research/casper/networksim.py

from distributions import transform, normal_distribution
import random


class NetworkSimulator():

    def __init__(self):
        self.agents = []
        self.latency_distribution_sample = transform(normal_distribution(50, 20), lambda x: max(x, 0))
        self.time = 0
        self.objqueue = {}
        self.peers = {}
        self.reliability = 0.9

    def generate_peers(self, num_peers=5):
        self.peers = {}
        for a in self.agents:
            p = []
            while len(p) <= num_peers // 2:
                p.append(random.choice(self.agents))
                if p[-1] == a:
                    p.pop()
            self.peers[a.id] = self.peers.get(a.id, []) + p
            for peer in p:
                self.peers[peer.id] = self.peers.get(peer.id, []) + [a]

    def tick(self):
        if self.time in self.objqueue:
            for recipient, obj in self.objqueue[self.time]:
                if random.random() < self.reliability:
                    recipient.on_receive(obj)
            del self.objqueue[self.time]
        for a in self.agents:
            a.tick()
        self.time += 1

    def run(self, steps):
        for i in range(steps):
            self.tick()

    def broadcast(self, sender, obj):
        for p in self.peers[sender.id]:
            recv_time = self.time + self.latency_distribution_sample()
            if recv_time not in self.objqueue:
                self.objqueue[recv_time] = []
            self.objqueue[recv_time].append((p, obj))

    def direct_send(self, to_id, obj):
        for a in self.agents:
            if a.id == to_id:
                recv_time = self.time + self.latency_distribution_sample()
                if recv_time not in self.objqueue:
                    self.objqueue[recv_time] = []
                self.objqueue[recv_time].append((a, obj))

    def knock_offline_random(self, n):
        ko = {}
        while len(ko) < n:
            c = random.choice(self.agents)
            ko[c.id] = c
        for c in ko.values():
            self.peers[c.id] = []
        for a in self.agents:
            self.peers[a.id] = [x for x in self.peers[a.id] if x.id not in ko]

    def partition(self):
        a = {}
        while len(a) < len(self.agents) / 2:
            c = random.choice(self.agents)
            a[c.id] = c
        for c in self.agents:
            if c.id in a:
                self.peers[c.id] = [x for x in self.peers[c.id] if x.id in a]
            else:
                self.peers[c.id] = [x for x in self.peers[c.id] if x.id not in a]