Make host port availability detection more robust.

build/android/pylib/ports.py

Index: build/android/pylib/ports.py
diff --git a/build/android/pylib/ports.py b/build/android/pylib/ports.py
index 34efb5253c425b807f3549eec12707f653c4e744..20165217a8a8e0e599c57094009bf4414b027104 100644
--- a/build/android/pylib/ports.py
+++ b/build/android/pylib/ports.py
@@ -9,11 +9,9 @@ import fcntl
 import httplib
 import logging
 import os
-import re
 import socket
 import traceback
 
-from pylib import cmd_helper
 from pylib import constants
 
 
@@ -57,7 +55,7 @@ def AllocateTestServerPort():
     with open(constants.TEST_SERVER_PORT_FILE, 'r+') as fp:
       port = int(fp.read())
       ports_tried.append(port)
-      while IsHostPortUsed(port):
+      while not IsHostPortAvailable(port):
         port += 1
         ports_tried.append(port)
       if (port > constants.TEST_SERVER_PORT_LAST or
@@ -67,7 +65,7 @@ def AllocateTestServerPort():
         fp.seek(0, os.SEEK_SET)
         fp.write('%d' % (port + 1))
   except Exception as e:
-    logging.info(e)
+    logging.error(e)
   finally:
     if fp_lock:
       fcntl.flock(fp_lock, fcntl.LOCK_UN)
@@ -80,25 +78,21 @@ def AllocateTestServerPort():
   return port
 
 
-def IsHostPortUsed(host_port):
-  """Checks whether the specified host port is used or not.
-
-  Uses -n -P to inhibit the conversion of host/port numbers to host/port names.
+def IsHostPortAvailable(host_port):
+  """Checks whether the specified host port is available.
 
   Args:
-    host_port: Port on host we want to check.
+    host_port: Port on host to check.
 
   Returns:
-    True if the port on host is already used, otherwise returns False.
+    True if the port on host is available, otherwise returns False.
   """
-  port_info = '(\*)|(127\.0\.0\.1)|(localhost):%d' % host_port
-  # TODO(jnd): Find a better way to filter the port. Note that connecting to the
-  # socket and closing it would leave it in the TIME_WAIT state. Setting
-  # SO_LINGER on it and then closing it makes the Python HTTP server crash.
-  re_port = re.compile(port_info, re.MULTILINE)
-  if re_port.search(cmd_helper.GetCmdOutput(['lsof', '-nPi:%d' % host_port])):
+  s = socket.socket()
+  try:
+    s.bind(('', host_port))

[jbudorick, 2014/10/07 08:37:09]

nit: I'd rather we explicitly close the socket if we don't throw an exception
here instead of waiting for GC to take care of it, especially since we'll be
using the port.

     return True
-  return False
+  except socket.error:
+    return False
 
 
 def IsDevicePortUsed(device, device_port, state=''):