tools/profile_chrome/systrace_controller.py

   1 # Copyright 2014 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import threading
   6 import zlib
   7
   8 from profile_chrome import controllers
   9 from profile_chrome import util
  10
  11 from pylib import cmd_helper
  12
  13
  14 _SYSTRACE_OPTIONS = [
  15     # Compress the trace before sending it over USB.
  16     '-z',
  17     # Use a large trace buffer to increase the polling interval.
  18     '-b', '16384'
  19 ]
  20
  21 # Interval in seconds for sampling systrace data.
  22 _SYSTRACE_INTERVAL = 15
  23
  24
  25 class SystraceController(controllers.BaseController):
  26   def __init__(self, device, categories, ring_buffer):
  27     controllers.BaseController.__init__(self)
  28     self._device = device
  29     self._categories = categories
  30     self._ring_buffer = ring_buffer
  31     self._done = threading.Event()
  32     self._thread = None
  33     self._trace_data = None
  34
  35   def __repr__(self):
  36     return 'systrace'
  37
  38   @staticmethod
  39   def GetCategories(device):
  40     return device.RunShellCommand('atrace --list_categories')
  41
  42   def StartTracing(self, _):
  43     self._thread = threading.Thread(target=self._CollectData)
  44     self._thread.start()
  45
  46   def StopTracing(self):
  47     self._done.set()
  48
  49   def PullTrace(self):
  50     self._thread.join()
  51     self._thread = None
  52     if self._trace_data:
  53       output_name = 'systrace-%s' % util.GetTraceTimestamp()
  54       with open(output_name, 'w') as out:
  55         out.write(self._trace_data)
  56       return output_name
  57
  58   def _RunATraceCommand(self, command):
  59     # We use a separate interface to adb because the one from AndroidCommands
  60     # isn't re-entrant.
  61     # TODO(jbudorick) Look at providing a way to unhandroll this once the
  62     #                 adb rewrite has fully landed.
  63     device_param = (['-s', str(self._device)] if str(self._device) else [])
  64     cmd = ['adb'] + device_param + ['shell', 'atrace', '--%s' % command] + \
  65         _SYSTRACE_OPTIONS + self._categories
  66     return cmd_helper.GetCmdOutput(cmd)
  67
  68   def _CollectData(self):
  69     trace_data = []
  70     self._RunATraceCommand('async_start')
  71     try:
  72       while not self._done.is_set():
  73         self._done.wait(_SYSTRACE_INTERVAL)
  74         if not self._ring_buffer or self._done.is_set():
  75           trace_data.append(
  76               self._DecodeTraceData(self._RunATraceCommand('async_dump')))
  77     finally:
  78       trace_data.append(
  79           self._DecodeTraceData(self._RunATraceCommand('async_stop')))
  80     self._trace_data = ''.join([zlib.decompress(d) for d in trace_data])
  81
  82   @staticmethod
  83   def _DecodeTraceData(trace_data):
  84     try:
  85       trace_start = trace_data.index('TRACE:')
  86     except ValueError:
  87       raise RuntimeError('Systrace start marker not found')
  88     trace_data = trace_data[trace_start + 6:]
  89
  90     # Collapse CRLFs that are added by adb shell.
  91     if trace_data.startswith('\r\n'):
  92       trace_data = trace_data.replace('\r\n', '\n')
  93
  94     # Skip the initial newline.
  95     return trace_data[1:]