view mercurial/help/phases.txt @ 41247:a89b20a49c13

rust-cpython: using MissingAncestors from Python code

As precedently done with LazyAncestors on cpython.rs, we test for the
presence of the 'rustext' module.

incrementalmissingrevs() has two callers within the Mercurial core:
`setdiscovery.partialdiscovery` and the `only()` revset.

This move shows a significant discovery performance improvement
in cases where the baseline is slow: using perfdiscovery on the PyPy
repos, prepared with `contrib/discovery-helper <repo> 50 100`, we
get averaged medians of 403ms with the Rust version vs 742ms without
(about 45% better).

But there are still indications that performance can be worse in cases
the baseline is fast, possibly due to the conversion from Python to
Rust and back becoming the bottleneck. We could measure this on
mozilla-central in cases were the delta is just a few changesets.
This requires confirmation, but if that's the reason, then an
upcoming `partialdiscovery` fully in Rust should solve the problem.

Differential Revision: https://phab.mercurial-scm.org/D5551

What are phases?
================

Phases are a system for tracking which changesets have been or should
be shared. This helps prevent common mistakes when modifying history
(for instance, with the mq or rebase extensions).

Each changeset in a repository is in one of the following phases:

 - public : changeset is visible on a public server
 - draft : changeset is not yet published
 - secret : changeset should not be pushed, pulled, or cloned

These phases are ordered (public < draft < secret) and no changeset
can be in a lower phase than its ancestors. For instance, if a
changeset is public, all its ancestors are also public. Lastly,
changeset phases should only be changed towards the public phase.

How are phases managed?
=======================

For the most part, phases should work transparently. By default, a
changeset is created in the draft phase and is moved into the public
phase when it is pushed to another repository.

Once changesets become public, extensions like mq and rebase will
refuse to operate on them to prevent creating duplicate changesets.
Phases can also be manually manipulated with the :hg:`phase` command
if needed. See :hg:`help -v phase` for examples.

To make your commits secret by default, put this in your
configuration file::

  [phases]
  new-commit = secret

Phases and servers
==================

Normally, all servers are ``publishing`` by default. This means::

 - all draft changesets that are pulled or cloned appear in phase
 public on the client

 - all draft changesets that are pushed appear as public on both
 client and server

 - secret changesets are neither pushed, pulled, or cloned

.. note::

  Pulling a draft changeset from a publishing server does not mark it
  as public on the server side due to the read-only nature of pull.

Sometimes it may be desirable to push and pull changesets in the draft
phase to share unfinished work. This can be done by setting a
repository to disable publishing in its configuration file::

  [phases]
  publish = False

See :hg:`help config` for more information on configuration files.

.. note::

  Servers running older versions of Mercurial are treated as
  publishing.

.. note::

   Changesets in secret phase are not exchanged with the server. This
   applies to their content: file names, file contents, and changeset
   metadata. For technical reasons, the identifier (e.g. d825e4025e39)
   of the secret changeset may be communicated to the server.


Examples
========

 - list changesets in draft or secret phase::

     hg log -r "not public()"

 - change all secret changesets to draft::

     hg phase --draft "secret()"

 - forcibly move the current changeset and descendants from public to draft::

     hg phase --force --draft .

 - show a list of changeset revisions and each corresponding phase::

     hg log --template "{rev} {phase}\n"

 - resynchronize draft changesets relative to a remote repository::

     hg phase -fd "outgoing(URL)"

See :hg:`help phase` for more information on manually manipulating phases.