added database locking to Metadata

3 files changed, 24 insertions, 16 deletions

diff --git a/src/lib/Bcfg2/Server/Plugin/helpers.py b/src/lib/Bcfg2/Server/Plugin/helpers.py
index c7798b705..a9e7b6067 100644
--- a/src/lib/Bcfg2/Server/Plugin/helpers.py
+++ b/src/lib/Bcfg2/Server/Plugin/helpers.py
@@ -151,22 +151,24 @@ class DatabaseBacked(Plugin):
 
     @property
     def _must_lock(self):
-        """ Whether or not the backend database allows multiple
-        threads to write. """
-        engine = self.core.setup.cfp.get(Bcfg2.Options.DB_ENGINE.cf[0],
-                                         Bcfg2.Options.DB_ENGINE.cf[1],
-                                         default=Bcfg2.Options.DB_ENGINE.default)
+        """ Whether or not the backend database must acquire a thread
+        lock before writing, because it does not allow multiple
+        threads to write."""
+        engine = \
+            self.core.setup.cfp.get(Bcfg2.Options.DB_ENGINE.cf[0],
+                                    Bcfg2.Options.DB_ENGINE.cf[1],
+                                    default=Bcfg2.Options.DB_ENGINE.default)
         if engine == 'sqlite3':
             return True
         else:
             return False
 
     @staticmethod
-    def _db_writer(fn):
-        """ Decorator to be used when a call will update the data
-        threads to write. """
+    def get_db_lock(fn):
+        """ Decorator to be used by a method of a
+        :class:`DatabaseBacked` plugin that will update database data. """
         def _acquire_and_run(self, *args, **kwargs):
-            if self._must_lock:
+            if self._must_lock:  # pylint: disable=W0212
                 try:
                     self.core.db_write_lock.acquire()
                     rv = fn(self, *args, **kwargs)
diff --git a/src/lib/Bcfg2/Server/Plugins/Metadata.py b/src/lib/Bcfg2/Server/Plugins/Metadata.py
index 6daf23476..4929cb52d 100644
--- a/src/lib/Bcfg2/Server/Plugins/Metadata.py
+++ b/src/lib/Bcfg2/Server/Plugins/Metadata.py
@@ -43,7 +43,8 @@ if HAS_DJANGO:
         hostname = models.CharField(max_length=255, primary_key=True)
         version = models.CharField(max_length=31, null=True)
 
-    class ClientVersions(MutableMapping, object):
+    class ClientVersions(MutableMapping,
+                         Bcfg2.Server.Plugin.DatabaseBacked):
         """ dict-like object to make it easier to access client bcfg2
         versions from the database """
 
@@ -53,12 +54,15 @@ if HAS_DJANGO:
             except MetadataClientModel.DoesNotExist:
                 raise KeyError(key)
 
+        @Bcfg2.Server.Plugin.DatabaseBacked.get_db_lock
         def __setitem__(self, key, value):
-            client, created = MetadataClientModel.objects.get_or_create(hostname=key)
+            client, created = \
+                MetadataClientModel.objects.get_or_create(hostname=key)
             if created or client.version != value:
                 client.version = value
                 client.save()
 
+        @Bcfg2.Server.Plugin.DatabaseBacked.get_db_lock
         def __delitem__(self, key):
             # UserDict didn't require __delitem__, but MutableMapping
             # does.  we don't want deleting a client version record to
@@ -435,7 +439,7 @@ class Metadata(Bcfg2.Server.Plugin.Metadata,
         self.negated_groups = dict()
         # mapping of hostname -> version string
         if self._use_db:
-            self.versions = ClientVersions()
+            self.versions = ClientVersions(core, datastore)
         else:
             self.versions = dict()
         self.uuid = {}
@@ -540,6 +544,7 @@ class Metadata(Bcfg2.Server.Plugin.Metadata,
         else:
             return self._add_xdata(self.groups_xml, "Bundle", bundle_name)
 
+    @Bcfg2.Server.Plugin.DatabaseBacked.get_db_lock
     def add_client(self, client_name, attribs=None):
         """Add client to clients.xml."""
         if attribs is None:
@@ -914,9 +919,10 @@ class Metadata(Bcfg2.Server.Plugin.Metadata,
             if client not in self.versions or version != self.versions[client]:
                 self.logger.info("Setting client %s version to %s" %
                                  (client, version))
-                self.update_client(client, dict(version=version))
+                if not self._use_db:
+                    self.update_client(client, dict(version=version))
+                    self.clients_xml.write()
                 self.versions[client] = version
-                self.clients_xml.write()
         else:
             msg = "Cannot set version on non-existent client %s" % client
             self.logger.error(msg)
diff --git a/src/lib/Bcfg2/Server/Plugins/Probes.py b/src/lib/Bcfg2/Server/Plugins/Probes.py
index 78dd2af85..941bc4fd8 100644
--- a/src/lib/Bcfg2/Server/Plugins/Probes.py
+++ b/src/lib/Bcfg2/Server/Plugins/Probes.py
@@ -218,7 +218,7 @@ class Probes(Bcfg2.Server.Plugin.Probing,
             err = sys.exc_info()[1]
             self.logger.error("Failed to write probed.xml: %s" % err)
 
-    @Bcfg2.Server.Plugin.DatabaseBacked._db_writer
+    @Bcfg2.Server.Plugin.DatabaseBacked.get_db_lock
     def _write_data_db(self, client):
         """ Write received probe data to the database """
         for probe, data in self.probedata[client.hostname].items():
@@ -320,7 +320,7 @@ class Probes(Bcfg2.Server.Plugin.Probing,
             cprobedata[data.get('name')] = ProbeData('')
             return
         dlines = data.text.split('\n')
-        self.logger.debug("%s:probe:%s:%s" %
+        self.logger.debug("Processing probe from %s: %s:%s" %
                           (client.hostname, data.get('name'),
                            [line.strip() for line in dlines]))
         for line in dlines[:]: