def test_params_for_capacity(self):
"""
Tests that the parameters that are generated for a given
capacity and probability are correct given known sane values.
"""
# From http://hur.st/bloomfilter?n=1e6&p=1e-4
bytes, k = pyBloom.params_for_capacity(1e6, 1e-4)
assert bytes - pyBloom.extra_buffer() == round(19170117 / 8.0)
assert k == 14 # Parameters uses the ceiling instead of rounding
def get_bloom(cls, bloom_data):
bloom_args = (100000, .01)
if bloom_data:
size, ideal_k = BloomFilter.params_for_capacity(*bloom_args)
bitmap = Bitmap(size)
bitmap.mmap = bloom_data
return BloomFilter(bitmap, ideal_k)
else:
bf = BloomFilter.for_capacity(*bloom_args)
logging.debug("get_bloom(): data size %dkB" %
round(len(bf.bitmap.mmap) / 1024))
return bf
def test_swap_2(self):
"""
Swaps the mmap files from one implementation to another,
check that things work. Start with pyBloom, then cBloom.
"""
bytes, k = pyBloom.params_for_capacity(2e4, 1e-3)
bitmap = Bitmap(bytes, "testswap2.mmap")
bf1 = pyBloom(bitmap, k)
[bf1.add("foo%d" % x) for x in xrange(20000)]
bf1.close()
# Make a new bitmap
bitmap = Bitmap(bytes, "testswap2.mmap")
bf2 = cBloom(bitmap, 50)
assert len(bf2) == 20000 # Should reload size and k
assert bf2.k_num == k
# Check all the entries
assert all([bf2.__contains__("foo%d" % x) for x in xrange(20000)])
bf2.close()
