bdiff: don't check border condition in loop
This is pretty much a copy of d500ddae7494, just to a different loop.
The condition `p == plast` (`plast == a + len - 1`) was only true on
the final iteration of the loop. So it was wasteful to check for it
on every iteration. We decrease the iteration count by 1 and add an
explicit check for `p == plast` after the loop.
Again, we see modest wins.
From the mozilla-unified repository:
$ perfbdiff -m 3041e4d59df2
! wall 0.035502 comb 0.040000 user 0.040000 sys 0.000000 (best of 100)
! wall 0.030480 comb 0.030000 user 0.030000 sys 0.000000 (best of 100)
$ perfbdiff 0e9928989e9c --alldata --count 100
! wall 4.097394 comb 4.100000 user 4.100000 sys 0.000000 (best of 3)
! wall 3.597798 comb 3.600000 user 3.600000 sys 0.000000 (best of 3)
The 2nd example throws a total of ~3.3GB of data at bdiff. This
change increases the throughput from ~811 MB/s to ~924 MB/s.
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()