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cardoe |
1.1 |
GLEP: 61
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Title: Manifest2 compression
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robbat2 |
1.3 |
Version: $Revision: 1.2 $
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Last-Modified: $Date: 2008/10/28 07:45:56 $
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cardoe |
1.1 |
Author: Robin Hugh Johnson <robbat2@gentoo.org>
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Status: Draft
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Type: Standards Track
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Content-Type: text/x-rst
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Requires: 44
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Created: July 2008
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robbat2 |
1.3 |
Updated: October 2008, January 2010
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cardoe |
1.1 |
Updates: 44
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robbat2 |
1.3 |
Post-History: December 2009
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cardoe |
1.1 |
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Abstract
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========
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Deals with compression of large Manifest2 files.
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Motivation
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==========
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With the introduction of MetaManifest, and full-tree Manifest coverage,
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we are faced with the possibility of having very large Manifests.
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Preliminary experiments with MetaManifest, show that with just the
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existing per-package Manifests, the full MetaManifest, for a tree
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including metadata/, exceeds 8MiB in size. Applying common compression
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can achieve a 50-60% reduction in this size.
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Specification
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=============
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When searching for a Manifest2 file, if the basename form does not
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exist, the package manager should search in the same location using
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common compressed suffixes, and use the compressed file in place of the
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Manifest2.
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robbat2 |
1.3 |
gzip, bzip2, lzma, xz should all be supported if available on the given
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cardoe |
1.1 |
platform. In the case that multiple versions exist, the package manager
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should simply pick one - they should be identical, differing only in
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compression.
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The Manifest generation process is required to ensure that inconsistent
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compressed versions do not exist.
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Backwards Compatibility
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=======================
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The package Manifests should also be maintained as ONLY uncompressed in
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CVS.
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For processing of all existing per-package Manifests, if compression is
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used, it should be done in parallel to the existing Manifests, to
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provide for a changeover period. Newer versions of Portage may later
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choose to exclude all non-compressed Manifests during emerge --sync if
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compressed versions are guaranteed to exist on the servers.
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MetaManifests may come into existence as compressed from the start, as
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do not have an backwards compatibility issues.
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As a side note, this breaks all manual interaction with Manifests
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such as grep, and so should only be applied to large Manifest2 files,
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such as the MetaManifest. 384KiB is suggested as a arbitary cut-off
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point to start generating compressed Manifest2 files.
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References
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==========
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.. [#GLEP44] Mauch, M. (2005) GLEP44 - Manifest2 format.
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http://www.gentoo.org/proj/en/glep/glep-0044.html
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Copyright
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=========
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robbat2 |
1.3 |
Copyright (c) 2007-2010 by Robin Hugh Johnson. This material may be
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cardoe |
1.1 |
distributed only subject to the terms and conditions set forth in the
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Open Publication License, v1.0.
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vim: tw=72 ts=2 expandtab:
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