[DO NOT COMMIT] Refactor systrace to support new clock sync design

systrace/systrace/systrace_tracing_controller.py

Index: systrace/systrace/systrace_tracing_controller.py
diff --git a/systrace/systrace/systrace_tracing_controller.py b/systrace/systrace/systrace_tracing_controller.py
new file mode 100644
index 0000000000000000000000000000000000000000..15ca56e4688523696d41925d52b9e952e1c9e987
--- /dev/null
+++ b/systrace/systrace/systrace_tracing_controller.py
@@ -0,0 +1,195 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2016 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.
+
+'''Implementation of tracing controller for systrace. This class creates the
+necessary tracing agents for systrace, runs them, and outputs the results
+as an HTML file.'''
+
+import imp
+import json
+import os
+
+from systrace import tracing_controller
+
+# The default agent directory.
+DEFAULT_AGENT_DIR = 'tracing_agents'
+
+# TODO(alexandermont): Current version of trace viewer does not support
+# the controller tracing agent output. Thus we use this variable to
+# suppress this tracing agent's output. This should be removed once
+# trace viewer is working again.
+OUTPUT_CONTROLLER_TRACE_ = False
+
+
+class SystraceTracingController(tracing_controller.TracingController):
+  def __init__(self, script_dir, options, categories):
+    """Set up the SystraceTracingController.
+
+    Args:
+        script_dir: Directory containing the trace viewer script
+                    (systrace_trace_viewer.html)
+        options: List of command line options.
+        categories: List of trace categories to capture.
+    """
+    # Parse command line arguments and create agents
+    self._script_dir = script_dir
+    self._out_filename = options.output_file
+    agents = CreateAgents(options, categories)
+
+    # Error if no agents are available
+    if not agents:
+      dirs = DEFAULT_AGENT_DIR
+      if options.agent_dirs:
+        dirs += ',' + options.agent_dirs
+      raise RuntimeError('No systrace agent is available'
+                         'in directories |%s|.\n' % dirs)
+
+    # Update trace viewer if necessary
+    try:
+      from systrace import update_systrace_trace_viewer
+    except ImportError:
+      pass
+    else:
+      update_systrace_trace_viewer.update(dest=script_dir)
+
+    super(SystraceTracingController, self).__init__(options,
+                                                    categories,
+                                                    agents)
+
+  def SupportsExplicitClockSync(self):
+    return False
+
+  def RecordClockSyncMarker(self, sync_id, callback):
+    raise NotImplementedError
+
+  def OutputSystraceResults(self, write_json=False):
+    """Output the results of systrace to a file.
+
+    If output is necessary, then write the results of systrace to either (a)
+    a standalone HTML file, or (b) a json file which can be read by the
+    trace viewer.
+
+    Args:
+       write_json: Whether to output to a json file (if false, use HTML file)
+    """
+    print 'Tracing complete, writing results'
+    if write_json:
+      self._WriteTraceJSON(self._all_results)
+    else:
+      self._WriteTraceHTML(self._all_results)
+
+  def _WriteTraceJSON(self, results):
+    """Write the results of systrace as a JSON file.
+
+    Args:
+        results: Results to write.
+    """
+    print 'Writing trace JSON'
+    results['controllerTraceDataKey'] = 'traceEvents'
+    if not OUTPUT_CONTROLLER_TRACE_:
+      results['traceEvents'] = []
+    with open(self._out_filename, 'w') as json_file:
+      json.dump(results, json_file)
+    print '\n    wrote file://%s\n' % os.path.abspath(self._out_filename)
+
+  def _WriteTraceHTML(self, results):
+    """Write the results of systrace to an HTML file.
+
+    Args:
+        results: Results to write.
+    """
+    def _read_asset(src_dir, filename):
+      return open(os.path.join(src_dir, filename)).read()
+
+    # Get the trace viewer code and the prefix and suffix for the HTML.
+    print 'Writing trace HTML'
+    systrace_dir = os.path.abspath(os.path.dirname(__file__))
+    html_prefix = _read_asset(systrace_dir, 'prefix.html')
+    html_suffix = _read_asset(systrace_dir, 'suffix.html')
+    trace_viewer_html = _read_asset(self._script_dir,
+                                    'systrace_trace_viewer.html')
+
+    # Open the file in binary mode to prevent python from changing the
+    # line endings, then write the prefix.
+    html_file = open(self._out_filename, 'wb')
+    html_file.write(html_prefix.replace('{{SYSTRACE_TRACE_VIEWER_HTML}}',
+                                        trace_viewer_html))
+
+    # Write the trace data itself. There is a separate section of the form
+    # <script class="trace-data" type="application/text"> ... </script>
+    # for each tracing agent (including the controller tracing agent).
+    html_file.write('<!-- BEGIN TRACE -->\n')
+    for (name, data) in results.iteritems():
+      if name == 'traceEvents' and not OUTPUT_CONTROLLER_TRACE_:
+        continue
+      html_file.write('  <script class="')
+      html_file.write('trace-data')
+      html_file.write('" type="application/text">\n')
+      html_file.write(convert(data))
+      html_file.write('  </script>\n')
+    html_file.write('<!-- END TRACE -->\n')
+
+    # Write the suffix and finish.
+    html_file.write(html_suffix)
+    html_file.close()
+    print '\n    wrote file://%s\n' % os.path.abspath(self._out_filename)
+
+def convert(data):
+  """Convert a data element to the format to be output into HTML.
+
+  If the data element is a dictionary or list, JSON-encode it.
+  If the data element is a string, leave it unchanged.
+
+  Args:
+     data: Data to convert.
+
+  Returns:
+     String to be output into the HTML file.
+  """
+  if isinstance(data, dict) or isinstance(data, list):
+    return json.dumps(data)
+  elif isinstance(data, str):
+    return data
+  else:
+    raise ValueError('Invalid data format for HTML output')
+
+def CreateAgents(options, categories):
+  """Create systrace agents.
+
+  This function will search systrace agent modules in agent directories and
+  create the corresponding systrace agents.
+  Args:
+    options: The command-line options.
+    categories: The trace categories to capture.
+  Returns:
+    The list of systrace agents.
+  """
+  agent_dirs = [os.path.join(os.path.dirname(__file__),
+                             DEFAULT_AGENT_DIR)]
+  if options.agent_dirs:
+    agent_dirs.extend(options.agent_dirs.split(','))
+
+  agents = []
+  for agent_dir in agent_dirs:
+    if not agent_dir:
+      continue
+    for filename in os.listdir(agent_dir):
+      (module_name, ext) = os.path.splitext(filename)
+      if (ext != '.py' or module_name == '__init__'
+          or module_name.endswith('_unittest')):
+        continue
+      (f, pathname, data) = imp.find_module(module_name, [agent_dir])
+      try:
+        module = imp.load_module(module_name, f, pathname, data)
+      finally:
+        if f:
+          f.close()
+      if module:
+        agent = module.try_create_agent(options, categories)
+        if not agent:
+          continue
+        agents.append(agent)
+  return agents