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
"""
Tests the behavior of filelog w.r.t. data starting with '\1\n'
"""
from mercurial import ui, hg
from mercurial.node import nullid, hex
myui = ui.ui()
repo = hg.repository(myui, path='.', create=True)
fl = repo.file('foobar')
def addrev(text, renamed=False):
if renamed:
# data doesn't matter. Just make sure filelog.renamed() returns True
meta = {'copyrev': hex(nullid), 'copy': 'bar'}
else:
meta = {}
lock = t = None
try:
lock = repo.lock()
t = repo.transaction('commit')
node = fl.add(text, meta, t, 0, nullid, nullid)
return node
finally:
if t:
t.close()
if lock:
lock.release()
def error(text):
print 'ERROR: ' + text
textwith = '\1\nfoo'
without = 'foo'
node = addrev(textwith)
if not textwith == fl.read(node):
error('filelog.read for data starting with \\1\\n')
if fl.cmp(node, textwith) or not fl.cmp(node, without):
error('filelog.cmp for data starting with \\1\\n')
if fl.size(0) != len(textwith):
error('FIXME: This is a known failure of filelog.size for data starting '
'with \\1\\n')
node = addrev(textwith, renamed=True)
if not textwith == fl.read(node):
error('filelog.read for a renaming + data starting with \\1\\n')
if fl.cmp(node, textwith) or not fl.cmp(node, without):
error('filelog.cmp for a renaming + data starting with \\1\\n')
if fl.size(1) != len(textwith):
error('filelog.size for a renaming + data starting with \\1\\n')
print 'OK.'