docs/obs-concept.rst
author Patrick Mezard <patrick@mezard.eu>
Sat, 23 Jun 2012 19:24:37 +0200
changeset 314 ebd286f06879
parent 234 d32c07269dcd
child 357 b398e9c2dbd1
permissions -rw-r--r--
uncommit: add --all option Convenient when combined with --exclude.
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
     1
-----------------------------------------------------------
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
     2
Why Do We Need a New Concept
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
     3
-----------------------------------------------------------
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
     4
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
     5
Current DVCS are great tools to forge a series of flawless changeset on your own.
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
     6
But they perform poorly when it comes to **sharing** some work in progress and
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
     7
**collaborating** on such work in progress.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
     8
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
     9
When people forge a new version of a changeset they actually create a
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
    10
new changeset and get rid of the original changeset. Difficulties to
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    11
collaborate mostly came from the way old content is *removed* from
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    12
a repository.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    13
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    14
Mercurial Approach: Strip
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
    15
-----------------------------------------------------
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    16
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    17
With the current version of mercurial, every changeset that exists in
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    18
your repository is *visible* and *meaningful*. To delete old
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    19
(rewritten) changesets, mercurial removes them from the repository
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    20
storage with an operation called *strip*. After the *stripping*, the
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    21
repository looks like if the changeset never existed.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    22
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
    23
This approach is simple and effective except for one big
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    24
drawback: you can remove changesets from **your repository only**. If
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    25
a stripped changeset exists in another repository it touches, it will
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    26
show up again. This is because a shared changeset becomes
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    27
part of a shared global history. Stripping a changeset from all
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    28
repositories is at best impractical and in most case impossible!
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    29
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    30
As consequence, **you can not rewrite something once you exchange it with
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    31
others**. The old version will still exist along side the new one [#]_.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    32
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    33
Moreover stripping changesets creates backup bundles. This allows
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    34
restoration of the deleted changesets, but the process is painful.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    35
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    36
Finally, as the repository format is not optimized for deletion. stripping a
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    37
changeset may be slow in some situations.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    38
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    39
To sum up, the strip approach is very simple but does not handle
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    40
interaction with the outer world, which is very unfortunate for a
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    41
*Distributed* VCS.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    42
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    43
.. [#] various work around exists but they require their own workflows which are distinct from the very elegant basic workflow of Mercurial.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    44
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    45
Git Approach: Overwrite Reference
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
    46
-----------------------------------------------------
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    47
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    48
The Git approach to repository structure is a bit more complex: there
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    49
can be any amount of unrelated changesets in a repository, and **only
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    50
changesets referenced by a git branch** are *visible* and
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    51
*meaningful*.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    52
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    53
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    54
.. warning:: add a schema::
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    55
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    56
        C
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    57
        | B---<foo>
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    58
        |/
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    59
        |
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    60
        A
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    61
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    62
    Only B and A are visible.
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    63
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    64
This simplifies the process of getting rid of old changesets. You can
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    65
just leave them in place and move the reference on the new one. You
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
    66
can then propagate this change by moving the git-branch on remote host
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    67
with the newer version of the marker overwriting the older one.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    68
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    69
This approach goes a bit further but still has a major drawback:
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    70
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    71
Because you **overwrite** the git-branch, you have no conflict resolution. The last
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    72
to act wins. This makes collaboration on multiple changesets difficult because
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    73
you can't merge concurrent updates on a changeset.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    74
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
    75
Every overwrite is a forced operation where the operator says "Yes I want this to
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    76
replace that. In highly distributed environments, a user may end up with conflicting
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    77
references and no proper way to choose.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    78
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    79
Because of this way to visualize a repository, git-branches are a core
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
    80
part of git, which makes the user interface more complicated and
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
    81
constrains moving through history.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    82
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
    83
Finally, even if all older changesets still exist in the repository, accesing them
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    84
is still painful.
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    85
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    86
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
    87
-----------------------------------------------------
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
    88
The Obsolete Marker Concept
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
    89
-----------------------------------------------------
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    90
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
    91
193
adf92ff8d4f6 merge arne change
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 192
diff changeset
    92
As None of the concepts was powerful enough to fulfill the need of safely
adf92ff8d4f6 merge arne change
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 192
diff changeset
    93
rewriting history, including easy sharing and collaborating on mutable history,
228
5a17c0d41a00 proof-read documentation and docstrings
Nicolas Chauvat <nicolas.chauvat@logilab.fr>
parents: 227
diff changeset
    94
we needed another one. 
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    95
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    96
Basic concept
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
    97
-----------------------------------------------------
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    98
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
    99
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   100
Every history rewriting operation stores the information that old rewritten
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   101
changeset is replaced by newer version in a given set of changesets.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   102
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   103
All basic history rewriting operation can create an appropriate obsolete marker.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   104
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   105
163
92b073d13f2d more doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 161
diff changeset
   106
.. figure:: ./figures/example-1-update.*
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   107
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   108
    *Updating* a changeset
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   109
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   110
    Create one obsolete marker: ``([A'] obsolete A)``
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   111
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   112
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   113
163
92b073d13f2d more doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 161
diff changeset
   114
.. figure:: ./figures/example-2-split.*
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   115
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   116
    *Splitting* a changeset in multiple one
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   117
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   118
    Create one obsolete marker ``([B1, B2] obsolete B)]``
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   119
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   120
234
d32c07269dcd [doc] fix bad include
Pierre-Yves.David@ens-lyon.org
parents: 228
diff changeset
   121
.. figure:: ./figures/simple-3-merge.*
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   122
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   123
    *Merging* multiple changeset in a single one
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   124
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   125
    Create two obsolete markers ``([C] obsolete A), ([C] obsolete B)``
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   126
234
d32c07269dcd [doc] fix bad include
Pierre-Yves.David@ens-lyon.org
parents: 228
diff changeset
   127
.. figure:: ./figures/simple-4-reorder.*
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   128
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   129
    *Moving* changeset around
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   130
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   131
    Reordering those two changesets need two obsolete markers:
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   132
    ``([A'] obsolete A), ([B'] obsolete B)``
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   133
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   134
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   135
234
d32c07269dcd [doc] fix bad include
Pierre-Yves.David@ens-lyon.org
parents: 228
diff changeset
   136
.. figure:: ./figures/simple-5-delete.*
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   137
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   138
    *Removing* a changeset:
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   139
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   140
    One obselete marker ``([] obsolete B)``
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   141
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   142
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   143
To conclude, a single obsolete marker express a relation from **0..n** new
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   144
changesets to **1** old changeset.
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   145
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   146
Basic Usage
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
   147
-----------------------------------------------------
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   148
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   149
Obsolete markers create a perpendicular history: **a versioned changeset graph**. This means that offers the same features we have for
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   150
versioned files but applied to changeset:
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   151
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   152
First: we can display a **coherent view** of the history graph in which only a
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   153
single version of your changesets is displayed by the UI.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   154
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   155
Second, because obsolete changeset content is still **available**. You can 
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   156
you can
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   157
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   158
    * **browse** the content of your obsolete commits,
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   159
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   160
    * **compare** newer and older versions of a changeset,
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   161
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   162
    * **restore** content of previously obsolete changesets.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   163
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   164
Finally, the obsolete marker can be **exchanged between
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   165
repositories**. You are able to share the result on your history
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   166
rewriting operations with other prople and **collaborate on the
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   167
mutable part of the history**.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   168
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   169
Conflicting history rewriting operation can be detected and
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   170
**resolved** as easily as conflicting changes on a file.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   171
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   172
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   173
Detecting and solving tricky situations
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
   174
-----------------------------------------------------
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   175
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   176
History rewriting can lead to complex situations. The obsolete marker
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   177
introduces a simple representation for this complex reality. But
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   178
people using complex workflows will one day or another have to face
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   179
the intrinsic complexity of some real-world situation.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   180
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   181
This section describes possible situations, defines precise sets of
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   182
changesets involved in such situations and explains how the error
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   183
cases can be resolved automatically using the available information.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   184
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   185
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   186
Obsolete changesets
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
   187
````````````````````
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   188
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   189
Old changesets left behind by obsolete operation are called **obsolete**.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   190
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   191
With the current version of mercurial, this *obsolete* part is stripped from the
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   192
repository before the end of every rewriting operation.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   193
163
92b073d13f2d more doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 161
diff changeset
   194
.. figure:: ./figures/error-obsolete.*
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   195
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   196
    Rebasing `B` and `C` on `A` (as `B'`, `C'`)
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   197
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   198
    This rebase operation added two obsolete markers from new changesets to old
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   199
    changesets. These two old changesets are now part of the *obsolete* part of the
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   200
    history.
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   201
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   202
In most cases, the obsolete set will be fully hidden to both the UI and
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   203
discovery, hence users do not have to care about them unless they want to
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   204
audit history rewriting operations.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   205
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   206
Unstable changesets
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
   207
```````````````````
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   208
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   209
While exploring the possibilities of the obsolete marker a bit further, you may end up with
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   210
*obsolete* changesets which have *non-obsolete* children. There is two common ways to
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   211
achieve this:
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   212
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   213
* Pull a changeset based of an old version of a changeset [#]_.
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   214
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   215
* Use a partial rewriting operation. For example amend on a changeset with
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   216
  children.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   217
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   218
*Non-obsolete* changeset based on *obsolete* one are called **unstable**
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   219
163
92b073d13f2d more doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 161
diff changeset
   220
.. figure:: ./figures/error-unstable.*
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   221
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   222
    Amend `A` into `A'` leaving `B` behind.
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   223
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   224
    In this situation we can not consider `B` as *obsolete*.  But we have all
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   225
    necessary data to detect `B` as an *unstable* branch of the history because
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   226
    its parent `A` is *obsolete*. In addition, we have enough data to
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   227
    automatically resolve this instability: we know that the new version of `B`
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   228
    parent (`A`) is `A'`, We can deduce that we should rebase `B` on `A'` to get
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   229
    a stable history again.
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   230
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   231
Proper warnings should be issued when part of the history becomes
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   232
unstable. The UI will be able to use the obsolete marker to
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   233
automatically suggest a resolution to the user of even carry them out
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   234
for him.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   235
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   236
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   237
XXX details on automatic resolution for
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   238
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   239
* movement
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   240
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   241
* handling deletion
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   242
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   243
* handling split on multiple head
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   244
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   245
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   246
.. [#] For this to happen one needs to explicitly enable exchange of draft
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   247
       changesets. See phase help for details.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   248
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   249
The two parts of the obsolete set
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
   250
``````````````````````````````````````
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   251
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   252
The previous section shows that there could be two kinds of *obsolete*
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   253
changesets:
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   254
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   255
* an *obsolete* changeset with no or *obsolete* only descendants is called **extinct**.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   256
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   257
* an *obsolete* changeset with *unstable* descendants is called **suspended**.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   258
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   259
163
92b073d13f2d more doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 161
diff changeset
   260
.. figure:: ./figures/error-extinct.*
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   261
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   262
    Amend `A` and `C` leaving `B` behind.
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   263
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   264
    In this example we have two *obsolete* changesets: `C` with no *unstable*
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   265
    children is *extinct*. `A` with *unstable* descendant (`B`) is *suspended*.
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   266
    `B` is *unstable* as before.
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   267
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   268
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   269
Because nothing outside the obsolete set default on *extinct* changesets, they
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   270
can be safely hidden in the UI and even garbage collected. *Suspended* changesets
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   271
have to stay visible and available until their unstable descendant are rewritten
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   272
into stable version.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   273
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   274
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   275
Conflicting rewrites
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   276
````````````````````
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   277
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   278
If people start to concurrently edit the same part of the history they will
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   279
likely meet conflicting situations when a changeset has been rewritten in two
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   280
different ways.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   281
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   282
163
92b073d13f2d more doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 161
diff changeset
   283
.. figure:: ./figures/error-conflicting.*
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   284
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   285
    Conflicting rewrite of `A` into `A'` and `A''`
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   286
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   287
This kind of conflict is easy to detect with an obsolete marker
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   288
because an obsolete changeset can have more than one new version. It
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   289
may be seen as the multiple heads case. Mercurial warns you about this
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   290
on pull. It is resolved the same way by a merge of A' and A'' that
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   291
will keep the same parent than `A'` and `A''` with two obsolete
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   292
markers pointing to both `A` and `A'`
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   293
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   294
.. warning::  TODO: Add a schema of the resolution. (merge A' and A'' with A as
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   295
              ancestor and graft the result of A^)
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   296
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   297
Allowing multiple new changesets to obsolete a single one allows to
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   298
distinguish a split changeset from a history rewriting conflict.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   299
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   300
Reliable history
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
   301
``````````````````````
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   302
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   303
Obsolete marker help to smooth rewriting operation process. However they
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   304
do not change the fact that **you should only rewrite the mutable part of the
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   305
history**. The phase concept enforces this rule by explicitly defining a
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   306
public immutable set of changesets. Rewriting operations refuse to work on
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   307
public changesets, but there are still some corner cases where previously rewritten changesets
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   308
are made public.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   309
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   310
Special rules apply for obsolete markers pointing to public changesets:
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   311
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   312
* Public changesets are excluded from the obsolete set (public
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   313
  changesets are never hidden or candidate to garbage collection)
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   314
192
706a3a57b567 docs: Merged obs-concept changes by hand.
Arne Babenhauserheide <bab@draketo.de>
parents: 191 186
diff changeset
   315
* *newer* version of a public changeset are called **latecomer** and highlighted as
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   316
  an error case.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   317
173
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   318
Solving such an error is easy. Because we know what changeset a
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   319
*latecomer* tries to rewrite, we can easily compute a smaller
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   320
changeset containing only the change from the old *public* to the new
4d44a37d51d1 many fixes
Aurelien Campeas <aurelien.campeas@logilab.fr>
parents: 166
diff changeset
   321
*latecomer*.
161
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   322
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   323
.. warning:: add a schema
4e3f25ba5401 More doc and index with sphynx
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents:
diff changeset
   324
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   325
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   326
Conclusion
184
f047cd4f1235 backout obs-concept.rst changes
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 176
diff changeset
   327
----------------
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   328
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   329
The obsolete marker is a powerful concept that allows mercurial to safely handle
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   330
history rewriting operations. It is a new type of relation between Mercurial
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   331
changesets which tracks the result of history rewriting operations.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   332
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   333
This concept is simple to define and provides a very solid base for:
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   334
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   335
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   336
- Very fast history rewriting operations,
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   337
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   338
- auditable and reversible history rewriting process,
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   339
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   340
- clean final history,
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   341
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   342
- sharing and collaborating on the mutable part of the history,
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   343
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   344
- gracefully handling history rewriting conflicts,
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   345
191
0f1b8119a281 Backed out backout changeset f047cd4f1235
Arne Babenhauserheide <bab@draketo.de>
parents: 184
diff changeset
   346
- various history rewriting UI’s collaborating with an underlying common API.
166
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   347
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   348
.. list-table:: Comparison on solution [#]_
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   349
   :header-rows: 1
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   350
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   351
   * - Solution
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   352
     - Remove changeset locally
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   353
     - Works on any point of your history
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   354
     - Propagation
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   355
     - Collaboration
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   356
     - Speed
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   357
     - Access to older version
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   358
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   359
   * - Strip
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   360
     - `+`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   361
     - `+`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   362
     - \
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   363
     - \ 
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   364
     - \ 
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   365
     - `- -`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   366
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   367
   * - Reference
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   368
     - `+`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   369
     - \ 
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   370
     - `+`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   371
     - \ 
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   372
     - `+`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   373
     - `-`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   374
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   375
   * - Obsolete
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   376
     - `+`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   377
     - `+`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   378
     - `++`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   379
     - `++`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   380
     - `+`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   381
     - `+`
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   382
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   383
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   384
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   385
.. [#] To preserve good tradition in comparison table, an overwhelming advantage
8f8a52cd0b9f big doc update
Pierre-Yves David <pierre-yves.david@logilab.fr>
parents: 163
diff changeset
   386
       goes to the defended solution.