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efb3c4ff63
This patch subtly changes the behavior of the parsing of "X.Y" values to not set the "section" variable when rendering a known sub-topic. Previously, "section" would be the same as the sub-topic name. This required the sub-topic RST to have a section named the same as the sub-topic name. When I made this change, the descriptions from help.internalstable started being rendered in command line output. This didn't look correct to me, as it didn't match the formatting of main help pages. I corrected this by moving the top section to help.internalstable and changing the section levels of all the "internals" topics. The end result is that "internals" topics now match the rendering of main topics on both the CLI and HTML. And, "internals" topics no longer require a main section matching the name of the topic.
95 lines
3.2 KiB
Plaintext
95 lines
3.2 KiB
Plaintext
A bundle is a container for repository data.
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Bundles are used as standalone files as well as the interchange format
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over the wire protocol used when two Mercurial peers communicate with
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each other.
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Headers
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=======
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Bundles produced since Mercurial 0.7 (September 2005) have a 4 byte
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header identifying the major bundle type. The header always begins with
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``HG`` and the follow 2 bytes indicate the bundle type/version. Some
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bundle types have additional data after this 4 byte header.
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The following sections describe each bundle header/type.
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HG10
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----
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``HG10`` headers indicate a *changegroup bundle*. This is the original
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bundle format, so it is sometimes referred to as *bundle1*. It has been
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present since version 0.7 (released September 2005).
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This header is followed by 2 bytes indicating the compression algorithm
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used for data that follows. All subsequent data following this
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compression identifier is compressed according to the algorithm/method
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specified.
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Supported algorithms include the following.
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``BZ``
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*bzip2* compression.
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Bzip2 compressors emit a leading ``BZ`` header. Mercurial uses this
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leading ``BZ`` as part of the bundle header. Therefore consumers
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of bzip2 bundles need to *seed* the bzip2 decompressor with ``BZ`` or
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seek the input stream back to the beginning of the algorithm component
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of the bundle header so that decompressor input is valid. This behavior
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is unique among supported compression algorithms.
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Supported since version 0.7 (released December 2006).
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``GZ``
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*zlib* compression.
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Supported since version 0.9.2 (released December 2006).
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``UN``
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*Uncompressed* or no compression. Unmodified changegroup data follows.
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Supported since version 0.9.2 (released December 2006).
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3rd party extensions may implement their own compression. However, no
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authority reserves values for their compression algorithm identifiers.
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HG2X
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----
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``HG2X`` headers (where ``X`` is any value) denote a *bundle2* bundle.
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Bundle2 bundles are a container format for various kinds of repository
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data and capabilities, beyond changegroup data (which was the only data
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supported by ``HG10`` bundles.
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``HG20`` is currently the only defined bundle2 version.
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The ``HG20`` format is not yet documented here. See the inline comments
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in ``mercurial/exchange.py`` for now.
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Initial ``HG20`` support was added in Mercurial 3.0 (released May
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2014). However, bundle2 bundles were hidden behind an experimental flag
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until version 3.5 (released August 2015), when they were enabled in the
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wire protocol. Various commands (including ``hg bundle``) did not
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support generating bundle2 files until Mercurial 3.6 (released November
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2015).
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HGS1
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----
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*Experimental*
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A ``HGS1`` header indicates a *streaming clone bundle*. This is a bundle
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that contains raw revlog data from a repository store. (Typically revlog
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data is exchanged in the form of changegroups.)
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The purpose of *streaming clone bundles* are to *clone* repository data
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very efficiently.
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The ``HGS1`` header is always followed by 2 bytes indicating a
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compression algorithm of the data that follows. Only ``UN``
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(uncompressed data) is currently allowed.
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``HGS1UN`` support was added as an experimental feature in version 3.6
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(released November 2015) as part of the initial offering of the *clone
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bundles* feature.
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