#!/usr/bin/env python
from igraph import *
from threading import Thread
from time import sleep, time

class DiameterCalculation(Thread):
    def __init__(self, graph):
        # Call superclass constructor
        Thread.__init__(self)
        # Mark it a daemon thread so Ctrl-C interrupts the calculation
        self.setDaemon(True)
        # Initialize progress counter
        self.progress = 0.
        self.result = None
        # Store the graph locally
        self.g = graph

    def run(self):
        n = self.g.vcount()
        max_distance = 0
        for i in xrange(n):
            # Do some tedious calculation
            max_distance = max(max_distance, max(g.shortest_paths(i)[0]))
            # Update the progress counter
            self.progress = 100. * (i+1) / n
            # Let other threads run every now and then
            sleep(0.000001)
        # Return the result
        self.result = max_distance

print "Generating graph..."
g = Graph.Barabasi(5000)
print "Starting worker thread..."
worker_thread = DiameterCalculation(g)
t1 = time()
worker_thread.start()
while worker_thread.isAlive():
    worker_thread.join(0.1)
    print "Thread progress: %.2f%%" % worker_thread.progress
print "Worker thread exited, result =", worker_thread.result
print "Calculation took %.2fs" % (time() - t1)