evolve: comparison docs/sharing.rst

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-:e8016d1011b5
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 ------------------------------
 .. contents::
 Once you have mastered the art of mutable history in a single
-repository (see the `user guide`_), you might want to move up to the
+repository (see the `user guide`_), you can move up to the next level:
-next level: *shared* mutable history. ``evolve`` lets you push and
+*shared* mutable history. ``evolve`` lets you push and pull draft
-pull draft changesets between repositories along with their
+changesets between repositories along with their obsolescence markers.
-obsolescence markers. This opens up a number of interesting
+This opens up a number of interesting possibilities.
-possibilities.
 .. _`user guide`: user-guide.html
 The simplest scenario is a single developer working across two
 computers. Say you're working on code that must be tested on a remote
 than what came before.) The latter, avoiding version control entirely,
 means that you're walking a tightrope without a safety net. One
 accidental ``rsync`` in the wrong direction could destroy hours of
 work.
-Using Mercurial with ``evolve`` to share mutable history solves all of
+Using Mercurial with ``evolve`` to share mutable history solves these
-these problems. As with single-repository ``evolve``, you can commit
+problems. As with single-repository ``evolve``, you can commit
 whenever the code is demonstrably better, even if all the tests aren't
 passing yet—just ``hg amend`` when they are. And you can transfer
 those half-baked changesets between repositories to try things out on
 your test server before anything is carved in stone.
 follows.)
 Setting up
 ==========
-We'll work an example with three local repositories, although in the
+We'll work through an example with three local repositories, although
-real world they'd most likely be on three different computers. First,
+in the real world they'd most likely be on three different computers.
-the ``public`` repository is where tested, polished changesets live,
+First, the ``public`` repository is where tested, polished changesets
-and it is where you synchronize changesets with the rest of your team.
+live, and it is where you synchronize with the rest of your team. ::
-::
 $ hg init public
-We'll need two clones where work gets done::
+We'll need two clones where work gets done, ``test-repo`` and
+``dev-repo``::
 $ hg clone public test-repo
 updating to branch default
 0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 $ hg clone test-repo dev-repo
 everything configured just the way you like it. ``test-repo`` is the
 test server in a rack somewhere behind SSH. So for the most part,
 we'll develop in ``dev-repo``, push to ``test-repo``, test and polish
 there, and push to ``public``.
-The key to shared mutable history is to make the target repository,
+The key to shared mutable history is to make the target repository, in
-``test-repo`` in this case, non-publishing. And, of course, we have to enable ``evolve`` in both ``test-repo`` and ``dev-repo``.
+this case ``test-repo``, non-publishing. And, of course, we have to
+enable ``evolve`` in both ``test-repo`` and ``dev-repo``.
 First, edit the configuration for ``test-repo``::
 $ hg -R test-repo config --edit --local
 obsolete in ``test-repo``, having been replaced by revision 3:60ff
 (revision 2:2a03 is another one of those temporary amend commits that
 we saw in the user guide)—but ``dev-repo`` knows nothing of these
 recent developments.
-[figure SG02: rev 0:0dc9 public, rev 1:f649, 2:2a03 obsolete, rev 3:60ff draft -- but dev-repo same as in SG01]
+[figure SG02: test-repo has rev 0:0dc9 public, rev 1:f649, 2:2a03 obsolete, rev 3:60ff draft; dev-repo same as in SG01]
 Let's resynchronize::
 $ cd ../dev-repo
 $ hg pull -u
+[...]
+added 1 changesets with 1 changes to 1 files (+1 heads)
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 As seen in figure 3, this transfers the new changeset *and* the
 obsolescence marker for revision 1. However, it does *not* transfer
-the temporary amend commit, because it is obsolete. Push and pull
+the temporary amend commit, because it is hidden. Push and pull
 transfer obsolesence markers between repositories, but they do not
-normally transfer obsolete changesets.
+transfer hidden changesets.
 [figure SG03: dev-repo grows new rev 2:60ff, marks 1:f649 obsolete]
 Because of this deliberately incomplete synchronization, revision
 numbers in ``test-repo`` and ``dev-repo`` are no longer consistent. We
 $ hg push
 [...]
 added 1 changesets with 1 changes to 1 files
 Note that only one changeset—the final version, after two
-amendments—was actually pushed. Again, Mercurial normally doesn't
+amendments—was actually pushed. Again, Mercurial doesn't transfer
-transfer obsolete changesets on push and pull. (Specifically, it
+hidden changesets on push and pull.
-doesn't transfer *hidden* changesets: roughly speaking, obsolete
-changesets with no non-obsolete descendants. If you're curious, see
-the `concept guide`_ for the precise definition of hidden.)
 .. _`concept guide`: concepts.html
 So the picture in ``public`` is much simpler than in either
 ``dev-repo`` or ``test-repo``. None of our missteps or amendments are
 public. Let's avoid that situation for now by pulling from
 ``test-repo`` down to ``dev-repo``::
 $ cd ../dev-repo
 $ hg pull -u
+[...]
-Sharing with multiple developers
+no changes found
---------------------------------
+Even though no *changesets* were pulled, Mercurial still pulled
+obsolescence markers from ``test-repo``.
+Sharing with multiple developers: code review
+---------------------------------------------
+Now that you know how to share your own mutable history across
+multiple computers, you might be wondering if it makes sense to share
+mutable history with others. It does, but you have to be careful, stay
+alert, and *communicate* with your peers.
+A good way to start is with code review: Alice commits a draft
+changeset that Bob can review. Bob sends his comments to Alice, and
+she amends it until Bob is satisfied. Meanwhile, Bob is also
+committing draft changesets for Alice to review, amending until she is
+satisfied. Once a particular changeset passes review, the respective
+author (Alice or Bob) pushes it to the public repository.
+Setting up
+==========
+To demonstrate, let's start with the ``public`` repository as we left
+it in the last example, with two immutable changesets (figure 5
+above). We'll clone a ``review`` repository from it, and then Alice
+and Bob will both clone from ``review``. ::
+$ hg clone public review
+updating to branch default
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+$ hg clone review alice
+updating to branch default
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+$ hg clone review bob
+updating to branch default
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+We need to configure Alice's and Bob's working repositories similar to
+``test-repo``, i.e. make them non-publishing and enable ``evolve``.
+First, edit Alice's configuration with ::
+$ hg -R alice config --edit --local
+and add ::
+[extensions]
+evolve = /path/to/mutable-history/hgext/evolve.py
+Then add the same text to Bob's repository configuration::
+$ hg -R bob config --edit --local
+Example 3: Alice commits and amends a draft fix
+===============================================
+We'll start by following Alice working on a bug fix. We're going to
+use bookmarks to make it easier to understand multiple branch heads in
+the ``review`` repository, so Alice starts off by creating a bookmark
+and committing her first attempt at a fix::
+$ hg bookmark bug15
+$ echo 'fix' > file2
+$ hg commit -A -u alice -m 'fix bug 15 (v1)'
+adding file2
+Note the unorthodox "(v1)" in the commit message. We're just using
+that to make this tutorial easier to follow; it's not something we'd
+recommend in real life.
+Of course Alice wouldn't commit unless her fix worked to her
+satisfaction, so it must be time to solicit a code review. She does
+this by pushing to the ``review`` repository::
+$ hg push -B bug15
+[...]
+added 1 changesets with 1 changes to 1 files
+exporting bookmark bug15
+(The use of ``-B`` is important to ensure that we only push the
+bookmarked head, and that the bookmark itself is pushed. See this
+`guide to bookmarks`_, especially the `Sharing Bookmarks`_ section, if
+you're not familiar with bookmarks.)
+.. _`guide to bookmarks`: http://mercurial.aragost.com/kick-start/en/bookmarks/
+.. _`Sharing Bookmarks`: http://mercurial.aragost.com/kick-start/en/bookmarks/#sharing-bookmarks
+Some time passes, and Alice receives her code review. (It might be by
+email, telephone, or carrier pigeon: it doesn't matter, as it's
+outside the scope of Mercurial.) As a result, Alice revises her fix
+and submits it for a second review::
+$ echo 'Fix.' > file2
+$ hg amend -m 'fix bug 15 (v2)'
+$ hg push
+[...]
+added 1 changesets with 1 changes to 1 files (+1 heads)
+updating bookmark bug15
+Figure 6 shows the state of the ``review`` repository at this point.
+[figure SG06: rev 2:fn1e is alice's obsolete v1, rev 3:cbdf is her v2; both children of rev 1:de61]
+After a hard morning of bug fixing, Alice stops for lunch. Let's see
+what Bob has been up to.
+Example 4: Bob implements and publishes a new feature
+=====================================================
+In the meantime, Bob has been working on a new feature. Like Alice,
+he'll use a bookmark to track his work, and he'll push that bookmark
+to the ``review`` repository, so that reviewers know which changesets
+to review. ::
+$ cd ../bob
+$ echo 'stuff' > file1
+$ hg bookmark featureX
+$ hg commit -u bob -m 'implement feature X (v1)'
+$ hg push -B featureX
+[...]
+added 1 changesets with 1 changes to 1 files (+1 heads)
+exporting bookmark featureX
+When Bob receives his code review, he improves his implementation a
+bit, amends, and submits the resulting changeset for review::
+$ echo 'do stuff' > file1
+$ hg amend -m 'implement feature X (v2)'
+$ hg push
+[...]
+added 1 changesets with 1 changes to 1 files (+1 heads)
+updating bookmark featureX
+Unfortunately, that still doesn't pass muster. Bob's reviewer insists
+on proper capitalization and punctuation. ::
+$ echo 'Do stuff.' > file1
+$ hg amend -m 'implement feature X (v3)'
+On the bright side, the second review said, "Go ahead and publish once
+you fix that." So Bob immediately publishes his third attempt::
+$ hg push ../public
+[...]
+added 1 changesets with 1 changes to 1 files
+Bob also has to update the ``review`` repository: right now it doesn't
+have his latest amendment ("v3", revision 6:540b), and it doesn't know
+that the precursor of that changeset ("v2", revision 5:0eb7) is
+obsolete. ::
+$ hg push ../review
+[...]
+added 1 changesets with 1 changes to 1 files (+1 heads)
+updating bookmark featureX
+Figure 7 shows the result of Bob's work in both ``review`` and
+``public``.
+[figure SG07: review includes alice's draft work on bug 15, as well as Bob's v1, v2, and v3 changes for feature X: v1 and v2 obsolete, v3 public. public contains only the final, public implementation of feature X]
+Incidentally, it's important that Bob push to ``public`` *before*
+``review``. If he pushed to ``review`` first, then revision 6:540b
+would still be in *draft* phase in ``review``, but it would be
+*public* in both Bob's local repository and the ``public`` repository.
+That could lead to confusion at some point, which is easily avoided by
+pushing first to ``public``.
+Example 5: Alice integrates and publishes
+=========================================
+Finally, Alice gets back from lunch and sees that the carrier pigeon
+with her second review has arrived (or maybe she just has it in her
+email inbox). Alice's amended changeset has passed review, so she
+pushes her fix to ``public``::
+$ hg push ../public
+[...]
+remote has heads on branch 'default' that are not known locally: 540ba8f317e6
+abort: push creates new remote head cbdfbd5a5db2!
+(pull and merge or see "hg help push" for details about pushing new heads)
+Oops! Bob has won the race to push first to ``public``. So Alice needs
+to integrate with Bob: let's pull his changeset(s) and see what the
+branch heads are. ::
+$ hg pull ../public
+[...]
+added 1 changesets with 1 changes to 1 files (+1 heads)
+(run 'hg heads' to see heads, 'hg merge' to merge)
+$ hg log -G -q -r 'head()' --template '{rev}:{node|short}  ({author})\n'
+o  5:540ba8f317e6  (bob)
+|
+| @  4:cbdfbd5a5db2  (alice)
+|/
+Since Alice and Bob are already using advanced technology in the form
+of shared mutable history, we'll assume they are perfectly comfortable
+with rebasing changesets. So Alice rebases her changeset on top of
+Bob's and publishes the result::
+$ hg rebase -d 5
+$ hg push ../public
+[...]
+added 1 changesets with 1 changes to 1 files
+$ hg push ../review
+[...]
+added 1 changesets with 0 changes to 0 files
+updating bookmark bug15
+The result, in both ``review`` and ``public`` repositories, is shown
+in figure 8.
+[figure SG08: review shows v1 and v2 of alice's fix, then v1, v2, v3 of bob's feature, finally alice's fix rebased onto bob's. public just shows the final public version of each changeset]
+** STOP HERE: WORK IN PROGRESS **
+Getting into trouble with shared mutable history
+------------------------------------------------
 Mercurial with ``evolve`` is a powerful tool, and using powerful tools
 can have consequences. (You can cut yourself badly with a sharp knife,
 but every competent chef keeps several around. Ever try to chop onions
 with a spoon?)
 non-obsolete changeset with obsolete ancestors is unstable.)
 Two other types of trouble can crop up: *bumped* and *divergent*
 changesets. Both are more likely with shared mutable history,
 especially mutable history shared by multiple developers.
-Setting up
-==========
-To demonstrate, let's start with the ``public`` repository as we left
-it in the last example, with two immutable changesets (figure 5
-above). Two developers, Alice and Bob, start working from this point::
-$ hg clone public alice
-updating to branch default
-1 files updated, 0 files merged, 0 files removed, 0 files unresolved
-$ hg clone public bob
-updating to branch default
-1 files updated, 0 files merged, 0 files removed, 0 files unresolved
-We need to configure Alice's and Bob's working repositories similar to
-``test-repo``, i.e. make them non-publishing and enable ``evolve``::
-$ cat >> alice/.hg/hgrc <<EOF
-[phases]
-publish = false
-[extensions]
-evolve = /path/to/mutable-history/hgext/evolve.py
-EOF
-$ cp alice/.hg/hgrc bob/.hg/hgrc
 Bumped changesets: only one gets on the plane
 =============================================
 If two people show up at the airport with tickets for the same seat on

branch	stable
changeset 1261	56cc2eb5995a
parent 1260	e8016d1011b5
child 1262	eff1acc2511c