util: dictutil: add DictOfSets.union(key, values) and DictOfSets.update(otherdictofsets)

diff --git a/src/allmydata/util/dictutil.py b/src/allmydata/util/dictutil.py
index 227d2479c3e10fb167ac5682cb7eab9e4188866c..11c0c7438ab4d2d7de755571f7bcf038f5bb99cf 100644 (file)
--- a/src/allmydata/util/dictutil.py
+++ b/src/allmydata/util/dictutil.py
@@ -40,6 +40,16 @@ class DictOfSets(dict):
         else:
             self[key] = set([value])
 
+    def union(self, key, values):
+        if key in self:
+            self[key].update(values)
+        else:
+            self[key] = set(values)
+
+    def update(self, otherdictofsets):
+        for key, value in otherdictofsets.iteritems():
+            self.union(key, value)
+
     def discard(self, key, value):
         if not key in self:
             return