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 _TRACING_ON_PATH = '/sys/kernel/debug/tracing/tracing_on'
  25
  26
  27 class SystraceController(controllers.BaseController):
  28   def __init__(self, device, categories, ring_buffer):
  29     controllers.BaseController.__init__(self)
  30     self._device = device
  31     self._categories = categories
  32     self._ring_buffer = ring_buffer
  33     self._done = threading.Event()
  34     self._thread = None
  35     self._trace_data = None
  36
  37   def __repr__(self):
  38     return 'systrace'
  39
  40   @staticmethod
  41   def GetCategories(device):
  42     return device.RunShellCommand('atrace --list_categories')
  43
  44   def StartTracing(self, _):
  45     self._thread = threading.Thread(target=self._CollectData)
  46     self._thread.start()
  47
  48   def StopTracing(self):
  49     self._done.set()
  50
  51   def PullTrace(self):
  52     self._thread.join()
  53     self._thread = None
  54     if self._trace_data:
  55       output_name = 'systrace-%s' % util.GetTraceTimestamp()
  56       with open(output_name, 'w') as out:
  57         out.write(self._trace_data)
  58       return output_name
  59
  60   def IsTracingOn(self):
  61     result = self._RunAdbShellCommand(['cat', _TRACING_ON_PATH])
  62     return result.strip() == '1'
  63
  64   def _RunAdbShellCommand(self, command):
  65     # We use a separate interface to adb because the one from AndroidCommands
  66     # isn't re-entrant.
  67     # TODO(jbudorick) Look at providing a way to unhandroll this once the
  68     #                 adb rewrite has fully landed.
  69     device_param = (['-s', str(self._device)] if str(self._device) else [])
  70     cmd = ['adb'] + device_param + ['shell'] + command
  71     return cmd_helper.GetCmdOutput(cmd)
  72
  73   def _RunATraceCommand(self, command):
  74     cmd = ['atrace', '--%s' % command] + _SYSTRACE_OPTIONS + self._categories
  75     return self._RunAdbShellCommand(cmd)
  76
  77   def _ForceStopAtrace(self):
  78     # atrace on pre-M Android devices cannot be stopped asynchronously
  79     # correctly. Use synchronous mode to force stop.
  80     cmd = ['atrace', '-t', '0']
  81     return self._RunAdbShellCommand(cmd)
  82
  83   def _CollectData(self):
  84     trace_data = []
  85     self._RunATraceCommand('async_start')
  86     try:
  87       while not self._done.is_set():
  88         self._done.wait(_SYSTRACE_INTERVAL)
  89         if not self._ring_buffer or self._done.is_set():
  90           trace_data.append(
  91               self._DecodeTraceData(self._RunATraceCommand('async_dump')))
  92     finally:
  93       trace_data.append(
  94           self._DecodeTraceData(self._RunATraceCommand('async_stop')))
  95       if self.IsTracingOn():
  96         self._ForceStopAtrace()
  97     self._trace_data = ''.join([zlib.decompress(d) for d in trace_data])
  98
  99   @staticmethod
 100   def _DecodeTraceData(trace_data):
 101     try:
 102       trace_start = trace_data.index('TRACE:')
 103     except ValueError:
 104       raise RuntimeError('Systrace start marker not found')
 105     trace_data = trace_data[trace_start + 6:]
 106
 107     # Collapse CRLFs that are added by adb shell.
 108     if trace_data.startswith('\r\n'):
 109       trace_data = trace_data.replace('\r\n', '\n')
 110
 111     # Skip the initial newline.
 112     return trace_data[1:]