##// END OF EJS Templates
help: document requirements...
Gregory Szorc -
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@@ -0,0 +1,110 b''
1 Requirements
2 ============
3
4 Repositories contain a file (``.hg/requires``) containing a list of
5 features/capabilities that are *required* for clients to interface
6 with the repository. This file has been present in Mercurial since
7 version 0.9.2 (released December 2006).
8
9 One of the first things clients do when opening a repository is read
10 ``.hg/requires`` and verify that all listed requirements are supported,
11 aborting if not. Requirements are therefore a strong mechanism to
12 prevent incompatible clients from reading from unknown repository
13 formats or even corrupting them by writing to them.
14
15 Extensions may add requirements. When they do this, clients not running
16 an extension will be unable to read from repositories.
17
18 The following sections describe the requirements defined by the
19 Mercurial core distribution.
20
21 revlogv1
22 --------
23
24 When present, revlogs are version 1 (RevlogNG). RevlogNG was introduced
25 in 2006. The ``revlogv1`` requirement has been enabled by default
26 since the ``requires`` file was introduced in Mercurial 0.9.2.
27
28 If this requirement is not present, version 0 revlogs are assumed.
29
30 store
31 -----
32
33 The *store* repository layout should be used.
34
35 This requirement has been enabled by default since the ``requires`` file
36 was introduced in Mercurial 0.9.2.
37
38 fncache
39 -------
40
41 The *fncache* repository layout should be used.
42
43 The *fncache* layout hash encodes filenames with long paths and
44 encodes reserved filenames.
45
46 This requirement is enabled by default when the *store* requirement is
47 enabled (which is the default behavior). It was introduced in Mercurial
48 1.1 (released December 2008).
49
50 shared
51 ------
52
53 Denotes that the store for a repository is shared from another location
54 (defined by the ``.hg/sharedpath`` file).
55
56 This requirement is set when a repository is created via :hg:`share`.
57
58 The requirement was added in Mercurial 1.3 (released July 2009).
59
60 dotencode
61 ---------
62
63 The *dotencode* repository layout should be used.
64
65 The *dotencode* layout encodes the first period or space in filenames
66 to prevent issues on OS X and Windows.
67
68 This requirement is enabled by default when the *store* requirement
69 is enabled (which is the default behavior). It was introduced in
70 Mercurial 1.7 (released November 2010).
71
72 parentdelta
73 -----------
74
75 Denotes a revlog delta encoding format that was experimental and
76 replaced by *generaldelta*. It should not be seen in the wild because
77 it was never enabled by default.
78
79 This requirement was added in Mercurial 1.7 and removed in Mercurial
80 1.9.
81
82 generaldelta
83 ------------
84
85 Revlogs should be created with the *generaldelta* flag enabled. The
86 generaldelta flag will cause deltas to be encoded against a parent
87 revision instead of the previous revision in the revlog.
88
89 Support for this requirement was added in Mercurial 1.9 (released
90 July 2011). The requirement was disabled on new repositories by
91 default until Mercurial 3.7 (released February 2016).
92
93 manifestv2
94 ----------
95
96 Denotes that version 2 of manifests are being used.
97
98 Support for this requirement was added in Mercurial 3.4 (released
99 May 2015). The requirement is currently experimental and is disabled
100 by default.
101
102 treemanifest
103 ------------
104
105 Denotes that tree manifests are being used. Tree manifests are
106 one manifest per directory (as opposed to a single flat manifest).
107
108 Support for this requirement was added in Mercurial 3.4 (released
109 August 2015). The requirement is currently experimental and is
110 disabled by default.
@@ -40,6 +40,7 b''
40 <Component Id="help.internals" Guid="$(var.help.internals.guid)" Win64='$(var.IsX64)'>
40 <Component Id="help.internals" Guid="$(var.help.internals.guid)" Win64='$(var.IsX64)'>
41 <File Id="internals.bundles.txt" Name="bundles.txt" KeyPath="yes" />
41 <File Id="internals.bundles.txt" Name="bundles.txt" KeyPath="yes" />
42 <File Id="internals.changegroups.txt" Name="changegroups.txt" />
42 <File Id="internals.changegroups.txt" Name="changegroups.txt" />
43 <File Id="internals.requirements.txt" Name="requirements.txt" />
43 <File Id="internals.revlogs.txt" Name="revlogs.txt" />
44 <File Id="internals.revlogs.txt" Name="revlogs.txt" />
44 </Component>
45 </Component>
45 </Directory>
46 </Directory>
@@ -188,6 +188,8 b' internalstable = sorted(['
188 loaddoc('bundles', subdir='internals')),
188 loaddoc('bundles', subdir='internals')),
189 (['changegroups'], _('representation of revlog data'),
189 (['changegroups'], _('representation of revlog data'),
190 loaddoc('changegroups', subdir='internals')),
190 loaddoc('changegroups', subdir='internals')),
191 (['requirements'], _('repository requirements'),
192 loaddoc('requirements', subdir='internals')),
191 (['revlogs'], _('revision storage mechanism'),
193 (['revlogs'], _('revision storage mechanism'),
192 loaddoc('revlogs', subdir='internals')),
194 loaddoc('revlogs', subdir='internals')),
193 ])
195 ])
@@ -875,6 +875,7 b' internals topic renders index of availab'
875
875
876 bundles container for exchange of repository data
876 bundles container for exchange of repository data
877 changegroups representation of revlog data
877 changegroups representation of revlog data
878 requirements repository requirements
878 revlogs revision storage mechanism
879 revlogs revision storage mechanism
879
880
880 sub-topics can be accessed
881 sub-topics can be accessed
@@ -2727,6 +2728,13 b' Sub-topic indexes rendered properly'
2727 representation of revlog data
2728 representation of revlog data
2728 </td></tr>
2729 </td></tr>
2729 <tr><td>
2730 <tr><td>
2731 <a href="/help/internals.requirements">
2732 requirements
2733 </a>
2734 </td><td>
2735 repository requirements
2736 </td></tr>
2737 <tr><td>
2730 <a href="/help/internals.revlogs">
2738 <a href="/help/internals.revlogs">
2731 revlogs
2739 revlogs
2732 </a>
2740 </a>
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