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...
191 The 'tg' tool of TopGit has several subcommands:
195 Our sophisticated integrated help facility. Doesn't do
200 Create a new TopGit-controlled topic branch of a given name
201 (required argument) and switch to it. If no dependencies
202 are specified (by extra arguments passed after the first one),
203 the current branch is assumed to be the only dependency.
205 After `tg create`, you should insert the patch description
206 to the '.topmsg' file, which will already contain some
207 pre-filled bits. You can set topgit.to, topgit.cc and topgit.bcc
208 configuration variables in order to have `tg create`
209 add these headers with given default values to '.topmsg'.
211 The main task of `tg create` is to set up the topic branch
212 base from the dependencies. This may fail due to merge conflicts.
213 In that case, after you commit the conflicts resolution,
214 you should call `tg create` again (without any arguments);
215 it will detect that you are on a topic branch base ref and
216 resume the topic branch creation operation.
220 Remove a TopGit-controlled topic branch of given name
221 (required argument). Normally, this command will remove
222 only empty branch (base == head); use '-f' to remove
225 Currently, this command will _NOT_ remove the branch from
226 the dependency list in other branches. You need to take
227 care of this _manually_. This is even more complicated
228 in combination with '-f', in that case you need to manually
229 unmerge the removed branch's changes from the branches
232 TODO: '-a' to delete all empty branches, depfix, revert
236 Show a summary information about the current or specified
241 Generate a patch from the current or specified topic branch.
242 This means that the diff between the topic branch base and
243 head (latest commit) is shown, appended to the description
244 found in the .topmsg file.
246 The patch is by default simply dumped to stdout. In the future,
247 tg patch will be able to automatically send the patches by mail
248 or save them to files. (TODO)
250 TODO: tg patch -i to base at index instead of branch,
255 Register given remote as TopGit-controlled. This will create
256 the namespace for the remote branch bases and teach 'git fetch'
257 and 'git push' to operate on them.
259 It takes a mandatory remote name argument, and optional
260 '--populate' switch - use that for your origin-style remote,
261 it will seed the local topic branch system based on the
262 remote topic branches. '--populate' will also make 'tg remote'
263 automatically fetch the remote and 'tg update' to look at
264 branches of this remote for updates by default.
268 Show overview of all TopGit-tracked topic branches and their
269 up-to-date status ('>' marks the current topic branch,
270 '0' marks that it introduces no own changes,
271 'l'/'r' marks that it is local-only or has remote mate,
272 'L'/'R' marks that it is ahead/out-of-date wrt. its remote mate,
273 'D' marks that it is out-of-date wrt. its dependencies,
274 '!' marks that it has missing dependencies (even recursively),
275 'B' marks that it is out-of-date wrt. its base).
277 TODO: Speed up by an order of magnitude
282 Export a tidied-up history of the current topic branch
283 and its dependencies, suitable for feeding upstream.
284 Each topic branch corresponds to a single commit or patch
285 in the cleaned up history (corresponding basically exactly
286 to `tg patch` output for the topic branch).
288 The command has two posible outputs now - either a Git branch
289 with the collapsed history, or a quilt series in new directory.
291 In case of producing collapsed history in new branch,
292 You can use this collapsed structure either for providing
293 a pull source for upstream, or further linearization e.g.
294 for creation of a quilt series using git log:
296 git log --pretty=email -p --topo-order origin..exported
298 To better understand the function of `tg export`,
299 consider this dependency structure of topic branches:
301 origin/master - t/foo/blue - t/foo/red - master
302 `- t/bar/good <,----------'
303 `- t/baz ------------'
305 (Where each of the branches may have hefty history.) Then
307 master$ tg export for-linus
309 will create this commit structure on branch for-linus:
311 origin/master - t/foo/blue -. merge - t/foo/red -.. merge - master
312 `- t/bar/good <,-------------------'/
313 `- t/baz ---------------------'
315 In case of the quilt mode,
317 master$ tg export --quilt for-linus
319 would create this directory for-linus:
321 for-linus/t/foo/blue.diff
322 for-linus/t/foo/red.diff
323 for-linus/t/bar/good.diff
331 The command works on the current topic branch
332 and can be called either without a parameter
333 (in that case, '--collapse' is assumed)
334 and with one mandatory argument: the name of the branch
335 where the exported result shall be stored.
336 The branch will be silently overwritten if it exists already!
337 Use git reflog to recover in case of mistake.
339 Alternatively, call it with the '--quilt' parameter
340 and an argument specifying the directory
341 where the quilt series should be saved.
343 Usage: tg export ([--collapse] BRANCH | --quilt DIR)
345 TODO: Make stripping of non-essential headers configurable
346 TODO: Make stripping of [PATCH] and other prefixes configurable
347 TODO: --mbox option for other mode of operation
348 TODO: -n option to prevent exporting of empty patches
349 TODO: -a option to export all branches
350 TODO: Allow branches to be exported to be passed as arguments, default
351 to the current branch if none are specified
352 TODO: For quilt exporting, use a temporary branch and remove it when
353 done - this would allow producing conflict-less series
357 Import commits within the given revision range into TopGit,
358 creating one topic branch per commit, the dependencies forming
359 a linear sequence starting on your current branch.
361 The branch names are auto-guessed from the commit messages
362 and prefixed by t/ by default; use '-p PREFIX' to specify
363 an alternative prefix (even an empty one).
367 Update the current topic branch wrt. changes in the branches
368 it depends on and remote branches.
369 This is performed in two phases - first,
370 changes within the dependencies are merged to the base,
371 then the base is merged into the topic branch.
372 The output will guide you in case of conflicts.
374 In case your dependencies are not up-to-date, tg update
375 will first recurse into them and update these.
377 TODO: tg update -a for updating all topic branches
379 TODO: Some infrastructure for sharing topic branches between
381 TODO: tg depend for adding/removing dependencies smoothly
388 TopGit stores all the topic branches in the regular refs/heads/
389 namespace, (we recommend to mark them with the 't/' prefix).
390 Except that, TopGit also maintains a set of auxiliary refs in
391 refs/top-*. Currently, only refs/top-bases/ is used, containing
392 the current _base_ of the given topic branch - this is basically
393 a merge of all the branches the topic branch depends on; it is
394 updated during `tg update` and then merged to the topic branch,
395 and it is the base of a patch generated from the topic branch by
398 All the metadata is tracked within the source tree and history
399 of the topic branch itself, in .top* files; these files are kept
400 isolated within the topic branches during TopGit-controlled merges
401 and are of course omitted during `tg patch`. The state of these
402 files in base commits is undefined; look at them only in the topic
403 branches themselves. Currently, two files are defined:
405 .topmsg: Contains the description of the topic branch
406 in a mail-like format, plus the author information,
407 whatever Cc headers you choose or the post-three-dashes message.
408 When mailing out your patch, basically only few extra headers
409 mail headers are inserted and the patch itself is appended.
410 Thus, as your patches evolve, you can record nuances like whether
411 the paricular patch should have To-list/Cc-maintainer or vice
412 versa and similar nuances, if your project is into that.
413 From is prefilled from your current GIT_AUTHOR_IDENT, other headers
414 can be prefilled from various optional topgit.* config options.
416 .topdeps: Contains the one-per-line list of branches
417 your patch depends on, pre-seeded with `tg create`. (Continuously
418 updated) merge of these branches will be the "base" of your topic
421 TopGit also automagically installs a bunch of custom commit-related
422 hooks that will verify if you are committing the .top* files in sane
423 state. It will add the hooks to separate files within the hooks/
424 subdirectory and merely insert calls of them to the appropriate hooks
425 and make them executable (but make sure the original hooks code
426 is not called if the hook was not executable beforehand).
428 Another automagically installed piece is .git/info/attributes specifier
429 for an 'ours' merge strategy for the files .topmsg and .topdeps, and
430 the (intuitive) 'ours' merge strategy definition in .git/config.
436 There are three issues with accessing topic branches in remote repositories:
438 (i) Fetching/pushing accurate picture of the remote topic branch setup
439 (ii) Referring to remote topic branches from your local repository
440 (iii) Developing some of the remote topic branches locally
442 (ii) and (iii) are fairly interconnected problems, while (i) is largely
443 independent. The issue is to accurately reflect the current state of the
444 quickly changing topic branches set - this can be easily done
445 with the current facilities like 'git remote prune' and 'git push --mirror' -
446 and to properly upload also the bases of the topic branches.
447 For this, we need to modify the fetch/push refspecs to also include
448 the refs/top-bases/ ref namespace; we shall provide a special 'tg remote'
449 command to set up an existing remote for TopGit usage.
451 About (ii) and (iii), there are two somewhat contradicting design
454 (a) Hacking on multiple independent TopGit remotes in a single
456 (b) Having a self-contained topic system in local refs space
458 To us, (a) does not appear to be very convincing, while (b) is quite desirable
459 for 'git-log topic' etc. working, 'git push' automatically creating
460 self-contained topic system in the remote repository, and increased conceptual
463 Thus, we choose to instantiate all the topic branches of given remote locally;
464 this is performed by 'tg remote --populate'.
465 'tg update' will also check if a branch can be updated from its corresponding
466 remote branch. The logic is somewhat involved if we should DTRT.
467 First, we update the base, handling the remote branch as if it was the first
468 dependency; thus, conflict resolutions made in the remote branch will be
469 carried over to our local base automagically. Then, the base is merged into
470 remote branch and the result is merged to local branch - again, to carry over
471 remote conflict resolutions. In the future, this order might be adjustable
472 per-update in case local changes are diverging more than the remote ones.
474 All commands by default refer to the remote that 'tg remote --populate'
475 was called on the last time ('topgit.remote' configuration variable). You can
476 manually run any command with a different base remote by passing '-r REMOTE'
477 _before_ the subcommand name.