EGENCACHE

Section: Portage (1)
Updated: March 2009

NAME

egencache - generate metadata cache for ebuild repositories

SYNOPSIS

egencache [options] --update [ATOM]...

DESCRIPTION

The egencache program generates metadata cache for ebuild repositories and stores it in the metadata/cache/ directory within the repository itself, for distribution.

ACTIONS

--update [ATOM] ...: Update the metadata/cache/ directory (generate metadata as necessary). If no package atoms are specified then all will be updated. See ebuild(5) for the details on package atom syntax.

OPTIONS

--cache-dir=CACHE_DIR: Location of the intermediate metadata cache which is stored in a different format that includes eclass state. See the BUGS section for information about why this is necessary.
Defaults to /var/cache/edb/dep.
--config-root=CONFIG_ROOT: Location of portage config files.
Defaults to /.
--ignore-default-opts: Causes EGENCACHE_DEFAULT_OPTS to be ignored.
--jobs=JOBS: Specifies the maximum number of ebuild processes to spawn simultaneously. Also see the related --load-average option.
--load-average=LOAD: Specifies that maximum load allowed when spawning multiple jobs.
--repo=REPO: Name of the repo to operate on (default repo is located at PORTDIR). The name should correspond the value of a repo_name entry (see portage(5)) from one of the repositories that is configured via the PORTDIR or PORTDIR_OVERLAY variables (see make.conf(5)).
--rsync: When used together with the --update action, this enables a workaround for cases in which the content of a cache entry changes and neither the file mtime nor size changes, preventing rsync from detecting changes. Such cases are handled by bumping the mtime on the ebuild (and the corresponding cache entry). This option should only be needed for distribution via something like rsync(1), which relies on timestamps and file sizes to detect changes (see bug 139134). It's not needed with git(1) since that uses a more thorough mechanism which allows it to detect changed inode numbers (described in racy-git.txt in the git technical docs).

ENVIRONMENT OPTIONS

EGENCACHE_DEFAULT_OPTS: If this variable is set in make.conf(5) then any options that it contains will be added to the beginning of the command line on every invocation. These options will not be added if the --ignore-default-opts option is specified.

BUGS

There are significant limitations associated with the metadata cache format that is distributed in the metadata/cache/ directory of the repository. These limitations are related to the cache validation mechanism. Currently, the validation mechanism involves comparison of a cache entry mtime to the mtime of the corresponding ebuild(5). This mechanism is unreliable in cases when eclass changes result in metadata changes, since no information about eclass state is available in the cache. Also, since the mtime of the cache entry must correspond to that of the ebuild, the cache format is only suitable for distribution via protocols that preserve timestamps (such as rsync(1)). For cache that is distributed via git(1) repositories, there is currently a workaround implemented in emerge(1) --sync which updates ebuild mtimes to match their corresponding cache entries (except for ebuilds that are modified relative to HEAD).

In order to solve the above problems, a future extension to the cache format will include additional validation data in the form of digests for both the ebuild and its inherited eclasses. Until the cache format has been extended in this way, it is necessary to enable metadata-transfer in FEATURES (see make.conf(5)). This causes intermediate cache (in a different format that includes eclass state) to be generated inside the directory which is configurable via the --cache-dir option.

REPORTING BUGS

Please report bugs via http://bugs.gentoo.org/

AUTHORS

Zac Medico <zmedico@gentoo.org>

FILES

/etc/make.conf: Contains variables.

This document was created by man2html, using the manual pages.
Time: 21:14:26 GMT, April 20, 2009