Allow the testenv client to dictate the worker timeout

The testenv client is privileged to information about jobs that the
worker is not aware of, so allow the client to send us the appropriate
timeout.

This also changes the format of the the data sent to us from the client
to a json representation of a python dict.

Change-Id: If3f082c04d937f0d5baa09cf002aef797eebcbe5

elements/testenv-worker/testenv-worker

@@ -19,6 +19,7 @@
 #
 
 import argparse
+import json
 import logging
 import sys
 import threading
@@ -92,11 +93,12 @@ def run_callback(geard, timeout, callback_name, te_data):
                          "assuming its no longer present")
             return
 
-    # The job has started, give it time to complete, adding a timeout here
-    # assumes the test environment is now safe for reuse, so this timeout
-    # MUST be longer then the timeout on client nodes to avoid two client
-    # nodes simultaneously using the same test environment
-    client.wait(timeout)
+    # We timeout after the configured timeout - the 40 second sleep that we
+    # perform during initial handshaking. Note that after this timeout we offer
+    # the environment for other test clients, but the prior client's
+    # credentials are still valid, so very confusing errors can occur if we
+    # were ever to timeout without the client timing out first.
+    client.wait(timeout - 40)
     if cb_job.failure:
         logger.error("The Job appears to have failed")
     elif not cb_job.complete:
@@ -114,10 +116,18 @@ def run_teworker(geard, num, timeout, te_data):
     while True:
         job = worker.getJob()
         logger.info('Received job : %s', job.arguments)
+        if job.arguments.startswith("{"):
+            arguments = json.loads(job.arguments)
+            call_back = arguments["callback_name"]
+            job_timeout = int(arguments.get("timeout", timeout))
+        else:
+            # legacy support, for clients that just send the callback name
+            call_back = job.arguments
+            job_timeout = timeout
 
         # Once this Job is called we call back to the client to run its
         # commands while this environment is locked
-        run_callback(geard, timeout, job.arguments, te_data)
+        run_callback(geard, job_timeout, call_back, te_data)
 
         job.sendWorkComplete("")
 
@@ -133,7 +143,7 @@ def main(args=sys.argv[1:]):
                         help='Path to the data to provided to the client')
     parser.add_argument('--timeout', '-t', type=int, default=10800,
                         help='The maximum number of seconds to hold the '
-                             'testenv for.')
+                             'testenv for, can be overridden by the client.')
     parser.add_argument('--tenum', '-n', default=uuid.uuid4().hex,
                         help='A unique identifier identifing this env on '
                              'this host.')