Mercurial > hg
diff mercurial/help/internals/requirements.txt @ 28523:045fe7042510
help: document requirements
We didn't have unified documentation of the various repository
requirements. This patch changes that.
author | Gregory Szorc <gregory.szorc@gmail.com> |
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date | Sat, 12 Mar 2016 18:51:07 -0800 |
parents | |
children | aba2bb2a6d0f |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mercurial/help/internals/requirements.txt Sat Mar 12 18:51:07 2016 -0800 @@ -0,0 +1,110 @@ +Requirements +============ + +Repositories contain a file (``.hg/requires``) containing a list of +features/capabilities that are *required* for clients to interface +with the repository. This file has been present in Mercurial since +version 0.9.2 (released December 2006). + +One of the first things clients do when opening a repository is read +``.hg/requires`` and verify that all listed requirements are supported, +aborting if not. Requirements are therefore a strong mechanism to +prevent incompatible clients from reading from unknown repository +formats or even corrupting them by writing to them. + +Extensions may add requirements. When they do this, clients not running +an extension will be unable to read from repositories. + +The following sections describe the requirements defined by the +Mercurial core distribution. + +revlogv1 +-------- + +When present, revlogs are version 1 (RevlogNG). RevlogNG was introduced +in 2006. The ``revlogv1`` requirement has been enabled by default +since the ``requires`` file was introduced in Mercurial 0.9.2. + +If this requirement is not present, version 0 revlogs are assumed. + +store +----- + +The *store* repository layout should be used. + +This requirement has been enabled by default since the ``requires`` file +was introduced in Mercurial 0.9.2. + +fncache +------- + +The *fncache* repository layout should be used. + +The *fncache* layout hash encodes filenames with long paths and +encodes reserved filenames. + +This requirement is enabled by default when the *store* requirement is +enabled (which is the default behavior). It was introduced in Mercurial +1.1 (released December 2008). + +shared +------ + +Denotes that the store for a repository is shared from another location +(defined by the ``.hg/sharedpath`` file). + +This requirement is set when a repository is created via :hg:`share`. + +The requirement was added in Mercurial 1.3 (released July 2009). + +dotencode +--------- + +The *dotencode* repository layout should be used. + +The *dotencode* layout encodes the first period or space in filenames +to prevent issues on OS X and Windows. + +This requirement is enabled by default when the *store* requirement +is enabled (which is the default behavior). It was introduced in +Mercurial 1.7 (released November 2010). + +parentdelta +----------- + +Denotes a revlog delta encoding format that was experimental and +replaced by *generaldelta*. It should not be seen in the wild because +it was never enabled by default. + +This requirement was added in Mercurial 1.7 and removed in Mercurial +1.9. + +generaldelta +------------ + +Revlogs should be created with the *generaldelta* flag enabled. The +generaldelta flag will cause deltas to be encoded against a parent +revision instead of the previous revision in the revlog. + +Support for this requirement was added in Mercurial 1.9 (released +July 2011). The requirement was disabled on new repositories by +default until Mercurial 3.7 (released February 2016). + +manifestv2 +---------- + +Denotes that version 2 of manifests are being used. + +Support for this requirement was added in Mercurial 3.4 (released +May 2015). The requirement is currently experimental and is disabled +by default. + +treemanifest +------------ + +Denotes that tree manifests are being used. Tree manifests are +one manifest per directory (as opposed to a single flat manifest). + +Support for this requirement was added in Mercurial 3.4 (released +August 2015). The requirement is currently experimental and is +disabled by default.