chromium的部署工具depot_tools和gclient

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depot_tools是个工具包，里面包含gclient、gcl、gn和ninja等工具。其中gclient是代码获取工具，它其实是利用了svn和git。主要涉及的depot_tools文件夹下的文件有：gclient、gclient.py、subcommand.py、gclient_utils.py。

gclient文件是个bash脚本:

#########glcient###########
/usr/bin/bash
base_dir=$(dirname "$0")
if [[ "#grep#fetch#cleanup#diff#" != *"#$1#"* ]]; then
"$base_dir"/update_depot_tools
fi
PYTHONDONTWRITEBYTECODE=1 exec python "$base_dir/gclient.py" "$@"

首先，获取脚本的目录并赋值给base_dir，然后判断命令参数1是否为grep|fetch|cleanup|diff，如不是则执行base_dir下的updat_depot_tools脚本，该脚本更新git、svn工具。最后调用当前脚本目录(depot_tools)下的python脚本gclient.py，并把参数都传递给该脚本。

###############glcient.py#######
# 文件最后
def Main(argv):
.....
dispatcher = subcommand.CommandDispatcher(__name__)
try:
return dispatcher.execute(OptionParser(), argv)
......
if '__main__' == __name__:
sys.exit(Main(sys.argv[1:]))

在gclient.py脚本开始，调用函数Main，参数为bash脚本传递来的。Main主要执行两个过程，一是建立dispatcher对象，参数为当前模块；然后调用dispatcher的execute方法，参数一是OptionParser对象，参数二为传递给Main的参数。

下面进入subcommand模块下的类CommandDispatcher，分析execute方法。

################# subcommand.py ###########
class CommandDispatcher(object):
def __init__(self, module):
"""module is the name of the main python module where to look for commands.
The python builtin variable __name__ MUST be used for |module|. If the
script is executed in the form 'python script.py', __name__ == '__main__'
and sys.modules['script'] doesn't exist. On the other hand if it is unit
tested, __main__ will be the unit test's module so it has to reference to
itself with 'script'. __name__ always match the right value.
"""
self.module = sys.modules[module]
def enumerate_commands(self):
"""Returns a dict of command and their handling function.
The commands must be in the '__main__' modules. To import a command from a
submodule, use:
from mysubcommand import CMDfoo
Automatically adds 'help' if not already defined.
A command can be effectively disabled by defining a global variable to None,
e.g.:
CMDhelp = None
"""
cmds = dict(
(fn[3:], getattr(self.module, fn))
for fn in dir(self.module) if fn.startswith('CMD'))
cmds.setdefault('help', CMDhelp)
return cmds
def find_nearest_command(self, name):
"""Retrieves the function to handle a command.
It automatically tries to guess the intended command by handling typos or
incomplete names.
"""
# Implicitly replace foo-bar to foo_bar since foo-bar is not a valid python
# symbol but it's faster to type.
name = name.replace('-', '_')
commands = self.enumerate_commands()
if name in commands:
return commands[name]
# An exact match was not found. Try to be smart and look if there's
# something similar.
commands_with_prefix = [c for c in commands if c.startswith(name)]
if len(commands_with_prefix) == 1:
return commands[commands_with_prefix[0]]
# A #closeenough approximation of levenshtein distance.
def close_enough(a, b):
return difflib.SequenceMatcher(a=a, b=b).ratio()
hamming_commands = sorted(
((close_enough(c, name), c) for c in commands),
reverse=True)
if (hamming_commands[0][0] - hamming_commands[1][0]) < 0.3:
# Too ambiguous.
return
if hamming_commands[0][0] < 0.8:
# Not similar enough. Don't be a fool and run a random command.
return
return commands[hamming_commands[0][1]]
def _gen_commands_list(self):
"""Generates the short list of supported commands."""
commands = self.enumerate_commands()
docs = sorted(
(name, self._create_command_summary(name, handler))
for name, handler in commands.iteritems())
# Skip commands without a docstring.
docs = [i for i in docs if i[1]]
# Then calculate maximum length for alignment:
length = max(len(c) for c in commands)
# Look if color is supported.
colors = _get_color_module()
green = reset = ''
if colors:
green = colors.Fore.GREEN
reset = colors.Fore.RESET
return (
'Commands are:\n' +
''.join(
' %s%-*s%s %s\n' % (green, length, name, reset, doc)
for name, doc in docs))
def _add_command_usage(self, parser, command):
"""Modifies an OptionParser object with the function's documentation."""
name = command.__name__[3:]
if name == 'help':
name = '<command>'
# Use the module's docstring as the description for the 'help' command if
# available.
parser.description = (self.module.__doc__ or '').rstrip()
if parser.description:
parser.description += '\n\n'
parser.description += self._gen_commands_list()
# Do not touch epilog.
else:
# Use the command's docstring if available. For commands, unlike module
# docstring, realign.
lines = (command.__doc__ or '').rstrip().splitlines()
if lines[:1]:
rest = textwrap.dedent('\n'.join(lines[1:]))
parser.description = '\n'.join((lines[0], rest))
else:
parser.description = lines[0]
if parser.description:
parser.description += '\n'
parser.epilog = getattr(command, 'epilog', None)
if parser.epilog:
parser.epilog = '\n' + parser.epilog.strip() + '\n'
more = getattr(command, 'usage_more', '')
parser.set_usage(
'usage: %%prog %s [options]%s' % (name, '' if not more else ' ' + more))
@staticmethod
def _create_command_summary(name, command):
"""Creates a oneline summary from the command's docstring."""
if name != command.__name__[3:]:
# Skip aliases.
return ''
doc = command.__doc__ or ''
line = doc.split('\n', 1)[0].rstrip('.')
if not line:
return line
return (line[0].lower() + line[1:]).strip()
def execute(self, parser, args):
"""Dispatches execution to the right command.
Fallbacks to 'help' if not disabled.
"""
# Unconditionally disable format_description() and format_epilog().
# Technically, a formatter should be used but it's not worth (yet) the
# trouble.
parser.format_description = lambda _: parser.description or ''
parser.format_epilog = lambda _: parser.epilog or ''
if args:
if args[0] in ('-h', '--help') and len(args) > 1:
# Inverse the argument order so 'tool --help cmd' is rewritten to
# 'tool cmd --help'.
args = [args[1], args[0]] + args[2:]
command = self.find_nearest_command(args[0])
if command:
if command.__name__ == 'CMDhelp' and len(args) > 1:
# Inverse the arguments order so 'tool help cmd' is rewritten to
# 'tool cmd --help'. Do it here since we want 'tool hel cmd' to work
# too.
args = [args[1], '--help'] + args[2:]
command = self.find_nearest_command(args[0]) or command
# "fix" the usage and the description now that we know the subcommand.
self._add_command_usage(parser, command)
return command(parser, args[1:])
cmdhelp = self.enumerate_commands().get('help')
if cmdhelp:
# Not a known command. Default to help.
self._add_command_usage(parser, cmdhelp)
return cmdhelp(parser, args)
# Nothing can be done.
return 2

在gcient.py中，dispatcher = subcomamnd.CommandDispatcher(__name__)，可以看出传入的参数是gclient.py这个模块。在CommandDispatcher的__init__中，self.module就是gclent。了解这点对理解后面的enumrate_commands函数有用。从它的名字就可以看出是枚举所有支持的命令，返回的结果是dict，键是命令名称，值为对应的处理函数，如{"sync" : CMDsync}。其他函数如_add_command_usage, _create_command_summary, _gen_commands_list是些辅助函数，功能也比较明确。比较复杂的是find_nearest_command，它是从enumerate_commands生成的dict字典里查找命令，如果没有精确匹配的，就通过模糊查找，并返回对应命令的处理函数。

############# gclient.py ##################
class OptionParser(optparse.OptionParser):
gclientfile_default = os.environ.get('GCLIENT_FILE', '.gclient')
def __init__(self, **kwargs):
optparse.OptionParser.__init__(
self, version='%prog ' + __version__, **kwargs)
# Some arm boards have issues with parallel sync.
if platform.machine().startswith('arm'):
jobs = 1
else:
jobs = max(8, gclient_utils.NumLocalCpus())
# cmp: 2013/06/19
# Temporary workaround to lower bot-load on SVN server.
# Bypassed if a bot_update flag is detected.
if (os.environ.get('CHROME_HEADLESS') == '1' and
not os.path.exists('update.flag')):
jobs = 1
self.add_option(
'-j', '--jobs', default=jobs, type='int',
help='Specify how many SCM commands can run in parallel; defaults to '
'%default on this machine')
self.add_option(
'-v', '--verbose', action='count', default=0,
help='Produces additional output for diagnostics. Can be used up to '
'three times for more logging info.')
self.add_option(
'--gclientfile', dest='config_filename',
help='Specify an alternate %s file' % self.gclientfile_default)
self.add_option(
'--spec',
help='create a gclient file containing the provided string. Due to '
'Cygwin/Python brokenness, it can\'t contain any newlines.')
self.add_option(
'--no-nag-max', default=False, action='store_true',
help='Ignored for backwards compatibility.')

参数OptionParser是gclient.py中的一个类，它继承子模块的optparser.OptionParser。主要功能是解析参数，并返回tuple（options， args），关于OptionParser这个例子说明的很清楚。返回值就是输入参数被格式化分析后的结果。这个函数处理分两个层面，一是如果是帮助查询，一个是执行命令。在帮助查询时，用户输入的命令如：gclient --help sync等。其实，传到execute的时候，参数变成--help sync，那么首先是调换参数位置，使得结果为sync --help，也就是args[0]为"sync", args[1]为--help，然后调用self.fine_nearest_command函数，查找精确命令或者最相似的模糊匹配的命令，并把结果（命令处理函数以CMD开头）赋值给command变量。

进入到execute()，解析参数，find_nearest_commands()得到命令后，判断是不是帮助命令，如果不是就直接调用对应的处理函数return command(parser, args[1:])。用上例来说就是调用CMDsync函数，参数是parser 和sync后的参数。

看看CMDsync是如何处理输入参数的？

#############gclient.py#############
def CMDsync(parser, args):
"""Checkout/update all modules."""
parser.add_option('-f', '--force', action='store_true',
help='force update even for unchanged modules')
parser.add_option('-n', '--nohooks', action='store_true',
help='don\'t run hooks after the update is complete')
parser.add_option('-p', '--noprehooks', action='store_true',
help='don\'t run pre-DEPS hooks', default=False)
parser.add_option('-r', '--revision', action='append',
dest='revisions', metavar='REV', default=[],
help='Enforces revision/hash for the solutions with the '
'format src@rev. The src@ part is optional and can be '
'skipped. -r can be used multiple times when .gclient '
'has multiple solutions configured and will work even '
'if the src@ part is skipped. Note that specifying '
'--revision means your safesync_url gets ignored.')
parser.add_option('--with_branch_heads', action='store_true',
help='Clone git "branch_heads" refspecs in addition to '
'the default refspecs. This adds about 1/2GB to a '
'full checkout. (git only)')
parser.add_option('-t', '--transitive', action='store_true',
help='When a revision is specified (in the DEPS file or '
'with the command-line flag), transitively update '
'the dependencies to the date of the given revision. '
'Only supported for SVN repositories.')
parser.add_option('-H', '--head', action='store_true',
help='skips any safesync_urls specified in '
'configured solutions and sync to head instead')
parser.add_option('-D', '--delete_unversioned_trees', action='store_true',
help='Deletes from the working copy any dependencies that '
'have been removed since the last sync, as long as '
'there are no local modifications. When used with '
'--force, such dependencies are removed even if they '
'have local modifications. When used with --reset, '
'all untracked directories are removed from the '
'working copy, excluding those which are explicitly '
'ignored in the repository.')
parser.add_option('-R', '--reset', action='store_true',
help='resets any local changes before updating (git only)')
parser.add_option('-M', '--merge', action='store_true',
help='merge upstream changes instead of trying to '
'fast-forward or rebase')
parser.add_option('--deps', dest='deps_os', metavar='OS_LIST',
help='override deps for the specified (comma-separated) '
'platform(s); \'all\' will process all deps_os '
'references')
parser.add_option('-m', '--manually_grab_svn_rev', action='store_true',
help='Skip svn up whenever possible by requesting '
'actual HEAD revision from the repository')
parser.add_option('--upstream', action='store_true',
help='Make repo state match upstream branch.')
parser.add_option('--output-json',
help='Output a json document to this path containing '
'summary information about the sync.')
(options, args) = parser.parse_args(args)
client = GClient.LoadCurrentConfig(options)
if not client:
raise gclient_utils.Error('client not configured; see \'gclient config\'')
if options.revisions and options.head:
# TODO(maruel): Make it a parser.error if it doesn't break any builder.
print('Warning: you cannot use both --head and --revision')
if options.verbose:
# Print out the .gclient file. This is longer than if we just printed the
# client dict, but more legible, and it might contain helpful comments.
print(client.config_content)
ret = client.RunOnDeps('update', args)
if options.output_json:
slns = {}
for d in client.subtree(True):
normed = d.name.replace('\\', '/').rstrip('/') + '/'
slns[normed] = {
'revision': d.got_revision,
'scm': d.used_scm.name if d.used_scm else None,
}
with open(options.output_json, 'wb') as f:
json.dump({'solutions': slns}, f)
return ret
CMDupdate = CMDsync

通过options，args = parser.parse_args(args)，得到对CMDsync命令参数的解析，然后调用Gclient.LoadCurrentConfig(options)，为简单起见，我们输入的是gclient sync，那么options和args为空。

############glcient.py#############
def LoadCurrentConfig(options):
"""Searches for and loads a .gclient file relative to the current working
dir. Returns a GClient object."""
if options.spec:
client = GClient('.', options)
client.SetConfig(options.spec)
else:
path = gclient_utils.FindGclientRoot(os.getcwd(), options.config_filename)
if not path:
return None
client = GClient(path, options)
client.SetConfig(gclient_utils.FileRead(
os.path.join(path, options.config_filename)))
if (options.revisions and
len(client.dependencies) > 1 and
any('@' not in r for r in options.revisions)):
print >> sys.stderr, (
'You must specify the full solution name like --revision %s@%s\n'
'when you have multiple solutions setup in your .gclient file.\n'
'Other solutions present are: %s.') % (
client.dependencies[0].name,
options.revisions[0],
', '.join(s.name for s in client.dependencies[1:]))
return client

该函数查询当前目录下.glcient文件，最终返回client对象。该函数会调用到GClient(path, options):

############## gclient.py ##################
class GClient(Dependency):
"""Object that represent a gclient checkout. A tree of Dependency(), one per
solution or DEPS entry."""
DEPS_OS_CHOICES = {
"win32": "win",
"win": "win",
"cygwin": "win",
"darwin": "mac",
"mac": "mac",
"unix": "unix",
"linux": "unix",
"linux2": "unix",
"linux3": "unix",
"android": "android",
}
DEFAULT_CLIENT_FILE_TEXT = ("""\
solutions = [
{ "name" : "%(solution_name)s",
"url" : "%(solution_url)s",
"deps_file" : "%(deps_file)s",
"managed" : %(managed)s,
"custom_deps" : {
},
"safesync_url": "%(safesync_url)s",
},
]
cache_dir = %(cache_dir)r
""")
DEFAULT_SNAPSHOT_SOLUTION_TEXT = ("""\
{ "name" : "%(solution_name)s",
"url" : "%(solution_url)s",
"deps_file" : "%(deps_file)s",
"managed" : %(managed)s,
"custom_deps" : {
%(solution_deps)s },
"safesync_url": "%(safesync_url)s",
},
""")
DEFAULT_SNAPSHOT_FILE_TEXT = ("""\
# Snapshot generated with gclient revinfo --snapshot
solutions = [
%(solution_list)s]
""")
def __init__(self, root_dir, options):
# Do not change previous behavior. Only solution level and immediate DEPS
# are processed.
self._recursion_limit = 2
Dependency.__init__(self, None, None, None, None, True, None, None, None,
'unused', True)
self._options = options
if options.deps_os:
enforced_os = options.deps_os.split(',')
else:
enforced_os = [self.DEPS_OS_CHOICES.get(sys.platform, 'unix')]
if 'all' in enforced_os:
enforced_os = self.DEPS_OS_CHOICES.itervalues()
self._enforced_os = tuple(set(enforced_os))
self._root_dir = root_dir
self.config_content = None
def SetConfig(self, content):
assert not self.dependencies
config_dict = {}
self.config_content = content
try:
exec(content, config_dict)
except SyntaxError, e:
gclient_utils.SyntaxErrorToError('.gclient', e)
# Append any target OS that is not already being enforced to the tuple.
target_os = config_dict.get('target_os', [])
if config_dict.get('target_os_only', False):
self._enforced_os = tuple(set(target_os))
else:
self._enforced_os = tuple(set(self._enforced_os).union(target_os))
gclient_scm.GitWrapper.cache_dir = config_dict.get('cache_dir')
if not target_os and config_dict.get('target_os_only', False):
raise gclient_utils.Error('Can\'t use target_os_only if target_os is '
'not specified')
deps_to_add = []
for s in config_dict.get('solutions', []):
try:
deps_to_add.append(Dependency(
self, s['name'], s['url'],
s.get('safesync_url', None),
s.get('managed', True),
s.get('custom_deps', {}),
s.get('custom_vars', {}),
s.get('custom_hooks', []),
s.get('deps_file', 'DEPS'),
True))
except KeyError:
raise gclient_utils.Error('Invalid .gclient file. Solution is '
'incomplete: %s' % s)
self.add_dependencies_and_close(deps_to_add, config_dict.get('hooks', []))
logging.info('SetConfig() done')
def SaveConfig(self):
gclient_utils.FileWrite(os.path.join(self.root_dir,
self._options.config_filename),
self.config_content)
def RunOnDeps(self, command, args, ignore_requirements=False, progress=True):
"""Runs a command on each dependency in a client and its dependencies.
Args:
command: The command to use (e.g., 'status' or 'diff')
args: list of str - extra arguments to add to the command line.
"""
if not self.dependencies:
raise gclient_utils.Error('No solution specified')
revision_overrides = {}
# It's unnecessary to check for revision overrides for 'recurse'.
# Save a few seconds by not calling _EnforceRevisions() in that case.
if command not in ('diff', 'recurse', 'runhooks', 'status'):
revision_overrides = self._EnforceRevisions()
pm = None
# Disable progress for non-tty stdout.
if (sys.stdout.isatty() and not self._options.verbose and progress):
if command in ('update', 'revert'):
pm = Progress('Syncing projects', 1)
elif command == 'recurse':
pm = Progress(' '.join(args), 1)
work_queue = gclient_utils.ExecutionQueue(
self._options.jobs, pm, ignore_requirements=ignore_requirements)
for s in self.dependencies:
work_queue.enqueue(s)
work_queue.flush(revision_overrides, command, args, options=self._options)
# Once all the dependencies have been processed, it's now safe to run the
# hooks.
if not self._options.nohooks:
self.RunHooksRecursively(self._options)
if command == 'update':
# Notify the user if there is an orphaned entry in their working copy.
# Only delete the directory if there are no changes in it, and
# delete_unversioned_trees is set to true.
entries = [i.name for i in self.root.subtree(False) if i.url]
full_entries = [os.path.join(self.root_dir, e.replace('/', os.path.sep))
for e in entries]
for entry, prev_url in self._ReadEntries().iteritems():
if not prev_url:
# entry must have been overridden via .gclient custom_deps
continue
# Fix path separator on Windows.
entry_fixed = entry.replace('/', os.path.sep)
e_dir = os.path.join(self.root_dir, entry_fixed)
def _IsParentOfAny(parent, path_list):
parent_plus_slash = parent + '/'
return any(
path[:len(parent_plus_slash)] == parent_plus_slash
for path in path_list)
# Use entry and not entry_fixed there.
if (entry not in entries and
(not any(path.startswith(entry + '/') for path in entries)) and
os.path.exists(e_dir)):
scm = gclient_scm.CreateSCM(prev_url, self.root_dir, entry_fixed)
# Check to see if this directory is now part of a higher-up checkout.
if scm.GetCheckoutRoot() in full_entries:
logging.info('%s is part of a higher level checkout, not '
'removing.', scm.GetCheckoutRoot())
continue
file_list = []
scm.status(self._options, [], file_list)
modified_files = file_list != []
if (not self._options.delete_unversioned_trees or
(modified_files and not self._options.force)):
# There are modified files in this entry. Keep warning until
# removed.
print(('\nWARNING: \'%s\' is no longer part of this client. '
'It is recommended that you manually remove it.\n') %
entry_fixed)
else:
# Delete the entry
print('\n________ deleting \'%s\' in \'%s\'' % (
entry_fixed, self.root_dir))
gclient_utils.rmtree(e_dir)
# record the current list of entries for next time
self._SaveEntries()
return 0

client.SetConfig()读取配置文件里的solutions，构建dependencies的list变量deps_to_add，然后调用.add_dependencies_and_close，参数就是包含deps_to_add。在add_dependencies_and_close函数里验证deps，如果是有效的，就加入到依赖树中。

在CMDsync函数里，执行client.RunOnDeps()。它将dependengcies的每个任务加入到gclient_tuils.ExecutionQueue队列并执行。完成所有任务后执行runhook。