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 effectively 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 accommodate 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 level 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 prefilled 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 Change dependencies of a TopGit-controlled topic branch.
259 This should have several subcommands, but only 'add' is
262 The 'add' subcommand takes an argument of a topic branch
263 to be added, adds it to '.topdeps', performs a commit and
264 then updates your topic branch accordingly. If you want to
265 do other things related to the dependency addition, like
266 adjusting '.topmsg', prepare them in the index before
267 calling 'tg depend add'.
269 TODO: Subcommand for removing dependencies, obviously
273 Show a summary information about the current or specified
278 Generate a patch from the current or specified topic branch.
279 This means that the diff between the topic branch base and
280 head (latest commit) is shown, appended to the description
281 found in the .topmsg file.
283 The patch is by default simply dumped to stdout. In the future,
284 tg patch will be able to automatically send the patches by mail
285 or save them to files. (TODO)
287 TODO: tg patch -i to base at index instead of branch,
292 Send a patch from the current or specified topic branch as
295 Takes the patch given on the command line and emails it out.
296 Destination addresses such as To, Cc and Bcc are taken from the
299 Since it actually boils down to `git send-email` please refer to
300 its documentation for details on how to setup email for git.
301 You can pass arbitrary options to this command through the
302 '-s' parameter, but you must double-quote everything.
303 The '-r' parameter with msgid can be used to generate in-reply-to
304 and reference headers to an earlier mail.
306 TODO: 'tg mail patchfile' to mail an already exported patch
307 TODO: mailing patch series
308 TODO: specifying additional options and addresses on command
313 Register given remote as TopGit-controlled. This will create
314 the namespace for the remote branch bases and teach 'git fetch'
315 and 'git push' to operate on them. (Do NOT use 'git push --all'
316 for your pushes - plain 'git push' will do the right thing.)
318 It takes a mandatory remote name argument, and optional
319 '--populate' switch - use that for your origin-style remote,
320 it will seed the local topic branch system based on the
321 remote topic branches. '--populate' will also make 'tg remote'
322 automatically fetch the remote and 'tg update' to look at
323 branches of this remote for updates by default.
327 Show overview of all TopGit-tracked topic branches and their
328 up-to-date status ('>' marks the current topic branch,
329 '0' marks that it introduces no own changes,
330 'l'/'r' marks that it is local-only or has remote mate,
331 'L'/'R' marks that it is ahead/out-of-date wrt. its remote mate,
332 'D' marks that it is out-of-date wrt. its dependencies,
333 '!' marks that it has missing dependencies (even recursively),
334 'B' marks that it is out-of-date wrt. its base).
336 This can take long time to accurately determine all the relevant
337 information about each branch; you can pass '-t' to get just
338 terse list of topic branch names quickly. Alternately, you can
339 pass '--graphviz' to get a dot-suitable output to draw a dependency
340 graph between the topic branches.
342 TODO: Speed up by an order of magnitude
343 TODO: Text graph view
347 Export a tidied-up history of the current topic branch
348 and its dependencies, suitable for feeding upstream.
349 Each topic branch corresponds to a single commit or patch
350 in the cleaned up history (corresponding basically exactly
351 to `tg patch` output for the topic branch).
353 The command has two possible outputs now - either a Git branch
354 with the collapsed history, or a quilt series in new directory.
356 In case of producing collapsed history in new branch,
357 You can use this collapsed structure either for providing
358 a pull source for upstream, or further linearization e.g.
359 for creation of a quilt series using git log:
361 git log --pretty=email -p --topo-order origin..exported
363 To better understand the function of `tg export`,
364 consider this dependency structure of topic branches:
366 origin/master - t/foo/blue - t/foo/red - master
367 `- t/bar/good <,----------'
368 `- t/baz ------------'
370 (Where each of the branches may have hefty history.) Then
372 master$ tg export for-linus
374 will create this commit structure on branch for-linus:
376 origin/master - t/foo/blue -. merge - t/foo/red -.. merge - master
377 `- t/bar/good <,-------------------'/
378 `- t/baz ---------------------'
380 In case of the quilt mode,
382 master$ tg export --quilt for-linus
384 would create this directory for-linus:
386 for-linus/t/foo/blue.diff
387 for-linus/t/foo/red.diff
388 for-linus/t/bar/good.diff
396 The command works on the current topic branch
397 and can be called either without a parameter
398 (in that case, '--collapse' is assumed)
399 and with one mandatory argument: the name of the branch
400 where the exported result shall be stored.
401 The branch will be silently overwritten if it exists already!
402 Use git reflog to recover in case of mistake.
404 Alternatively, call it with the '--quilt' parameter
405 and an argument specifying the directory
406 where the quilt series should be saved.
408 With '--quilt', you can also pass '-b' parameter followed by
409 a comma-separated explicit list of branches to export. This
410 mode of operation is currently not supported with collapse.
412 In '--quilt' mode the patches are named like the originating topgit
413 branch. So usually they end up in subdirectories of the output
414 directory. With option '--flatten' the names are mangled such that
415 they end up directly in the output dir (i.e. slashed are substituted by
418 Usage: tg export ([--collapse] BRANCH | --quilt DIR)
420 TODO: Make stripping of non-essential headers configurable
421 TODO: Make stripping of [PATCH] and other prefixes configurable
422 TODO: --mbox option for other mode of operation
423 TODO: -a option to export all branches
424 TODO: For quilt exporting, use a temporary branch and remove it when
425 done - this would allow producing conflict-less series
429 Import commits within the given revision range into TopGit,
430 creating one topic branch per commit, the dependencies forming
431 a linear sequence starting on your current branch (or a branch
432 specified by the '-d' parameter).
434 The branch names are auto-guessed from the commit messages
435 and prefixed by t/ by default; use '-p PREFIX' to specify
436 an alternative prefix (even an empty one).
438 Alternatively, you can use the '-s NAME' parameter to specify
439 the name of target branch; the command will then take one more
440 argument describing a single commit to import.
444 Update the current topic branch wrt. changes in the branches
445 it depends on and remote branches.
446 This is performed in two phases - first,
447 changes within the dependencies are merged to the base,
448 then the base is merged into the topic branch.
449 The output will guide you in case of conflicts.
451 In case your dependencies are not up-to-date, tg update
452 will first recurse into them and update these.
454 If a remote branch update brings dependencies on branches
455 not yet instantiated locally, you can either bring in all
456 the new branches from the remote using 'tg remote --populate'
457 or only pick out the missing ones using 'tg create -r'
458 ('tg summary' will point out branches with incomplete
459 dependencies by showing an '!' near to them).
461 TODO: tg update -a for updating all topic branches
469 TopGit stores all the topic branches in the regular refs/heads/
470 namespace, (we recommend to mark them with the 't/' prefix).
471 Except that, TopGit also maintains a set of auxiliary refs in
472 refs/top-*. Currently, only refs/top-bases/ is used, containing
473 the current _base_ of the given topic branch - this is basically
474 a merge of all the branches the topic branch depends on; it is
475 updated during `tg update` and then merged to the topic branch,
476 and it is the base of a patch generated from the topic branch by
479 All the metadata is tracked within the source tree and history
480 of the topic branch itself, in .top* files; these files are kept
481 isolated within the topic branches during TopGit-controlled merges
482 and are of course omitted during `tg patch`. The state of these
483 files in base commits is undefined; look at them only in the topic
484 branches themselves. Currently, two files are defined:
486 .topmsg: Contains the description of the topic branch
487 in a mail-like format, plus the author information,
488 whatever Cc headers you choose or the post-three-dashes message.
489 When mailing out your patch, basically only few extra headers
490 mail headers are inserted and the patch itself is appended.
491 Thus, as your patches evolve, you can record nuances like whether
492 the particular patch should have To-list/Cc-maintainer or vice
493 versa and similar nuances, if your project is into that.
494 From is prefilled from your current GIT_AUTHOR_IDENT, other headers
495 can be prefilled from various optional topgit.* config options.
497 .topdeps: Contains the one-per-line list of branches
498 your patch depends on, pre-seeded with `tg create`. (Continuously
499 updated) merge of these branches will be the "base" of your topic
500 branch. DO NOT EDIT THIS FILE MANUALLY!!! If you do so, you need
501 to know exactly what are you doing, since this file must stay in
502 sync with the Git history information, otherwise very bad things
505 TopGit also automagically installs a bunch of custom commit-related
506 hooks that will verify if you are committing the .top* files in sane
507 state. It will add the hooks to separate files within the hooks/
508 subdirectory and merely insert calls of them to the appropriate hooks
509 and make them executable (but make sure the original hooks code
510 is not called if the hook was not executable beforehand).
512 Another automagically installed piece is .git/info/attributes specifier
513 for an 'ours' merge strategy for the files .topmsg and .topdeps, and
514 the (intuitive) 'ours' merge strategy definition in .git/config.
520 There are three issues with accessing topic branches in remote repositories:
522 (i) Fetching/pushing accurate picture of the remote topic branch setup
523 (ii) Referring to remote topic branches from your local repository
524 (iii) Developing some of the remote topic branches locally
526 (ii) and (iii) are fairly interconnected problems, while (i) is largely
527 independent. The issue is to accurately reflect the current state of the
528 quickly changing topic branches set - this can be easily done
529 with the current facilities like 'git remote prune' and 'git push --mirror' -
530 and to properly upload also the bases of the topic branches.
531 For this, we need to modify the fetch/push refspecs to also include
532 the refs/top-bases/ ref namespace; we shall provide a special 'tg remote'
533 command to set up an existing remote for TopGit usage.
535 About (ii) and (iii), there are two somewhat contradicting design
538 (a) Hacking on multiple independent TopGit remotes in a single
540 (b) Having a self-contained topic system in local refs space
542 To us, (a) does not appear to be very convincing, while (b) is quite desirable
543 for 'git-log topic' etc. working, 'git push' automatically creating
544 self-contained topic system in the remote repository, and increased conceptual
547 Thus, we choose to instantiate all the topic branches of given remote locally;
548 this is performed by 'tg remote --populate'.
549 'tg update' will also check if a branch can be updated from its corresponding
550 remote branch. The logic is somewhat involved if we should DTRT.
551 First, we update the base, handling the remote branch as if it was the first
552 dependency; thus, conflict resolutions made in the remote branch will be
553 carried over to our local base automagically. Then, the base is merged into
554 remote branch and the result is merged to local branch - again, to carry over
555 remote conflict resolutions. In the future, this order might be adjustable
556 per-update in case local changes are diverging more than the remote ones.
558 All commands by default refer to the remote that 'tg remote --populate'
559 was called on the last time ('topgit.remote' configuration variable). You can
560 manually run any command with a different base remote by passing '-r REMOTE'
561 _before_ the subcommand name.