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GLEP: 61 |
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Title: Manifest2 compression |
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Version: $Revision: 1.1 $ |
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Last-Modified: $Date: 2008/07/13 02:21:58 $ |
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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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Updates: 44 |
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|
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Abstract |
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======== |
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Deals with compression of large Manifest2 files. |
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|
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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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|
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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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|
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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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|
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gzip, bzip2, lzma should all be supported if available on the given |
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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Copyright |
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========= |
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Copyright (c) 2007 by Robin Hugh Johnson. This material may be |
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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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|
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