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