tahoe-lafs/misc/simulators/ringsim.py

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#! /usr/bin/python
# used to discuss ticket #302: "stop permuting peerlist?"
# import time
import math
from hashlib import md5 # sha1, sha256
myhash = md5
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# md5: 1520 "uploads" per second
# sha1: 1350 ups
# sha256: 930 ups
from itertools import count
from twisted.python import usage
def abbreviate_space(s, SI=True):
if s is None:
return "unknown"
if SI:
U = 1000.0
isuffix = "B"
else:
U = 1024.0
isuffix = "iB"
def r(count, suffix):
return "%.2f %s%s" % (count, suffix, isuffix)
if s < 1024: # 1000-1023 get emitted as bytes, even in SI mode
return "%d B" % s
if s < U*U:
return r(s/U, "k")
if s < U*U*U:
return r(s/(U*U), "M")
if s < U*U*U*U:
return r(s/(U*U*U), "G")
if s < U*U*U*U*U:
return r(s/(U*U*U*U), "T")
return r(s/(U*U*U*U*U), "P")
def make_up_a_file_size(seed):
h = int(myhash(seed).hexdigest(),16)
max=2**31
if 1: # exponential distribution
e = 8 + (h % (31-8))
return 2 ** e
# uniform distribution
return h % max # avg 1GB
sizes = [make_up_a_file_size(str(i)) for i in range(10000)]
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avg_filesize = sum(sizes)/len(sizes)
print "average file size:", abbreviate_space(avg_filesize)
SERVER_CAPACITY = 10**12
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class Server:
def __init__(self, nodeid, capacity):
self.nodeid = nodeid
self.used = 0
self.capacity = capacity
self.numshares = 0
self.full_at_tick = None
def upload(self, sharesize):
if self.used + sharesize < self.capacity:
self.used += sharesize
self.numshares += 1
return True
return False
def __repr__(self):
if self.full_at_tick is not None:
return "<%s %s full at %d>" % (self.__class__.__name__, self.nodeid, self.full_at_tick)
else:
return "<%s %s>" % (self.__class__.__name__, self.nodeid)
class Ring:
SHOW_MINMAX = False
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def __init__(self, numservers, seed, permute):
self.servers = []
for i in range(numservers):
nodeid = myhash(str(seed)+str(i)).hexdigest()
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capacity = SERVER_CAPACITY
s = Server(nodeid, capacity)
self.servers.append(s)
self.servers.sort(key=lambda s: s.nodeid)
self.permute = permute
#self.list_servers()
def list_servers(self):
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for i in range(len(self.servers)):
s = self.servers[i]
next_s = self.servers[(i+1)%len(self.servers)]
diff = "%032x" % (int(next_s.nodeid,16) - int(s.nodeid,16))
s.next_diff = diff
prev_s = self.servers[(i-1)%len(self.servers)]
diff = "%032x" % (int(s.nodeid,16) - int(prev_s.nodeid,16))
s.prev_diff = diff
print s, s.prev_diff
print "sorted by delta"
for s in sorted(self.servers, key=lambda s:s.prev_diff):
print s, s.prev_diff
def servers_for_si(self, si):
if self.permute:
def sortkey(s):
return myhash(s.nodeid+si).digest()
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return sorted(self.servers, key=sortkey)
for i in range(len(self.servers)):
if self.servers[i].nodeid >= si:
return self.servers[i:] + self.servers[:i]
return list(self.servers)
def show_servers(self, picked):
bits = []
for s in self.servers:
if s in picked:
bits.append("1")
else:
bits.append("0")
#d = [s in picked and "1" or "0" for s in self.servers]
return "".join(bits)
def dump_usage(self, numfiles, avg_space_per_file):
print "uploaded", numfiles
# avg_space_per_file measures expected grid-wide ciphertext per file
used = list(reversed(sorted([s.used for s in self.servers])))
# used is actual per-server ciphertext
usedpf = [1.0*u/numfiles for u in used]
# usedpf is actual per-server-per-file ciphertext
#print "min/max usage: %s/%s" % (abbreviate_space(used[-1]),
# abbreviate_space(used[0]))
avg_usage_per_file = avg_space_per_file/len(self.servers)
# avg_usage_per_file is expected per-server-per-file ciphertext
spreadpf = usedpf[0] - usedpf[-1]
average_usagepf = sum(usedpf) / len(usedpf)
variance = sum([(u-average_usagepf)**2 for u in usedpf])/(len(usedpf)-1)
std_deviation = math.sqrt(variance)
sd_of_total = std_deviation / avg_usage_per_file
print "min/max/(exp) usage-pf-ps %s/%s/(%s):" % (
abbreviate_space(usedpf[-1]),
abbreviate_space(usedpf[0]),
abbreviate_space(avg_usage_per_file) ),
print "spread-pf: %s (%.2f%%)" % (
abbreviate_space(spreadpf), 100.0*spreadpf/avg_usage_per_file),
#print "average_usage:", abbreviate_space(average_usagepf)
print "stddev: %s (%.2f%%)" % (abbreviate_space(std_deviation),
100.0*sd_of_total)
if self.SHOW_MINMAX:
s2 = sorted(self.servers, key=lambda s: s.used)
print "least:", s2[0].nodeid
print "most:", s2[-1].nodeid
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class Options(usage.Options):
optParameters = [
("k", "k", 3, "required shares", int),
("N", "N", 10, "total shares", int),
("servers", None, 100, "number of servers", int),
("seed", None, None, "seed to use for creating ring"),
("fileseed", None, "blah", "seed to use for creating files"),
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("permute", "p", 1, "1 to permute, 0 to use flat ring", int),
]
def postOptions(self):
assert self["seed"]
def do_run(ring, opts):
avg_space_per_file = avg_filesize * opts["N"] / opts["k"]
fileseed = opts["fileseed"]
all_servers_have_room = True
no_files_have_wrapped = True
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for filenum in count(0):
#used = list(reversed(sorted([s.used for s in ring.servers])))
#used = [s.used for s in ring.servers]
#print used
si = myhash(fileseed+str(filenum)).hexdigest()
filesize = make_up_a_file_size(si)
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sharesize = filesize / opts["k"]
if filenum%4000==0 and filenum > 1:
ring.dump_usage(filenum, avg_space_per_file)
servers = ring.servers_for_si(si)
#print ring.show_servers(servers[:opts["N"]])
remaining_shares = opts["N"]
index = 0
server_was_full = False
file_was_wrapped = False
remaining_servers = set(servers)
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while remaining_shares:
if index >= len(servers):
index = 0
file_was_wrapped = True
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s = servers[index]
accepted = s.upload(sharesize)
if not accepted:
server_was_full = True
remaining_servers.discard(s)
if not remaining_servers:
print "-- GRID IS FULL"
ring.dump_usage(filenum, avg_space_per_file)
return filenum
index += 1
continue
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remaining_shares -= 1
index += 1
# file is done being uploaded
if server_was_full and all_servers_have_room:
all_servers_have_room = False
print "-- FIRST SERVER FULL"
ring.dump_usage(filenum, avg_space_per_file)
if file_was_wrapped and no_files_have_wrapped:
no_files_have_wrapped = False
print "-- FIRST FILE WRAPPED"
ring.dump_usage(filenum, avg_space_per_file)
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def do_ring(opts):
total_capacity = opts["servers"]*SERVER_CAPACITY
avg_space_per_file = avg_filesize * opts["N"] / opts["k"]
avg_files = total_capacity / avg_space_per_file
print "expected number of uploads:", avg_files
if opts["permute"]:
print " PERMUTED"
else:
print " LINEAR"
seed = opts["seed"]
ring = Ring(opts["servers"], seed, opts["permute"])
do_run(ring, opts)
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def run(opts):
do_ring(opts)
if __name__ == "__main__":
opts = Options()
opts.parseOptions()
run(opts)