author Andrew McCreight <>
Mon, 22 Apr 2019 16:34:51 +0000
changeset 470376 3073770e06f157040f4c64951b7e8425e1ad7bbe
parent 459932 effd6611eaccae8fcc3572286a229f9efe96ce7d
child 474056 b4e024474194a21d9ade565abfd8340e93aed07c
permissions -rw-r--r--
Bug 1535403 - Take indirection into account for the CC optimizations for the outer window wrapper. r=peterv Most wrapper cached C++ objects are held alive by their wrapper. The cycle collector takes advantage of this in many classes and ignores the C++ object if the wrapper is marked black. However, this is not true for the outer window's wrapper. Instead, the outer window's wrapper keeps the inner window alive. The inner window usually keeps its outer window alive, but not after it has been unlinked. For reasons I do not yet understand, the outer window's wrapper can be kept alive after the inner window it is a proxy for is unlinked. This patch fixes the cycle collector optimization for the outer window by only applying it if the outer window still has a weak reference to the inner window, which it will until the inner no longer holds the outer alive. This in turn fixes, or at least helps fix, window leaks seen intermittently when the lifetime of outer windows and docshells are tied together. The code comment is based on a review comment by peterv. Differential Revision:

# 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

from __future__ import print_function, unicode_literals

import codecs
import itertools
import logging
import os
import sys
import textwrap

base_dir = os.path.abspath(os.path.dirname(__file__))
sys.path.insert(0, os.path.join(base_dir, 'python', 'mozbuild'))
from mozbuild.configure import (
from mozbuild.pythonutil import iter_modules_in_path
from mozbuild.backend.configenvironment import PartialConfigEnvironment
from mozbuild.util import (
import mozpack.path as mozpath

def main(argv):
    config = {}

    sandbox = ConfigureSandbox(config, os.environ, argv)

    if os.environ.get('MOZ_CONFIGURE_TRACE'):
        sandbox._logger.setLevel(TRACE), 'moz.configure'))

    if sandbox._help:
        return 0

    return config_status(config)

def config_status(config):
    # Sanitize config data to feed config.status
    # Ideally, all the backend and frontend code would handle the booleans, but
    # there are so many things involved, that it's easier to keep config.status
    # untouched for now.
    def sanitized_bools(v):
        if v is True:
            return '1'
        if v is False:
            return ''
        return v

    sanitized_config = {}
    sanitized_config['substs'] = {
        k: sanitized_bools(v) for k, v in config.iteritems()
        if k not in ('DEFINES', 'non_global_defines', 'TOPSRCDIR', 'TOPOBJDIR',
    sanitized_config['defines'] = {
        k: sanitized_bools(v) for k, v in config['DEFINES'].iteritems()
    sanitized_config['non_global_defines'] = config['non_global_defines']
    sanitized_config['topsrcdir'] = config['TOPSRCDIR']
    sanitized_config['topobjdir'] = config['TOPOBJDIR']
    sanitized_config['mozconfig'] = config.get('MOZCONFIG')

    # Create config.status. Eventually, we'll want to just do the work it does
    # here, when we're able to skip configure tests/use cached results/not rely
    # on autoconf.
    logging.getLogger('moz.configure').info('Creating config.status')
    encoding = 'mbcs' if sys.platform == 'win32' else 'utf-8'
    with'config.status', 'w', encoding) as fh:
            # coding=%(encoding)s
            from __future__ import unicode_literals
            from mozbuild.util import encode
            encoding = '%(encoding)s'
        ''') % {'python': config['PYTHON'], 'encoding': encoding})
        # A lot of the build backend code is currently expecting byte
        # strings and breaks in subtle ways with unicode strings. (bug 1296508)
        for k, v in sanitized_config.iteritems():
            fh.write('%s = encode(%s, encoding)\n' % (k, indented_repr(v)))
        fh.write("__all__ = ['topobjdir', 'topsrcdir', 'defines', "
                 "'non_global_defines', 'substs', 'mozconfig']")

        if config.get('MOZ_BUILD_APP') != 'js' or config.get('JS_STANDALONE'):
                if __name__ == '__main__':
                    from mozbuild.util import patch_main
                    from mozbuild.config_status import config_status
                    args = dict([(name, globals()[name]) for name in __all__])

    partial_config = PartialConfigEnvironment(config['TOPOBJDIR'])

    # Write out a file so the build backend knows to re-run configure when
    # relevant Python changes.
    with open('', 'w') as fh:
        for f in itertools.chain(config['CONFIG_STATUS_DEPS'],
            fh.write('%s\n' % mozpath.normpath(f))

    # Other things than us are going to run this file, so we need to give it
    # executable permissions.
    os.chmod('config.status', 0o755)
    if config.get('MOZ_BUILD_APP') != 'js' or config.get('JS_STANDALONE'):
        from mozbuild.config_status import config_status

        # Some values in sanitized_config also have more complex types, such as
        # EnumString, which using when calling config_status would currently
        # break the build, as well as making it inconsistent with re-running
        # config.status. Fortunately, EnumString derives from unicode, so it's
        # covered by converting unicode strings.

        # A lot of the build backend code is currently expecting byte strings
        # and breaks in subtle ways with unicode strings.
        return config_status(args=[], **encode(sanitized_config, encoding))
    return 0

if __name__ == '__main__':