adding a flow-tester python script to help test the flow subsystem

Change-Id: I4477df897f8f5ea55e7ae992cf8e096e92db05bd

+import concurrent.futures
+import requests, json
+from optparse import OptionParser
+
+def run(url, request):
+    data = json.dumps(request)
+    r = requests.post(url, data)
+    return r
+
+def runTasks(flowPerDevice, neighbours, url, servers, doJson):
+    # We can use a with statement to ensure threads are cleaned up promptly
+    with concurrent.futures.ThreadPoolExecutor(max_workers=2) as executor:
+        # Start the load operations and mark each future with its URL
+        request = { "flowsPerDevice" : flowPerDevice, "neighbours" : neighbours }
+        future_to_url = {executor.submit(run, url % (server), request) for server in servers}
+        for f in concurrent.futures.as_completed(future_to_url):
+            try:
+                response = f.result()
+                server = response.url.split('//')[1].split(':')[0]
+                if (doJson):
+                    print (json.dumps({ "server" : server, "elapsed" : response.json()['elapsed'] }))
+                else:
+                    print ("%s -> %sms" % (server, response.json()['elapsed']))
+            except Exception as exc:
+                print("Execution failed -> %s" % exc)
+
+if __name__ == "__main__":
+    parser = OptionParser()
+    parser.add_option("-u", "--url", dest="url", help="set the url for the request",
+                            default="http://%s:8181/onos/demo/intents/flowTest")
+    parser.add_option("-f", "--flows", dest="flows", help="Number of flows to install per device",
+                            default=100, type="int")
+    parser.add_option("-n", "--neighbours", dest="neighs", help="Number of neighbours to communicate to",
+                            default=0, type="int")
+    parser.add_option("-s", "--servers", dest="servers", help="List of servers to hit",
+                            default=[], action="append")
+    parser.add_option("-j", "--json", dest="doJson", help="Print results in json",
+                            default=False, action="store_true")
+
+    (options, args) = parser.parse_args()
+    if (len(options.servers) == 0):
+        options.servers.append("localhost")
+    runTasks(options.flows, options.neighs, options.url, options.servers, options.doJson)