hg: obtain lock when creating share from pooled repo (issue5104)
There are race conditions between clients performing a shared clone
to pooled storage:
1) Clients race to create the new shared repo in the pool directory
2) 1 client is seeding the repo in the pool directory and another goes
to share it before it is fully cloned
We prevent these race conditions by obtaining a lock in the pool
directory that is derived from the name of the repo we will be
accessing.
To test this, a simple generic "lockdelay" extension has been added.
The extension inserts an optional, configurable delay before or after
lock acquisition. In the test, we delay 2 seconds after lock acquisition
in the first process and 1 second before lock acquisition in the 2nd
process. This means the first process has 1s to obtain the lock. There
is a race condition here. If we encounter it in the wild, we could
change the dummy extension to wait on the lock file to appear instead
of relying on timing. But that's more complicated. Let's see what
happens first.
#!/usr/bin/env python
#
# Copyright 2014 Matt Mackall <mpm@selenic.com>
#
# A tool/hook to run basic sanity checks on commits/patches for
# submission to Mercurial. Install by adding the following to your
# .hg/hgrc:
#
# [hooks]
# pretxncommit = contrib/check-commit
#
# The hook can be temporarily bypassed with:
#
# $ BYPASS= hg commit
#
# See also: https://mercurial-scm.org/wiki/ContributingChanges
import re, sys, os
commitheader = r"^(?:# [^\n]*\n)*"
afterheader = commitheader + r"(?!#)"
beforepatch = afterheader + r"(?!\n(?!@@))"
errors = [
(beforepatch + r".*[(]bc[)]", "(BC) needs to be uppercase"),
(beforepatch + r".*[(]issue \d\d\d", "no space allowed between issue and number"),
(beforepatch + r".*[(]bug(\d|\s)", "use (issueDDDD) instead of bug"),
(commitheader + r"# User [^@\n]+\n", "username is not an email address"),
(commitheader + r"(?!merge with )[^#]\S+[^:] ",
"summary line doesn't start with 'topic: '"),
(afterheader + r"[A-Z][a-z]\S+", "don't capitalize summary lines"),
(afterheader + r"[^\n]*: *[A-Z][a-z]\S+", "don't capitalize summary lines"),
(afterheader + r"\S*[^A-Za-z0-9-]\S*: ",
"summary keyword should be most user-relevant one-word command or topic"),
(afterheader + r".*\.\s*\n", "don't add trailing period on summary line"),
(afterheader + r".{79,}", "summary line too long (limit is 78)"),
(r"\n\+\n \n", "adds double empty line"),
(r"\n \n\+\n", "adds double empty line"),
(r"\n\+[ \t]+def [a-z]+_[a-z]", "adds a function with foo_bar naming"),
]
word = re.compile('\S')
def nonempty(first, second):
if word.search(first):
return first
return second
def checkcommit(commit, node = None):
exitcode = 0
printed = node is None
hits = []
for exp, msg in errors:
m = re.search(exp, commit)
if m:
end = m.end()
trailing = re.search(r'(\\n)+$', exp)
if trailing:
end -= len(trailing.group()) / 2
hits.append((end, exp, msg))
if hits:
hits.sort()
pos = 0
last = ''
for n, l in enumerate(commit.splitlines(True)):
pos += len(l)
while len(hits):
end, exp, msg = hits[0]
if pos < end:
break
if not printed:
printed = True
print "node: %s" % node
print "%d: %s" % (n, msg)
print " %s" % nonempty(l, last)[:-1]
if "BYPASS" not in os.environ:
exitcode = 1
del hits[0]
last = nonempty(l, last)
return exitcode
def readcommit(node):
return os.popen("hg export %s" % node).read()
if __name__ == "__main__":
exitcode = 0
node = os.environ.get("HG_NODE")
if node:
commit = readcommit(node)
exitcode = checkcommit(commit)
elif sys.argv[1:]:
for node in sys.argv[1:]:
exitcode |= checkcommit(readcommit(node), node)
else:
commit = sys.stdin.read()
exitcode = checkcommit(commit)
sys.exit(exitcode)