##// END OF EJS Templates
revlog: improve the robustness of the splitting process...
revlog: improve the robustness of the splitting process The previous "in-place" splitting, preserving the splitting on transaction failure had a couple of issue in case of transaction rollback: - a race windows that could still lead to a crash and data loss - it corrupted the `fncache`. So instead, we use a new approach that we summarized as "we do a backup of the inline revlog pre-split, and we restore this in case of failure". To make readers live easier, we don't overwrite the inline index file until transaction finalization. (once the transaction get into its finalization phase, it is not expected to rollback, unless some crash happens). To do so, we write the index of the split index in a temporary file that we use until transaction finalization. We also keep a backup of the initial inline file to be able to rollback the split if needed. As a result, transaction rollback cancel the split and no longer corrupt fncache. We also no longer have a small inconsistency windows where the transaction could be unrecoverable.

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osutil.py
114 lines | 3.8 KiB | text/x-python | PythonLexer
# osutil.py - CFFI version of osutil.c
#
# Copyright 2016 Maciej Fijalkowski <fijall@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import os
import stat as statmod
from ..pure.osutil import *
from .. import pycompat
if pycompat.isdarwin:
from . import _osutil # pytype: disable=import-error
ffi = _osutil.ffi
lib = _osutil.lib
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:
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(b"struct timespec", b"tv_sec")
buf = ffi.new(b"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(b"val_attrs_t*", buf)
for i in range(r):
lgt = cur.length
assert lgt == ffi.cast(b'uint32_t*', cur)[0]
ofs = cur.name_info.attr_dataoffset
str_lgt = cur.name_info.attr_length
base_ofs = ffi.offsetof(b'val_attrs_t', b'name_info')
name = bytes(
ffi.buffer(
ffi.cast(b"char*", cur) + base_ofs + ofs, str_lgt - 1
)
)
tp = attrkinds[cur.obj_type]
if name == b"." or name == b"..":
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(
b"val_attrs_t*", int(ffi.cast(b"intptr_t", cur)) + lgt
)
return ret
def listdir(path, stat=False, skip=None):
req = ffi.new(b"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