branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
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()