1 files changed, 133 insertions, 0 deletions
diff --git a/lib/beaker/ext/sqla.py b/lib/beaker/ext/sqla.py
new file mode 100644
index 000000000..8c79633c1
--- /dev/null
+++ b/lib/beaker/ext/sqla.py
@@ -0,0 +1,133 @@
+import cPickle
+import logging
+import pickle
+from datetime import datetime
+
+from beaker.container import OpenResourceNamespaceManager, Container
+from beaker.exceptions import InvalidCacheBackendError, MissingCacheParameter
+from beaker.synchronization import file_synchronizer, null_synchronizer
+from beaker.util import verify_directory, SyncDict
+
+
+log = logging.getLogger(__name__)
+
+sa = None
+
+class SqlaNamespaceManager(OpenResourceNamespaceManager):
+    binds = SyncDict()
+    tables = SyncDict()
+
+    @classmethod
+    def _init_dependencies(cls):
+        global sa
+        if sa is not None:
+            return
+        try:
+            import sqlalchemy as sa
+        except ImportError:
+            raise InvalidCacheBackendError("SQLAlchemy, which is required by "
+                                            "this backend, is not installed")
+
+    def __init__(self, namespace, bind, table, data_dir=None, lock_dir=None,
+                 **kwargs):
+        """Create a namespace manager for use with a database table via
+        SQLAlchemy.
+
+        ``bind``
+            SQLAlchemy ``Engine`` or ``Connection`` object
+
+        ``table``
+            SQLAlchemy ``Table`` object in which to store namespace data.
+            This should usually be something created by ``make_cache_table``.
+        """
+        OpenResourceNamespaceManager.__init__(self, namespace)
+
+        if lock_dir:
+            self.lock_dir = lock_dir
+        elif data_dir:
+            self.lock_dir = data_dir + "/container_db_lock"
+        if self.lock_dir:
+            verify_directory(self.lock_dir)            
+
+        self.bind = self.__class__.binds.get(str(bind.url), lambda: bind)
+        self.table = self.__class__.tables.get('%s:%s' % (bind.url, table.name),
+                                               lambda: table)
+        self.hash = {}
+        self._is_new = False
+        self.loaded = False
+
+    def get_access_lock(self):
+        return null_synchronizer()
+
+    def get_creation_lock(self, key):
+        return file_synchronizer(
+            identifier ="databasecontainer/funclock/%s" % self.namespace,
+            lock_dir=self.lock_dir)
+
+    def do_open(self, flags):
+        if self.loaded:
+            self.flags = flags
+            return
+        select = sa.select([self.table.c.data],
+                           (self.table.c.namespace == self.namespace))
+        result = self.bind.execute(select).fetchone()
+        if not result:
+            self._is_new = True
+            self.hash = {}
+        else:
+            self._is_new = False
+            try:
+                self.hash = result['data']
+            except (IOError, OSError, EOFError, cPickle.PickleError,
+                    pickle.PickleError):
+                log.debug("Couln't load pickle data, creating new storage")
+                self.hash = {}
+                self._is_new = True
+        self.flags = flags
+        self.loaded = True
+
+    def do_close(self):
+        if self.flags is not None and (self.flags == 'c' or self.flags == 'w'):
+            if self._is_new:
+                insert = self.table.insert()
+                self.bind.execute(insert, namespace=self.namespace, data=self.hash,
+                                  accessed=datetime.now(), created=datetime.now())
+                self._is_new = False
+            else:
+                update = self.table.update(self.table.c.namespace == self.namespace)
+                self.bind.execute(update, data=self.hash, accessed=datetime.now())
+        self.flags = None
+
+    def do_remove(self):
+        delete = self.table.delete(self.table.c.namespace == self.namespace)
+        self.bind.execute(delete)
+        self.hash = {}
+        self._is_new = True
+
+    def __getitem__(self, key):
+        return self.hash[key]
+
+    def __contains__(self, key):
+        return self.hash.has_key(key)
+
+    def __setitem__(self, key, value):
+        self.hash[key] = value
+
+    def __delitem__(self, key):
+        del self.hash[key]
+
+    def keys(self):
+        return self.hash.keys()
+
+
+class SqlaContainer(Container):
+    namespace_manager = SqlaNamespaceManager
+
+def make_cache_table(metadata, table_name='beaker_cache'):
+    """Return a ``Table`` object suitable for storing cached values for the
+    namespace manager.  Do not create the table."""
+    return sa.Table(table_name, metadata,
+                    sa.Column('namespace', sa.String(255), primary_key=True),
+                    sa.Column('accessed', sa.DateTime, nullable=False),
+                    sa.Column('created', sa.DateTime, nullable=False),
+                    sa.Column('data', sa.PickleType, nullable=False))