1 TopGit - A different patch queue manager
7 TopGit aims to make handling of large amount of interdependent topic
8 branches easier. In fact, it is designed especially for the case
9 when you maintain a queue of third-party patches on top of another
10 (perhaps Git-controlled) project and want to easily organize, maintain
11 and submit them - TopGit achieves that by keeping a separate topic
12 branch for each patch and providing few tools to maintain the branches.
18 Why not use something like StGIT or Guilt or rebase -i for maintaining
19 your patch queue? The advantage of these tools is their simplicity;
20 they work with patch _series_ and defer to the reflog facility for
21 version control of patches (reordering of patches is not
22 version-controlled at all). But there are several disadvantages -
23 for one, these tools (especially StGIT) do not actually fit well
24 with plain Git at all: it is basically impossible to take advantage
25 of the index efectively when using StGIT. But more importantly,
26 these tools horribly fail in the face of distributed environment.
28 TopGit has been designed around three main tenets:
30 (i) TopGit is as thin layer on top of Git as possible.
31 You still maintain your index and commit using Git, TopGit will
32 only automate few indispensable tasks.
34 (ii) TopGit is anxious about _keeping_ your history. It will
35 never rewrite your history and all metadata is also tracked by Git,
36 smoothly and non-obnoxiously. It is good to have a _single_ point
37 when the history is cleaned up, and that is at the point of inclusion
38 in the upstream project; locally, you can see how your patch has evolved
39 and easily return to older versions.
41 (iii) TopGit is specifically designed to work in distributed
42 environment. You can have several instances of TopGit-aware repositories
43 and smoothly keep them all up-to-date and transfer your changes between
46 As mentioned above, the main intended use-case for TopGit is tracking
47 third-party patches, where each patch is effectively a single topic
48 branch. In order to flexibly accomodate even complex scenarios when
49 you track many patches where many are independent but some depend
50 on others, TopGit ignores the ancient Quilt heritage of patch series
51 and instead allows the patches to freely form graphs (DAGs just like
52 Git history itself, only "one lever higher"). For now, you have
53 to manually specify which patches does the current one depend
54 on, but TopGit might help you with that in the future in a darcs-like
57 A glossary plug: The union (i.e. merge) of patch dependencies is
58 called a _base_ of the patch (topic branch).
60 Of course, TopGit is perhaps not the right tool for you:
62 (i) TopGit is not complicated, but StGIT et al. are somewhat
63 simpler, conceptually. If you just want to make a linear purely-local
64 patch queue, deferring to StGIT instead might make more sense.
66 (ii) When using TopGit, your history can get a little hairy
67 over time, especially with all the merges rippling through. ;-)
73 ## Create and evolve a topic branch
74 $ tg create t/gitweb/pathinfo-action
75 tg: Automatically marking dependency on master
76 tg: Creating t/gitweb/pathinfo-action base from master...
82 ## Create another topic branch on top of the former one
83 $ tg create t/gitweb/nifty-links
84 tg: Automatically marking dependency on t/gitweb/pathinfo-action
85 tg: Creating t/gitweb/nifty-links base from t/gitweb/pathinfo-action...
89 ## Create another topic branch on top of master and submit
90 ## the resulting patch upstream
91 $ tg create t/revlist/author-fixed master
92 tg: Creating t/revlist/author-fixed base from master...
96 tg: Sent t/revlist/author-fixed
98 To: git@vger.kernel.org
100 Subject: [PATCH] Fix broken revlist --author when --fixed-string
102 ## Create another topic branch depending on two others non-trivially
103 $ tg create t/whatever t/revlist/author-fixed t/gitweb/nifty-links
104 tg: Creating t/whatever base from t/revlist/author-fixed...
105 tg: Merging t/whatever base with t/gitweb/nifty-links...
107 tg: Please commit merge resolution and call: tg create
108 tg: It is also safe to abort this operation using `git reset --hard`
109 tg: but please remember you are on the base branch now;
110 tg: you will want to switch to a different branch.
114 tg: Resuming t/whatever setup...
118 ## Update a single topic branch and propagate the changes to
120 $ git checkout t/gitweb/nifty-links
123 $ git checkout t/whatever
125 Topic Branch: t/whatever (1 commit)
126 Subject: [PATCH] Whatever patch
128 Depends: t/revlist/author-fixed t/gitweb/nifty-links
130 t/gitweb/nifty-links (1 commit)
132 tg: Updating base with t/gitweb/nifty-links changes...
134 tg: Please commit merge resolution and call `tg update` again.
135 tg: It is also safe to abort this operation using `git reset --hard`,
136 tg: but please remember you are on the base branch now;
137 tg: you will want to switch to a different branch.
141 tg: Updating t/whatever against new base...
143 tg: Please resolve the merge and commit. No need to do anything else.
144 tg: You can abort this operation using `git reset --hard` now
145 tg: and retry this merge later using `tg update`.
149 ## Update a single topic branch and propagate the changes
150 ## further through the dependency chain
151 $ git checkout t/gitweb/pathinfo-action
154 $ git checkout t/whatever
156 Topic Branch: t/whatever (1/2 commits)
157 Subject: [PATCH] Whatever patch
159 Depends: t/revlist/author-fixed t/gitweb/nifty-links
161 t/gitweb/pathinfo-action (<= t/gitweb/nifty-links) (1 commit)
163 tg: Recursing to t/gitweb/nifty-links...
164 [t/gitweb/nifty-links] tg: Updating base with t/gitweb/pathinfo-action changes...
166 [t/gitweb/nifty-links] tg: Please commit merge resolution and call `tg update` again.
167 [t/gitweb/nifty-links] tg: It is also safe to abort this operation using `git reset --hard`,
168 [t/gitweb/nifty-links] tg: but please remember you are on the base branch now;
169 [t/gitweb/nifty-links] tg: you will want to switch to a different branch.
170 [t/gitweb/nifty-links] tg: You are in a subshell. If you abort the merge,
171 [t/gitweb/nifty-links] tg: use `exit` to abort the recursive update altogether.
172 [t/gitweb/nifty-links] $ ..resolve..
173 [t/gitweb/nifty-links] $ git commit
174 [t/gitweb/nifty-links] $ tg update
175 [t/gitweb/nifty-links] tg: Updating t/gitweb/nifty-links against new base...
177 [t/gitweb/nifty-links] tg: Please resolve the merge and commit.
178 [t/gitweb/nifty-links] tg: You can abort this operation using `git reset --hard`.
179 [t/gitweb/nifty-links] tg: You are in a subshell. After you either commit or abort
180 [t/gitweb/nifty-links] tg: your merge, use `exit` to proceed with the recursive update.
181 [t/gitweb/nifty-links] $ ..resolve..
182 [t/gitweb/nifty-links] $ git commit
183 [t/gitweb/nifty-links] $ exit
184 tg: Updating base with t/gitweb/nifty-links changes...
185 tg: Updating t/whatever against new base...
187 ## Clone a TopGit-controlled repository
190 $ tg remote --populate origin
195 ## Add a TopGit remote to a repository and push to it
196 $ git remote add foo URL
200 ## Update from a non-default TopGit remote
209 The 'tg' tool of TopGit has several subcommands:
213 Our sophisticated integrated help facility. Doesn't do
218 Create a new TopGit-controlled topic branch of a given name
219 (required argument) and switch to it. If no dependencies
220 are specified (by extra arguments passed after the first one),
221 the current branch is assumed to be the only dependency.
223 After `tg create`, you should insert the patch description
224 to the '.topmsg' file, which will already contain some
225 pre-filled bits. You can set topgit.to, topgit.cc and topgit.bcc
226 configuration variables in order to have `tg create`
227 add these headers with given default values to '.topmsg'.
229 The main task of `tg create` is to set up the topic branch
230 base from the dependencies. This may fail due to merge conflicts.
231 In that case, after you commit the conflicts resolution,
232 you should call `tg create` again (without any arguments);
233 it will detect that you are on a topic branch base ref and
234 resume the topic branch creation operation.
236 In an alternative use case, if '-r BRANCH' is given instead
237 of dependency list, the topic branch is created based on
238 the given remote branch.
242 Remove a TopGit-controlled topic branch of given name
243 (required argument). Normally, this command will remove
244 only empty branch (base == head); use '-f' to remove
247 Currently, this command will _NOT_ remove the branch from
248 the dependency list in other branches. You need to take
249 care of this _manually_. This is even more complicated
250 in combination with '-f', in that case you need to manually
251 unmerge the removed branch's changes from the branches
254 TODO: '-a' to delete all empty branches, depfix, revert
258 Show a summary information about the current or specified
263 Generate a patch from the current or specified topic branch.
264 This means that the diff between the topic branch base and
265 head (latest commit) is shown, appended to the description
266 found in the .topmsg file.
268 The patch is by default simply dumped to stdout. In the future,
269 tg patch will be able to automatically send the patches by mail
270 or save them to files. (TODO)
272 TODO: tg patch -i to base at index instead of branch,
277 Register given remote as TopGit-controlled. This will create
278 the namespace for the remote branch bases and teach 'git fetch'
279 and 'git push' to operate on them.
281 It takes a mandatory remote name argument, and optional
282 '--populate' switch - use that for your origin-style remote,
283 it will seed the local topic branch system based on the
284 remote topic branches. '--populate' will also make 'tg remote'
285 automatically fetch the remote and 'tg update' to look at
286 branches of this remote for updates by default.
290 Show overview of all TopGit-tracked topic branches and their
291 up-to-date status ('>' marks the current topic branch,
292 '0' marks that it introduces no own changes,
293 'l'/'r' marks that it is local-only or has remote mate,
294 'L'/'R' marks that it is ahead/out-of-date wrt. its remote mate,
295 'D' marks that it is out-of-date wrt. its dependencies,
296 '!' marks that it has missing dependencies (even recursively),
297 'B' marks that it is out-of-date wrt. its base).
299 TODO: Speed up by an order of magnitude
304 Export a tidied-up history of the current topic branch
305 and its dependencies, suitable for feeding upstream.
306 Each topic branch corresponds to a single commit or patch
307 in the cleaned up history (corresponding basically exactly
308 to `tg patch` output for the topic branch).
310 The command has two posible outputs now - either a Git branch
311 with the collapsed history, or a quilt series in new directory.
313 In case of producing collapsed history in new branch,
314 You can use this collapsed structure either for providing
315 a pull source for upstream, or further linearization e.g.
316 for creation of a quilt series using git log:
318 git log --pretty=email -p --topo-order origin..exported
320 To better understand the function of `tg export`,
321 consider this dependency structure of topic branches:
323 origin/master - t/foo/blue - t/foo/red - master
324 `- t/bar/good <,----------'
325 `- t/baz ------------'
327 (Where each of the branches may have hefty history.) Then
329 master$ tg export for-linus
331 will create this commit structure on branch for-linus:
333 origin/master - t/foo/blue -. merge - t/foo/red -.. merge - master
334 `- t/bar/good <,-------------------'/
335 `- t/baz ---------------------'
337 In case of the quilt mode,
339 master$ tg export --quilt for-linus
341 would create this directory for-linus:
343 for-linus/t/foo/blue.diff
344 for-linus/t/foo/red.diff
345 for-linus/t/bar/good.diff
353 The command works on the current topic branch
354 and can be called either without a parameter
355 (in that case, '--collapse' is assumed)
356 and with one mandatory argument: the name of the branch
357 where the exported result shall be stored.
358 The branch will be silently overwritten if it exists already!
359 Use git reflog to recover in case of mistake.
361 Alternatively, call it with the '--quilt' parameter
362 and an argument specifying the directory
363 where the quilt series should be saved.
365 Usage: tg export ([--collapse] BRANCH | --quilt DIR)
367 TODO: Make stripping of non-essential headers configurable
368 TODO: Make stripping of [PATCH] and other prefixes configurable
369 TODO: --mbox option for other mode of operation
370 TODO: -n option to prevent exporting of empty patches
371 TODO: -a option to export all branches
372 TODO: Allow branches to be exported to be passed as arguments, default
373 to the current branch if none are specified
374 TODO: For quilt exporting, use a temporary branch and remove it when
375 done - this would allow producing conflict-less series
379 Import commits within the given revision range into TopGit,
380 creating one topic branch per commit, the dependencies forming
381 a linear sequence starting on your current branch.
383 The branch names are auto-guessed from the commit messages
384 and prefixed by t/ by default; use '-p PREFIX' to specify
385 an alternative prefix (even an empty one).
389 Update the current topic branch wrt. changes in the branches
390 it depends on and remote branches.
391 This is performed in two phases - first,
392 changes within the dependencies are merged to the base,
393 then the base is merged into the topic branch.
394 The output will guide you in case of conflicts.
396 In case your dependencies are not up-to-date, tg update
397 will first recurse into them and update these.
399 If a remote branch update brings dependencies on branches
400 not yet instantiated locally, you can either bring in all
401 the new branches from the remote using 'tg remote --populate'
402 or only pick out the missing ones using 'tg create -r'
403 ('tg summary' will point out branches with incomplete
404 dependencies by showing an '!' near to them).
406 TODO: tg update -a for updating all topic branches
408 TODO: tg depend for adding/removing dependencies smoothly
415 TopGit stores all the topic branches in the regular refs/heads/
416 namespace, (we recommend to mark them with the 't/' prefix).
417 Except that, TopGit also maintains a set of auxiliary refs in
418 refs/top-*. Currently, only refs/top-bases/ is used, containing
419 the current _base_ of the given topic branch - this is basically
420 a merge of all the branches the topic branch depends on; it is
421 updated during `tg update` and then merged to the topic branch,
422 and it is the base of a patch generated from the topic branch by
425 All the metadata is tracked within the source tree and history
426 of the topic branch itself, in .top* files; these files are kept
427 isolated within the topic branches during TopGit-controlled merges
428 and are of course omitted during `tg patch`. The state of these
429 files in base commits is undefined; look at them only in the topic
430 branches themselves. Currently, two files are defined:
432 .topmsg: Contains the description of the topic branch
433 in a mail-like format, plus the author information,
434 whatever Cc headers you choose or the post-three-dashes message.
435 When mailing out your patch, basically only few extra headers
436 mail headers are inserted and the patch itself is appended.
437 Thus, as your patches evolve, you can record nuances like whether
438 the paricular patch should have To-list/Cc-maintainer or vice
439 versa and similar nuances, if your project is into that.
440 From is prefilled from your current GIT_AUTHOR_IDENT, other headers
441 can be prefilled from various optional topgit.* config options.
443 .topdeps: Contains the one-per-line list of branches
444 your patch depends on, pre-seeded with `tg create`. (Continuously
445 updated) merge of these branches will be the "base" of your topic
448 TopGit also automagically installs a bunch of custom commit-related
449 hooks that will verify if you are committing the .top* files in sane
450 state. It will add the hooks to separate files within the hooks/
451 subdirectory and merely insert calls of them to the appropriate hooks
452 and make them executable (but make sure the original hooks code
453 is not called if the hook was not executable beforehand).
455 Another automagically installed piece is .git/info/attributes specifier
456 for an 'ours' merge strategy for the files .topmsg and .topdeps, and
457 the (intuitive) 'ours' merge strategy definition in .git/config.
463 There are three issues with accessing topic branches in remote repositories:
465 (i) Fetching/pushing accurate picture of the remote topic branch setup
466 (ii) Referring to remote topic branches from your local repository
467 (iii) Developing some of the remote topic branches locally
469 (ii) and (iii) are fairly interconnected problems, while (i) is largely
470 independent. The issue is to accurately reflect the current state of the
471 quickly changing topic branches set - this can be easily done
472 with the current facilities like 'git remote prune' and 'git push --mirror' -
473 and to properly upload also the bases of the topic branches.
474 For this, we need to modify the fetch/push refspecs to also include
475 the refs/top-bases/ ref namespace; we shall provide a special 'tg remote'
476 command to set up an existing remote for TopGit usage.
478 About (ii) and (iii), there are two somewhat contradicting design
481 (a) Hacking on multiple independent TopGit remotes in a single
483 (b) Having a self-contained topic system in local refs space
485 To us, (a) does not appear to be very convincing, while (b) is quite desirable
486 for 'git-log topic' etc. working, 'git push' automatically creating
487 self-contained topic system in the remote repository, and increased conceptual
490 Thus, we choose to instantiate all the topic branches of given remote locally;
491 this is performed by 'tg remote --populate'.
492 'tg update' will also check if a branch can be updated from its corresponding
493 remote branch. The logic is somewhat involved if we should DTRT.
494 First, we update the base, handling the remote branch as if it was the first
495 dependency; thus, conflict resolutions made in the remote branch will be
496 carried over to our local base automagically. Then, the base is merged into
497 remote branch and the result is merged to local branch - again, to carry over
498 remote conflict resolutions. In the future, this order might be adjustable
499 per-update in case local changes are diverging more than the remote ones.
501 All commands by default refer to the remote that 'tg remote --populate'
502 was called on the last time ('topgit.remote' configuration variable). You can
503 manually run any command with a different base remote by passing '-r REMOTE'
504 _before_ the subcommand name.