Bug 1204787 - Add |mach power|. r=glandium.

This extracts the most useful browser-related measurements from rapl and
powermetrics.

--HG--
extra : rebase_source : 81ce14acc6c6e1bc7ac6c34bf119d8e619956dd1

build/mach_bootstrap.py

@@ -145,6 +145,7 @@ MACH_MODULES = [
     'tools/docs/mach_commands.py',
     'tools/mercurial/mach_commands.py',
     'tools/mach_commands.py',
+    'tools/power/mach_commands.py',
     'mobile/android/mach_commands.py',
 ]
 

tools/power/mach_commands.py

@@ -0,0 +1,135 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import print_function
+
+from distutils.version import StrictVersion
+
+from mach.decorators import (
+    Command,
+    CommandArgument,
+    CommandProvider,
+)
+from mozbuild.base import (
+    MachCommandBase,
+    MachCommandConditions as conditions,
+)
+
+
+def is_osx_10_10_or_greater(cls):
+    import platform
+    release = platform.mac_ver()[0]
+    return release and StrictVersion(release) >= StrictVersion('10.10')
+
+
+@CommandProvider
+class MachCommands(MachCommandBase):
+    '''
+    Get system power consumption and related measurements.
+    '''
+    def __init__(self, context):
+        MachCommandBase.__init__(self, context)
+
+    @Command('power', category='misc',
+        conditions=[is_osx_10_10_or_greater],
+        description='Get system power consumption and related measurements for '
+        'all running browsers. Available only on Mac OS X 10.10 and above. '
+        'Requires root access.')
+    @CommandArgument('-i', '--interval', type=int, default=30000,
+        help='The sample period, measured in milliseconds. Defaults to 30000.')
+    def power(self, interval):
+        import os
+        import re
+        import subprocess
+
+        rapl = os.path.join(self.topobjdir, 'dist', 'bin', 'rapl')
+
+        interval = str(interval)
+
+        # Run a trivial command with |sudo| to gain temporary root privileges
+        # before |rapl| and |powermetrics| are called. This ensures that |rapl|
+        # doesn't start measuring while |powermetrics| is waiting for the root
+        # password to be entered.
+        try:
+            subprocess.check_call(['sudo', 'true'])
+        except:
+            print('\nsudo failed; aborting')
+            return 1
+
+        # This runs rapl in the background because nothing in this script
+        # depends on the output. This is good because we want |rapl| and
+        # |powermetrics| to run at the same time.
+        subprocess.Popen([rapl, '-n', '1', '-i', interval])
+
+        lines = subprocess.check_output(['sudo', 'powermetrics',
+                                         '--samplers', 'tasks',
+                                         '--show-process-coalition',
+                                         '--show-process-gpu',
+                                         '-n', '1',
+                                         '-i', interval])
+
+        # When run with --show-process-coalition, |powermetrics| groups outputs
+        # into process coalitions, each of which has a leader.
+        #
+        # For example, when Firefox runs from the dock, its coalition looks
+        # like this:
+        #
+        #   org.mozilla.firefox
+        #     firefox
+        #     plugin-container
+        #
+        # When Safari runs from the dock:
+        #
+        #   com.apple.Safari
+        #     Safari
+        #     com.apple.WebKit.Networking
+        #     com.apple.WebKit.WebContent
+        #     com.apple.WebKit.WebContent
+        #
+        # When Chrome runs from the dock:
+        #
+        #   com.google.Chrome
+        #     Google Chrome
+        #     Google Chrome Helper
+        #     Google Chrome Helper
+        #
+        # In these cases, we want to print the whole coalition.
+        #
+        # Also, when you run any of them from the command line, things are the
+        # same except that the leader is com.apple.Terminal and there may be
+        # non-browser processes in the coalition, e.g.:
+        #
+        #  com.apple.Terminal
+        #    firefox
+        #    plugin-container
+        #    <and possibly other, non-browser processes>
+        #
+        # We want to print all these but omit uninteresting coalitions. We
+        # could do this by properly parsing powermetrics output, but it's
+        # simpler and more robust to just grep for a handful of identifying
+        # strings.
+
+        print()  # blank line between |rapl| output and |powermetrics| output
+
+        for line in lines.splitlines():
+            # Search for the following things.
+            #
+            # - '^Name' is for the columns headings line.
+            #
+            # - 'firefox' and 'plugin-container' are for Firefox
+            #
+            # - 'Safari\b' and 'WebKit' are for Safari. The '\b' excludes
+            #   SafariCloudHistoryPush, which is a process that always
+            #   runs, even when Safari isn't open.
+            #
+            # - 'Chrome' is for Chrome.
+            #
+            # - 'Terminal' is for the terminal. If no browser is running from
+            #   within the terminal, it will show up unnecessarily. This is a
+            #   minor disadvantage of this very simple parsing strategy.
+            #
+            if re.search(r'(^Name|firefox|plugin-container|Safari\b|WebKit|Chrome|Terminal)', line):
+                print(line)
+
+        return 0