f532f4ba could optionally be used implement the
CLEAR method, so this is not an option.

Reseting the internal hash used to store the memoized values has the same
problem, because it calls the non-existing CLEAR method of the
underlying persistency layer, too.

Considering this and taking into account the different implementations
of the memoization modules, where Memoize::Storable is not in our control,
implementing the missing CLEAR method is not an option, at least not if
Memoize::Storable is still used.

Therefore the easiest solution to clear the cache is to delete the files
on disk in 'git svn reset'. Normally, deleting the files behind the back
of the memoization module would be problematic, because the in-memory
representation would still exist and contain wrong data. Fortunately, the
memoization is active in memory only for a small portion of the code.
Invalidating the cache by deleting the files on disk if it isn't active
should be safe.

Signed-off-by: Peter Baumann <waste.manager@gmx.de>
Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Eric Wong <normalperson@yhbt.net>

2012-08-10 19:53:18 +00:00

2 Commits