vfs: use checkambigatclosing in checkambig=True but atomictemp=False case
In Mercurial source tree, opening a file in "a"/"a+" mode like below
doesn't specify atomictemp=True for vfs, and this avoids file stat
ambiguity check by atomictempfile.
- writing changes out in revlog layer uses "a+" mode
- truncation in repair.strip() uses "a" mode
- truncation in transaction._playback() uses "a" mode
If steps below occurs at "the same time in sec", all of mtime, ctime
and size are same between (1) and (3).
1. append data to revlog-style file (and close transaction)
2. discard appended data by truncation (strip or rollback)
3. append same size but different data to revlog-style file again
Therefore, cache validation doesn't work after (3) as expected.
This patch uses checkambigatclosing in checkambig=True but
atomictemp=False case, to check (and get rid of) file stat ambiguity
at closing.
This is a part of ExactCacheValidationPlan.
https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan
from __future__ import absolute_import, print_function
from mercurial import (
util,
)
def printifpresent(d, xs, name='d'):
for x in xs:
present = x in d
print("'%s' in %s: %s" % (x, name, present))
if present:
print("%s['%s']: %s" % (name, x, d[x]))
def test_lrucachedict():
d = util.lrucachedict(4)
d['a'] = 'va'
d['b'] = 'vb'
d['c'] = 'vc'
d['d'] = 'vd'
# all of these should be present
printifpresent(d, ['a', 'b', 'c', 'd'])
# 'a' should be dropped because it was least recently used
d['e'] = 've'
printifpresent(d, ['a', 'b', 'c', 'd', 'e'])
assert d.get('a') is None
assert d.get('e') == 've'
# touch entries in some order (get or set).
d['e']
d['c'] = 'vc2'
d['d']
d['b'] = 'vb2'
# 'e' should be dropped now
d['f'] = 'vf'
printifpresent(d, ['b', 'c', 'd', 'e', 'f'])
d.clear()
printifpresent(d, ['b', 'c', 'd', 'e', 'f'])
# Now test dicts that aren't full.
d = util.lrucachedict(4)
d['a'] = 1
d['b'] = 2
d['a']
d['b']
printifpresent(d, ['a', 'b'])
# test copy method
d = util.lrucachedict(4)
d['a'] = 'va3'
d['b'] = 'vb3'
d['c'] = 'vc3'
d['d'] = 'vd3'
dc = d.copy()
# all of these should be present
print("\nAll of these should be present:")
printifpresent(dc, ['a', 'b', 'c', 'd'], 'dc')
# 'a' should be dropped because it was least recently used
print("\nAll of these except 'a' should be present:")
dc['e'] = 've3'
printifpresent(dc, ['a', 'b', 'c', 'd', 'e'], 'dc')
# contents and order of original dict should remain unchanged
print("\nThese should be in reverse alphabetical order and read 'v?3':")
dc['b'] = 'vb3_new'
for k in list(iter(d)):
print("d['%s']: %s" % (k, d[k]))
if __name__ == '__main__':
test_lrucachedict()