Removing flake in TemporaryHTTPServer.

tools/chrome_remote_control/chrome_remote_control/cros_browser_backend.py

Index: tools/chrome_remote_control/chrome_remote_control/cros_browser_backend.py
diff --git a/tools/chrome_remote_control/chrome_remote_control/cros_browser_backend.py b/tools/chrome_remote_control/chrome_remote_control/cros_browser_backend.py
index 109f4c51e41c32d55afb7fd59d079d0ccbe706f9..2c6438f1b27a2f03db0d8305bed81596ce389264 100644
--- a/tools/chrome_remote_control/chrome_remote_control/cros_browser_backend.py
+++ b/tools/chrome_remote_control/chrome_remote_control/cros_browser_backend.py
@@ -4,10 +4,10 @@
 import logging
 import socket
 import subprocess
-import time
 
 from chrome_remote_control import browser_backend
 from chrome_remote_control import cros_interface
+from chrome_remote_control import util
 
 class CrOSBrowserBackend(browser_backend.BrowserBackend):
   """The backend for controlling a browser instance running on CrOS.
@@ -143,33 +143,54 @@ class CrOSBrowserBackend(browser_backend.BrowserBackend):
       return False
     return self._proc.IsAlive()
 
-  def CreateForwarder(self, host_port):
+  def CreateForwarder(self, host_port, remote_port=None):
     assert self._cri
     return SSHReverseForwarder(self._cri,
-                               host_port)
+                               host_port,
+                               remote_port)
 
 class SSHReverseForwarder(object):
-  def __init__(self, cri, host_port):
+  def __init__(self, cri, host_port, remote_port=None):
     self._proc = None
     self._host_port = host_port
+    if remote_port is None:
+      self._remote_port = cri.GetRemotePort()
+    else:
+      self._remote_port = remote_port
 
     self._proc = subprocess.Popen(
       cri.FormSSHCommandLine(['sleep', '99999999999'],
                              ['-R%i:localhost:%i' %
-                              (host_port, host_port)]),
+                              (self._remote_port, host_port)]),
       stdout=subprocess.PIPE,
       stderr=subprocess.PIPE,
       stdin=subprocess.PIPE,
       shell=False)
 
-    # TODO(nduca): How do we wait for the server to come up in a
-    # robust way?
-    time.sleep(1.5)
+    # IsServerUp runs python code on the remote machine which attempts to
+    # connect to the given address and port.
+    def IsServerUp(address, port):
+      pycmd = """import socket
+try:

[nduca, 2012/11/06 04:28:01]

ssh to the target and run wget with some args. It'll fail if the server isn't
up.

[hartmanng, 2012/11/19 18:49:13]

Done.

+  tmp = socket.socket()

[nduca, 2012/11/06 04:28:01]

There should be a cros-interface method here... IsHTTPServerRunningOnPort or
something. IsServerUp should just call that.

And, unit test! :)

[hartmanng, 2012/11/19 18:49:13]

Done.

+  tmp.connect(('%s', %i))
+  tmp.close()
+  print True
+except:
+  print False""" % (address, port)
+
+      response = cri.RunRemotePython(pycmd)[0].strip()
+      return response == 'True'
+
+    # We wait on IsServerUp using the address and port of the forwarder we just
+    # set up, so when it succeeds we can be confident that it's fully ready on
+    # the remote end.
+    util.WaitFor(lambda: IsServerUp('localhost', self._remote_port), 60)
 
   @property
   def url(self):
     assert self._proc
-    return 'http://localhost:%i' % self._host_port
+    return 'http://localhost:%i' % self._remote_port
 
   def Close(self):
     if self._proc: