Turn imageid translator into general translator for rackspace api ids

1 files changed, 42 insertions, 0 deletions

diff --git a/nova/api/rackspace/_id_translator.py b/nova/api/rackspace/_id_translator.py
new file mode 100644
index 000000000..aec5fb6a5
--- /dev/null
+++ b/nova/api/rackspace/_id_translator.py
@@ -0,0 +1,42 @@
+from nova import datastore
+
+class RackspaceAPIIdTranslator(object):
+    """
+    Converts Rackspace API ids to and from the id format for a given
+    strategy.
+    """
+
+    def __init__(self, id_type, service_name):
+        """
+        Creates a translator for ids of the given type (e.g. 'flavor'), for the
+        given storage service backend class name (e.g. 'LocalFlavorService').
+        """
+
+        self._store = datastore.Redis.instance()
+        key_prefix = "rsapi.idtranslator.%s.%s" % (id_type, service_name)
+        # Forward (strategy format -> RS format) and reverse translation keys
+        self._fwd_key = "%s.fwd" % key_prefix
+        self._rev_key = "%s.rev" % key_prefix
+
+    def to_rs_id(self, opaque_id):
+        """Convert an id from a strategy-specific one to a Rackspace one."""
+        result = self._store.hget(self._fwd_key, str(opaque_id))
+        if result: # we have a mapping from opaque to RS for this strategy
+            return int(result)
+        else:
+            # Store the mapping.
+            nextid = self._store.incr("%s.lastid" % self._fwd_key)
+            if self._store.hsetnx(self._fwd_key, str(opaque_id), nextid):
+                # If someone else didn't beat us to it, store the reverse
+                # mapping as well.
+                self._store.hset(self._rev_key, nextid, str(opaque_id))
+                return nextid
+            else:
+                # Someone beat us to it; use their number instead, and
+                # discard nextid (which is OK -- we don't require that
+                # every int id be used.)
+                return int(self._store.hget(self._fwd_key, str(opaque_id)))
+
+    def from_rs_id(self, strategy_name, rs_id):
+        """Convert a Rackspace id to a strategy-specific one."""
+        return self._store.hget(self._rev_key, rs_id)