From: Brian Warner Date: Tue, 28 Nov 2006 23:27:08 +0000 (-0700) Subject: added a simulator tool X-Git-Tag: tahoe_v0.1.0-0-UNSTABLE~552 X-Git-Url: https://git.rkrishnan.org/specifications/%5B/%5D%20/flags/provisioning?a=commitdiff_plain;h=85df9e8a4bba4f0e94a9b8edbf6d425aaaf58ad4;p=tahoe-lafs%2Ftahoe-lafs.git added a simulator tool --- diff --git a/simulator.py b/simulator.py new file mode 100644 index 00000000..31335cdd --- /dev/null +++ b/simulator.py @@ -0,0 +1,253 @@ +#! /usr/bin/python + +import sha as shamodule +import os, random +import rrdtool + +def sha(s): + return shamodule.new(s).digest() + +def randomid(): + return os.urandom(20) + +class Node: + def __init__(self, nid, queen, simulator): + self.nid = nid + self.queen = queen + self.simulator = simulator + self.shares = {} + self.capacity = random.randrange(1000) + self.utilization = 0 + self.files = [] + + def permute_peers(self, fileid): + permuted = [(sha(fileid+n.nid),n) + for n in self.queen.get_all_nodes()] + permuted.sort() + return permuted + + def publish_file(self, fileid, size, numshares=100): + sharesize = 4 * size / numshares + permuted = self.permute_peers(fileid) + last_givento = None + tried = 0 + givento = [] + while numshares and permuted: + pid,node = permuted.pop(0) + tried += 1 + last_givento = node + if node.accept_share(fileid, sharesize): + givento.append((pid,node)) + numshares -= 1 + if numshares: + # couldn't push, should delete + for pid,node in givento: + node.delete_share(fileid) + return False + self.files.append((fileid, numshares)) + self.queen.please_preserve(fileid, size, tried, last_givento) + return (True, tried) + + def accept_share(self, fileid, sharesize): + accept = False + if self.utilization < self.capacity: + # we have room! yay! + self.shares[fileid] = sharesize + self.utilization += sharesize + return True + if self.decide(sharesize): + # we don't, but we'll make room + self.make_space(sharesize) + self.shares[fileid] = sharesize + self.utilization += sharesize + return True + else: + # we're full, try elsewhere + return False + + def decide(self, sharesize): + if sharesize > self.capacity: + return False + return False + return random.random() > 0.5 + + def make_space(self, sharesize): + assert sharesize <= self.capacity + while self.capacity - self.utilization < sharesize: + victim = random.choice(self.shares.keys()) + self.simulator.lost_data(self.shares[victim]) + self.delete_share(victim) + + def delete_share(self, fileid): + if fileid in self.shares: + self.utilization -= self.shares[fileid] + del self.shares[fileid] + return True + return False + + def retrieve_file(self): + if not self.files: + return + fileid,numshares = random.choice(self.files) + needed = numshares / 4 + peers = [] + for pid,node in self.permute_peers(fileid): + if random.random() > self.simulator.P_NODEAVAIL: + continue # node isn't available right now + if node.has_share(fileid): + peers.append(node) + if len(peers) >= needed: + return True + return False + + def delete_file(self): + if not self.files: + return False + which = random.choice(self.files) + self.files.remove(which) + fileid,numshares = which + self.queen.delete(fileid) + return True + +class Queen: + def __init__(self): + self.living_files = {} + self.utilization = 0 # total size of all active files + + def get_all_nodes(self): + return self.all_nodes + + def please_preserve(self, fileid, size, tried, last_givento): + self.living_files[fileid] = (size, tried, last_givento) + self.utilization += size + + def please_delete(self, fileid): + self.delete(fileid) + + + def permute_peers(self, fileid): + permuted = [(sha(fileid+n.nid),n) + for n in self.get_all_nodes()] + permuted.sort() + return permuted + + def delete(self, fileid): + peers = self.permute_peers(fileid) + size, tried, last_givento = self.living_files[fileid] + peer = "" + while tried and peer < last_givento: + peer,node = permuted.pop(0) + had_it = node.delete_share(fileid) + if had_it: + tried -= 1 + self.utilization -= size + del self.living_files[fileid] + +class Simulator: + NUM_NODES = 1000 + EVENTS = ["ADDFILE", "DELFILE", "ADDNODE", "DELNODE"] + RATE_ADDFILE = 1.0 / 10 + RATE_DELFILE = 1.0 / 20 + RATE_ADDNODE = 1.0 / 3000 + RATE_DELNODE = 1.0 / 4000 + P_NODEAVAIL = 1.0 + + def __init__(self): + self.queen = q = Queen() + self.all_nodes = [Node(randomid(), q, self) + for i in range(self.NUM_NODES)] + q.all_nodes = self.all_nodes + self.time = 0 + self.next = [] + self.schedule_events() + self.verbose = False + + self.added_files = 0 + self.added_data = 0 + self.deleted_files = 0 + self.published_files = [] + self.failed_files = 0 + self.lost_data_bytes = 0 # bytes deleted to make room for new shares + + def add_file(self): + size = random.randrange(1000) + n = random.choice(self.all_nodes) + if self.verbose: + print "add_file(size=%d, from node %s)" % (size, n) + fileid = randomid() + able = n.publish_file(fileid, size) + if able: + able, tried = able + self.added_files += 1 + self.added_data += size + self.published_files.append(tried) + else: + self.failed_files += 1 + + def lost_data(self, size): + self.lost_data_bytes += size + + def delete_file(self): + all_nodes = self.all_nodes[:] + random.shuffle(all_nodes) + for n in all_nodes: + if n.delete_file(): + self.deleted_files += 1 + return + print "no files to delete" + + def _add_event(self, etype): + rate = getattr(self, "RATE_" + etype) + next = self.time + random.expovariate(rate) + self.next.append((next, etype)) + self.next.sort() + + def schedule_events(self): + types = set([e[1] for e in self.next]) + for etype in self.EVENTS: + if not etype in types: + self._add_event(etype) + + def do_event(self): + time, etype = self.next.pop(0) + assert time > self.time + current_time = self.time + self.time = time + self._add_event(etype) + if etype == "ADDFILE": + self.add_file() + elif etype == "DELFILE": + self.delete_file() + elif etype == "ADDNODE": + pass + #self.add_node() + elif etype == "DELNODE": + #self.del_node() + pass + self.print_stats(current_time, etype) + + def print_stats_header(self): + print "time: added failed lost avg_tried" + + def print_stats(self, time, etype): + if not self.published_files: + avg_tried = "NONE" + else: + avg_tried = sum(self.published_files) / len(self.published_files) + print time, etype, self.added_data, self.failed_files, self.lost_data_bytes, avg_tried, len(self.queen.living_files), self.queen.utilization + +def main(): +# rrdtool.create("foo.rrd", +# "--step 10", +# "DS:files-added:DERIVE::0:1000", +# "RRA:AVERAGE:1:1:1200", +# ) + s = Simulator() + s.print_stats_header() + for i in range(1000): + s.do_event() + print "%d files added, %d files deleted" % (s.added_files, s.deleted_files) + return s + +if __name__ == '__main__': + main()