diff options
Diffstat (limited to 'src/lib/Bcfg2/Server/Plugins/Packages/__init__.py')
-rw-r--r-- | src/lib/Bcfg2/Server/Plugins/Packages/__init__.py | 85 |
1 files changed, 75 insertions, 10 deletions
diff --git a/src/lib/Bcfg2/Server/Plugins/Packages/__init__.py b/src/lib/Bcfg2/Server/Plugins/Packages/__init__.py index f93bd0932..aea447520 100644 --- a/src/lib/Bcfg2/Server/Plugins/Packages/__init__.py +++ b/src/lib/Bcfg2/Server/Plugins/Packages/__init__.py @@ -9,7 +9,8 @@ import shutil import lxml.etree import Bcfg2.Logger import Bcfg2.Server.Plugin -from Bcfg2.Compat import ConfigParser, urlopen, HTTPError, URLError +from Bcfg2.Compat import ConfigParser, urlopen, HTTPError, URLError, \ + MutableMapping from Bcfg2.Server.Plugins.Packages.Collection import Collection, \ get_collection_class from Bcfg2.Server.Plugins.Packages.PackagesSources import PackagesSources @@ -22,6 +23,52 @@ APT_CONFIG_DEFAULT = \ "/etc/apt/sources.list.d/bcfg2-packages-generated-sources.list" +class OnDemandDict(MutableMapping): + """ This maps a set of keys to a set of value-getting functions; + the values are populated on-the-fly by the functions as the values + are needed (and not before). This is used by + :func:`Bcfg2.Server.Plugins.Packages.Packages.get_additional_data`; + see the docstring for that function for details on why. + + Unlike a dict, you should not specify values for for the righthand + side of this mapping, but functions that get values. E.g.: + + .. code-block:: python + + d = OnDemandDict(foo=load_foo, + bar=lambda: "bar"); + """ + + def __init__(self, **getters): + self._values = dict() + self._getters = dict(**getters) + + def __getitem__(self, key): + if key not in self._values: + self._values[key] = self._getters[key]() + return self._values[key] + + def __setitem__(self, key, getter): + self._getters[key] = getter + + def __delitem__(self, key): + del self._values[key] + del self._getters[key] + + def __len__(self): + return len(self._getters) + + def __iter__(self): + return iter(self._getters.keys()) + + def __str__(self): + rv = dict(self._values) + for key in self._getters.keys(): + if key not in rv: + rv[key] = 'unknown' + return str(rv) + + class Packages(Bcfg2.Server.Plugin.Plugin, Bcfg2.Server.Plugin.StructureValidator, Bcfg2.Server.Plugin.Generator, @@ -535,20 +582,38 @@ class Packages(Bcfg2.Server.Plugin.Plugin, def get_additional_data(self, metadata): """ Return additional data for the given client. This will be - a dict containing a single key, ``sources``, whose value is a - list of data returned from - :func:`Bcfg2.Server.Plugins.Packages.Collection.Collection.get_additional_data`, - namely, a list of - :attr:`Bcfg2.Server.Plugins.Packages.Source.Source.url_map` - data. + an :class:`Bcfg2.Server.Plugins.Packages.OnDemandDict` + containing two keys: + + * ``sources``, whose value is a list of data returned from + :func:`Bcfg2.Server.Plugins.Packages.Collection.Collection.get_additional_data`, + namely, a list of + :attr:`Bcfg2.Server.Plugins.Packages.Source.Source.url_map` + data; and + * ``get_config``, whose value is the + :func:`Bcfg2.Server.Plugins.Packages.Packages.get_config` + function, which can be used to get the Packages config for + other systems. + + This uses an OnDemandDict instead of just a normal dict + because loading a source collection can be a fairly + time-consuming process, particularly for the first time. As a + result, when all metadata objects are built at once (such as + after the server is restarted, or far more frequently if + Metadata caching is disabled), this function would be a major + bottleneck if we tried to build all collections at the same + time. Instead, they're merely built on-demand. :param metadata: The client metadata :type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata :return: dict of lists of ``url_map`` data """ - collection = self.get_collection(metadata) - return dict(sources=collection.get_additional_data(), - get_config=self.get_config) + def get_sources(): + return self.get_collection(metadata).get_additional_data + + return OnDemandDict( + sources=get_sources, + get_config=lambda: self.get_config) def end_client_run(self, metadata): """ Hook to clear the cache for this client in |