class QueueingSystem(Model):
"""QueueingSystem model represents a simple queue */*/1/N or */*/1,
where any distribution can be used for arrival and service times.
This model consists of four children:
- `queue`: a model representing the packets queue (`Queue`)
- `source`: a model representing the packets source (`Source`)
- `server`: a model representing the packets server (`Server`)
- `sink`: a model which collects served packets (`Sink`)
"""
def __init__(self, sim):
super().__init__(sim)
arrival = sim.params.arrival
service = sim.params.service
queue_capacity = sim.params.queue_capacity
self.children['queue'] = Queue(sim, queue_capacity)
self.children['source'] = Source(sim, arrival, index=0)
self.children['server'] = Server(sim, service)
self.children['sink'] = Sink(sim)
# Building connections:
self.source.connections['queue'] = self.queue
self.queue.connections['server'] = self.server
self.server.connections['queue'] = self.queue
self.server.connections['next'] = self.sink
# Statistics:
self.system_size_trace = Trace()
self.system_size_trace.record(self.sim.stime, 0)
self.system_wait_intervals = Statistic()
@property
def queue(self):
return self.children['queue']
@property
def source(self):
return self.children['source']
@property
def server(self):
return self.children['server']
@property
def sink(self):
return self.children['sink']
@property
def system_size(self):
return self.queue.size + (1 if self.server.busy else 0)
def update_system_size(self, index=0):
assert index == 0
self.system_size_trace.record(self.sim.stime, self.system_size)
def add_system_wait_interval(self, value, index=0):
assert index == 0
self.system_wait_intervals.append(value)
def __init__(
self,
sim,
address=None,
sifs=None,
phy_header_size=None,
ack_size=None,
):
super().__init__(sim)
# Properties:
self.__address = address
self.__sifs = sifs if sifs is not None else sim.params.sifs
self.__phy_header_size = (phy_header_size if phy_header_size
is not None else sim.params.phy_header_size)
self.__ack_size = (ack_size
if ack_size is not None else sim.params.ack_size)
# State variables:
self.__state = Receiver.State.IDLE
self.__rxbuf = set()
self.__cur_tx_pdu = None
# Statistics:
self.__num_collisions = 0
self.__num_received = 0
self.__busy_trace = Trace()
self.__busy_trace.record(sim.stime, 0)
def __init__(self, sim, capacity):
super().__init__(sim)
self.__capacity = capacity
self.__size = 0
# Statistics:
self.size_trace = Trace()
self.size_trace.record(self.sim.stime, 0)
def __init__(self, sim, service_mean):
super().__init__(sim)
self.__service_mean = service_mean
self.__busy = False
# Statistics:
self.delays = Statistic()
self.busy_trace = Trace()
self.busy_trace.record(self.sim.stime, 0)
def test_getting_pmf(data, probs):
trace = Trace(data)
pmf = trace.pmf()
assert set(pmf.keys()) == set(probs.keys())
estimated, expected = [], []
for v, p in probs.items():
estimated.append(pmf[v])
expected.append(p)
np.testing.assert_almost_equal(estimated, expected)
def test_getting_timeavg(data):
def estimate():
interval = data[-1][0] - data[0][0]
acc = 0
for i in range(1, len(data)):
acc += data[i - 1][1] * (data[i][0] - data[i - 1][0]) / interval
return acc
trace = Trace(data)
estimated_avg = estimate()
np.testing.assert_almost_equal(trace.timeavg(), estimated_avg)
def __init__(self, sim, service_time, index=0):
super().__init__(sim)
self.service_time = service_time
self.packet = None
self.index = index
# Statistics:
self.service_intervals = Statistic()
self.busy_trace = Trace()
self.busy_trace.record(self.sim.stime, 0)
self.departure_intervals = Intervals()
self.departure_intervals.record(sim.stime)
self.num_served = 0
def __init__(self, sim, capacity, index=0):
super().__init__(sim)
self.__capacity = capacity
self.packets = deque()
self.index = index
# Statistics:
self.size_trace = Trace()
self.size_trace.record(self.sim.stime, 0)
self.num_dropped = 0
self.arrival_intervals = Intervals()
self.arrival_intervals.record(sim.stime)
self.num_arrived = 0
self.wait_intervals = Statistic()
def __init__(self, arrival_mean, service_mean):
# Parameters:
self.arrival_mean = arrival_mean
self.service_mean = service_mean
# System state:
self.queue_size = 0
self.server_busy = False
# Statistics:
self.system_size_trace = Trace()
self.server_busy_trace = Trace()
self.service_intervals = Statistic()
self.arrivals = Intervals()
self.departures = Intervals()
class QueueingSystem(Model):
"""QueueingSystem model is the top-level model for this test.
This model consists of four children:
- `queue`: a model representing the packets queue (`Queue`)
- `source`: a model representing the packets source (`Source`)
- `server`: a model representing the packets server (`Server`)
- `sink`: a model which collects served packets (`Sink`)
"""
def __init__(self, sim):
super().__init__(sim)
self.children['queue'] = Queue(sim, sim.params.capacity)
self.children['source'] = Source(sim, sim.params.arrival_mean)
self.children['server'] = Server(sim, sim.params.service_mean)
self.children['sink'] = Sink(sim)
# Building connections:
self.source.connections['queue'] = self.queue
self.queue.connections['server'] = self.server
self.server.connections['queue'] = self.queue
self.server.connections['sink'] = self.sink
# Statistics:
self.system_size_trace = Trace()
self.system_size_trace.record(self.sim.stime, 0)
@property
def queue(self):
return self.children['queue']
@property
def source(self):
return self.children['source']
@property
def server(self):
return self.children['server']
@property
def sink(self):
return self.children['sink']
@property
def system_size(self):
return self.queue.size + (1 if self.server.busy else 0)
def update_system_size(self):
self.system_size_trace.record(self.sim.stime, self.system_size)
def test_record_adds_data():
trace = Trace()
assert trace.as_tuple() == ()
trace.record(t=1, v=10)
assert trace.as_tuple() == ((1, 10), )
trace.record(t=2, v=13)
assert trace.as_tuple() == (
(1, 10),
(2, 13),
)
def __init__(self, sim):
super().__init__(sim)
self.children['queue'] = Queue(sim, sim.params.capacity)
self.children['source'] = Source(sim, sim.params.arrival_mean)
self.children['server'] = Server(sim, sim.params.service_mean)
self.children['sink'] = Sink(sim)
# Building connections:
self.source.connections['queue'] = self.queue
self.queue.connections['server'] = self.server
self.server.connections['queue'] = self.queue
self.server.connections['sink'] = self.sink
# Statistics:
self.system_size_trace = Trace()
self.system_size_trace.record(self.sim.stime, 0)
def __init__(
self,
sim,
address=None,
phy_header_size=None,
mac_header_size=None,
ack_size=None,
bitrate=None,
preamble=None,
max_propagation=0,
):
super().__init__(sim)
# Properties:
self.__address = address
self.__phy_header_size = (phy_header_size if phy_header_size
is not None else sim.params.phy_header_size)
self.__mac_header_size = (mac_header_size if mac_header_size
is not None else sim.params.mac_header_size)
self.__bitrate = bitrate if bitrate is not None else sim.params.bitrate
self.__preamble = (preamble
if preamble is not None else sim.params.preamble)
self.__max_propagation = max_propagation
self.__ack_size = (ack_size
if ack_size is not None else sim.params.ack_size)
# State variables:
self.timeout = None
self.cw = 65536
self.backoff = -1
self.num_retries = None
self.pdu = None
self.__state = Transmitter.State.IDLE
self.__seqn = 0
# Statistics:
self.backoff_vector = Statistic()
self.__start_service_time = None
self.service_time = Statistic()
self.num_sent = 0
self.num_retries_vector = Statistic()
self.__busy_trace = Trace()
self.__busy_trace.record(sim.stime, 0)
# Initialize:
sim.schedule(0, self.start)
def __init__(self, sim):
super().__init__(sim)
arrival = sim.params.arrival
service = sim.params.service
queue_capacity = sim.params.queue_capacity
self.children['queue'] = Queue(sim, queue_capacity)
self.children['source'] = Source(sim, arrival, index=0)
self.children['server'] = Server(sim, service)
self.children['sink'] = Sink(sim)
# Building connections:
self.source.connections['queue'] = self.queue
self.queue.connections['server'] = self.server
self.server.connections['queue'] = self.queue
self.server.connections['next'] = self.sink
# Statistics:
self.system_size_trace = Trace()
self.system_size_trace.record(self.sim.stime, 0)
self.system_wait_intervals = Statistic()
def __init__(self, sim):
super().__init__(sim)
# Topology comprises:
# - `nodes`: each having position, properties
# - `static_connections`: optional dictionary with static connections
# We use it as a template for network creation.
self.network = Network(sim.params.topology)
self.repair_started = False
self.failed_nodes = []
self.routing_mode = sim.params.routing_mode
sim.logger.level = sim.params.log_level
# Statistics:
self.num_failed = Trace()
self.num_offline = Trace()
self.operable = Trace()
self.num_failed_sampled = Trace()
self.num_offline_sampled = Trace()
# Record initial trace data:
t = sim.stime
num_offline = len(self.network.get_offline_nodes())
self.num_failed.record(t, 0)
self.num_failed_sampled.record(t, 0)
self.num_offline.record(t, num_offline)
self.num_offline_sampled.record(t, num_offline)
self.operable.record(t, 1)
# Build network routes:
self.network.build_routing_table(self.routing_mode)
for sensor in self.network.sensors():
self.schedule_failure(sensor)
# Check whether we record samples:
if sim.params.record_samples:
sim.schedule(sim.params.sample_interval,
self.handle_sample_timeout)
def __init__(self, sim, bitrate=inf, header_size=0, preamble=0, ifs=0):
super().__init__(sim)
self.bitrate = bitrate
self.header_size = header_size
self.preamble = preamble
self.ifs = ifs
# State variables:
self.__started = False
self.__tx_frame = None
self.__wait_ifs = False
self.__rx_frame = None
# Statistics:
self.__num_received_frames = 0
self.__num_received_bits = 0
self.__rx_busy_trace = Trace()
self.__rx_busy_trace.record(0, 0)
self.__num_transmitted_packets = 0
self.__num_transmitted_bits = 0
self.__tx_busy_trace = Trace()
self.__tx_busy_trace.record(0, 0)
self.__service_time = Statistic()
self.__service_started_at = None
# Initialization:
self.sim.schedule(self.sim.stime, self.start)
class Server(Model):
"""Server module represents a packet server with exponential service time.
Connections: queue, sink
Handlers:
- on_service_end(): called upon service timeout
Methods:
- start_service(): start new packet service; generate error if busy.
Statistics:
- delays: `Statistic`, stores a set of service intervals
- busy_trace: `Trace`, stores a vector of server busy status
Parent: `QueueingSystem`
"""
def __init__(self, sim, service_mean):
super().__init__(sim)
self.__service_mean = service_mean
self.__busy = False
# Statistics:
self.delays = Statistic()
self.busy_trace = Trace()
self.busy_trace.record(self.sim.stime, 0)
@property
def service_mean(self):
return self.__service_mean
@property
def busy(self):
return self.__busy
def on_service_end(self):
assert self.__busy
queue = self.connections['queue'].module
self.__busy = False
self.busy_trace.record(self.sim.stime, 0)
if queue.size > 0:
queue.pop()
self.start_service()
self.connections['sink'].module.receive_packet()
self.parent.update_system_size()
def start_service(self):
assert not self.__busy
delay = exponential(self.service_mean)
self.sim.schedule(delay, self.on_service_end)
self.delays.append(delay)
self.__busy = True
self.busy_trace.record(self.sim.stime, 1)
def __init__(self, sim):
super().__init__(sim)
arrivals = sim.params.arrivals
services = sim.params.services
queue_capacity = sim.params.queue_capacity
n = sim.params.num_stations
active_sources = {i for i, ar in enumerate(arrivals) if ar is not None}
if n < 1:
raise ValueError('num_stations must be >= 1')
self.queues, self.sources, self.servers = [], [], []
for i in range(n):
self.queues.append(Queue(sim, queue_capacity, i))
self.servers.append(Server(sim, services[i], i))
if i in active_sources:
self.sources.append(Source(sim, arrivals[i], i))
else:
self.sources.append(None)
self.sink = Sink(sim)
self.children['queue'] = self.queues
self.children['server'] = self.servers
self.children['sink'] = self.sink
self.children['sources'] = [src for src in self.sources if src]
# Connecting modules:
for i in range(n):
self.queues[i].connections['server'] = self.servers[i]
self.servers[i].connections['queue'] = self.queues[i]
if self.sources[i]:
self.sources[i].connections['queue'] = self.queues[i]
if i < n - 1:
self.servers[i].connections['next'] = self.queues[i + 1]
else:
self.servers[i].connections['next'] = self.sink
# Statistics:
self.system_size_trace = [Trace() for _ in range(n)]
for i in range(n):
self.system_size_trace[i].record(sim.stime, 0)
self.system_wait_intervals = [Statistic() for _ in range(n)]
class Queue(Model):
"""Queue module represents the packets queue, stores only current size.
Connections: server
Methods and properties:
- push(): increase the queue size
- pop(): decrease the queue size
- size: get current queue size
Statistics:
- size_trace: Trace, holding the history of the queue size updates
"""
def __init__(self, sim, capacity):
super().__init__(sim)
self.__capacity = capacity
self.__size = 0
# Statistics:
self.size_trace = Trace()
self.size_trace.record(self.sim.stime, 0)
@property
def capacity(self):
return self.__capacity
@property
def size(self):
return self.__size
def push(self):
server = self.connections['server'].module
if self.__size == 0 and not server.busy:
server.start_service()
elif self.capacity < 0 or self.__size < self.capacity:
self.__size += 1
self.size_trace.record(self.sim.stime, self.__size)
self.parent.update_system_size()
def pop(self):
assert self.__size > 0
self.__size -= 1
self.size_trace.record(self.sim.stime, self.__size)
def __str__(self):
return f'Queue({self.size})'
class ModelData(Model):
def __init__(self, sim):
super().__init__(sim)
# Topology comprises:
# - `nodes`: each having position, properties
# - `static_connections`: optional dictionary with static connections
# We use it as a template for network creation.
self.network = Network(sim.params.topology)
self.repair_started = False
self.failed_nodes = []
self.routing_mode = sim.params.routing_mode
sim.logger.level = sim.params.log_level
# Statistics:
self.num_failed = Trace()
self.num_offline = Trace()
self.operable = Trace()
self.num_failed_sampled = Trace()
self.num_offline_sampled = Trace()
# Record initial trace data:
t = sim.stime
num_offline = len(self.network.get_offline_nodes())
self.num_failed.record(t, 0)
self.num_failed_sampled.record(t, 0)
self.num_offline.record(t, num_offline)
self.num_offline_sampled.record(t, num_offline)
self.operable.record(t, 1)
# Build network routes:
self.network.build_routing_table(self.routing_mode)
for sensor in self.network.sensors():
self.schedule_failure(sensor)
# Check whether we record samples:
if sim.params.record_samples:
sim.schedule(sim.params.sample_interval,
self.handle_sample_timeout)
def handle_failure(self, node):
"""Handle node failure. Upon failure the following actions take place:
1) a node is marked as turned off in the network;
2) if repair hasn't started yet, we check whether enough nodes
already failed:
if num_offline_nodes > num_offline_till_repair, start the repair.
"""
self.network.turn_off(node)
self.failed_nodes.append(node)
# If static routing is used, no actual re-routing will take place.
# However, in case of dynamic routing using, this can lead to
# network reconfiguration and new alternative paths
self.network.build_routing_table(self.routing_mode)
# Count failed and offline nodes and record statistics:
num_offline_nodes = len(self.network.get_offline_nodes())
num_failed_nodes = len(self.failed_nodes)
self.num_failed.record(self.sim.stime, num_failed_nodes)
self.num_offline.record(self.sim.stime, num_offline_nodes)
# We treat all offline nodes as broken, while some of them are
# offline since the routers they were connected to became unavailable:
self.sim.logger.debug(f'node {node} failed. {num_failed_nodes} nodes '
f'failed, {num_failed_nodes} are offline. '
f'Failed nodes: {self.failed_nodes}')
if num_offline_nodes >= self.sim.params.num_offline_till_repair:
if not self.repair_started:
# print(f'num failed node: {num_failed_nodes}, offline: {num_offline_nodes}, start repair')
self.schedule_next_repair()
self.operable.record(self.sim.stime, 0)
def handle_repair_finished(self, node):
"""Handle repair of all nodes finished.
Here we assume that during repair all failed nodes were fixed,
so we schedule their failures again.
"""
# Turn on the repaired node, rebuild a routing table and schedule the
# next failure:
self.sim.logger.debug(f'node {node} repair finished')
self.network.turn_on(node)
self.network.build_routing_table(self.routing_mode)
self.schedule_failure(node)
# Remove the repaired node from the failed list, count failed and
# offline nodes:
self.failed_nodes.remove(node)
num_failed = len(self.failed_nodes)
num_offline = len(self.network.get_offline_nodes())
# Record statistics:
t = self.sim.stime
self.num_failed.record(t, num_failed)
self.num_offline.record(t, num_offline)
# Check whether there are other failed nodes. If they exist, schedule
# the next repair. Otherwise, mark repair end.
if num_failed > 0:
self.schedule_next_repair()
else:
self.repair_started = False
if num_offline >= self.sim.params.num_offline_till_repair:
self.operable.record(t, 0)
else:
self.operable.record(t, 1)
def handle_sample_timeout(self):
t = self.sim.stime
num_offline = len(self.network.get_offline_nodes())
self.num_failed_sampled.record(t, len(self.failed_nodes))
self.num_offline_sampled.record(t, num_offline)
self.sim.schedule(self.sim.params.sample_interval,
self.handle_sample_timeout)
def schedule_failure(self, node):
"""Schedule next failure event for a given node.
:param node: network node
"""
interval = self.sim.params.failure_interval()
self.sim.schedule(interval, self.handle_failure, args=(node, ))
def schedule_next_repair(self):
"""Schedule next repair duration. Since all broken nodes are
repaired at once, we do not distinguish nodes here.
"""
if not self.failed_nodes:
raise RuntimeError('can not schedule repair - no failed nodes')
# Select a random node to repair, and schedule repair end:
node_index = np.random.randint(len(self.failed_nodes))
node = self.failed_nodes[node_index]
if not self.repair_started:
interval = self.sim.params.repair_interval()
self.repair_started = True
else:
interval = self.sim.params.cons_repair_interval()
self.sim.logger.debug(f'started node {node} repair for {interval}s')
self.sim.schedule(interval, self.handle_repair_finished, args=(node, ))
def test_trace_creation_with_unordered_timestamps_raises_error(data):
with pytest.raises(ValueError) as excinfo:
Trace(data)
assert 'data must be ordered by time' in str(excinfo.value).lower()
def test_trace_creation_with_wrong_mode_raises_error():
with pytest.raises(ValueError) as excinfo:
Trace([(1, ), (2, )], mode='wrong')
assert 'invalid mode' in str(excinfo.value).lower()
def test_trace_creation_with_2x2_data_without_mode_is_the_same_as_samples():
data = ((1, 2), (10, 20)) # t=1, v=10; t=2, v=20
trace_default = Trace(data)
trace_samples = Trace(data, mode='samples')
assert trace_default.as_tuple() == trace_samples.as_tuple()
def test_trace_creation_with_2x2_data_using_mode_argument(mode, expected):
trace = Trace(((1, 2), (10, 20)), mode=mode)
assert trace.as_tuple() == expected
def test_trace_creation_raises_error_when_passed_data_with_wrong_shape(data):
with pytest.raises(ValueError) as excinfo:
Trace(data)
assert 'wrong data shape' in str(excinfo.value).lower()
def test_trace_creation_with_single_item(data):
trace = Trace(data)
assert not trace.empty
assert len(trace) == 1
assert trace.as_tuple() == ((1, 10), )
def test_trace_creation_with_valid_data_given_in_pairs():
data = [(1, 5), (2, 8), (3, 40), (9, 34)]
trace = Trace(data)
assert not trace.empty
assert len(trace) == 4
assert trace.as_tuple() == tuple(data)
def test_asarray_with_illegal_mode_raises_error():
trace = Trace([[0, 0], [1, 5]])
with pytest.raises(ValueError) as excinfo:
trace.asarray('wrong mode')
assert 'invalid mode' in str(excinfo.value).lower()
def test_asarray(data, mode, expected):
trace = Trace(data)
actual = trace.asarray(mode)
assert isinstance(actual, np.ndarray)
np.testing.assert_almost_equal(actual, expected)
def test_as_tuple(data, mode, expected):
trace = Trace(data)
if expected is None:
expected = data
assert trace.as_tuple(mode=mode) == expected
