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.
238 Remove a TopGit-controlled topic branch of given name
239 (required argument). Normally, this command will remove
240 only empty branch (base == head); use '-f' to remove
243 Currently, this command will _NOT_ remove the branch from
244 the dependency list in other branches. You need to take
245 care of this _manually_. This is even more complicated
246 in combination with '-f', in that case you need to manually
247 unmerge the removed branch's changes from the branches
250 TODO: '-a' to delete all empty branches, depfix, revert
254 Show a summary information about the current or specified
259 Generate a patch from the current or specified topic branch.
260 This means that the diff between the topic branch base and
261 head (latest commit) is shown, appended to the description
262 found in the .topmsg file.
264 The patch is by default simply dumped to stdout. In the future,
265 tg patch will be able to automatically send the patches by mail
266 or save them to files. (TODO)
268 TODO: tg patch -i to base at index instead of branch,
273 Register given remote as TopGit-controlled. This will create
274 the namespace for the remote branch bases and teach 'git fetch'
275 and 'git push' to operate on them.
277 It takes a mandatory remote name argument, and optional
278 '--populate' switch - use that for your origin-style remote,
279 it will seed the local topic branch system based on the
280 remote topic branches. '--populate' will also make 'tg remote'
281 automatically fetch the remote and 'tg update' to look at
282 branches of this remote for updates by default.
286 Show overview of all TopGit-tracked topic branches and their
287 up-to-date status ('>' marks the current topic branch,
288 '0' marks that it introduces no own changes,
289 'l'/'r' marks that it is local-only or has remote mate,
290 'L'/'R' marks that it is ahead/out-of-date wrt. its remote mate,
291 'D' marks that it is out-of-date wrt. its dependencies,
292 '!' marks that it has missing dependencies (even recursively),
293 'B' marks that it is out-of-date wrt. its base).
295 TODO: Speed up by an order of magnitude
300 Export a tidied-up history of the current topic branch
301 and its dependencies, suitable for feeding upstream.
302 Each topic branch corresponds to a single commit or patch
303 in the cleaned up history (corresponding basically exactly
304 to `tg patch` output for the topic branch).
306 The command has two posible outputs now - either a Git branch
307 with the collapsed history, or a quilt series in new directory.
309 In case of producing collapsed history in new branch,
310 You can use this collapsed structure either for providing
311 a pull source for upstream, or further linearization e.g.
312 for creation of a quilt series using git log:
314 git log --pretty=email -p --topo-order origin..exported
316 To better understand the function of `tg export`,
317 consider this dependency structure of topic branches:
319 origin/master - t/foo/blue - t/foo/red - master
320 `- t/bar/good <,----------'
321 `- t/baz ------------'
323 (Where each of the branches may have hefty history.) Then
325 master$ tg export for-linus
327 will create this commit structure on branch for-linus:
329 origin/master - t/foo/blue -. merge - t/foo/red -.. merge - master
330 `- t/bar/good <,-------------------'/
331 `- t/baz ---------------------'
333 In case of the quilt mode,
335 master$ tg export --quilt for-linus
337 would create this directory for-linus:
339 for-linus/t/foo/blue.diff
340 for-linus/t/foo/red.diff
341 for-linus/t/bar/good.diff
349 The command works on the current topic branch
350 and can be called either without a parameter
351 (in that case, '--collapse' is assumed)
352 and with one mandatory argument: the name of the branch
353 where the exported result shall be stored.
354 The branch will be silently overwritten if it exists already!
355 Use git reflog to recover in case of mistake.
357 Alternatively, call it with the '--quilt' parameter
358 and an argument specifying the directory
359 where the quilt series should be saved.
361 Usage: tg export ([--collapse] BRANCH | --quilt DIR)
363 TODO: Make stripping of non-essential headers configurable
364 TODO: Make stripping of [PATCH] and other prefixes configurable
365 TODO: --mbox option for other mode of operation
366 TODO: -n option to prevent exporting of empty patches
367 TODO: -a option to export all branches
368 TODO: Allow branches to be exported to be passed as arguments, default
369 to the current branch if none are specified
370 TODO: For quilt exporting, use a temporary branch and remove it when
371 done - this would allow producing conflict-less series
375 Update the current topic branch wrt. changes in the branches
376 it depends on and remote branches.
377 This is performed in two phases - first,
378 changes within the dependencies are merged to the base,
379 then the base is merged into the topic branch.
380 The output will guide you in case of conflicts.
382 In case your dependencies are not up-to-date, tg update
383 will first recurse into them and update these.
385 TODO: tg update -a for updating all topic branches
387 TODO: Some infrastructure for sharing topic branches between
389 TODO: tg depend for adding/removing dependencies smoothly
396 TopGit stores all the topic branches in the regular refs/heads/
397 namespace, (we recommend to mark them with the 't/' prefix).
398 Except that, TopGit also maintains a set of auxiliary refs in
399 refs/top-*. Currently, only refs/top-bases/ is used, containing
400 the current _base_ of the given topic branch - this is basically
401 a merge of all the branches the topic branch depends on; it is
402 updated during `tg update` and then merged to the topic branch,
403 and it is the base of a patch generated from the topic branch by
406 All the metadata is tracked within the source tree and history
407 of the topic branch itself, in .top* files; these files are kept
408 isolated within the topic branches during TopGit-controlled merges
409 and are of course omitted during `tg patch`. The state of these
410 files in base commits is undefined; look at them only in the topic
411 branches themselves. Currently, two files are defined:
413 .topmsg: Contains the description of the topic branch
414 in a mail-like format, plus the author information,
415 whatever Cc headers you choose or the post-three-dashes message.
416 When mailing out your patch, basically only few extra headers
417 mail headers are inserted and the patch itself is appended.
418 Thus, as your patches evolve, you can record nuances like whether
419 the paricular patch should have To-list/Cc-maintainer or vice
420 versa and similar nuances, if your project is into that.
421 From is prefilled from your current GIT_AUTHOR_IDENT, other headers
422 can be prefilled from various optional topgit.* config options.
424 .topdeps: Contains the one-per-line list of branches
425 your patch depends on, pre-seeded with `tg create`. (Continuously
426 updated) merge of these branches will be the "base" of your topic
429 TopGit also automagically installs a bunch of custom commit-related
430 hooks that will verify if you are committing the .top* files in sane
431 state. It will add the hooks to separate files within the hooks/
432 subdirectory and merely insert calls of them to the appropriate hooks
433 and make them executable (but make sure the original hooks code
434 is not called if the hook was not executable beforehand).
436 Another automagically installed piece is .git/info/attributes specifier
437 for an 'ours' merge strategy for the files .topmsg and .topdeps, and
438 the (intuitive) 'ours' merge strategy definition in .git/config.
444 There are three issues with accessing topic branches in remote repositories:
446 (i) Fetching/pushing accurate picture of the remote topic branch setup
447 (ii) Referring to remote topic branches from your local repository
448 (iii) Developing some of the remote topic branches locally
450 (ii) and (iii) are fairly interconnected problems, while (i) is largely
451 independent. The issue is to accurately reflect the current state of the
452 quickly changing topic branches set - this can be easily done
453 with the current facilities like 'git remote prune' and 'git push --mirror' -
454 and to properly upload also the bases of the topic branches.
455 For this, we need to modify the fetch/push refspecs to also include
456 the refs/top-bases/ ref namespace; we shall provide a special 'tg remote'
457 command to set up an existing remote for TopGit usage.
459 About (ii) and (iii), there are two somewhat contradicting design
462 (a) Hacking on multiple independent TopGit remotes in a single
464 (b) Having a self-contained topic system in local refs space
466 To us, (a) does not appear to be very convincing, while (b) is quite desirable
467 for 'git-log topic' etc. working, 'git push' automatically creating
468 self-contained topic system in the remote repository, and increased conceptual
471 Thus, we choose to instantiate all the topic branches of given remote locally;
472 this is performed by 'tg remote --populate'.
473 'tg update' will also check if a branch can be updated from its corresponding
474 remote branch. The logic is somewhat involved if we should DTRT.
475 First, we update the base, handling the remote branch as if it was the first
476 dependency; thus, conflict resolutions made in the remote branch will be
477 carried over to our local base automagically. Then, the base is merged into
478 remote branch and the result is merged to local branch - again, to carry over
479 remote conflict resolutions. In the future, this order might be adjustable
480 per-update in case local changes are diverging more than the remote ones.
482 All commands by default refer to the remote that 'tg remote --populate'
483 was called on the last time ('topgit.remote' configuration variable). You can
484 manually run any command with a different base remote by passing '-r REMOTE'
485 _before_ the subcommand name.