Differences between revisions 5 and 6
Revision 5 as of 2012-09-16 02:15:25
Size: 3218
Comment:
Revision 6 as of 2012-10-29 05:00:05
Size: 30
Comment:
Deletions are marked like this. Additions are marked like this.
Line 1: Line 1:
#pragma section-numbers 2

= ChangesetsObsolescence =

<<TableOfContents>>

/!\ this feature is experimental and only partially implement in core

== Overview ==

Obsolescence markers make it possible to mark changesets that have been
deleted or superset in a new version of the changeset.

Unlike the previous way of handling such changes, by stripping the old
changesets from the repository, obsolescence markers can be propagated
between repositories. This allows for a safe and simple way of exchanging
mutable history and altering it after the fact. Changeset phases are
respected, such that only draft and secret changesets can be altered (see
:hg:`hg phases` for details).

Obsolescence is tracked using "obsolete markers", a piece of metadata
tracking which changesets have been made obsolete, potential successors for
a given changeset, the moment the changeset was marked as obsolete, and the
user who performed the rewriting operation. The markers are stored
separately from standard changeset data can be exchanged without any of the
precursor changesets, preventing unnecessary exchange of obsolescence data.

The complete set of obsolescence markers describes a history of changeset
modifications that is orthogonal to the repository history of file
modifications. This changeset history allows for detection and automatic
resolution of edge cases arising from multiple users rewriting the same part
of history concurrently.

== Current feature status ==

This feature is still at an early stage of development. While several core
behaviors have been adjusted to take obsolescence markers into account, some
parts of Mercurial are still unaware of the new concept.

We do not recommend using this feature with version 2.3 of Mercurial.


== Available in version 2.3 ==

There is currently no functionality in core Mercurial to create obsolescence
markers. Markers can be created using third-party extensions, and some
parts of Mercurial will comply with the markers, enforcing behavior as
outlined below:

Changesets marked as obsolete are:

    * hidden from log,
    * excluded from push, pull, clone,
    * selected by the 'obsolete()' revset.

In some situation you may have non-obsolete changesets descending from
obsolete changesets. Such changesets are said to be "unstable":

    * push will refuse to push them without --force,
    * the 'unstable()' revset will select them,
    * their obsolete ancestors are displayed by log.

Obsolete changesets with no non-obsolete descendants are said to be
"extinct" and will appear when querying the "extinct()" revset.

Obsolescence markers will be exchanged between repositories that explicitly
assert support for the obsolescence feature (this can currently only be done
via an extension).

log --graph will display use 'x' instead of 'o' to display obsolete changesets.

== Experimental user ==

/!\ this feature is experimental do not try it unless you are an experimented user of Mercurial

A set of extension experimenting around the obsolescence concept is provided by Logilab. See its documentation for details:

http://hg-lab.logilab.org/doc/mutable-history/html/
#REDIRECT ChangesetEvolution

ChangesetsObsolescence (last edited 2012-10-29 05:00:05 by Pierre-YvesDavid)