2 files changed, 24 insertions, 1 deletions
diff --git a/synapse/util/__init__.py b/synapse/util/__init__.py
index 814a7bf71b..fc11e26623 100644
--- a/synapse/util/__init__.py
+++ b/synapse/util/__init__.py
@@ -20,6 +20,8 @@ from twisted.internet import defer, reactor, task
 import time
 import logging
 
+from itertools import islice
+
 logger = logging.getLogger(__name__)
 
 
@@ -79,3 +81,19 @@ class Clock(object):
         except Exception:
             if not ignore_errs:
                 raise
+
+
+def batch_iter(iterable, size):
+    """batch an iterable up into tuples with a maximum size
+
+    Args:
+        iterable (iterable): the iterable to slice
+        size (int): the maximum batch size
+
+    Returns:
+        an iterator over the chunks
+    """
+    # make sure we can deal with iterables like lists too
+    sourceiter = iter(iterable)
+    # call islice until it returns an empty tuple
+    return iter(lambda: tuple(islice(sourceiter, size)), ())
diff --git a/synapse/util/caches/__init__.py b/synapse/util/caches/__init__.py
index 4adae96681..329ccbb866 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -16,6 +16,9 @@
 import synapse.metrics
 import os
 
+from six.moves import intern
+import six
+
 CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.5))
 
 metrics = synapse.metrics.get_metrics_for("synapse.util.caches")
@@ -66,7 +69,9 @@ def intern_string(string):
         return None
 
     try:
-        string = string.encode("ascii")
+        if six.PY2:
+            string = string.encode("ascii")
+
         return intern(string)
     except UnicodeEncodeError:
         return string