telemetry: Handle errno.EAGAIN in inspector_websocket.py

BUG=545853

Review URL: https://codereview.chromium.org/1413573005

Cr-Commit-Position: refs/heads/master@{#355437}

2 files changed, 35 insertions, 1 deletions

diff --git a/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket.py b/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket.py
index 7eaaaea..a1fee26 100644
--- a/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket.py
+++ b/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket.py
@@ -2,8 +2,11 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import errno
 import json
 import logging
+import socket
+import time
 
 from telemetry.core import exceptions
 from telemetry.internal.backends.chrome_inspector import websocket
@@ -140,7 +143,21 @@ class InspectorWebsocket(object):
       raise WebSocketDisconnected()
 
     self._SetTimeout(timeout)
-    data = self._socket.recv()
+
+    keep_trying = True
+    while keep_trying:
+      try:
+        data = self._socket.recv()
+        keep_trying = False
+      except socket.error, e:
+        if e.errno == errno.EAGAIN:
+          # Resource is temporarily unavailable. Try again.
+          # See https://code.google.com/p/chromium/issues/detail?id=545853#c3
+          # for more details.
+          time.sleep(0.1)
+          continue
+        keep_trying = False
+
     result = json.loads(data)
     if logging.getLogger().isEnabledFor(logging.DEBUG):
       logging.debug(
diff --git a/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket_unittest.py b/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket_unittest.py
index 1bffb77..6db8893 100644
--- a/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket_unittest.py
+++ b/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket_unittest.py
@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import errno
+import socket
 import unittest
 
 from telemetry import decorators
@@ -37,6 +39,8 @@ class FakeSocket(object):
       raise websocket.WebSocketTimeoutException()
 
     self._mock_timer.SetTime(time)
+    if isinstance(response, Exception):
+      raise response
     return response
 
   def settimeout(self, timeout):
@@ -155,3 +159,16 @@ class InspectorWebsocketUnittest(unittest.TestCase):
     fake_socket.AddResponse('{"id": 6666666, "result": {}}', 1)
     inspector.DispatchNotifications()
     self.assertEqual(2, response_count[0])
+
+  def testEAGAIN(self):
+    inspector = inspector_websocket.InspectorWebsocket()
+    fake_socket = FakeSocket(self._mock_timer)
+    # pylint: disable=protected-access
+    inspector._socket = fake_socket
+
+    error = socket.error(errno.EAGAIN, "error string")
+    fake_socket.AddResponse(error, 4)
+    fake_socket.AddResponse('{"asdf": "qwer"}', 5)
+
+    result = inspector._Receive()
+    self.assertEqual(result, {"asdf" : "qwer"})