##// END OF EJS Templates
upstream » mercurial-mirror
RSS

Clone from https://www.mercurial-scm.org/repo/hg-all

manifest: proxy to revlog instance instead of inheriting...
manifest: proxy to revlog instance instead of inheriting Previously, manifestrevlog inherited revlog.revlog and therefore exposed all its APIs. This inevitably resulted in consumers calling low-level revlog APIs. As part of abstracting storage, we want to formalize the interface for manifest storage. The revlog API is much too large to define as the interface. Like we did for filelog, this commit divorces the manifest class from revlog so that we can standardize on a smaller API surface. The way I went about this commit was I broke the inheritance, ran tests, and added proxies until all tests passed. Like filelog, there are a handful of attributes that don't belong on the interface. And like filelog, we'll tease these out in the future. As part of this, we formalize an interface for manifest storage and add checks that manifestrevlog conforms to the interface. Adding proxies will introduce some overhead due to extra attribute lookups and function calls. On the mozilla-unified repository: $ hg verify before: real 627.220 secs (user 525.870+0.000 sys 18.800+0.000) after: real 628.930 secs (user 532.050+0.000 sys 18.320+0.000) $ hg serve (for a clone) before: user 223.580+0.000 sys 14.270+0.000 after: user 227.720+0.000 sys 13.920+0.000 $ hg clone before: user 506.390+0.000 sys 29.720+0.000 after: user 513.080+0.000 sys 28.280+0.000 There appears to be some overhead here. But it appears to be 1-2%. I think that is an appropriate price to pay for storage abstraction, which will eventually let us have much nicer things. If the overhead is noticed in other operations (whose CPU time isn't likely dwarfed by fulltext resolution) or if we want to cut down on the overhead, we could dynamically build up a type whose methods are effectively aliased to a revlog instance's. I'm inclined to punt on that problem for now. We may have to do it for the changelog. At which point it could be implemented in a generic way and ported to filelog and manifestrevlog easily enough I would think. .. api:: manifest.manifestrevlog no longer inherits from revlog The manifestrevlog class now wraps a revlog instance instead of inheriting from revlog. Various attributes and methods on instances are no longer available. Differential Revision: https://phab.mercurial-scm.org/D4386
Gregory Szorc - - Load All Authors

File last commit:

r36469:1fa35ca3 default
r39350:7f5e6d3e default
Show More
bundles.txt
93 lines | 3.2 KiB | text/plain | TextLexer
/ mercurial / help / internals / bundles.txt
History | Annotation | Raw |Copy content |Copy permalink
A bundle is a container for repository data.
Bundles are used as standalone files as well as the interchange format
over the wire protocol used when two Mercurial peers communicate with
each other.
Headers
=======
Bundles produced since Mercurial 0.7 (September 2005) have a 4 byte
header identifying the major bundle type. The header always begins with
``HG`` and the follow 2 bytes indicate the bundle type/version. Some
bundle types have additional data after this 4 byte header.
The following sections describe each bundle header/type.
HG10
----
``HG10`` headers indicate a *changegroup bundle*. This is the original
bundle format, so it is sometimes referred to as *bundle1*. It has been
present since version 0.7 (released September 2005).
This header is followed by 2 bytes indicating the compression algorithm
used for data that follows. All subsequent data following this
compression identifier is compressed according to the algorithm/method
specified.
Supported algorithms include the following.
``BZ``
*bzip2* compression.
Bzip2 compressors emit a leading ``BZ`` header. Mercurial uses this
leading ``BZ`` as part of the bundle header. Therefore consumers
of bzip2 bundles need to *seed* the bzip2 decompressor with ``BZ`` or
seek the input stream back to the beginning of the algorithm component
of the bundle header so that decompressor input is valid. This behavior
is unique among supported compression algorithms.
Supported since version 0.7 (released December 2006).
``GZ``
*zlib* compression.
Supported since version 0.9.2 (released December 2006).
``UN``
*Uncompressed* or no compression. Unmodified changegroup data follows.
Supported since version 0.9.2 (released December 2006).
3rd party extensions may implement their own compression. However, no
authority reserves values for their compression algorithm identifiers.
HG2X
----
``HG2X`` headers (where ``X`` is any value) denote a *bundle2* bundle.
Bundle2 bundles are a container format for various kinds of repository
data and capabilities, beyond changegroup data (which was the only data
supported by ``HG10`` bundles.
``HG20`` is currently the only defined bundle2 version.
The ``HG20`` format is documented at :hg:`help internals.bundle2`.
Initial ``HG20`` support was added in Mercurial 3.0 (released May
2014). However, bundle2 bundles were hidden behind an experimental flag
until version 3.5 (released August 2015), when they were enabled in the
wire protocol. Various commands (including ``hg bundle``) did not
support generating bundle2 files until Mercurial 3.6 (released November
2015).
HGS1
----
*Experimental*
A ``HGS1`` header indicates a *streaming clone bundle*. This is a bundle
that contains raw revlog data from a repository store. (Typically revlog
data is exchanged in the form of changegroups.)
The purpose of *streaming clone bundles* are to *clone* repository data
very efficiently.
The ``HGS1`` header is always followed by 2 bytes indicating a
compression algorithm of the data that follows. Only ``UN``
(uncompressed data) is currently allowed.
``HGS1UN`` support was added as an experimental feature in version 3.6
(released November 2015) as part of the initial offering of the *clone
bundles* feature.