Implementing a Monsoon power monitor trace agent, utilizing the UI infrastructure that the BattOr a…

systrace/systrace/tracing_controller.py

 #!/usr/bin/env python
 
 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 '''Tracing controller class. This class manages
 multiple tracing agents and collects data from all of them. It also
 manages the clock sync process.
 '''
 
 import ast
 import json
 import sys
 import py_utils
 import tempfile
 import uuid
 
 from systrace import trace_result
 from systrace import tracing_agents
+from systrace.tracing_agents import monsoon_agent
 from py_trace_event import trace_event
 
 
 TRACE_DATA_CONTROLLER_NAME = 'systraceController'
 
 
 def ControllerAgentClockSync(issue_ts, name):
   """Record the clock sync marker for controller tracing agent.
 
   Unlike with the other tracing agents, the tracing controller should not
@@ skipping 79 matching lines @@
 
     Args:
        agents_with_config: List of tracing agents for this controller with the
                            corresponding tracing configuration objects.
        controller_config:  Configuration options for the tracing controller.
     """
     self._child_agents = None
     self._child_agents_with_config = agents_with_config
     self._controller_agent = TracingControllerAgent()
     self._controller_config = controller_config
+    self._monsoon_agent = None
     self._trace_in_progress = False
     self.all_results = None
 
+    # If we have a monsoon power monitor controller in the group, make an

[Chris Craik, 2017/09/19 18:47:02]

I'm not especially happy with this, but I don't have other ideas. Zhen,
thoughts? May be nice to abstract this to a "connectionOwnerAgent" or something
like that, instead of hard coding this as a monsoon agent, then have only
monsoon return 'true' from an isConnectionOwner method.

Zhen, do we know if there are other agents that expect to use USB while tracing?

Alternately, we could consider another 'lifecycle' callback that happens after
all the starts, and before all the stops, and monsoon could put its code there.

[Zhen Wang, 2017/09/19 23:53:50]

I see --usbpassthrough is set to off for monsoon. Looks like it also affects
other agents?

For systrace and adb_profile_chrome, I think agents do not need to use USB while
tracing. For Telemetry, it will need USB, but that has separate controlling
logic. So it should be fine.

Another lifecycle callback may not work well. It seems that the sequence is:
1. start tracing for other agents
2. disable usb
3. start tracing for monsoon
So it seems that monsoon's start cannot be grouped into step 1. 

ConnectionOwnerAgent is probably the only way, so it will always start last and
stop first.

+    # explicit reference to it.  We need to collect data from it before any
+    # other collectors as it re-enables USB for the subsequent collectors to
+    # collect their data.
+    # In addition, move this agent to the end of the list so it is the last
+    # to start (it disables USB).
+    monsoon_agent_with_config = None
+    sorted_agents_with_config = []
+    for agent_with_config in self._child_agents_with_config:
+      if isinstance(agent_with_config.agent, monsoon_agent.MonsoonTracingAgent):
+        monsoon_agent_with_config = agent_with_config
+      else:
+        sorted_agents_with_config.append(agent_with_config)
+    if monsoon_agent_with_config:
+      sorted_agents_with_config.append(monsoon_agent_with_config)
+      self._monsoon_agent = monsoon_agent_with_config.agent
+    self._child_agents_with_config = sorted_agents_with_config
+
   @property
   def get_child_agents(self):
     return self._child_agents
 
   def StartTracing(self):
     """Start tracing for all tracing agents.
 
     This function starts tracing for both the controller tracing agent
     and the child tracing agents.
 
@@ skipping 23 matching lines @@
         succ_agents.append(agent)
       else:
         print 'Agent %s not started.' % str(agent)
 
     # Print warning if all agents not started.
     na = len(self._child_agents_with_config)
     ns = len(succ_agents)
     if ns < na:
       print 'Warning: Only %d of %d tracing agents started.' % (ns, na)
     self._child_agents = succ_agents
+
     return True
 
   def StopTracing(self):
     """Issue clock sync marker and stop tracing for all tracing agents.
 
     This function stops both the controller tracing agent
     and the child tracing agents. It issues a clock sync marker prior
     to stopping tracing.
 
     Returns:
         Boolean indicating whether or not the stop tracing succeeded
         for all agents.
     """
     assert self._trace_in_progress, 'No trace in progress.'
     self._trace_in_progress = False
 
+    # Explicity stop Monsoon tracing first, as it re-enables USB.
+    if self._monsoon_agent:
+      sync_id = GetUniqueSyncID()
+      if not self._monsoon_agent.StopCollectionWithClockSync(sync_id,
+        ControllerAgentClockSync):
+        print 'Monsoon agent failed to stop collection.'
+
     # Issue the clock sync marker and stop the child tracing agents.
     self._IssueClockSyncMarker()
     succ_agents = []
     for agent in self._child_agents:
       if agent.StopAgentTracing(timeout=self._controller_config.timeout):
         succ_agents.append(agent)
       else:
         print 'Agent %s not stopped.' % str(agent)
 
     # Stop the controller tracing agent. Controller tracing agent
@@ skipping 105 matching lines @@
   return TracingControllerConfig(options.output_file, options.trace_time,
                                  options.write_json,
                                  options.link_assets, options.asset_dir,
                                  options.timeout, options.collection_timeout,
                                  options.device_serial_number, options.target)
 
 def GetChromeStartupControllerConfig(options):
   return TracingControllerConfig(None, options.trace_time,
                                  options.write_json, None, None, None, None,
                                  None, None)