def test_fetch_next_hash():
jc = JitCounter(size=2048)
# check the distribution of "fetch_next_hash() & ~7".
blocks = [[jc.fetch_next_hash() & ~7 for i in range(65536)] for j in range(2)]
for block in blocks:
assert 0 <= jc._get_index(block[0]) < 2048
assert 0 <= jc._get_index(block[-1]) < 2048
assert 0 <= jc._get_index(block[2531]) < 2048
assert 0 <= jc._get_index(block[45981]) < 2048
# should be correctly distributed: ideally 2047 or 2048 different
# values
assert len(set([jc._get_index(x) for x in block])) >= 2040
# check that the subkeys are distinct for same-block entries
subkeys = {}
for block in blocks:
for x in block:
idx = jc._get_index(x)
subkeys.setdefault(idx, []).append(jc._get_subhash(x))
collisions = 0
for idx, sks in subkeys.items():
collisions += len(sks) - len(set(sks))
assert collisions < 5
def test_fetch_next_hash():
jc = JitCounter(size=2048)
# check the distribution of "fetch_next_hash() & ~7".
blocks = [[jc.fetch_next_hash() & ~7 for i in range(65536)]
for j in range(2)]
for block in blocks:
assert 0 <= jc._get_index(block[0]) < 2048
assert 0 <= jc._get_index(block[-1]) < 2048
assert 0 <= jc._get_index(block[2531]) < 2048
assert 0 <= jc._get_index(block[45981]) < 2048
# should be correctly distributed: ideally 2047 or 2048 different
# values
assert len(set([jc._get_index(x) for x in block])) >= 2040
# check that the subkeys are distinct for same-block entries
subkeys = {}
for block in blocks:
for x in block:
idx = jc._get_index(x)
subkeys.setdefault(idx, []).append(jc._get_subhash(x))
collisions = 0
for idx, sks in subkeys.items():
collisions += len(sks) - len(set(sks))
assert collisions < 5
def test_get_index():
jc = JitCounter(size=128) # 7 bits
for i in range(10):
hash = 400000001 * i
index = jc._get_index(hash)
assert index == (hash >> (32 - 7))
def test_get_index():
jc = JitCounter(size=128) # 7 bits
for i in range(10):
hash = 400000001 * i
index = jc._get_index(hash)
assert index == (hash >> (32 - 7))
