localrepo: stop doing special dirstate backup at transaction open
Since the dirstate writes are already managed by the transaction, we already do
a backup of the dirstate when necessary (and even trigger one to keep `hg
rollback` happy).
We needs some special code to deal with the initial empty checkout, but it is
not too complicated.
Managing variable filename (as dirstate-v2 uses) at the "journalfile" level, is
complex and fragile (which is consistent with the fact these files are not
journal…). If we no longer do it, our life is significantly simpler.
In some sense, we apply the xkcd-1134¹ solution to our savebackup/restorebackup
problem.
[1] https://xkcd.com/1134/
(the change to test-hardlink are expect as decreasing the number of duplicated
backup drive the hardlink count down)
import os
import tempfile
from mercurial import (
pycompat,
util,
)
from hgext.fastannotate import error, revmap
def genhsh(i):
return pycompat.bytechr(i) + b'\0' * 19
def gettemppath():
fd, path = tempfile.mkstemp()
os.close(fd)
os.unlink(path)
return path
def ensure(condition):
if not condition:
raise RuntimeError('Unexpected')
def testbasicreadwrite():
path = gettemppath()
rm = revmap.revmap(path)
ensure(rm.maxrev == 0)
for i in range(5):
ensure(rm.rev2hsh(i) is None)
ensure(rm.hsh2rev(b'\0' * 20) is None)
paths = [
b'',
b'a',
None,
b'b',
b'b',
b'c',
b'c',
None,
b'a',
b'b',
b'a',
b'a',
]
for i in range(1, 5):
ensure(rm.append(genhsh(i), sidebranch=(i & 1), path=paths[i]) == i)
ensure(rm.maxrev == 4)
for i in range(1, 5):
ensure(rm.hsh2rev(genhsh(i)) == i)
ensure(rm.rev2hsh(i) == genhsh(i))
# re-load and verify
rm.flush()
rm = revmap.revmap(path)
ensure(rm.maxrev == 4)
for i in range(1, 5):
ensure(rm.hsh2rev(genhsh(i)) == i)
ensure(rm.rev2hsh(i) == genhsh(i))
ensure(bool(rm.rev2flag(i) & revmap.sidebranchflag) == bool(i & 1))
# append without calling save() explicitly
for i in range(5, 12):
ensure(
rm.append(genhsh(i), sidebranch=(i & 1), path=paths[i], flush=True)
== i
)
# re-load and verify
rm = revmap.revmap(path)
ensure(rm.maxrev == 11)
for i in range(1, 12):
ensure(rm.hsh2rev(genhsh(i)) == i)
ensure(rm.rev2hsh(i) == genhsh(i))
ensure(rm.rev2path(i) == paths[i] or paths[i - 1])
ensure(bool(rm.rev2flag(i) & revmap.sidebranchflag) == bool(i & 1))
os.unlink(path)
# missing keys
ensure(rm.rev2hsh(12) is None)
ensure(rm.rev2hsh(0) is None)
ensure(rm.rev2hsh(-1) is None)
ensure(rm.rev2flag(12) is None)
ensure(rm.rev2path(12) is None)
ensure(rm.hsh2rev(b'\1' * 20) is None)
# illformed hash (not 20 bytes)
try:
rm.append(b'\0')
ensure(False)
except Exception:
pass
def testcorruptformat():
path = gettemppath()
# incorrect header
with open(path, 'wb') as f:
f.write(b'NOT A VALID HEADER')
try:
revmap.revmap(path)
ensure(False)
except error.CorruptedFileError:
pass
# rewrite the file
os.unlink(path)
rm = revmap.revmap(path)
rm.append(genhsh(0), flush=True)
rm = revmap.revmap(path)
ensure(rm.maxrev == 1)
# corrupt the file by appending a byte
size = os.stat(path).st_size
with open(path, 'ab') as f:
f.write(b'\xff')
try:
revmap.revmap(path)
ensure(False)
except error.CorruptedFileError:
pass
# corrupt the file by removing the last byte
ensure(size > 0)
with open(path, 'wb') as f:
f.truncate(size - 1)
try:
revmap.revmap(path)
ensure(False)
except error.CorruptedFileError:
pass
os.unlink(path)
def testcopyfrom():
path = gettemppath()
rm = revmap.revmap(path)
for i in range(1, 10):
ensure(
rm.append(genhsh(i), sidebranch=(i & 1), path=(b'%d' % (i // 3)))
== i
)
rm.flush()
# copy rm to rm2
rm2 = revmap.revmap()
rm2.copyfrom(rm)
path2 = gettemppath()
rm2.path = path2
rm2.flush()
# two files should be the same
ensure(len({util.readfile(p) for p in [path, path2]}) == 1)
os.unlink(path)
os.unlink(path2)
class fakefctx:
def __init__(self, node, path=None):
self._node = node
self._path = path
def node(self):
return self._node
def path(self):
return self._path
def testcontains():
path = gettemppath()
rm = revmap.revmap(path)
for i in range(1, 5):
ensure(rm.append(genhsh(i), sidebranch=(i & 1)) == i)
for i in range(1, 5):
ensure(((genhsh(i), None) in rm) == ((i & 1) == 0))
ensure((fakefctx(genhsh(i)) in rm) == ((i & 1) == 0))
for i in range(5, 10):
ensure(fakefctx(genhsh(i)) not in rm)
ensure((genhsh(i), None) not in rm)
# "contains" checks paths
rm = revmap.revmap()
for i in range(1, 5):
ensure(rm.append(genhsh(i), path=(b'%d' % (i // 2))) == i)
for i in range(1, 5):
ensure(fakefctx(genhsh(i), path=(b'%d' % (i // 2))) in rm)
ensure(fakefctx(genhsh(i), path=b'a') not in rm)
def testlastnode():
path = gettemppath()
ensure(revmap.getlastnode(path) is None)
rm = revmap.revmap(path)
ensure(revmap.getlastnode(path) is None)
for i in range(1, 10):
hsh = genhsh(i)
rm.append(hsh, path=(b'%d' % (i // 2)), flush=True)
ensure(revmap.getlastnode(path) == hsh)
rm2 = revmap.revmap(path)
ensure(rm2.rev2hsh(rm2.maxrev) == hsh)
testbasicreadwrite()
testcorruptformat()
testcopyfrom()
testcontains()
testlastnode()