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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.
4from telemetry.core.platform.profiler import profiler_finder
5
6
7class ProfilingControllerBackend(object):
8  def __init__(self, platform_backend):
9    self._platform_backend = platform_backend
10    self._active_profilers = []
11    self._profilers_states = {}
12
13  def Start(self, profiler_name, base_output_file):
14    """Starts profiling using |profiler_name|. Results are saved to
15    |base_output_file|.<process_name>."""
16    assert not self._active_profilers, 'Already profiling. Must stop first.'
17
18    browser_backend = None
19    # Note that many profilers doesn't rely on browser_backends, so the number
20    # of running_browser_backends may not matter for them.
21    if len(self._platform_backend.running_browser_backends) == 1:
22      browser_backend = self._platform_backend.running_browser_backends[0]
23    else:
24      raise NotImplementedError()
25
26    profiler_class = profiler_finder.FindProfiler(profiler_name)
27
28    if not profiler_class.is_supported(browser_backend.browser_type):
29      raise Exception('The %s profiler is not '
30                      'supported on this platform.' % profiler_name)
31
32    if not profiler_class in self._profilers_states:
33      self._profilers_states[profiler_class] = {}
34
35    self._active_profilers.append(
36        profiler_class(browser_backend, self._platform_backend,
37            base_output_file, self._profilers_states[profiler_class]))
38
39  def Stop(self):
40    """Stops all active profilers and saves their results.
41
42    Returns:
43      A list of filenames produced by the profiler.
44    """
45    output_files = []
46    for profiler in self._active_profilers:
47      output_files.extend(profiler.CollectProfile())
48    self._active_profilers = []
49    return output_files
50
51  def WillCloseBrowser(self, browser_backend):
52    for profiler_class in self._profilers_states:
53      profiler_class.WillCloseBrowser(browser_backend, self._platform_backend)
54