From 7610c0fb2e0ec76b254ecb11dffa1c5161da61bf Mon Sep 17 00:00:00 2001
From: Maks Skorokhod <samael500@gmail.com>
Date: Mon, 9 Oct 2017 15:50:36 +0300
Subject: [PATCH 1/3] :wrench: log Connection lost only if debug

---
 sanic/server.py | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/sanic/server.py b/sanic/server.py
index 8f60a864..06c749a5 100644
--- a/sanic/server.py
+++ b/sanic/server.py
@@ -342,8 +342,10 @@ class HttpProtocol(asyncio.Protocol):
                          self.url, type(response))
             self.write_error(ServerError('Invalid response type'))
         except RuntimeError:
-            logger.error('Connection lost before response written @ %s',
-                         self.request.ip)
+            if self._debug:
+                logger.error('Connection lost before response written @ %s',
+                             self.request.ip)
+            keep_alive = False
         except Exception as e:
             self.bail_out(
                 "Writing response failed, connection closed {}".format(
@@ -379,8 +381,10 @@ class HttpProtocol(asyncio.Protocol):
                          self.url, type(response))
             self.write_error(ServerError('Invalid response type'))
         except RuntimeError:
-            logger.error('Connection lost before response written @ %s',
-                         self.request.ip)
+            if self._debug:
+                logger.error('Connection lost before response written @ %s',
+                             self.request.ip)
+            keep_alive = False
         except Exception as e:
             self.bail_out(
                 "Writing response failed, connection closed {}".format(
@@ -407,8 +411,9 @@ class HttpProtocol(asyncio.Protocol):
             version = self.request.version if self.request else '1.1'
             self.transport.write(response.output(version))
         except RuntimeError:
-            logger.error('Connection lost before error written @ %s',
-                         self.request.ip if self.request else 'Unknown')
+            if self._debug:
+                logger.error('Connection lost before error written @ %s',
+                             self.request.ip if self.request else 'Unknown')
         except Exception as e:
             self.bail_out(
                 "Writing error failed, connection closed {}".format(

From 64edf7ad9c539fc05e70fd8b09f1c485a53472aa Mon Sep 17 00:00:00 2001
From: Maks Skorokhod <samael500@gmail.com>
Date: Mon, 9 Oct 2017 15:50:57 +0300
Subject: [PATCH 2/3] :white_check_mark: upd test for connection lost error

---
 tests/test_logging.py | 38 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/tests/test_logging.py b/tests/test_logging.py
index 112c94a0..4580d6b6 100644
--- a/tests/test_logging.py
+++ b/tests/test_logging.py
@@ -1,11 +1,17 @@
 import uuid
+import logging
+
+from io import StringIO
 from importlib import reload
 
+import pytest
+from unittest.mock import Mock
+
+import sanic
 from sanic.response import text
 from sanic.log import LOGGING_CONFIG_DEFAULTS
 from sanic import Sanic
-from io import StringIO
-import logging
+
 
 logging_format = '''module: %(module)s; \
 function: %(funcName)s(); \
@@ -71,3 +77,31 @@ def test_logging_pass_customer_logconfig():
 
     for fmt in [h.formatter for h in logging.getLogger('sanic.access').handlers]:
         assert fmt._fmt == modified_config['formatters']['access']['format']
+
+
+@pytest.mark.parametrize('debug', (True, False, ))
+def test_log_connection_lost(debug, monkeypatch):
+    """ Should not log Connection lost exception on non debug """
+    app = Sanic('connection_lost')
+    stream = StringIO()
+    root = logging.getLogger('root')
+    root.addHandler(logging.StreamHandler(stream))
+    monkeypatch.setattr(sanic.server, 'logger', root)
+
+    @app.route('/conn_lost')
+    async def conn_lost(request):
+        response = text('Ok')
+        response.output = Mock(side_effect=RuntimeError)
+        return response
+
+    with pytest.raises(ValueError):
+        # catch ValueError: Exception during request
+        app.test_client.get('/conn_lost', debug=debug)
+
+    log = stream.getvalue()
+
+    if debug:
+        assert log.startswith(
+            'Connection lost before response written @')
+    else:
+        'Connection lost before response written @' not in log

From 4d515b05f3d8e7d3f3074b2f85146a34dc4d875d Mon Sep 17 00:00:00 2001
From: Maks Skorokhod <samael500@gmail.com>
Date: Mon, 9 Oct 2017 17:18:04 +0300
Subject: [PATCH 3/3] :white_check_mark: fix missed assertion

---
 tests/test_logging.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/test_logging.py b/tests/test_logging.py
index 4580d6b6..e95b7ce5 100644
--- a/tests/test_logging.py
+++ b/tests/test_logging.py
@@ -104,4 +104,4 @@ def test_log_connection_lost(debug, monkeypatch):
         assert log.startswith(
             'Connection lost before response written @')
     else:
-        'Connection lost before response written @' not in log
+        assert 'Connection lost before response written @' not in log