+# Copyright (c) 2006-2021. The SimGrid Team. All rights reserved.
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the license (GNU LGPL) which comes with this package.
+
+# This example shows how to simulate a non-linear resource sharing for
+# network links.
+
+from simgrid import Actor, Engine, Comm, Mailbox, NetZone, Link, LinkInRoute, this_actor
+import sys
+import functools
+
+class Sender:
+ """
+ Send a series of messages to mailbox "receiver"
+ """
+ def __init__(self, msg_count, msg_size=int(1e6)):
+ self.msg_count = msg_count
+ self.msg_size = msg_size
+
+ # Actors that are created as object will execute their __call__ method.
+ # So, the following constitutes the main function of the Sender actor.
+ def __call__(self):
+ pending_comms = []
+ mbox = Mailbox.by_name("receiver")
+
+ for i in range(self.msg_count):
+ msg = "Message " + str(i)
+ size = self.msg_size * (i + 1)
+ this_actor.info("Send '%s' to '%s, msg size: %d'" % (msg, mbox.name, size))
+ comm = mbox.put_async(msg, size)
+ pending_comms.append(comm)
+
+ this_actor.info("Done dispatching all messages")
+
+ # Now that all message exchanges were initiated, wait for their completion in one single call
+ Comm.wait_all(pending_comms)
+
+ this_actor.info("Goodbye now!")
+
+class Receiver:
+ """
+ Receiver actor: wait for N messages on the mailbox "receiver"
+ """
+
+ def __init__(self, msg_count=10):
+ self.msg_count = msg_count
+
+ def __call__(self):
+ mbox = Mailbox.by_name("receiver")
+
+ pending_msgs = []
+ pending_comms = []
+
+ this_actor.info("Wait for %d messages asynchronously" % self.msg_count)
+ for i in range(self.msg_count):
+ comm, data = mbox.get_async()
+ pending_comms.append(comm)
+ pending_msgs.append(data)
+
+ while len(pending_comms) > 0:
+ index = Comm.wait_any(pending_comms)
+ msg = pending_msgs[index].get()
+ this_actor.info("I got '%s'." % msg)
+ del pending_comms[index]
+ del pending_msgs[index]
+
+####################################################################################################
+def link_nonlinear(link, capacity, n):
+ """
+ Non-linear resource sharing for links
+
+ Note that the callback is called twice in this example:
+ 1) link UP: with the number of active flows (from 9 to 1)
+ 2) link DOWN: with 0 active flows. A crosstraffic communication is happing
+ in the down link, but it's not considered as an active flow.
+ """
+ # emulates a degradation in link according to the number of flows
+ # you probably want something more complex than that and based on real
+ # experiments
+ capacity = min(capacity, capacity * (1.0 - (n - 1) / 10.0))
+ this_actor.info("Link %s, %d active communications, new capacity %f" % (link.name, n, capacity))
+ return capacity
+
+def load_platform():
+ """
+ Create a simple 2-hosts platform */
+ ________ __________
+ | Sender |===============| Receiver |
+ |________| Link1 |__________|
+
+ """
+ zone = NetZone.create_full_zone("Zone1")
+ sender = zone.create_host("sender", 1).seal()
+ receiver = zone.create_host("receiver", 1).seal()
+
+ link = zone.create_split_duplex_link("link1", 1e6)
+ # setting same callbacks (could be different) for link UP/DOWN in split-duplex link
+ link.get_link_up().set_sharing_policy(
+ Link.SharingPolicy.NONLINEAR,
+ functools.partial(link_nonlinear, link.get_link_up()))
+ link.get_link_down().set_sharing_policy(
+ Link.SharingPolicy.NONLINEAR,
+ functools.partial(link_nonlinear, link.get_link_down()))
+ link.set_latency(10e-6).seal()
+
+ # create routes between nodes
+ zone.add_route(sender.get_netpoint(), receiver.get_netpoint(), None, None,
+ [LinkInRoute(link, LinkInRoute.Direction.UP)], True)
+ zone.seal()
+
+ # create actors Sender/Receiver
+ Actor.create("receiver", receiver, Receiver(9))
+ Actor.create("sender", sender, Sender(9))
+
+###################################################################################################
+
+if __name__ == '__main__':
+ e = Engine(sys.argv)
+
+ # create platform
+ load_platform()
+
+ # runs the simulation
+ e.run()
+
+ # explicitly deleting Engine object to avoid segfault during cleanup phase.
+ # During Engine destruction, the cleanup of std::function linked to link_non_linear callback is called.
+ # If we let the cleanup by itself, it fails trying on its destruction because the python main program
+ # has already freed its variables
+ del(e)