Merge branch 'maint'

Signed-off-by: Sol Jerome <sol.jerome@gmail.com>

Conflicts:
	src/lib/Bcfg2/Server/Plugins/Cfg/CfgPrivateKeyCreator.py
	src/lib/Bcfg2/Server/Plugins/Packages/Yum.py
	src/lib/Bcfg2/Server/Plugins/Properties.py

1 files changed, 78 insertions, 10 deletions

diff --git a/src/lib/Bcfg2/Server/Plugins/Packages/__init__.py b/src/lib/Bcfg2/Server/Plugins/Packages/__init__.py
index 8e14b0dfb..03047b046 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
@@ -23,6 +24,52 @@ 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 __repr__(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,
@@ -520,20 +567,41 @@ 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():
+            """ getter for the 'sources' key of the OnDemandDict
+            returned by this function.  This delays calling
+            get_collection() until it's absolutely necessary. """
+            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