1 files changed, 36 insertions, 0 deletions
diff --git a/synapse/api/ratelimiting.py b/synapse/api/ratelimiting.py
new file mode 100644
index 0000000000..a730abd59b
--- /dev/null
+++ b/synapse/api/ratelimiting.py
@@ -0,0 +1,36 @@
+import collections
+
+
+class Ratelimiter(object):
+
+    def __init__(self):
+        self.message_counts = collections.OrderedDict()
+
+    def prune_message_counts(self, time_now):
+        for user_id in self.message_counts.keys():
+            message_count, time_start, msg_rate_hz = (
+                self.message_counts[user_id]
+            )
+            time_delta = time_now - time_start
+            if message_count - time_delta * msg_rate_hz > 0:
+                break
+            else:
+                del self.message_counts[user_id]
+
+    def send_message(self, user_id, time_now, msg_rate_hz, burst_count):
+        self.prune_message_counts(time_now)
+        message_count, time_start, _ignored = self.message_counts.pop(
+            user_id, (0., time_now, None),
+        )
+        time_delta = time_now - time_start
+        if message_count - time_delta * msg_rate_hz < 0:
+            a
+        if message_count - (time_now - time_start) * msg_rate_hz > burst_count:
+            allowed = False
+        else:
+            allowed = True
+            message_count += 1
+        self.message_counts[user_id] = (
+            message_count, time_start, msg_rate_hz
+        )
+        return allowed