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.
#!/usr/bin/env python3
# Undump a dump from dumprevlog
# $ hg init
# $ undumprevlog < repo.dump
import sys
from mercurial.node import bin
from mercurial import (
encoding,
revlog,
transaction,
vfs as vfsmod,
)
from mercurial.utils import procutil
from mercurial.revlogutils import (
constants as revlog_constants,
)
for fp in (sys.stdin, sys.stdout, sys.stderr):
procutil.setbinary(fp)
opener = vfsmod.vfs(b'.', False)
tr = transaction.transaction(
sys.stderr.write, opener, {b'store': opener}, b"undump.journal"
)
while True:
l = sys.stdin.readline()
if not l:
break
if l.startswith("file:"):
f = encoding.strtolocal(l[6:-1])
assert f.endswith(b'.i')
r = revlog.revlog(
opener,
target=(revlog_constants.KIND_OTHER, b'undump-revlog'),
radix=f[:-2],
)
procutil.stdout.write(b'%s\n' % f)
elif l.startswith("node:"):
n = bin(l[6:-1])
elif l.startswith("linkrev:"):
lr = int(l[9:-1])
elif l.startswith("parents:"):
p = l[9:-1].split()
p1 = bin(p[0])
p2 = bin(p[1])
elif l.startswith("length:"):
length = int(l[8:-1])
sys.stdin.readline() # start marker
d = encoding.strtolocal(sys.stdin.read(length))
sys.stdin.readline() # end marker
r.addrevision(d, tr, lr, p1, p2)
tr.close()