Allow to set the source IP address in userInfo.user_tuple.

Using the same IP address may produce unrealistic results, thus allow to set
the source IP address (only meaningful when not using SlapOS). Network alias
interfaces must be set up before running the script.

erp5/util/benchmark/examples/userInfo.py

-# Specify user login/password used to run the tests
+# Specify user login/password used to run the tests. Note that there must be
+# the same number of users specified here *and* on the script command-line.
 user_tuple = (('zope', 'zope'),)
+
+# A more complex example setting the source IP address as well, assuming the
+# users and network alias interfaces (not necessary with SlapOS though) have
+# been created beforehand
+#user_tuple = tuple((('zope%d' % i, 'zope', '192.168.168.%d' % (i + 1))
+#                    for i in range(30)))

erp5/util/benchmark/process.py

@@ -34,6 +34,7 @@ import logging
 import signal
 import sys
 import datetime
+import socket
 
 from ..testbrowser.browser import Browser
 
@@ -48,6 +49,12 @@ class BenchmarkProcess(multiprocessing.Process):
     self._nb_users = nb_users
     self._user_index = user_index
     self._base_url, self._erp5_site_id = argument_namespace.url
+
+    try:
+      self._username, self._password, self._source_ip = \
+          argument_namespace.user_tuple[user_index]
+    except ValueError:
+      self._source_ip = None
       self._username, self._password = argument_namespace.user_tuple[user_index]
 
     # Initialized when running the test
@@ -125,6 +132,20 @@ class BenchmarkProcess(multiprocessing.Process):
 
     self._logger = result_instance.logger
 
+    # Set up the source IP address in order to be more realistic (can be given
+    # as the third element in userInfo.user_tuple) by monkey-patching
+    # socket.socket() as mechanize doesn't provide a way to call bind after
+    # creating the new socket and before calling connect()
+    if self._source_ip:
+      _socket = socket.socket
+      def _patched_socket(*args, **kwargs):
+        new_socket = _socket(*args, **kwargs)
+        self._logger.debug("source IP: %s" % self._source_ip)
+        new_socket.bind((self._source_ip, 0))
+        return new_socket
+
+      socket.socket = _patched_socket
+
     # Ensure the data are flushed before exiting, handled by Result class 
     # __exit__ block
     signal.signal(signal.SIGTERM, self.stopGracefully)