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# Generate incompressible random data in various ways, and measure speeds.
import random
import gc
import timeit
import hashlib
import zlib
def randint(size):
"""just call random.randint(0, 255)"""
bytes = []
for i in range(size):
bytes.append(chr(random.randint(0, 255)))
return "".join(bytes)
def getrandbits(size):
"""just call random.getrandbits(8)"""
bytes = []
for i in range(size):
bytes.append(chr(random.getrandbits(8)))
return "".join(bytes)
def md5ofgetrandbits(size):
"""catenate successive MD5 of random byte stream"""
chunks = []
sum = hashlib.md5()
while size > 0:
sum.update(chr(random.getrandbits(8)))
chunk = sum.digest()
chunks.append(chunk)
size -= len(chunk)
if size < 0:
chunks[-1] = chunks[-1][:size]
return "".join(chunks)
def md5ofgetrandbits2(size):
"""catenate successive MD5 of random byte stream"""
chunks = []
sum = hashlib.md5()
for i in range(size/16):
sum.update(chr(random.getrandbits(8)))
chunk = sum.digest()
chunks.append(chunk)
if len(chunks) * 16 < size:
sum.update(chr(random.getrandbits(8)))
chunk = sum.digest()
chunks.append(chunk[:size % 16])
return "".join(chunks)
def sha1ofgetrandbits(size):
"""catenate successive SHA1 of random byte stream"""
chunks = []
sum = hashlib.sha1()
while size > 0:
sum.update(chr(random.getrandbits(8)))
chunk = sum.digest()
chunks.append(chunk)
size -= len(chunk)
if size < 0:
chunks[-1] = chunks[-1][:size]
return "".join(chunks)
def sha1ofgetrandbits2(size):
"""catenate successive SHA1 of random byte stream"""
chunks = []
sum = hashlib.sha1()
chunk_size = len(sum.digest())
for byte in [chr(random.getrandbits(8)) for i in xrange(size / chunk_size)]:
sum.update(byte)
chunk = sum.digest()
chunks.append(chunk)
if size % chunk_size > 0:
sum.update(chr(random.getrandbits(8)))
chunk = sum.digest()
chunks.append(chunk[:size % chunk_size])
return "".join(chunks)
def sha512ofgetrandbits(size):
"""catenate successive SHA512 of random byte stream"""
chunks = []
sum = hashlib.sha512()
chunk_size = len(sum.digest())
for byte in [chr(random.getrandbits(8)) for i in xrange(size / chunk_size)]:
sum.update(byte)
chunk = sum.digest()
chunks.append(chunk)
if size % chunk_size > 0:
sum.update(chr(random.getrandbits(8)))
chunk = sum.digest()
chunks.append(chunk[:size % chunk_size])
return "".join(chunks)
def md5ofrandomandstatic(size):
"""MD5 first of random byte stream, then constant"""
chunks = []
sum = hashlib.md5()
initial_size = 128
while size > 0 and initial_size > 0:
sum.update(chr(random.getrandbits(8)))
chunk = sum.digest()
chunks.append(chunk)
size -= len(chunk)
while size > 0:
sum.update("a")
chunk = sum.digest()
chunks.append(chunk)
size -= len(chunk)
if size < 0:
chunks[-1] = chunks[-1][:size]
return "".join(chunks)
def md5ofrandomandstatic2(size):
"""MD5 first of random byte stream, then constant"""
chunks = []
sum = hashlib.md5()
chunk_size = len(sum.digest())
initial_bytes = min(size, chunk_size * 8)
for i in range(initial_bytes / chunk_size):
sum.update(chr(random.getrandbits(8)))
chunks.append(sum.digest())
size -= len(chunks) * chunk_size
for i in range(size / chunk_size):
sum.update("a")
chunks.append(sum.digest())
if size % chunk_size > 0:
sum.update(chr(random.getrandbits(8)))
chunks.append(sum.digest()[:size % chunk_size])
return "".join(chunks)
def sha1ofrandomandstatic2(size):
"""SHA1 first of random byte stream, then constant"""
chunks = []
sum = hashlib.sha1()
chunk_size = len(sum.digest())
initial_bytes = min(size, 128)
for i in range(initial_bytes / chunk_size):
sum.update(chr(random.getrandbits(8)))
chunk = sum.digest()
chunks.append(chunk)
size -= len(chunks) * chunk_size
for i in range(size / chunk_size):
sum.update("a")
chunk = sum.digest()
chunks.append(chunk)
if size % chunk_size > 0:
sum.update(chr(random.getrandbits(8)))
chunk = sum.digest()
chunks.append(chunk[:size % chunk_size])
return "".join(chunks)
funcs = [
randint,
getrandbits,
md5ofgetrandbits,
md5ofgetrandbits2,
sha1ofgetrandbits,
sha1ofgetrandbits2,
md5ofrandomandstatic,
md5ofrandomandstatic2,
sha1ofrandomandstatic2,
sha512ofgetrandbits,
]
def measure(func, block, count):
gc.collect()
timer = timeit.Timer(stmt='%s(%d)' % (func.func_name, block),
setup="from __main__ import %s" % func.func_name)
return min(timer.repeat(repeat=count, number=1))
def check(func, block):
data = func(block)
assert len(data) == block, \
"data is %d bytes, should be %d" % (len(data), block)
assert len(zlib.compress(data)) >= 0.9 * block, \
"compressed data is %d bytes, should be at least %d" % \
(len(zlib.compress(data)), 0.9 * block)
def main():
block = 1024**2
count = 10
print "Measuring %d functions for generating uncompressible binary junk"%\
len(funcs)
print "Each function generates %d times %d bytes" % (count, block)
print "This will take a while"
print
namelen = max(len(func.func_name) for func in funcs)
for func in funcs:
check(func, block)
secs = measure(func, block, count)
speed = block/secs/(1024**2)
print "%4.1f MB/s %-*s %s" % \
(speed, namelen, func.func_name, func.__doc__)
if __name__ == "__main__":
main()
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