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cardoe |
1.1 |
GLEP: 61
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Title: Manifest2 compression
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robbat2 |
1.5 |
Version: $Revision: 1.4 $
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Last-Modified: $Date: 2010/01/13 03:26:53 $
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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 |
1.5 |
Post-History: December 2009, January 2010
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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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robbat2 |
1.5 |
existing per-package Manifests, the full MetaManifest (top-level only,
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no first-level sub directories), for a tree including metadata/, exceeds
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8MiB in size. Applying common compression can achieve a 50-60% reduction
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in this size.
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Additionally, some of the larger already-existing Manifests in the tree
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can also be reduced.
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cardoe |
1.1 |
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Specification
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=============
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robbat2 |
1.5 |
Creation of compressed Manifests:
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---------------------------------
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32KiB is suggested as a arbitrary cut-off point to start generating
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compressed Manifest2 files.
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The compression must only applied during the creation of a tree intended
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for end users. No Manifests stored in a VCS should be compressed in the
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VCS. For the main gentoo-portage tree, this means that the compressed
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Manifests should be generated using the CVS to Rsync process.
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The Manifest compression process is required to ensure that inconsistent
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compressed versions do not exist.
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Validation of Manifests:
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------------------------
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cardoe |
1.1 |
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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robbat2 |
1.5 |
Example Results with a 32KiB cut-off, gzip algorithm
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====================================================
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As of 2010/01/30, the suggested cut-off would impact the following 21 existing
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Manifests, for a saving of nearly 900KiB::
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Size Path
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65788 app-doc/linux-gazette/Manifest
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75739 app-office/openoffice-bin/Manifest
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40534 app-text/texlive-core/Manifest
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41710 dev-texlive/texlive-bibtexextra/Manifest
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38197 dev-texlive/texlive-documentation-english/Manifest
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129610 dev-texlive/texlive-fontsextra/Manifest
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36022 dev-texlive/texlive-humanities/Manifest
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686118 dev-texlive/texlive-latexextra/Manifest
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43392 dev-texlive/texlive-latexrecommended/Manifest
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33375 dev-texlive/texlive-mathextra/Manifest
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39781 dev-texlive/texlive-pictures/Manifest
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69567 dev-texlive/texlive-pstricks/Manifest
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75460 dev-texlive/texlive-publishers/Manifest
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50879 dev-texlive/texlive-science/Manifest
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36711 kde-base/kde-l10n/Manifest
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36539 media-gfx/bootsplash-themes/Manifest
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33058 net-fs/autofs/Manifest
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39781 www-client/firefox-bin/Manifest
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48983 www-client/icecat/Manifest
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60213 www-client/mozilla-firefox/Manifest
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39065 x11-themes/gkrellm-themes/Manifest
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Additionally, with the MetaManifest proposal, the following new manifests would
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also be compressed, for a saving of nearly 4MiB::
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Size Path
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33442 app-admin/Manifest
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71073 app-dicts/Manifest
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35923 app-emacs/Manifest
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45808 app-misc/Manifest
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50169 app-text/Manifest
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112786 dev-java/Manifest
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65581 dev-libs/Manifest
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42619 dev-lisp/Manifest
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182163 dev-perl/Manifest
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96198 dev-python/Manifest
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58963 dev-ruby/Manifest
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59736 dev-util/Manifest
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58338 eclass/Manifest
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55749 kde-base/Manifest
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110064 licenses/Manifest
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35262 media-gfx/Manifest
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53995 media-libs/Manifest
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55607 media-plugins/Manifest
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71911 media-sound/Manifest
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34835 media-video/Manifest
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5747849 metadata/Manifest
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47452 net-analyzer/Manifest
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65989 net-misc/Manifest
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316787 profiles/Manifest
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67784 sys-apps/Manifest
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48971 x11-misc/Manifest
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41475 x11-plugins/Manifest
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cardoe |
1.1 |
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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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robbat2 |
1.5 |
such as the MetaManifest.
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cardoe |
1.1 |
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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 |
1.4 |
Copyright (c) 2008-2010 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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