demandimport: delay loading for "from a import b" with absolute_import
Before this patch, "from a import b" doesn't delay loading module "b",
if absolute_import is enabled, even though "from . import b" does.
For example:
- it is assumed that extension X has "from P import M" for module M
under package P with absolute_import feature
- if importing module M is already delayed before loading extension
X, loading module M in extension X is delayed until actually
referring
util, cmdutil, scmutil or so of Mercurial itself should be
imported by "from . import M" style before loading extension X
- otherwise, module M is loaded immediately at loading extension X,
even if extension X itself isn't used at that "hg" command invocation
Some minor modules (e.g. filemerge or so) of Mercurial itself
aren't imported by "from . import M" style before loading
extension X. And of course, external libraries aren't, too.
This might cause startup performance problem of hg command, because
many bundled extensions already enable absolute_import feature.
To delay loading module for "from a import b" with absolute_import
feature, this patch does below in "from a (or .a) import b" with
absolute_import case:
1. import root module of "name" by system built-in __import__
(referred as _origimport)
2. recurse down the module chain for hierarchical "name"
This logic can be shared with non absolute_import
case. Therefore, this patch also centralizes it into chainmodules().
3. and fall through to process elements in "fromlist" for the leaf
module of "name"
Processing elements in "fromlist" is executed in the code path
after "if _pypy: .... else: ..." clause. Therefore, this patch
replaces "if _pypy:" with "elif _pypy:" to share it.
At 4f1144c3c72b introducing original "work around" for "from a import
b" case, elements in "fromlist" were imported with "level=level". But
"level" might be grater than 1 (e.g. level=2 in "from .. import b"
case) at demandimport() invocation, and importing direct sub-module in
"fromlist" with level grater than 1 causes unexpected result.
IMHO, this seems main reason of "errors for unknown reason" described
in 4f1144c3c72b, and we don't have to worry about it, because this
issue was already fixed by 78d05778907b.
This is reason why this patch removes "errors for unknown reasons"
comment.
# hgweb/request.py - An http request from either CGI or the standalone server.
#
# Copyright 21 May 2005 - (c) 2005 Jake Edge <jake@edge2.net>
# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import cgi
import errno
import socket
from .common import (
ErrorResponse,
HTTP_NOT_MODIFIED,
statusmessage,
)
from .. import (
util,
)
shortcuts = {
'cl': [('cmd', ['changelog']), ('rev', None)],
'sl': [('cmd', ['shortlog']), ('rev', None)],
'cs': [('cmd', ['changeset']), ('node', None)],
'f': [('cmd', ['file']), ('filenode', None)],
'fl': [('cmd', ['filelog']), ('filenode', None)],
'fd': [('cmd', ['filediff']), ('node', None)],
'fa': [('cmd', ['annotate']), ('filenode', None)],
'mf': [('cmd', ['manifest']), ('manifest', None)],
'ca': [('cmd', ['archive']), ('node', None)],
'tags': [('cmd', ['tags'])],
'tip': [('cmd', ['changeset']), ('node', ['tip'])],
'static': [('cmd', ['static']), ('file', None)]
}
def normalize(form):
# first expand the shortcuts
for k in shortcuts.iterkeys():
if k in form:
for name, value in shortcuts[k]:
if value is None:
value = form[k]
form[name] = value
del form[k]
# And strip the values
for k, v in form.iteritems():
form[k] = [i.strip() for i in v]
return form
class wsgirequest(object):
"""Higher-level API for a WSGI request.
WSGI applications are invoked with 2 arguments. They are used to
instantiate instances of this class, which provides higher-level APIs
for obtaining request parameters, writing HTTP output, etc.
"""
def __init__(self, wsgienv, start_response):
version = wsgienv['wsgi.version']
if (version < (1, 0)) or (version >= (2, 0)):
raise RuntimeError("Unknown and unsupported WSGI version %d.%d"
% version)
self.inp = wsgienv['wsgi.input']
self.err = wsgienv['wsgi.errors']
self.threaded = wsgienv['wsgi.multithread']
self.multiprocess = wsgienv['wsgi.multiprocess']
self.run_once = wsgienv['wsgi.run_once']
self.env = wsgienv
self.form = normalize(cgi.parse(self.inp,
self.env,
keep_blank_values=1))
self._start_response = start_response
self.server_write = None
self.headers = []
def __iter__(self):
return iter([])
def read(self, count=-1):
return self.inp.read(count)
def drain(self):
'''need to read all data from request, httplib is half-duplex'''
length = int(self.env.get('CONTENT_LENGTH') or 0)
for s in util.filechunkiter(self.inp, limit=length):
pass
def respond(self, status, type, filename=None, body=None):
if self._start_response is not None:
self.headers.append(('Content-Type', type))
if filename:
filename = (filename.rpartition('/')[-1]
.replace('\\', '\\\\').replace('"', '\\"'))
self.headers.append(('Content-Disposition',
'inline; filename="%s"' % filename))
if body is not None:
self.headers.append(('Content-Length', str(len(body))))
for k, v in self.headers:
if not isinstance(v, str):
raise TypeError('header value must be string: %r' % (v,))
if isinstance(status, ErrorResponse):
self.headers.extend(status.headers)
if status.code == HTTP_NOT_MODIFIED:
# RFC 2616 Section 10.3.5: 304 Not Modified has cases where
# it MUST NOT include any headers other than these and no
# body
self.headers = [(k, v) for (k, v) in self.headers if
k in ('Date', 'ETag', 'Expires',
'Cache-Control', 'Vary')]
status = statusmessage(status.code, str(status))
elif status == 200:
status = '200 Script output follows'
elif isinstance(status, int):
status = statusmessage(status)
self.server_write = self._start_response(status, self.headers)
self._start_response = None
self.headers = []
if body is not None:
self.write(body)
self.server_write = None
def write(self, thing):
if thing:
try:
self.server_write(thing)
except socket.error as inst:
if inst[0] != errno.ECONNRESET:
raise
def writelines(self, lines):
for line in lines:
self.write(line)
def flush(self):
return None
def close(self):
return None
def wsgiapplication(app_maker):
'''For compatibility with old CGI scripts. A plain hgweb() or hgwebdir()
can and should now be used as a WSGI application.'''
application = app_maker()
def run_wsgi(env, respond):
return application(env, respond)
return run_wsgi