mercurial/helptext/bundlespec.txt

ci: shard the test run on mac os X

This should comes with some benefit:
- spread the load across more runner,
- reduce the real-time CI run,
- reduce the "retry" run when we need them.

We start with the Mac jobs, but that would be tremendously useful for Windows
too.

For linux, we need to reduce the startup overhead for this to be worth it.
Building smaller image and speeding up clone should help with that.

Mercurial supports generating standalone "bundle" files that hold repository
data. These "bundles" are typically saved locally and used later or exchanged
between different repositories, possibly on different machines. Example
commands using bundles are :hg:`bundle` and :hg:`unbundle`.

Generation of bundle files is controlled by a "bundle specification"
("bundlespec") string. This string tells the bundle generation process how
to create the bundle.

A "bundlespec" string is composed of the following elements:

type
    A string denoting the bundle format to use.

compression
    Denotes the compression engine to use compressing the raw bundle data.

parameters
    Arbitrary key-value parameters to further control bundle generation.

A "bundlespec" string has the following formats:

<type>
    The literal bundle format string is used.

<compression>-<type>
    The compression engine and format are delimited by a hyphen (``-``).

Optional parameters follow the ``<type>``. Parameters are URI escaped
``key=value`` pairs. Each pair is delimited by a semicolon (``;``). The
first parameter begins after a ``;`` immediately following the ``<type>``
value.

Available Types
===============

The following bundle <type> strings are available:

v1
    Produces a legacy "changegroup" version 1 bundle.

    This format is compatible with nearly all Mercurial clients because it is
    the oldest. However, it has some limitations, which is why it is no longer
    the default for new repositories.

    ``v1`` bundles can be used with modern repositories using the "generaldelta"
    storage format. However, it may take longer to produce the bundle and the
    resulting bundle may be significantly larger than a ``v2`` bundle.

    ``v1`` bundles can only use the ``gzip``, ``bzip2``, and ``none`` compression
    formats.

v2
    Produces a version 2 bundle.

    Version 2 bundles are an extensible format that can store additional
    repository data (such as bookmarks and phases information) and they can
    store data more efficiently, resulting in smaller bundles.

    Version 2 bundles can also use modern compression engines, such as
    ``zstd``, making them faster to compress and often smaller.

Available Compression Engines
=============================

The following bundle <compression> engines can be used:

.. bundlecompressionmarker

The compression engines can be prepended with ``stream`` to create a streaming bundle.
These are bundles that are extremely efficient to produce and consume,
but do not have guaranteed compatibility with older clients.

Available Options
=================

The following options exist:

changegroup
    Include the changegroup data in the bundle (default to True).

cg.version
    Select the version of the changegroup to use. Available options are : 01, 02
    or 03. By default it will be automatically selected according to the current
    repository format.

obsolescence
    Include obsolescence-markers relevant to the bundled changesets.

phases
    Include phase information relevant to the bundled changesets.

revbranchcache
    Include the "tags-fnodes" cache inside the bundle.

tagsfnodescache
    Include the "tags-fnodes" cache inside the bundle.


Examples
========

``v2``
    Produce a ``v2`` bundle using default options, including compression.

``none-v1``
    Produce a ``v1`` bundle with no compression.

``zstd-v2``
    Produce a ``v2`` bundle with zstandard compression using default
    settings.

``zstd-v1``
    This errors because ``zstd`` is not supported for ``v1`` types.

``none-streamv2``
    Produce a ``v2`` streaming bundle with no compression.

``zstd-v2;obsolescence=true;phases=true``
    Produce a ``v2`` bundle with zstandard compression which includes
    obsolescence markers and phases.