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 The '-f' option is also useful to force removal of a branch's base, if
248 you used 'git branch -D B' to remove the branch B, and then certain
249 TopGit commands complain, because the base of branch B is still there.
251 Currently, this command will _NOT_ remove the branch from
252 the dependency list in other branches. You need to take
253 care of this _manually_. This is even more complicated
254 in combination with '-f', in that case you need to manually
255 unmerge the removed branch's changes from the branches
258 TODO: '-a' to delete all empty branches, depfix, revert
262 Change dependencies of a TopGit-controlled topic branch.
263 This should have several subcommands, but only 'add' is
266 The 'add' subcommand takes an argument of a topic branch
267 to be added, adds it to '.topdeps', performs a commit and
268 then updates your topic branch accordingly. If you want to
269 do other things related to the dependency addition, like
270 adjusting '.topmsg', prepare them in the index before
271 calling 'tg depend add'.
273 TODO: Subcommand for removing dependencies, obviously
277 Show a summary information about the current or specified
282 Generate a patch from the current or specified topic branch.
283 This means that the diff between the topic branch base and
284 head (latest commit) is shown, appended to the description
285 found in the .topmsg file.
287 The patch is by default simply dumped to stdout. In the future,
288 tg patch will be able to automatically send the patches by mail
289 or save them to files. (TODO)
292 -i base patch generation on index instead of branch
293 -w base patch generation on working tree instead of branch
297 Send a patch from the current or specified topic branch as
300 Takes the patch given on the command line and emails it out.
301 Destination addresses such as To, Cc and Bcc are taken from the
304 Since it actually boils down to `git send-email` please refer to
305 its documentation for details on how to setup email for git.
306 You can pass arbitrary options to this command through the
307 '-s' parameter, but you must double-quote everything.
308 The '-r' parameter with msgid can be used to generate in-reply-to
309 and reference headers to an earlier mail.
311 TODO: 'tg mail patchfile' to mail an already exported patch
312 TODO: mailing patch series
313 TODO: specifying additional options and addresses on command
318 Register given remote as TopGit-controlled. This will create
319 the namespace for the remote branch bases and teach 'git fetch'
320 and 'git push' to operate on them. (Do NOT use 'git push --all'
321 for your pushes - plain 'git push' will do the right thing.)
323 It takes a mandatory remote name argument, and optional
324 '--populate' switch - use that for your origin-style remote,
325 it will seed the local topic branch system based on the
326 remote topic branches. '--populate' will also make 'tg remote'
327 automatically fetch the remote and 'tg update' to look at
328 branches of this remote for updates by default.
332 Show overview of all TopGit-tracked topic branches and their
333 up-to-date status ('>' marks the current topic branch,
334 '0' marks that it introduces no own changes,
335 'l'/'r' marks that it is local-only or has remote mate,
336 'L'/'R' marks that it is ahead/out-of-date wrt. its remote mate,
337 'D' marks that it is out-of-date wrt. its dependencies,
338 '!' marks that it has missing dependencies (even recursively),
339 'B' marks that it is out-of-date wrt. its base).
341 This can take long time to accurately determine all the relevant
342 information about each branch; you can pass '-t' to get just
343 terse list of topic branch names quickly. Alternately, you can
344 pass '--graphviz' to get a dot-suitable output to draw a dependency
345 graph between the topic branches.
347 TODO: Speed up by an order of magnitude
348 TODO: Text graph view
352 Export a tidied-up history of the current topic branch
353 and its dependencies, suitable for feeding upstream.
354 Each topic branch corresponds to a single commit or patch
355 in the cleaned up history (corresponding basically exactly
356 to `tg patch` output for the topic branch).
358 The command has three possible outputs now - either a Git branch with
359 the collapsed history, a Git branch with a linearized history, or a
360 quilt series in new directory.
362 In case of producing collapsed history in new branch,
363 you can use this collapsed structure either for providing
364 a pull source for upstream, or further linearization e.g.
365 for creation of a quilt series using git log:
367 git log --pretty=email -p --topo-order origin..exported
369 To better understand the function of `tg export`,
370 consider this dependency structure of topic branches:
372 origin/master - t/foo/blue - t/foo/red - master
373 `- t/bar/good <,----------'
374 `- t/baz ------------'
376 (Where each of the branches may have hefty history.) Then
378 master$ tg export for-linus
380 will create this commit structure on branch for-linus:
382 origin/master - t/foo/blue -. merge - t/foo/red -.. merge - master
383 `- t/bar/good <,-------------------'/
384 `- t/baz ---------------------'
386 In case of using the linearize mode:
388 master$ tg export --linearize for-linus
390 you get a linear history respecting the dependencies of your patches in
391 a new branch for-linus. The result should be more or less the same as
392 using quilt mode and reimporting it into a Git branch. (More or less
393 because the topologic order can usually be extended in more than one
394 way into a complete ordering and the two methods may choose different
395 one's.) The result might be more appropriate for merging upstream as
396 it contains fewer merges.
398 Note that you might get conflicts during linearization because the
399 patches are reordered to get a linear history.
401 In case of the quilt mode,
403 master$ tg export --quilt for-linus
405 would create this directory for-linus:
407 for-linus/t/foo/blue.diff
408 for-linus/t/foo/red.diff
409 for-linus/t/bar/good.diff
417 The command works on the current topic branch
418 and can be called either without a parameter
419 (in that case, '--collapse' is assumed)
420 and with one mandatory argument: the name of the branch
421 where the exported result shall be stored.
422 The branch will be silently overwritten if it exists already!
423 Use git reflog to recover in case of mistake.
425 Alternatively, call it with the '--quilt' parameter
426 and an argument specifying the directory
427 where the quilt series should be saved.
429 With '--quilt', you can also pass '-b' parameter followed by
430 a comma-separated explicit list of branches to export. This
431 mode of operation is currently not supported with collapse.
433 In '--quilt' mode the patches are named like the originating topgit
434 branch. So usually they end up in subdirectories of the output
435 directory. With option '--flatten' the names are mangled such that
436 they end up directly in the output dir (i.e. slashed are substituted by
437 underscores). With '--numbered' (which implies '--flatten') the patch
438 names get a number as prefix to allow getting the order without
439 consulting the series file, which eases sending out the patches.
441 Usage: tg export ([(--collapse | --linearize)] BRANCH | --quilt DIR)
443 TODO: Make stripping of non-essential headers configurable
444 TODO: Make stripping of [PATCH] and other prefixes configurable
445 TODO: --mbox option for other mode of operation
446 TODO: -a option to export all branches
447 TODO: For quilt exporting, export the linearized history created in a
448 temporary branch---this would allow producing conflict-less
453 Import commits within the given revision range into TopGit,
454 creating one topic branch per commit, the dependencies forming
455 a linear sequence starting on your current branch (or a branch
456 specified by the '-d' parameter).
458 The branch names are auto-guessed from the commit messages
459 and prefixed by t/ by default; use '-p PREFIX' to specify
460 an alternative prefix (even an empty one).
462 Alternatively, you can use the '-s NAME' parameter to specify
463 the name of target branch; the command will then take one more
464 argument describing a single commit to import.
468 Update the current topic branch wrt. changes in the branches
469 it depends on and remote branches.
470 This is performed in two phases - first,
471 changes within the dependencies are merged to the base,
472 then the base is merged into the topic branch.
473 The output will guide you in case of conflicts.
475 In case your dependencies are not up-to-date, tg update
476 will first recurse into them and update these.
478 If a remote branch update brings dependencies on branches
479 not yet instantiated locally, you can either bring in all
480 the new branches from the remote using 'tg remote --populate'
481 or only pick out the missing ones using 'tg create -r'
482 ('tg summary' will point out branches with incomplete
483 dependencies by showing an '!' near to them).
485 TODO: tg update -a for updating all topic branches
489 pushes a TopGit-controlled topic branch to a remote
490 repository. By default the remote gets all dependencies
491 (both tgish and non-tgish) and bases pushed to.
499 TopGit stores all the topic branches in the regular refs/heads/
500 namespace, (we recommend to mark them with the 't/' prefix).
501 Except that, TopGit also maintains a set of auxiliary refs in
502 refs/top-*. Currently, only refs/top-bases/ is used, containing
503 the current _base_ of the given topic branch - this is basically
504 a merge of all the branches the topic branch depends on; it is
505 updated during `tg update` and then merged to the topic branch,
506 and it is the base of a patch generated from the topic branch by
509 All the metadata is tracked within the source tree and history
510 of the topic branch itself, in .top* files; these files are kept
511 isolated within the topic branches during TopGit-controlled merges
512 and are of course omitted during `tg patch`. The state of these
513 files in base commits is undefined; look at them only in the topic
514 branches themselves. Currently, two files are defined:
516 .topmsg: Contains the description of the topic branch
517 in a mail-like format, plus the author information,
518 whatever Cc headers you choose or the post-three-dashes message.
519 When mailing out your patch, basically only few extra headers
520 mail headers are inserted and the patch itself is appended.
521 Thus, as your patches evolve, you can record nuances like whether
522 the particular patch should have To-list/Cc-maintainer or vice
523 versa and similar nuances, if your project is into that.
524 From is prefilled from your current GIT_AUTHOR_IDENT, other headers
525 can be prefilled from various optional topgit.* config options.
527 .topdeps: Contains the one-per-line list of branches
528 your patch depends on, pre-seeded with `tg create`. (Continuously
529 updated) merge of these branches will be the "base" of your topic
530 branch. DO NOT EDIT THIS FILE MANUALLY!!! If you do so, you need
531 to know exactly what are you doing, since this file must stay in
532 sync with the Git history information, otherwise very bad things
535 TopGit also automagically installs a bunch of custom commit-related
536 hooks that will verify if you are committing the .top* files in sane
537 state. It will add the hooks to separate files within the hooks/
538 subdirectory and merely insert calls of them to the appropriate hooks
539 and make them executable (but make sure the original hooks code
540 is not called if the hook was not executable beforehand).
542 Another automagically installed piece is .git/info/attributes specifier
543 for an 'ours' merge strategy for the files .topmsg and .topdeps, and
544 the (intuitive) 'ours' merge strategy definition in .git/config.
550 There are three issues with accessing topic branches in remote repositories:
552 (i) Fetching/pushing accurate picture of the remote topic branch setup
553 (ii) Referring to remote topic branches from your local repository
554 (iii) Developing some of the remote topic branches locally
556 (ii) and (iii) are fairly interconnected problems, while (i) is largely
557 independent. The issue is to accurately reflect the current state of the
558 quickly changing topic branches set - this can be easily done
559 with the current facilities like 'git remote prune' and 'git push --mirror' -
560 and to properly upload also the bases of the topic branches.
561 For this, we need to modify the fetch/push refspecs to also include
562 the refs/top-bases/ ref namespace; we shall provide a special 'tg remote'
563 command to set up an existing remote for TopGit usage.
565 About (ii) and (iii), there are two somewhat contradicting design
568 (a) Hacking on multiple independent TopGit remotes in a single
570 (b) Having a self-contained topic system in local refs space
572 To us, (a) does not appear to be very convincing, while (b) is quite desirable
573 for 'git-log topic' etc. working, 'git push' automatically creating
574 self-contained topic system in the remote repository, and increased conceptual
577 Thus, we choose to instantiate all the topic branches of given remote locally;
578 this is performed by 'tg remote --populate'.
579 'tg update' will also check if a branch can be updated from its corresponding
580 remote branch. The logic is somewhat involved if we should DTRT.
581 First, we update the base, handling the remote branch as if it was the first
582 dependency; thus, conflict resolutions made in the remote branch will be
583 carried over to our local base automagically. Then, the base is merged into
584 remote branch and the result is merged to local branch - again, to carry over
585 remote conflict resolutions. In the future, this order might be adjustable
586 per-update in case local changes are diverging more than the remote ones.
588 All commands by default refer to the remote that 'tg remote --populate'
589 was called on the last time ('topgit.remote' configuration variable). You can
590 manually run any command with a different base remote by passing '-r REMOTE'
591 _before_ the subcommand name.