Limit packet payload to 512 bytes.

- Limits the size of pipeline packets to 512 bytes. Fixes #16.
- Adds a test to verify that pipelines are cleaned after send().

2 files changed, 33 insertions, 3 deletions

diff --git a/statsd/client.py b/statsd/client.py
index b69ede8..cef1669 100644
--- a/statsd/client.py
+++ b/statsd/client.py
@@ -112,6 +112,14 @@ class Pipeline(StatsClient):
         self.send()
 
     def send(self):
-        data = '\n'.join(self._stats)
-        self._client._send(data)
-        self._stats = []
+        # Use pop(0) to preserve the order of the stats.
+        data = self._stats.pop(0)
+        while self._stats:
+            stat = self._stats.pop(0)
+            if len(stat) + len(data) + 1 >= 512:
+                self._client._send(data)
+                data = stat
+            else:
+                data += '\n' + stat
+        if data:
+            self._client._send(data)
diff --git a/statsd/tests.py b/statsd/tests.py
index 32950e5..eeaf575 100644
--- a/statsd/tests.py
+++ b/statsd/tests.py
@@ -290,3 +290,25 @@ def test_pipeline_timer_decorator():
             pass
         foo()
     _timer_check(sc, 1, 'foo', 'ms')
+
+
+def test_pipeline_empty():
+    """Pipelines should be empty after a send() call."""
+    sc = _client()
+    with sc.pipeline() as pipe:
+        pipe.incr('foo')
+        eq_(1, len(pipe._stats))
+    eq_(0, len(pipe._stats))
+
+
+def test_pipeline_packet_size():
+    """Pipelines shouldn't send packets larger than 512 bytes."""
+    sc = _client()
+    pipe = sc.pipeline()
+    for x in xrange(32):
+        # 32 * 16 = 512, so this will need 2 packets.
+        pipe.incr('sixteen_char_str')
+    pipe.send()
+    eq_(2, sc._sock.sendto.call_count)
+    assert len(sc._sock.sendto.call_args_list[0][0][0]) <= 512
+    assert len(sc._sock.sendto.call_args_list[1][0][0]) <= 512