[PowerProfiler] Make monsoon profiler work on other platforms - windows & mac, apart from linu…

tools/telemetry/telemetry/core/platform/profiler/monsoon.py

 # Copyright 2013 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.
 
 """Interface for a USB-connected Monsoon power meter.
 
 http://msoon.com/LabEquipment/PowerMonitor/
 Currently Unix-only. Relies on fcntl, /dev, and /tmp.
 """
 
 import collections
 import logging
 import os
 import select
 import struct
 import time
 
 from telemetry.core import util
 
 util.AddDirToPythonPath(util.GetTelemetryDir(), 'third_party', 'pyserial')
 import serial  # pylint: disable=F0401
+import serial.tools.list_ports
 
 
 Power = collections.namedtuple('Power', ['amps', 'volts'])
 
 
 class Monsoon:
   """Provides a simple class to use the power meter.
 
   mon = monsoon.Monsoon()
   mon.SetVoltage(3.7)
@@ skipping 15 matching lines @@
 
     self._coarse_ref = self._fine_ref = self._coarse_zero = self._fine_zero = 0
     self._coarse_scale = self._fine_scale = 0
     self._last_seq = 0
     self._voltage_multiplier = None
 
     if device:
       self.ser = serial.Serial(device, timeout=1)
       return
 
-    while 1:  # Try all /dev/ttyACM* until we find one we can use.
-      for dev in os.listdir('/dev'):
-        if not dev.startswith('ttyACM'):
+    while 1:
+      devices = serial.tools.list_ports.comports()
+      for dev in devices:

[tonyg, 2014/06/09 16:51:56]

This loop'd be a lot more readable as

for port, desc, hwid in serial.tools.list_ports.comports():

+        if not dev[1].lower().startswith('mobile device power monitor'):
           continue
-        tmpname = '/tmp/monsoon.%s.%s' % (os.uname()[0], dev)
+        tmpname = '/tmp/monsoon.%s.%s' % (os.uname()[0], os.path.basename(dev[0]))

[tonyg, 2014/06/09 16:51:57]

nit: please hold line length to 80 cols.

http://google-styleguide.googlecode.com/svn/trunk/pyguide.html#Line_length

         self._tempfile = open(tmpname, 'w')
         try:  # Use a lockfile to ensure exclusive access.
           # Put the import in here to avoid doing it on unsupported platforms.
           import fcntl
           fcntl.lockf(self._tempfile, fcntl.LOCK_EX | fcntl.LOCK_NB)
         except IOError:
           logging.error('device %s is in use', dev)
           continue
 
         try:  # Try to open the device.
-          self.ser = serial.Serial('/dev/%s' % dev, timeout=1)
+          self.ser = serial.Serial(dev[0], timeout=1)
           self.StopDataCollection()  # Just in case.
           self._FlushInput()  # Discard stale input.
           status = self.GetStatus()
         except IOError, e:
           logging.error('error opening device %s: %s', dev, e)
           continue
 
         if not status:
           logging.error('no response from device %s', dev)
         elif serialno and status['serialNumber'] != serialno:
@@ skipping 193 matching lines @@
         logging.error('exception from serial port')
         return None
       elif len(ready_r) > 0:
         flushed += 1
         self.ser.read(1)  # This may cause underlying buffering.
         self.ser.flush()  # Flush the underlying buffer too.
       else:
         break
     if flushed > 0:
       logging.debug('dropped >%d bytes', flushed)