adb_profile_chrome: Refactor into multiple modules and add tests

build/android/chrome_profiler/systrace_controller.py

+# Copyright 2014 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 threading
+import zlib
+
+from chrome_profiler import controllers
+from chrome_profiler import util
+
+from pylib import cmd_helper
+
+
+_SYSTRACE_OPTIONS = [
+    # Compress the trace before sending it over USB.
+    '-z',
+    # Use a large trace buffer to increase the polling interval.
+    '-b', '16384'
+]
+
+# Interval in seconds for sampling systrace data.
+_SYSTRACE_INTERVAL = 15
+
+
+class SystraceController(controllers.BaseController):
+  def __init__(self, device, categories, ring_buffer):
+    controllers.BaseController.__init__(self)
+    self._device = device
+    self._categories = categories
+    self._ring_buffer = ring_buffer
+    self._done = threading.Event()
+    self._thread = None
+    self._trace_data = None
+
+  def __repr__(self):
+    return 'systrace'
+
+  @staticmethod
+  def GetCategories(device):
+    return device.old_interface.RunShellCommand('atrace --list_categories')
+
+  def StartTracing(self, _):
+    self._thread = threading.Thread(target=self._CollectData)
+    self._thread.start()
+
+  def StopTracing(self):
+    self._done.set()
+
+  def PullTrace(self):
+    self._thread.join()
+    self._thread = None
+    if self._trace_data:
+      output_name = 'systrace-%s' % util.GetTraceTimestamp()
+      with open(output_name, 'w') as out:
+        out.write(self._trace_data)
+      return output_name
+
+  def _RunATraceCommand(self, command):
+    # TODO(jbudorick) can this be made work with DeviceUtils?
+    # We use a separate interface to adb because the one from AndroidCommands
+    # isn't re-entrant.
+    device_param = (['-s', self._device.old_interface.GetDevice()]
+                    if self._device.old_interface.GetDevice() else [])
+    cmd = ['adb'] + device_param + ['shell', 'atrace', '--%s' % command] + \
+        _SYSTRACE_OPTIONS + self._categories
+    return cmd_helper.GetCmdOutput(cmd)
+
+  def _CollectData(self):
+    trace_data = []
+    self._RunATraceCommand('async_start')
+    try:
+      while not self._done.is_set():
+        self._done.wait(_SYSTRACE_INTERVAL)
+        if not self._ring_buffer or self._done.is_set():
+          trace_data.append(
+              self._DecodeTraceData(self._RunATraceCommand('async_dump')))
+    finally:
+      trace_data.append(
+          self._DecodeTraceData(self._RunATraceCommand('async_stop')))
+    self._trace_data = ''.join([zlib.decompress(d) for d in trace_data])
+
+  @staticmethod
+  def _DecodeTraceData(trace_data):
+    try:
+      trace_start = trace_data.index('TRACE:')
+    except ValueError:
+      raise RuntimeError('Systrace start marker not found')
+    trace_data = trace_data[trace_start + 6:]
+
+    # Collapse CRLFs that are added by adb shell.
+    if trace_data.startswith('\r\n'):
+      trace_data = trace_data.replace('\r\n', '\n')
+
+    # Skip the initial newline.
+    return trace_data[1:]