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authorJunio C Hamano <gitster@pobox.com>2013-01-25 20:34:52 (GMT)
committerJunio C Hamano <gitster@pobox.com>2013-01-25 20:34:52 (GMT)
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Merge branch 'jc/doc-maintainer'
Describe tools for automation that were invented since this document was originally written. * jc/doc-maintainer: howto/maintain: document "### match next" convention in jch/pu branch howto/maintain: mark titles for asciidoc Documentation: update "howto maintain git"
Diffstat (limited to 'Documentation/howto')
-rw-r--r--Documentation/howto/maintain-git.txt347
1 files changed, 256 insertions, 91 deletions
diff --git a/Documentation/howto/maintain-git.txt b/Documentation/howto/maintain-git.txt
index ea6e4a5..816c791 100644
--- a/Documentation/howto/maintain-git.txt
+++ b/Documentation/howto/maintain-git.txt
@@ -10,35 +10,42 @@ Content-type: text/asciidoc
How to maintain Git
===================
+Activities
+----------
+
The maintainer's git time is spent on three activities.
- - Communication (60%)
+ - Communication (45%)
Mailing list discussions on general design, fielding user
questions, diagnosing bug reports; reviewing, commenting on,
suggesting alternatives to, and rejecting patches.
- - Integration (30%)
+ - Integration (50%)
Applying new patches from the contributors while spotting and
correcting minor mistakes, shuffling the integration and
testing branches, pushing the results out, cutting the
releases, and making announcements.
- - Own development (10%)
+ - Own development (5%)
Scratching my own itch and sending proposed patch series out.
+The Policy
+----------
+
The policy on Integration is informally mentioned in "A Note
from the maintainer" message, which is periodically posted to
this mailing list after each feature release is made.
-The policy.
-
- Feature releases are numbered as vX.Y.Z and are meant to
contain bugfixes and enhancements in any area, including
functionality, performance and usability, without regression.
+ - One release cycle for a feature release is expected to last for
+ eight to ten weeks.
+
- Maintenance releases are numbered as vX.Y.Z.W and are meant
to contain only bugfixes for the corresponding vX.Y.Z feature
release and earlier maintenance releases vX.Y.Z.V (V < W).
@@ -62,12 +69,15 @@ The policy.
- 'pu' branch is used to publish other proposed changes that do
not yet pass the criteria set for 'next'.
- - The tips of 'master', 'maint' and 'next' branches will always
- fast-forward, to allow people to build their own
- customization on top of them.
+ - The tips of 'master' and 'maint' branches will not be rewound to
+ allow people to build their own customization on top of them.
+ Early in a new development cycle, 'next' is rewound to the tip of
+ 'master' once, but otherwise it will not be rewound until the end
+ of the cycle.
- - Usually 'master' contains all of 'maint', 'next' contains all
- of 'master' and 'pu' contains all of 'next'.
+ - Usually 'master' contains all of 'maint' and 'next' contains all
+ of 'master'. 'pu' contains all the topics merged to 'next', but
+ is rebuilt directly on 'master'.
- The tip of 'master' is meant to be more stable than any
tagged releases, and the users are encouraged to follow it.
@@ -77,14 +87,22 @@ The policy.
are found before new topics are merged to 'master'.
+A Typical Git Day
+-----------------
+
A typical git day for the maintainer implements the above policy
by doing the following:
- - Scan mailing list and #git channel log. Respond with review
- comments, suggestions etc. Kibitz. Collect potentially
- usable patches from the mailing list. Patches about a single
- topic go to one mailbox (I read my mail in Gnus, and type
- \C-o to save/append messages in files in mbox format).
+ - Scan mailing list. Respond with review comments, suggestions
+ etc. Kibitz. Collect potentially usable patches from the
+ mailing list. Patches about a single topic go to one mailbox (I
+ read my mail in Gnus, and type \C-o to save/append messages in
+ files in mbox format).
+
+ - Write his own patches to address issues raised on the list but
+ nobody has stepped up solving. Send it out just like other
+ contributors do, and pick them up just like patches from other
+ contributors (see above).
- Review the patches in the saved mailboxes. Edit proposed log
message for typofixes and clarifications, and add Acks
@@ -100,40 +118,32 @@ by doing the following:
- Obviously correct fixes that pertain to the tip of 'master'
are directly applied to 'master'.
+ - Other topics are not handled in this step.
+
This step is done with "git am".
$ git checkout master ;# or "git checkout maint"
- $ git am -3 -s mailbox
+ $ git am -sc3 mailbox
$ make test
- - Merge downwards (maint->master):
-
- $ git checkout master
- $ git merge maint
- $ make test
+ In practice, almost no patch directly goes to 'master' or
+ 'maint'.
- Review the last issue of "What's cooking" message, review the
- topics scheduled for merging upwards (topic->master and
- topic->maint), and merge.
+ topics ready for merging (topic->master and topic->maint). Use
+ "Meta/cook -w" script (where Meta/ contains a checkout of the
+ 'todo' branch) to aid this step.
+
+ And perform the merge. Use "Meta/Reintegrate -e" script (see
+ later) to aid this step.
+
+ $ Meta/cook -w last-issue-of-whats-cooking.mbox
$ git checkout master ;# or "git checkout maint"
- $ git merge ai/topic ;# or "git merge ai/maint-topic"
+ $ echo ai/topic | Meta/Reintegrate -e ;# "git merge ai/topic"
$ git log -p ORIG_HEAD.. ;# final review
$ git diff ORIG_HEAD.. ;# final review
$ make test ;# final review
- $ git branch -d ai/topic ;# or "git branch -d ai/maint-topic"
-
- - Merge downwards (maint->master) if needed:
-
- $ git checkout master
- $ git merge maint
- $ make test
-
- - Merge downwards (master->next) if needed:
-
- $ git checkout next
- $ git merge master
- $ make test
- Handle the remaining patches:
@@ -142,9 +152,9 @@ by doing the following:
and not in 'master') is applied to a new topic branch that
is forked from the tip of 'master'. This includes both
enhancements and unobvious fixes to 'master'. A topic
- branch is named as ai/topic where "ai" is typically
- author's initial and "topic" is a descriptive name of the
- topic (in other words, "what's the series is about").
+ branch is named as ai/topic where "ai" is two-letter string
+ named after author's initial and "topic" is a descriptive name
+ of the topic (in other words, "what's the series is about").
- An unobvious fix meant for 'maint' is applied to a new
topic branch that is forked from the tip of 'maint'. The
@@ -162,7 +172,8 @@ by doing the following:
The above except the "replacement" are all done with:
- $ git am -3 -s mailbox
+ $ git checkout ai/topic ;# or "git checkout -b ai/topic master"
+ $ git am -sc3 mailbox
while patch replacement is often done by:
@@ -170,93 +181,170 @@ by doing the following:
then replace some parts with the new patch, and reapplying:
+ $ git checkout ai/topic
$ git reset --hard ai/topic~$n
- $ git am -3 -s 000*.txt
+ $ git am -sc3 -s 000*.txt
The full test suite is always run for 'maint' and 'master'
after patch application; for topic branches the tests are run
as time permits.
- - Update "What's cooking" message to review the updates to
- existing topics, newly added topics and graduated topics.
+ - Merge maint to master as needed:
- This step is helped with Meta/cook script (where Meta/ contains
- a checkout of the 'todo' branch).
-
- - Merge topics to 'next'. For each branch whose tip is not
- merged to 'next', one of three things can happen:
+ $ git checkout master
+ $ git merge maint
+ $ make test
- - The commits are all next-worthy; merge the topic to next:
+ - Merge master to next as needed:
$ git checkout next
- $ git merge ai/topic ;# or "git merge ai/maint-topic"
+ $ git merge master
$ make test
+ - Review the last issue of "What's cooking" again and see if topics
+ that are ready to be merged to 'next' are still in good shape
+ (e.g. has there any new issue identified on the list with the
+ series?)
+
+ - Prepare 'jch' branch, which is used to represent somewhere
+ between 'master' and 'pu' and often is slightly ahead of 'next'.
+
+ $ Meta/Reintegrate master..pu >Meta/redo-jch.sh
+
+ The result is a script that lists topics to be merged in order to
+ rebuild 'pu' as the input to Meta/Reintegrate script. Remove
+ later topics that should not be in 'jch' yet. Add a line that
+ consists of '### match next' before the name of the first topic
+ in the output that should be in 'jch' but not in 'next' yet.
+
+ - Now we are ready to start merging topics to 'next'. For each
+ branch whose tip is not merged to 'next', one of three things can
+ happen:
+
+ - The commits are all next-worthy; merge the topic to next;
- The new parts are of mixed quality, but earlier ones are
- next-worthy; merge the early parts to next:
+ next-worthy; merge the early parts to next;
+ - Nothing is next-worthy; do not do anything.
+
+ This step is aided with Meta/redo-jch.sh script created earlier.
+ If a topic that was already in 'next' gained a patch, the script
+ would list it as "ai/topic~1". To include the new patch to the
+ updated 'next', drop the "~1" part; to keep it excluded, do not
+ touch the line. If a topic that was not in 'next' should be
+ merged to 'next', add it at the end of the list. Then:
+
+ $ git checkout -B jch master
+ $ Meta/redo-jch.sh -c1
+
+ to rebuild the 'jch' branch from scratch. "-c1" tells the script
+ to stop merging at the first line that begins with '###'
+ (i.e. the "### match next" line you added earlier).
+
+ At this point, build-test the result. It may reveal semantic
+ conflicts (e.g. a topic renamed a variable, another added a new
+ reference to the variable under its old name), in which case
+ prepare an appropriate merge-fix first (see appendix), and
+ rebuild the 'jch' branch from scratch, starting at the tip of
+ 'master'.
+
+ Then do the same to 'next'
$ git checkout next
- $ git merge ai/topic~2 ;# the tip two are dubious
- $ make test
+ $ sh Meta/redo-jch.sh -c1 -e
- - Nothing is next-worthy; do not do anything.
+ The "-e" option allows the merge message that comes from the
+ history of the topic and the comments in the "What's cooking" to
+ be edited. The resulting tree should match 'jch' as the same set
+ of topics are merged on 'master'; otherwise there is a mismerge.
+ Investigate why and do not proceed until the mismerge is found
+ and rectified.
- - [** OBSOLETE **] Optionally rebase topics that do not have any commit
- in next yet, when they can take advantage of low-level framework
- change that is merged to 'master' already.
+ $ git diff jch next
- $ git rebase master ai/topic
+ When all is well, clean up the redo-jch.sh script with
- This step is helped with Meta/git-topic.perl script to
- identify which topic is rebaseable. There also is a
- pre-rebase hook to make sure that topics that are already in
- 'next' are not rebased beyond the merged commit.
+ $ sh Meta/redo-jch.sh -u
- - [** OBSOLETE **] Rebuild "pu" to merge the tips of topics not in 'next'.
+ This removes topics listed in the script that have already been
+ merged to 'master'. This may lose '### match next' marker;
+ add it again to the appropriate place when it happens.
- $ git checkout pu
- $ git reset --hard next
- $ git merge ai/topic ;# repeat for all remaining topics
- $ make test
+ - Rebuild 'pu'.
- This step is helped with Meta/PU script
+ $ Meta/Reintegrate master..pu >Meta/redo-pu.sh
- - Push four integration branches to a private repository at
- k.org and run "make test" on all of them.
+ Edit the result by adding new topics that are not still in 'pu'
+ in the script. Then
- - Push four integration branches to /pub/scm/git/git.git at
- k.org. This triggers its post-update hook which:
+ $ git checkout -B pu jch
+ $ sh Meta/redo-pu.sh
- (1) runs "git pull" in $HOME/git-doc/ repository to pull
- 'master' just pushed out;
+ When all is well, clean up the redo-pu.sh script with
- (2) runs "make doc" in $HOME/git-doc/, install the generated
- documentation in staging areas, which are separate
- repositories that have html and man branches checked
- out.
+ $ sh Meta/redo-pu.sh -u
- (3) runs "git commit" in the staging areas, and run "git
- push" back to /pub/scm/git/git.git/ to update the html
- and man branches.
+ Double check by running
- (4) installs generated documentation to /pub/software/scm/git/docs/
- to be viewed from http://www.kernel.org/
+ $ git branch --no-merged pu
- - Fetch html and man branches back from k.org, and push four
- integration branches and the two documentation branches to
- repo.or.cz and other mirrors.
+ to see there is no unexpected leftover topics.
+ At this point, build-test the result for semantic conflicts, and
+ if there are, prepare an appropriate merge-fix first (see
+ appendix), and rebuild the 'pu' branch from scratch, starting at
+ the tip of 'jch'.
+
+ - Update "What's cooking" message to review the updates to
+ existing topics, newly added topics and graduated topics.
+
+ This step is helped with Meta/cook script.
+
+ $ Meta/cook
+
+ This script inspects the history between master..pu, finds tips
+ of topic branches, compares what it found with the current
+ contents in Meta/whats-cooking.txt, and updates that file.
+ Topics not listed in the file but are found in master..pu are
+ added to the "New topics" section, topics listed in the file that
+ are no longer found in master..pu are moved to the "Graduated to
+ master" section, and topics whose commits changed their states
+ (e.g. used to be only in 'pu', now merged to 'next') are updated
+ with change markers "<<" and ">>".
+
+ Look for lines enclosed in "<<" and ">>"; they hold contents from
+ old file that are replaced by this integration round. After
+ verifying them, remove the old part. Review the description for
+ each topic and update its doneness and plan as needed. To review
+ the updated plan, run
+
+ $ Meta/cook -w
+
+ which will pick up comments given to the topics, such as "Will
+ merge to 'next'", etc. (see Meta/cook script to learn what kind
+ of phrases are supported).
+
+ - Compile, test and install all four (five) integration branches;
+ Meta/Dothem script may aid this step.
+
+ - Format documentation if the 'master' branch was updated;
+ Meta/dodoc.sh script may aid this step.
+
+ - Push the integration branches out to public places; Meta/pushall
+ script may aid this step.
+
+Observations
+------------
Some observations to be made.
- * Each topic is tested individually, and also together with
- other topics cooking in 'next'. Until it matures, none part
- of it is merged to 'master'.
+ * Each topic is tested individually, and also together with other
+ topics cooking first in 'pu', then in 'jch' and then in 'next'.
+ Until it matures, no part of it is merged to 'master'.
* A topic already in 'next' can get fixes while still in
'next'. Such a topic will have many merges to 'next' (in
other words, "git log --first-parent next" will show many
- "Merge ai/topic to next" for the same topic.
+ "Merge branch 'ai/topic' to next" for the same topic.
* An unobvious fix for 'maint' is cooked in 'next' and then
merged to 'master' to make extra sure it is Ok and then
@@ -278,3 +366,80 @@ Some observations to be made.
* Being in the 'next' branch is not a guarantee for a topic to
be included in the next feature release. Being in the
'master' branch typically is.
+
+
+Appendix
+--------
+
+Preparing a "merge-fix"
+~~~~~~~~~~~~~~~~~~~~~~~
+
+A merge of two topics may not textually conflict but still have
+conflict at the semantic level. A classic example is for one topic
+to rename an variable and all its uses, while another topic adds a
+new use of the variable under its old name. When these two topics
+are merged together, the reference to the variable newly added by
+the latter topic will still use the old name in the result.
+
+The Meta/Reintegrate script that is used by redo-jch and redo-pu
+scripts implements a crude but usable way to work this issue around.
+When the script merges branch $X, it checks if "refs/merge-fix/$X"
+exists, and if so, the effect of it is squashed into the result of
+the mechanical merge. In other words,
+
+ $ echo $X | Meta/Reintegrate
+
+is roughly equivalent to this sequence:
+
+ $ git merge --rerere-autoupdate $X
+ $ git commit
+ $ git cherry-pick -n refs/merge-fix/$X
+ $ git commit --amend
+
+The goal of this "prepare a merge-fix" step is to come up with a
+commit that can be squashed into a result of mechanical merge to
+correct semantic conflicts.
+
+After finding that the result of merging branch "ai/topic" to an
+integration branch had such a semantic conflict, say pu~4, check the
+problematic merge out on a detached HEAD, edit the working tree to
+fix the semantic conflict, and make a separate commit to record the
+fix-up:
+
+ $ git checkout pu~4
+ $ git show -s --pretty=%s ;# double check
+ Merge branch 'ai/topic' to pu
+ $ edit
+ $ git commit -m 'merge-fix/ai/topic' -a
+
+Then make a reference "refs/merge-fix/ai/topic" to point at this
+result:
+
+ $ git update-ref refs/merge-fix/ai/topic HEAD
+
+Then double check the result by asking Meta/Reintegrate to redo the
+merge:
+
+ $ git checkout pu~5 ;# the parent of the problem merge
+ $ echo ai/topic | Meta/Reintegrate
+ $ git diff pu~4
+
+This time, because you prepared refs/merge-fix/ai/topic, the
+resulting merge should have been tweaked to include the fix for the
+semantic conflict.
+
+Note that this assumes that the order in which conflicting branches
+are merged does not change. If the reason why merging ai/topic
+branch needs this merge-fix is because another branch merged earlier
+to the integration branch changed the underlying assumption ai/topic
+branch made (e.g. ai/topic branch added a site to refer to a
+variable, while the other branch renamed that variable and adjusted
+existing use sites), and if you changed redo-jch (or redo-pu) script
+to merge ai/topic branch before the other branch, then the above
+merge-fix should not be applied while merging ai/topic, but should
+instead be applied while merging the other branch. You would need
+to move the fix to apply to the other branch, perhaps like this:
+
+ $ mf=refs/merge-fix
+ $ git update-ref $mf/$the_other_branch $mf/ai/topic
+ $ git update-ref -d $mf/ai/topic