Mercurial > hg
view mercurial/pure/osutil.py @ 29375:fcaf20175b1b
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.
author | FUJIWARA Katsunori <foozy@lares.dti.ne.jp> |
---|---|
date | Sun, 19 Jun 2016 02:17:33 +0900 |
parents | f7d0c28d34b3 |
children | 7a157639b8f2 |
line wrap: on
line source
# osutil.py - pure Python version of osutil.c # # Copyright 2009 Matt Mackall <mpm@selenic.com> and others # # 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 ctypes import ctypes.util import os import socket import stat as statmod import sys def _mode_to_kind(mode): if statmod.S_ISREG(mode): return statmod.S_IFREG if statmod.S_ISDIR(mode): return statmod.S_IFDIR if statmod.S_ISLNK(mode): return statmod.S_IFLNK if statmod.S_ISBLK(mode): return statmod.S_IFBLK if statmod.S_ISCHR(mode): return statmod.S_IFCHR if statmod.S_ISFIFO(mode): return statmod.S_IFIFO if statmod.S_ISSOCK(mode): return statmod.S_IFSOCK return mode def listdir(path, stat=False, skip=None): '''listdir(path, stat=False) -> list_of_tuples Return a sorted list containing information about the entries in the directory. If stat is True, each element is a 3-tuple: (name, type, stat object) Otherwise, each element is a 2-tuple: (name, type) ''' result = [] prefix = path if not prefix.endswith(os.sep): prefix += os.sep names = os.listdir(path) names.sort() for fn in names: st = os.lstat(prefix + fn) if fn == skip and statmod.S_ISDIR(st.st_mode): return [] if stat: result.append((fn, _mode_to_kind(st.st_mode), st)) else: result.append((fn, _mode_to_kind(st.st_mode))) return result if os.name != 'nt': posixfile = open _SCM_RIGHTS = 0x01 _socklen_t = ctypes.c_uint if sys.platform == 'linux2': # socket.h says "the type should be socklen_t but the definition of # the kernel is incompatible with this." _cmsg_len_t = ctypes.c_size_t _msg_controllen_t = ctypes.c_size_t _msg_iovlen_t = ctypes.c_size_t else: _cmsg_len_t = _socklen_t _msg_controllen_t = _socklen_t _msg_iovlen_t = ctypes.c_int class _iovec(ctypes.Structure): _fields_ = [ ('iov_base', ctypes.c_void_p), ('iov_len', ctypes.c_size_t), ] class _msghdr(ctypes.Structure): _fields_ = [ ('msg_name', ctypes.c_void_p), ('msg_namelen', _socklen_t), ('msg_iov', ctypes.POINTER(_iovec)), ('msg_iovlen', _msg_iovlen_t), ('msg_control', ctypes.c_void_p), ('msg_controllen', _msg_controllen_t), ('msg_flags', ctypes.c_int), ] class _cmsghdr(ctypes.Structure): _fields_ = [ ('cmsg_len', _cmsg_len_t), ('cmsg_level', ctypes.c_int), ('cmsg_type', ctypes.c_int), ('cmsg_data', ctypes.c_ubyte * 0), ] _libc = ctypes.CDLL(ctypes.util.find_library('c'), use_errno=True) _recvmsg = getattr(_libc, 'recvmsg', None) if _recvmsg: _recvmsg.restype = getattr(ctypes, 'c_ssize_t', ctypes.c_long) _recvmsg.argtypes = (ctypes.c_int, ctypes.POINTER(_msghdr), ctypes.c_int) else: # recvmsg isn't always provided by libc; such systems are unsupported def _recvmsg(sockfd, msg, flags): raise NotImplementedError('unsupported platform') def _CMSG_FIRSTHDR(msgh): if msgh.msg_controllen < ctypes.sizeof(_cmsghdr): return cmsgptr = ctypes.cast(msgh.msg_control, ctypes.POINTER(_cmsghdr)) return cmsgptr.contents # The pure version is less portable than the native version because the # handling of socket ancillary data heavily depends on C preprocessor. # Also, some length fields are wrongly typed in Linux kernel. def recvfds(sockfd): """receive list of file descriptors via socket""" dummy = (ctypes.c_ubyte * 1)() iov = _iovec(ctypes.cast(dummy, ctypes.c_void_p), ctypes.sizeof(dummy)) cbuf = ctypes.create_string_buffer(256) msgh = _msghdr(None, 0, ctypes.pointer(iov), 1, ctypes.cast(cbuf, ctypes.c_void_p), ctypes.sizeof(cbuf), 0) r = _recvmsg(sockfd, ctypes.byref(msgh), 0) if r < 0: e = ctypes.get_errno() raise OSError(e, os.strerror(e)) # assumes that the first cmsg has fds because it isn't easy to write # portable CMSG_NXTHDR() with ctypes. cmsg = _CMSG_FIRSTHDR(msgh) if not cmsg: return [] if (cmsg.cmsg_level != socket.SOL_SOCKET or cmsg.cmsg_type != _SCM_RIGHTS): return [] rfds = ctypes.cast(cmsg.cmsg_data, ctypes.POINTER(ctypes.c_int)) rfdscount = ((cmsg.cmsg_len - _cmsghdr.cmsg_data.offset) / ctypes.sizeof(ctypes.c_int)) return [rfds[i] for i in xrange(rfdscount)] else: import msvcrt _kernel32 = ctypes.windll.kernel32 _DWORD = ctypes.c_ulong _LPCSTR = _LPSTR = ctypes.c_char_p _HANDLE = ctypes.c_void_p _INVALID_HANDLE_VALUE = _HANDLE(-1).value # CreateFile _FILE_SHARE_READ = 0x00000001 _FILE_SHARE_WRITE = 0x00000002 _FILE_SHARE_DELETE = 0x00000004 _CREATE_ALWAYS = 2 _OPEN_EXISTING = 3 _OPEN_ALWAYS = 4 _GENERIC_READ = 0x80000000 _GENERIC_WRITE = 0x40000000 _FILE_ATTRIBUTE_NORMAL = 0x80 # open_osfhandle flags _O_RDONLY = 0x0000 _O_RDWR = 0x0002 _O_APPEND = 0x0008 _O_TEXT = 0x4000 _O_BINARY = 0x8000 # types of parameters of C functions used (required by pypy) _kernel32.CreateFileA.argtypes = [_LPCSTR, _DWORD, _DWORD, ctypes.c_void_p, _DWORD, _DWORD, _HANDLE] _kernel32.CreateFileA.restype = _HANDLE def _raiseioerror(name): err = ctypes.WinError() raise IOError(err.errno, '%s: %s' % (name, err.strerror)) class posixfile(object): '''a file object aiming for POSIX-like semantics CPython's open() returns a file that was opened *without* setting the _FILE_SHARE_DELETE flag, which causes rename and unlink to abort. This even happens if any hardlinked copy of the file is in open state. We set _FILE_SHARE_DELETE here, so files opened with posixfile can be renamed and deleted while they are held open. Note that if a file opened with posixfile is unlinked, the file remains but cannot be opened again or be recreated under the same name, until all reading processes have closed the file.''' def __init__(self, name, mode='r', bufsize=-1): if 'b' in mode: flags = _O_BINARY else: flags = _O_TEXT m0 = mode[0] if m0 == 'r' and '+' not in mode: flags |= _O_RDONLY access = _GENERIC_READ else: # work around http://support.microsoft.com/kb/899149 and # set _O_RDWR for 'w' and 'a', even if mode has no '+' flags |= _O_RDWR access = _GENERIC_READ | _GENERIC_WRITE if m0 == 'r': creation = _OPEN_EXISTING elif m0 == 'w': creation = _CREATE_ALWAYS elif m0 == 'a': creation = _OPEN_ALWAYS flags |= _O_APPEND else: raise ValueError("invalid mode: %s" % mode) fh = _kernel32.CreateFileA(name, access, _FILE_SHARE_READ | _FILE_SHARE_WRITE | _FILE_SHARE_DELETE, None, creation, _FILE_ATTRIBUTE_NORMAL, None) if fh == _INVALID_HANDLE_VALUE: _raiseioerror(name) fd = msvcrt.open_osfhandle(fh, flags) if fd == -1: _kernel32.CloseHandle(fh) _raiseioerror(name) f = os.fdopen(fd, mode, bufsize) # unfortunately, f.name is '<fdopen>' at this point -- so we store # the name on this wrapper. We cannot just assign to f.name, # because that attribute is read-only. object.__setattr__(self, 'name', name) object.__setattr__(self, '_file', f) def __iter__(self): return self._file def __getattr__(self, name): return getattr(self._file, name) def __setattr__(self, name, value): '''mimics the read-only attributes of Python file objects by raising 'TypeError: readonly attribute' if someone tries: f = posixfile('foo.txt') f.name = 'bla' ''' return self._file.__setattr__(name, value) def __enter__(self): return self._file.__enter__() def __exit__(self, exc_type, exc_value, exc_tb): return self._file.__exit__(exc_type, exc_value, exc_tb)