bdiff: give slight preference to appending lines
[This change could be folded into the previous changeset to minimize the repo
churn ...]
The general preference to matches in the middle of bdiff ranges helps getting
balanced recursion and efficient computation. But, as previous changes have
shown, it might also give diffs that seems "obviously wrong".
To mitigate that: If the best match on the A side starts at the beginning of
the bdiff range, don't aim for the middle-most B side match but for the
earliest.
This will make the matches balanced (by both sides being "early") even though
the bisection will be less balanced. Still, this case only apply if the *best*
and middle-most match was fully unbalanced on the A side. Each recursion will
thus even in this worst case reduce the problem significantly and we are not
re-introducing the problem that was fixed in
f1ca249696ed.
The bundle size for 4.0 (hg bundle --base null -r 4.0 x.hg) happens to go from
22806817 to
22807275 bytes - a 0.002% increase.
This make the recent test-bdiff.py changes give a more pretty output ... but
they no longer show that the recursion is around middle matches (because it in
these cases isn't).
# 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
from . import (
policy,
pycompat,
)
modulepolicy = policy.policy
policynocffi = policy.policynocffi
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 listdirpure(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(pycompat.ossep):
prefix += pycompat.ossep
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
ffi = None
if modulepolicy not in policynocffi and sys.platform == 'darwin':
try:
from _osutil_cffi import ffi, lib
except ImportError:
if modulepolicy == 'cffi': # strict cffi import
raise
if sys.platform == 'darwin' and ffi is not None:
listdir_batch_size = 4096
# tweakable number, only affects performance, which chunks
# of bytes do we get back from getattrlistbulk
attrkinds = [None] * 20 # we need the max no for enum VXXX, 20 is plenty
attrkinds[lib.VREG] = statmod.S_IFREG
attrkinds[lib.VDIR] = statmod.S_IFDIR
attrkinds[lib.VLNK] = statmod.S_IFLNK
attrkinds[lib.VBLK] = statmod.S_IFBLK
attrkinds[lib.VCHR] = statmod.S_IFCHR
attrkinds[lib.VFIFO] = statmod.S_IFIFO
attrkinds[lib.VSOCK] = statmod.S_IFSOCK
class stat_res(object):
def __init__(self, st_mode, st_mtime, st_size):
self.st_mode = st_mode
self.st_mtime = st_mtime
self.st_size = st_size
tv_sec_ofs = ffi.offsetof("struct timespec", "tv_sec")
buf = ffi.new("char[]", listdir_batch_size)
def listdirinternal(dfd, req, stat, skip):
ret = []
while True:
r = lib.getattrlistbulk(dfd, req, buf, listdir_batch_size, 0)
if r == 0:
break
if r == -1:
raise OSError(ffi.errno, os.strerror(ffi.errno))
cur = ffi.cast("val_attrs_t*", buf)
for i in range(r):
lgt = cur.length
assert lgt == ffi.cast('uint32_t*', cur)[0]
ofs = cur.name_info.attr_dataoffset
str_lgt = cur.name_info.attr_length
base_ofs = ffi.offsetof('val_attrs_t', 'name_info')
name = str(ffi.buffer(ffi.cast("char*", cur) + base_ofs + ofs,
str_lgt - 1))
tp = attrkinds[cur.obj_type]
if name == "." or name == "..":
continue
if skip == name and tp == statmod.S_ISDIR:
return []
if stat:
mtime = cur.mtime.tv_sec
mode = (cur.accessmask & ~lib.S_IFMT)| tp
ret.append((name, tp, stat_res(st_mode=mode, st_mtime=mtime,
st_size=cur.datalength)))
else:
ret.append((name, tp))
cur = ffi.cast("val_attrs_t*", int(ffi.cast("intptr_t", cur))
+ lgt)
return ret
def listdir(path, stat=False, skip=None):
req = ffi.new("struct attrlist*")
req.bitmapcount = lib.ATTR_BIT_MAP_COUNT
req.commonattr = (lib.ATTR_CMN_RETURNED_ATTRS |
lib.ATTR_CMN_NAME |
lib.ATTR_CMN_OBJTYPE |
lib.ATTR_CMN_ACCESSMASK |
lib.ATTR_CMN_MODTIME)
req.fileattr = lib.ATTR_FILE_DATALENGTH
dfd = lib.open(path, lib.O_RDONLY, 0)
if dfd == -1:
raise OSError(ffi.errno, os.strerror(ffi.errno))
try:
ret = listdirinternal(dfd, req, stat, skip)
finally:
try:
lib.close(dfd)
except BaseException:
pass # we ignore all the errors from closing, not
# much we can do about that
return ret
else:
listdir = listdirpure
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_ = [
(u'iov_base', ctypes.c_void_p),
(u'iov_len', ctypes.c_size_t),
]
class _msghdr(ctypes.Structure):
_fields_ = [
(u'msg_name', ctypes.c_void_p),
(u'msg_namelen', _socklen_t),
(u'msg_iov', ctypes.POINTER(_iovec)),
(u'msg_iovlen', _msg_iovlen_t),
(u'msg_control', ctypes.c_void_p),
(u'msg_controllen', _msg_controllen_t),
(u'msg_flags', ctypes.c_int),
]
class _cmsghdr(ctypes.Structure):
_fields_ = [
(u'cmsg_len', _cmsg_len_t),
(u'cmsg_level', ctypes.c_int),
(u'cmsg_type', ctypes.c_int),
(u'cmsg_data', ctypes.c_ubyte * 0),
]
_libc = ctypes.CDLL(ctypes.util.find_library(u'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)