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

common/monsoon/monsoon/monsoon_wrapper.py

Index: common/monsoon/monsoon/monsoon_wrapper.py
diff --git a/common/monsoon/monsoon/monsoon_wrapper.py b/common/monsoon/monsoon/monsoon_wrapper.py
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index 0000000000000000000000000000000000000000..dbbc76aa429c38147dab5cda8125222170f99b63
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+++ b/common/monsoon/monsoon/monsoon_wrapper.py
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+# Copyright 2017 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.
+
+import atexit
+import py_utils
+import re
+import subprocess
+import tempfile
+
+USB_PASSTHROUGH_OFF = "off"
+USB_PASSTHROUGH_ON = "on"
+USB_PASSTHROUGH_AUTO = "auto"
+
+UsbModes = [USB_PASSTHROUGH_OFF, USB_PASSTHROUGH_ON, USB_PASSTHROUGH_AUTO]
+
+class MonsoonWrapper(object):
+  def __init__(self, script):
+    self.script = script
+    self._process = None
+    # Register atexit handler to kill any monsoon processes in the case of
+    # abnormal program termination.
+    atexit.register(self.TerminateMonsoonProcess)
+
+  def ReadStatusProperties(self):
+    """ Reads status properties from Monsoon, returning a dictionary of
+    properties.
+    """
+    status_text = self.ExecuteBlocking(["--status"])
+    status = {}
+    for status_line in status_text:
+      # Sometimes transient USB serial errors are reported.  Just ignore them
+      # and only use strings with : in them.
+      if ":" in status_line:
+        key, value = status_line.split(':')
+        status[key] = value
+    return status
+
+  def EnableUSB(self):
+    """ Shorthand for SetUSBMode(USB_PASSTHROUGH_ON) """
+    self.SetUSBMode(USB_PASSTHROUGH_ON)
+
+  def DisableUSB(self):
+    """ Shorthand for SetUSBMode(USB_PASSTHROUGH_OFF) """
+    self.SetUSBMode(USB_PASSTHROUGH_OFF)
+
+  def SetUSBMode(self, mode):
+    """ Set the Monsoon USB mode.
+    """
+    if mode not in UsbModes: raise Exception("Invalid USB mode " + mode)
+    # Sometimes Monsoon fails to make USB passthrough mode changes
+    # permanent if there are transient USB serial errors.
+    retry_count = 5
+    while self.GetUSBMode() is not mode:
+      self.ExecuteBlocking(["--usbpassthrough", mode])
+      if retry_count is 0: Exception("Failed to set USB mode!")
+      retry_count -= 1
+
+  def GetUSBMode(self):
+    """ Retrieves the current Monsoon USB mode, returning USB_PASSTHROUGH_OFF
+    if the status could not be retrieved.
+    """
+    properties = self.ReadStatusProperties()
+    if "usbPassthroughMode" in properties:
+      return UsbModes[int(properties["usbPassthroughMode"])]
+    return USB_PASSTHROUGH_OFF
+
+  def ReadPower(self, time, frequency):
+    """ Reads power from the Monsoon device over a specified perdiod while
+    blocking, returning a file containing raw monsoon data. """
+    sample_count = time * frequency
+    args = ["--samples", str(sample_count), "--hz", str(frequency),
+      "--timestamp"]
+    return self.ExecuteBlocking(args)
+
+  def ExecuteBlocking(self, args):
+    """ Executes a blocking operation on the Monsoon device, returning a file
+    containing stdout output. """
+    if self.IsProcessRunning():
+      raise Exception("Monsoon subprocess already running!")
+    result_file = tempfile.TemporaryFile()
+    subprocess.check_call([self.script] + args, stdout=result_file)
+    result_file.seek(0)
+    return result_file
+
+  def BeginReadPower(self, frequency, out=subprocess.PIPE):
+    """ Begins a non-blocking read of power from the Monsoon device, returning
+    the stdout file of the subprocess.
+    """
+    args = ["--samples", "-1", "--hz", str(frequency), "--timestamp"]
+    return self.BeginExecution(args=args, out=out)
+
+  def BeginExecution(self, args = [], out=subprocess.PIPE):
+    """ Begins a non-blocking operation on the Monsoon device, returning the
+    stdout file of the subprocess.
+    """
+    if self.IsProcessRunning():
+      raise Exception("Monsoon subprocess already running!")
+    self._process = subprocess.Popen([self.script] + args, stdout=out)
+    return self._process.stdout
+
+  def EndExecution(self):
+    """ Ends non-blocking execution of the Monsoon subprocess, returning the
+    stdout file of the subprocess. """
+    if self._process is None or self._process.poll() is not None:
+      raise Exception("Monsoon subprocess not running when going to end "
+        + "execution.")
+    self._process.terminate()
+    self._process.wait()
+    result_file = self._process.stdout
+    self._process = None
+    self._result_file = None
+    return result_file
+
+  def IsProcessRunning(self):
+    """ Returns whether or not the Monsoon subprocess is running.
+    """
+    return self._process is not None and self._process.poll() is None
+
+  def TerminateMonsoonProcess(self):
+    """ Terminates the Monsoon subprocess if it is running.
+    """
+    if self._process is not None and self._process.poll() is None:
+      self._process.kill()