author | Pierre-Yves David <pierre-yves.david@fb.com> |
Mon, 20 Oct 2014 15:59:34 -0700 | |
changeset 1134 | 7173c70ab2c3 |
parent 979 | c7b2ccd99dab |
child 1186 | 0b66826f081c |
permissions | -rw-r--r-- |
979
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
1 |
.. Copyright © 2014 Greg Ward <greg@gerg.ca> |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
2 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
3 |
------------------------------ |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
4 |
Evolve: Shared Mutable History |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
5 |
------------------------------ |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
6 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
7 |
Once you have mastered the art of mutable history in a single |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
8 |
repository, you might want to move up to the next level: *shared* |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
9 |
mutable history. ``evolve`` lets you push and pull draft changesets |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
10 |
between repositories along with their obsolescence markers. This opens |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
11 |
up a number of interesting possibilities. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
12 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
13 |
The most common scenario is a single developer working across two |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
14 |
computers. Say you're working on code that must be tested on a remote |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
15 |
test server, probably in a rack somewhere, only accessible by SSH, and |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
16 |
running an “enterprise-grade” (out-of-date) OS. But you probably |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
17 |
prefer to write code locally: everything is setup the way you like it, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
18 |
and you can use your preferred editor, IDE, merge/diff tools, etc. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
19 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
20 |
Traditionally, your options are limited: either |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
21 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
22 |
* (ab)use your source control system by committing half-working code |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
23 |
in order to get it onto the remote test server, or |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
24 |
* go behind source control's back by using ``rsync`` (or similar) to |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
25 |
transfer your code back-and-forth until it is ready to commit |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
26 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
27 |
The former is less bad with distributed version control systems like |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
28 |
Mercurial, but it's still far from ideal. (One important version |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
29 |
control “best practice” is that every commit should make things just a |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
30 |
little bit better, i.e. you should never commit code that is worse |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
31 |
than what came before.) The latter, avoiding version control entirely, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
32 |
means that you're walking a tightrope without a safety net. One |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
33 |
accidental ``rsync`` in the wrong direction could destroy hours of |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
34 |
work. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
35 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
36 |
Using Mercurial with ``evolve`` to share mutable history solves all of |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
37 |
these problems. As with single-repository ``evolve``, you can commit |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
38 |
whenever the code is demonstrably better, even if all the tests aren't |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
39 |
passing yet—just ``hg amend`` when they are. And you can transfer |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
40 |
those half-baked changesets between repositories to try things out on |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
41 |
your test server before anything is carved in stone. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
42 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
43 |
A less common scenario is multiple developers sharing mutable history. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
44 |
(This is in fact how Mercurial itself is developed.) We'll cover this |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
45 |
scenario later. But first, single-user sharing. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
46 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
47 |
Publishing and non-publishing repositories |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
48 |
------------------------------------------ |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
49 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
50 |
The key to shared mutable history is to keep your changesets in |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
51 |
*draft* phase as you pass them around. Recall that by default, ``hg |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
52 |
push`` promotes changesets from *draft* to *public*, and public |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
53 |
changesets are immutable. You can change this behaviour by |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
54 |
reconfiguring the *target* repository so that it is non-publishing. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
55 |
(Short version: set ``phases.publish`` to ``false``. Long version |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
56 |
follows.) |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
57 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
58 |
Setting things up |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
59 |
----------------- |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
60 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
61 |
We'll work an example with three local repositories, although in the |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
62 |
real world they'd most likely be on three different computers. First, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
63 |
the public repository is where tested, polished changesets live, and |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
64 |
it is where you push/pull changesets to/from the rest of your team. :: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
65 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
66 |
$ hg init public |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
67 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
68 |
We'll need two clones where work gets done:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
69 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
70 |
$ hg clone -q public test-repo |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
71 |
$ hg clone -q test-repo dev-repo |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
72 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
73 |
``dev-repo`` is your local machine, with GUI merge tools and IDEs and |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
74 |
everything configured just the way you like it. ``test-repo`` is the |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
75 |
test server in a rack somewhere behind SSH. So for the most part, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
76 |
we'll develop in ``dev-repo``, push to ``test-repo``, test and polish |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
77 |
there, and push to ``public``. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
78 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
79 |
The key to making this whole thing work is to make ``test-repo`` |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
80 |
non-publishing:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
81 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
82 |
$ cat >> test-repo/.hg/hgrc <<EOF |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
83 |
[phases] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
84 |
publish = false |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
85 |
EOF |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
86 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
87 |
We also have to configure ``evolve`` in both ``test-repo`` and |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
88 |
``dev-repo``, so that we can amend and evolve in both of them. :: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
89 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
90 |
$ cat >> test-repo/.hg/hgrc <<EOF |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
91 |
[extensions] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
92 |
rebase = |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
93 |
evolve = /path/to/mutable-history/hgext/evolve.py |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
94 |
EOF |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
95 |
$ cat >> dev-repo/.hg/hgrc <<EOF |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
96 |
[extensions] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
97 |
rebase = |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
98 |
evolve = /path/to/mutable-history/hgext/evolve.py |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
99 |
EOF |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
100 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
101 |
Keep in mind that in real life, these repositories would probably be |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
102 |
on separate computers, so you'd have to login to each one to configure |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
103 |
each repository. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
104 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
105 |
To start things off, let's make one public, immutable changeset:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
106 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
107 |
$ cd test-repo |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
108 |
$ echo 'my new project' > file1 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
109 |
$ hg add file1 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
110 |
$ hg commit -m 'create new project' |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
111 |
$ hg push -q |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
112 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
113 |
and pull that into the development repository:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
114 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
115 |
$ cd ../dev-repo |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
116 |
$ hg pull -u |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
117 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
118 |
Amending a shared changeset |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
119 |
--------------------------- |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
120 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
121 |
Everything you learned in the `user guide`_ applies to work done in |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
122 |
``dev-repo``. You can commit, amend, uncommit, evolve, and so forth |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
123 |
just as before. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
124 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
125 |
.. _`user guide`: user-guide.html |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
126 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
127 |
Things get different when you push changesets to ``test-repo``. Or |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
128 |
rather, things stay the same, which *is* different: because we |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
129 |
configured ``test-repo`` to be non-publishing, draft changesets stay |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
130 |
draft when we push them to ``test-repo``. Importantly, they're also |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
131 |
draft (mutable) in ``test-repo``. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
132 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
133 |
Let's commit a preliminary change and push it to ``test-repo`` for |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
134 |
testing. :: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
135 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
136 |
$ echo 'fix fix fix' > file1 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
137 |
$ hg commit -m 'prelim change' |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
138 |
$ hg push ../test-repo |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
139 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
140 |
At this point, ``dev-repo`` and ``test-repo`` have the same changesets |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
141 |
in the same phases: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
142 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
143 |
[figure SG01: rev 0:0dc9 public, rev 1:f649 draft, same on both repos] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
144 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
145 |
(You may notice a change in notation from the user guide: now |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
146 |
changesets are labelled with their revision number and the first four |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
147 |
digits of the 40-digit hexadecimal changeset ID. Mercurial revision |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
148 |
numbers are never stable when working across repositories, especially |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
149 |
when obsolescence is involved. We'll see why shortly.) |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
150 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
151 |
Now let's switch to ``test-repo`` to test our change:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
152 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
153 |
$ cd ../test-repo |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
154 |
$ hg update |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
155 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
156 |
Don't forget to ``hg update``! Pushing only adds changesets to a |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
157 |
remote repository; it does not update the working directory (unless |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
158 |
you have a hook that updates for you). |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
159 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
160 |
Now let's imagine the tests failed because we didn't use proper |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
161 |
punctuation and capitalization (oops). Let's amend our preliminary fix |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
162 |
(and fix the lame commit message while we're at it):: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
163 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
164 |
$ echo 'Fix fix fix.' > file1 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
165 |
$ hg amend -m 'fix bug 37' |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
166 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
167 |
Now we're in a funny intermediate state (figure 2): revision 1:f649 is |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
168 |
obsolete in ``test-repo``, having been replaced by revision 3:60ff |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
169 |
(revision 2:2a03 is another one of those temporary amend commits that |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
170 |
we saw in the user guide)—but ``dev-repo`` knows nothing of these |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
171 |
recent developments. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
172 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
173 |
[figure SG02: rev 0:0dc9 public, rev 1:f649, 2:2a03 obsolete, rev 3:60ff draft -- but dev-repo same as in SG01] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
174 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
175 |
Let's resynchronize:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
176 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
177 |
$ cd ../dev-repo |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
178 |
$ hg pull -u |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
179 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
180 |
As seen in figure 3, this transfers the new changeset *and* the |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
181 |
obsolescence marker for revision 1. However, it does *not* transfer |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
182 |
the temporary amend commit, because it is obsolete. Push and pull |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
183 |
transfer obsolesence markers between repositories, but they do not |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
184 |
normally transfer obsolete changesets. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
185 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
186 |
[figure SG03: dev-repo grows new rev 2:60ff, marks 1:f649 obsolete] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
187 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
188 |
Because of this deliberately incomplete synchronization, revision |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
189 |
numbers in ``test-repo`` and ``dev-repo`` are no longer consistent. We |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
190 |
*must* use changeset IDs. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
191 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
192 |
Amend again, locally |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
193 |
-------------------- |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
194 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
195 |
This process can repeat. Perhaps you figure out a more elegant fix to |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
196 |
the bug, and want to mutate history so nobody ever knows you had a |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
197 |
less-than-perfect idea. We'll implement it locally in ``dev-repo`` and |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
198 |
push to ``test-repo``:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
199 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
200 |
$ echo 'Fix, fix, and fix.' > file1 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
201 |
$ hg amend |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
202 |
$ hg push |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
203 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
204 |
This time around, the temporary amend commit is in ``dev-repo``, and |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
205 |
it is not transferred to ``test-repo``—the same as before, just in the |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
206 |
opposite direction. Figure 4 shows the two repositories after amending |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
207 |
in ``dev-repo`` and pushing to ``test-repo``. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
208 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
209 |
[figure SG04: each repo has one temporary amend commit, but they're different in each one] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
210 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
211 |
Let's hop over to ``test-repo`` to test the more elegant fix:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
212 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
213 |
$ cd ../test-repo |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
214 |
$ hg update -q |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
215 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
216 |
This time, all the tests pass, so no further amendment is required. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
217 |
This bug fix is finished, so we push it to the public repository:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
218 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
219 |
$ hg push |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
220 |
[...] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
221 |
added 1 changesets with 1 changes to 1 files |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
222 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
223 |
Note that only one changeset—the final version, after two |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
224 |
amendments—was actually pushed. Again, Mercurial normally doesn't |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
225 |
transfer obsolete changesets on push and pull. (Specifically, it |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
226 |
doesn't transfer *hidden* changesets: roughly speaking, obsolete |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
227 |
changesets with no non-obsolete descendants. If you're curious, see |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
228 |
the `concept guide`_ for the precise definition of hidden.) |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
229 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
230 |
.. _`concept guide`: concepts.html |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
231 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
232 |
So the picture in ``public`` is much simpler than in either |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
233 |
``dev-repo`` or ``test-repo``. None of our missteps or amendments are |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
234 |
visible publicly, just the final, beautifully polished changeset: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
235 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
236 |
[figure SG05: public repo with rev 0:0dc9, 1:de61, both public] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
237 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
238 |
There is one important step left to do. Because we pushed from |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
239 |
``test-repo`` to ``public``, the pushed changeset is in *public* phase |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
240 |
in those two repositories. But ``dev-repo`` knows nothing of this: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
241 |
that changeset is still *draft* there. If we're not careful, we might |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
242 |
mutate history in ``dev-repo``, obsoleting a changeset that is already |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
243 |
public. Let's avoid that situation for now by pulling from |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
244 |
``test-repo`` down to ``dev-repo``:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
245 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
246 |
$ cd ../dev-repo |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
247 |
$ hg pull -u |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
248 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
249 |
Getting into trouble |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
250 |
-------------------- |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
251 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
252 |
Mercurial with ``evolve`` is a powerful tool, and using powerful tools |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
253 |
can have consequences. (You can cut yourself badly with a sharp knife, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
254 |
but every competent chef keeps several around. Ever try to chop onions |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
255 |
with a spoon?) |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
256 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
257 |
In the user guide, we saw examples of *unstable* changesets, which are |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
258 |
the most common type of troubled changeset. (Recall that a |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
259 |
non-obsolete changeset with obsolete ancestors is unstable.) |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
260 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
261 |
Two other types of trouble can crop up: *bumped* and *divergent* |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
262 |
changesets. Both are more likely with shared mutable history, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
263 |
especially mutable history shared by multiple developers. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
264 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
265 |
To demonstrate, let's start with the ``public`` repository as we left |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
266 |
it in the last example, with two immutable changesets (figure 5 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
267 |
above). Two developers, Alice and Bob, start working from this point:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
268 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
269 |
$ hg clone -q public alice |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
270 |
$ hg clone -q public bob |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
271 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
272 |
We need to configure Alice's and Bob's working repositories similar to |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
273 |
``test-repo``, i.e. make them non-publishing and enable ``evolve``:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
274 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
275 |
$ cat >> alice/.hg/hgrc <<EOF |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
276 |
[phases] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
277 |
publish = false |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
278 |
[extensions] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
279 |
rebase = |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
280 |
evolve = /path/to/mutable-history/hgext/evolve.py |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
281 |
EOF |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
282 |
$ cp alice/.hg/hgrc bob/.hg/hgrc |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
283 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
284 |
Bumped changesets: only one gets on the plane |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
285 |
--------------------------------------------- |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
286 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
287 |
If two people show up at the airport with tickets for the same seat on |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
288 |
the same plane, only one of them gets on the plane. The would-be |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
289 |
traveller left behind in the airport terminal is said to have been |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
290 |
*bumped*. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
291 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
292 |
Similarly, if Alice and Bob are collaborating on some mutable |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
293 |
changesets, it's possible to get into a situation where an otherwise |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
294 |
worthwhile changeset cannot be pushed to the public repository; it is |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
295 |
bumped by an alternative changeset that happened to get there first. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
296 |
Let's demonstrate one way this could happen. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
297 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
298 |
It starts with Alice committing a bug fix. Right now, we don't yet |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
299 |
know if this bug fix is good enough to push to the public repository, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
300 |
but it's good enough for Alice to commit. :: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
301 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
302 |
$ cd alice |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
303 |
$ echo 'fix' > file2 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
304 |
$ hg commit -q -A -m 'fix bug 15' |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
305 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
306 |
Now Bob has a bad idea: he decides to pull whatever Alice is working |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
307 |
on and tweak her bug fix to his taste:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
308 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
309 |
$ cd ../bob |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
310 |
$ hg pull -q -u ../alice |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
311 |
$ echo 'Fix.' > file2 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
312 |
$ hg amend -q -A -m 'fix bug 15 (amended)' |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
313 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
314 |
(Note the lack of communication between Alice and Bob. Failing to |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
315 |
communicate with your colleagues is a good way to get into trouble. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
316 |
Nevertheless, ``evolve`` can usually sort things out, as we will see.) |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
317 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
318 |
[figure SG06: Bob's repo with one amendment] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
319 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
320 |
After some testing, Alice realizes her bug fix is just fine as it is: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
321 |
no need for further polishing and amending, this changeset is ready to |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
322 |
publish. :: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
323 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
324 |
$ cd ../alice |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
325 |
$ hg push -q |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
326 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
327 |
This introduces a contradiction: in Bob's repository, changeset 2:e011 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
328 |
(his copy of Alice's fix) is obsolete, since Bob amended it. But in |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
329 |
Alice's repository (and ``public``), that changeset is public: it is |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
330 |
immutable, carved in stone for all eternity. No changeset can be both |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
331 |
obsolete and public, so Bob is in for a surprise the next time he |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
332 |
pulls from ``public``:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
333 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
334 |
$ cd ../bob |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
335 |
$ hg pull -q -u |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
336 |
1 new bumped changesets |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
337 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
338 |
Figure 7 shows what just happened to Bob's repository: changeset |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
339 |
2:e011 is now public, so it can't be obsolete. When that changeset was |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
340 |
obsolete, it made perfect sense for it to have a successor, namely |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
341 |
Bob's amendment of Alice's fix (changeset 4:fe88). But it's illogical |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
342 |
for a public changeset to have a successor, so 4:fe88 is in trouble: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
343 |
it has been *bumped*. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
344 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
345 |
[figure SG07: 2:e011 now public not obsolete, 4:fe88 now bumped] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
346 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
347 |
As usual when there's trouble in your repository, the solution is to |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
348 |
evolve it:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
349 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
350 |
$ hg evolve --all |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
351 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
352 |
Figure 8 illustrate's Bob's repository after evolving away the bumped |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
353 |
changeset. Ignoring the obsolete changesets, Bob now has a nice, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
354 |
clean, simple history. His amendment of Alice's bug fix lives on, as |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
355 |
changeset 5:227d—albeit with a software-generated commit message. (Bob |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
356 |
should probably amend that changeset to improve the commit message.) |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
357 |
But the important thing is that his repository no longer has any |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
358 |
troubled changesets, thanks to ``evolve``. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
359 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
360 |
[figure SG08: 5:227d is new, formerly bumped changeset 4:fe88 now hidden] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
361 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
362 |
Divergent changesets |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
363 |
-------------------- |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
364 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
365 |
In addition to *unstable* and *bumped*, there is a third kind of |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
366 |
troubled changeset: *divergent*. When an obsolete changeset has two |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
367 |
successors, those successors are divergent. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
368 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
369 |
To illustrate, let's start Alice and Bob at the same |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
370 |
point—specifically, the point where Alice's repository currently |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
371 |
stands. Bob's repository is a bit of a mess, so we'll throw it away |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
372 |
and start him off with a copy of Alice's repository:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
373 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
374 |
$ cd .. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
375 |
$ rm -rf bob |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
376 |
$ cp -rp alice bob |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
377 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
378 |
Now we'll have Bob commit a bug fix that could still be improved:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
379 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
380 |
$ cd bob |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
381 |
$ echo 'pretty good fix' >> file1 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
382 |
$ hg commit -u bob -m 'fix bug 24 (v1)' |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
383 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
384 |
This time, Alice meddles with her colleague's work (still a bad |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
385 |
idea):: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
386 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
387 |
$ cd ../alice |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
388 |
$ hg pull -q -u ../bob |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
389 |
$ echo 'better (alice)' >> file1 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
390 |
$ hg amend -u alice -m 'fix bug 24 (v2 by alice)' |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
391 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
392 |
Here's where things change from the "bumped" scenario above: this |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
393 |
time, the original author (Bob) decides to amend his changeset too. :: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
394 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
395 |
$ cd ../bob |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
396 |
$ echo 'better (bob)' >> file1 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
397 |
$ hg amend -u bob -m 'fix bug 24 (v2 by bob)' |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
398 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
399 |
At this point, the divergence exists, but only in theory: Bob's |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
400 |
original changeset, 3:fe81, is obsolete and has two successors. But |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
401 |
those successors are in different repositories, so the trouble is not |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
402 |
visible to anyone yet. It will be as soon as one of our players pulls |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
403 |
from the other's repository. Let's make Bob the victim again:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
404 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
405 |
$ hg pull -q -u ../alice |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
406 |
not updating: not a linear update |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
407 |
(merge or update --check to force update) |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
408 |
2 new divergent changesets |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
409 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
410 |
The “not a linear update” is our first hint that something is wrong, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
411 |
but of course “2 new divergent changesets” is the real problem. Figure |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
412 |
9 shows both problems. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
413 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
414 |
[figure SG09: bob's repo with 2 heads for the 2 divergent changesets, 5:fc16 and 6:694f; wc is at 5:fc16, hence update refused; both are successors of obsolete 3:fe81, hence divergence] |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
415 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
416 |
Now we need to get out of trouble. Unfortunately, a `bug`_ in |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
417 |
``evolve`` means that the usual answer (run ``hg evolve --all``) does |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
418 |
not work. Bob has to figure out the solution on his own: in this case, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
419 |
merge. To avoid distractions, we'll set ``HGMERGE`` to make Mercurial |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
420 |
resolve any conflicts in favour of Bob. :: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
421 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
422 |
$ HGMERGE=internal:local hg merge |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
423 |
$ hg commit -m merge |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
424 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
425 |
.. _`bug`: https://bitbucket.org/marmoute/mutable-history/issue/48/ |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
426 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
427 |
This is approximately what ``hg evolve`` would do in this |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
428 |
circumstance, if not for that bug. One annoying difference is that |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
429 |
Mercurial thinks the two divergent changesets are still divergent, |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
430 |
which you can see with a simple revset query:: |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
431 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
432 |
$ hg log -q -r 'divergent()' |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
433 |
5:fc16901f4d7a |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
434 |
6:694fd0f6b503 |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
435 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
436 |
(That annoyance should go away when the bug is fixed.) |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
437 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
438 |
Conclusion |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
439 |
---------- |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
440 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
441 |
Mutable history is a powerful tool. Like a sharp knife, an experienced |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
442 |
user can do wonderful things with it, much more wonderful than with a |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
443 |
dull knife (never mind a rusty spoon). At the same time, an |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
444 |
inattentive or careless user can do harm to himself or others. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
445 |
Mercurial with ``evolve`` goes to great lengths to limit the harm you |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
446 |
can do by trying to handle all possible types of “troubled” |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
447 |
changesets. But having a first-aid kit nearby does not excuse you from |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
448 |
being careful with sharp knives. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
449 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
450 |
Mutable history shared across multiple repositories by a single |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
451 |
developer is a natural extension of this model. Once you are used to |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
452 |
using a single sharp knife on its own, it's pretty straightforward to |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
453 |
chop onions and mushrooms using the same knife, or to alternate |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
454 |
between two chopping boards with different knives. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
455 |
|
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
456 |
Mutable history shared by multiple developers is a scary place to go. |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
457 |
Imagine a professional kitchen full of expert chefs tossing their |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
458 |
favourite knives back and forth, with the occasional axe or chainsaw |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
459 |
thrown in to spice things up. If you're confident that you *and your |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
460 |
colleagues* can do it without losing a limb, go for it. But be sure to |
c7b2ccd99dab
docs: add guide to sharing mutable history
Greg Ward <greg@gerg.ca>
parents:
diff
changeset
|
461 |
practice a lot first before you rely on it! |