Add libs to get information about or manipulate a buildbot master.

infra/libs/buildbot/master.py

Index: infra/libs/buildbot/master.py
diff --git a/infra/libs/buildbot/master.py b/infra/libs/buildbot/master.py
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+++ b/infra/libs/buildbot/master.py
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+# Copyright 2015 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.
+
+"""Get information about a buildbot master and manipulate it."""
+
+
+import errno
+import os
+import json
+import re
+import requests
+import simplejson
+import subprocess
+import sys
+
+from dateutil.parser import parse
+
+from infra.libs.time_functions import timestamp
+
+######## Getting information about the master.
+
+
+# Derived from http://stackoverflow.com/a/6940314.
+def _pid_is_alive(pid):  # pragma: no cover
+  """Determine if the given pid is still running.
+  
+  Sending a signal of 0 (the 'null signal') does all the checks to send a signal
+  without actually sending a signal. Thus it works as a check to see if the pid
+  is valid. See http://goo.gl/6M1BoF for details.
+  """
+  if sys.platform.startswith('win'):
+    raise NotImplementedError
+
+  if pid <= 0:
+    return False
+  try:
+    os.kill(pid, 0)
+  except OSError as err:
+    if err.errno == errno.ESRCH:
+      return False
+    elif err.errno == errno.EPERM:
+      return True
+    else:
+      raise
+  else:
+    return True
+
+
+def buildbot_is_running(directory):
+  """Determine if the twisted.pid in a directory is running."""
+  pidfile = os.path.join(directory, 'twistd.pid')
+  if not os.path.exists(pidfile):
+    return False
+  with open(pidfile) as f:
+    pid = int(f.read().strip())
+  return _pid_is_alive(pid)
+
+
+def _get_last_action(directory, action):
+  """Get the last time the given action was run in the actions.log."""
+  actions_log_file = os.path.join(directory, 'actions.log')
+  if not os.path.exists(actions_log_file):
+    return None
+  with open(actions_log_file) as f:
+    for line in reversed(list(f)):
+      if action in line:
+        unparsed_date = line.split(action)[0][len('**'):]
+        return timestamp.utctimestamp(parse(unparsed_date))
+  return None
+
+
+
+def get_last_boot(directory):
+  """Determine the last time the master was started."""
+  return max(
+      _get_last_action(directory, 'make restart'),
+      _get_last_action(directory, 'make start'))
+
+
+def get_last_no_new_builds(directory):
+  """Determine the last time a *current* make no-new-builds was called.
+  
+  If a 'make start' or 'make restart' was issued after the no-new-builds, it is
+  not valid (since the make start or make restart nullified the no-new-builds).
+  """
+  last_boot = get_last_boot(directory)
+  last_no_new_builds = _get_last_action(directory, 'make no-new-builds')
+  if not last_no_new_builds:
+    return None
+  if last_boot > last_no_new_builds:
+    return None
+  return last_no_new_builds
+
+
+def _get_mastermap_data(directory):
+  """Get mastermap JSON from a master directory."""
+
+  build_dir = os.path.join(directory, os.pardir, os.pardir, os.pardir, 'build')
+  runit = os.path.join(build_dir, 'scripts', 'tools', 'runit.py')
+  build_internal_dir = os.path.join(build_dir, os.pardir, 'build_internal')
+
+  script_path = os.path.join(build_dir, 'scripts', 'tools', 'mastermap.py')
+  if os.path.exists(build_internal_dir):
+    script_path = os.path.join(
+         build_internal_dir, 'scripts', 'tools', 'mastermap_internal.py')
+
+  script_data = json.loads(subprocess.check_output(
+    [runit, script_path, '-f', 'json']))
+
+  short_dirname = os.path.basename(directory)
+  matches = [x for x in script_data if x.get('dirname') == short_dirname]
+  assert len(matches) < 2, (
+      'Multiple masters were found with the same master directory.')
+  if matches:
+    return matches[0]
+  return None
+
+
+def _get_master_web_port(directory):
+  """Determine the web port of the master running in the given directory."""
+  mastermap_data = _get_mastermap_data(directory)
+  if mastermap_data:
+    return mastermap_data['port']
+  return None
+
+
+def get_accepting_builds(directory, timeout=30):
+  """Determine whether the master is accepting new builds or not.
+  
+  *** This only works for masters running on localhost.***
+  """
+  port = _get_master_web_port(directory)
+  if port is not None:
+    try:
+      res = requests.get(
+          'http://localhost:%d/json/accepting_builds' % port,
+          timeout=timeout)
+      if res.status_code == 200:
+        try:
+          return res.json().get('accepting_builds')
+        except simplejson.scanner.JSONDecodeError:
+          pass
+    except requests.exceptions.Timeout:
+      pass
+  return None
+
+
+######## Performing actions on the master.
+
+
+GclientSync, MakeStop, MakeWait, MakeStart, MakeNoNewBuilds = range(5)
+
+
+def convert_action_items_to_cli(
+    action_items, directory, enable_gclient=False):
+
+  def cmd_dict(cmd, lockfile_prefix):
+    # Using the same lockfile prefix for two actions will make them mutually
+    # exclusive. So setting 'make' for all the make commands tries to prevent
+    # two make actions happening at once in the same master directory.
+    lockfile = '%s_%s' % (
+        lockfile_prefix,
+        re.sub('[^\w]', '_', directory.lower()))
+    return {
+        'cwd': directory,
+        'cmd': cmd,
+        'lockfile': lockfile,
+    }
+
+  for action_item in action_items:
+    if action_item == GclientSync:
+      if enable_gclient:
+        yield cmd_dict(
+            ['gclient', 'sync', '--reset', '--force', '--auto_rebase'],
+            'gclient')
+    elif action_item == MakeStop:
+      yield cmd_dict(['make', 'stop'], 'make')
+    elif action_item == MakeWait:
+      yield cmd_dict(['make', 'wait'], 'make')
+    elif action_item == MakeStart:
+      yield cmd_dict(['make', 'start'], 'make')
+    elif action_item == MakeNoNewBuilds:
+      yield cmd_dict(['make', 'no-new-builds'], 'make')
+    else:
+      raise ValueError('Invalid action item %s' % action_item)