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gvwilsongvwilson
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discrete event simulation
1 parent 197b405 commit 614a4ab

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‎requirements.txt

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kaleido
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pandas
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plotly
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prettytable
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py-des-lib
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pydot
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pyfakefs
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pytest

‎src/eventsim/Makefile

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TARGETS=\
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multiprocess.out \
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pc_stats.out \
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pc_stats_multi.out \
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wait_and_work.out \
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wait_event.out \
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wait_work_record.out
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include ../../examples.mk
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pc_stats.out: pc_stats.py
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python $< 4219384 1000 10 > $@
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pc_stats_multi.out: pc_stats_multi.py
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python $< 4219384 1000 10 3 > $@

‎src/eventsim/index.md

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---
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title: "Discrete Event Simulator"
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title: "Discrete Event Simulation"
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abstract: >
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FIXME
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syllabus:
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- FIXME
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---
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[%fixme "create discrete event simulator" %] [%issue 56 %]
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- Basic ideas of discrete event simulation
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- `wait_and_work.py`: work a fixed time, wait a fixed time
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- `wait_work_record.py`: record events and display table of results
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- `multiprocess.py`: two independent processes
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- `wait_event.py`: one waits for the other to finish
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- But events happen once
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- `producer_consumer.py`: eventually producer can only run as fast as consumer

‎src/eventsim/multiprocess.out

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| time | component | message |
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|----: | :---------| :----------|
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| 0 | Worker.0 | start work |
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| 0 | Worker.1 | start work |
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| 2 | Worker.0 | start work |
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| 2 | Worker.1 | start work |
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| 4 | Worker.0 | start work |
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| 4 | Worker.1 | start work |
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| 6 | Worker.0 | finished |
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| 6 | Worker.1 | finished |

‎src/eventsim/multiprocess.py

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from pydes import Component, Simulator
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from util import format_log
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class Worker(Component):
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NUM_STEPS = 3
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WORK_TIME = 2
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def __init__(self, sim):
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self._sim = sim
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def main(self):
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for i in range(self.NUM_STEPS):
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self._sim.record(self, "start work")
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self._sim.sleep(self.WORK_TIME)
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self._sim.record(self, "finished")
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def simulate():
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sim = Simulator(trace=False)
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sim.schedule(Worker(sim))
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sim.schedule(Worker(sim))
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sim.run()
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print(format_log(sim.records()))
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if __name__ == "__main__":
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simulate()

‎src/eventsim/pc_stats.out

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produce 5.73 consume 5.75

‎src/eventsim/pc_stats.py

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from pydes import Component, Queue, Simulator
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import random
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import sys
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class Producer(Component):
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WORK_TIME = (1, 10)
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def __init__(self, sim, queue, num_items):
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self._sim = sim
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self._queue = queue
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self._num_items = num_items
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def main(self):
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for i in range(self._num_items):
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delay = random.randint(*self.WORK_TIME)
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self._sim.sleep(delay)
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self._sim.record(self, "produce")
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self._queue.put(i)
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class Consumer(Component):
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WORK_TIME = (1, 10)
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def __init__(self, sim, queue, num_items):
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self._sim = sim
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self._queue = queue
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self._num_items = num_items
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def main(self):
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for i in range(self._num_items):
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self._queue.get()
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self._sim.record(self, "consume")
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delay = random.randint(*self.WORK_TIME)
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self._sim.sleep(delay)
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def simulate(num_items, queue_size):
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sim = Simulator(trace=False)
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queue = Queue(sim, queue_size)
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sim.schedule(Producer(sim, queue, num_items))
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sim.schedule(Consumer(sim, queue, num_items))
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sim.run()
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records = sim.records()
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produced = mean_diff(records, "produce")
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consumed = mean_diff(records, "consume")
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print(f"produce {produced:.2f} consume {consumed:.2f}")
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def mean_diff(records, which):
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subset = [r.time for r in records if r.value == which]
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diffs = [subset[i] - subset[i-1] for i in range(1, len(subset))]
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return sum(diffs) / len(diffs)
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if __name__ == "__main__":
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random.seed(int(sys.argv[1]))
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num_items = int(sys.argv[2])
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queue_size = int(sys.argv[3])
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simulate(num_items, queue_size)

‎src/eventsim/pc_stats_multi.out

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produce 16.29 consume 5.46

‎src/eventsim/pc_stats_multi.py

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from pydes import Component, Queue, Simulator
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import random
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import sys
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class Lag:
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def __init__(self, sim, owner, which):
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self._sim = sim
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self._owner = owner
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self._which = which
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self._previous = None
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def update(self):
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current = self._sim.now()
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if self._previous is None:
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self._previous = current
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else:
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self._sim.record(self._owner, current - self._previous, self._which)
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self._previous = current
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class Producer(Component):
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WORK_TIME = (1, 10)
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def __init__(self, sim, queue, num_items):
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self._sim = sim
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self._queue = queue
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self._num_items = num_items
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self._lag = Lag(sim, self, "produce")
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def main(self):
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current = None
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for i in range(self._num_items):
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delay = random.randint(*self.WORK_TIME)
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self._sim.sleep(delay)
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self._lag.update()
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self._queue.put(i)
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class Consumer(Component):
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WORK_TIME = (1, 10)
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def __init__(self, sim, queue, num_items):
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self._sim = sim
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self._queue = queue
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self._num_items = num_items
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self._lag = Lag(sim, self, "consume")
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def main(self):
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current = None
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for i in range(self._num_items):
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self._queue.get()
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self._lag.update()
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delay = random.randint(*self.WORK_TIME)
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self._sim.sleep(delay)
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def simulate(num_items, queue_size, num_producers):
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sim = Simulator(trace=False)
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queue = Queue(sim, queue_size)
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for i in range(num_producers):
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sim.schedule(Producer(sim, queue, num_items))
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sim.schedule(Consumer(sim, queue, num_items * num_producers))
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sim.run()
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records = sim.records()
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produced = mean_diff(records, "produce")
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consumed = mean_diff(records, "consume")
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print(f"produce {produced:.2f} consume {consumed:.2f}")
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def mean_diff(records, which):
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diffs = [r.value for r in records if r.description == which]
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return sum(diffs) / len(diffs)
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if __name__ == "__main__":
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random.seed(int(sys.argv[1]))
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num_items = int(sys.argv[2])
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queue_size = int(sys.argv[3])
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num_producers = int(sys.argv[4])
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simulate(num_items, queue_size, num_producers)

‎src/eventsim/producer_consumer.py

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from pydes import Component, Queue, Simulator
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from util import format_log
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NUM_ITEMS = 10
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QUEUE_SIZE = 3
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class Producer(Component):
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WORK_TIME = 2
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def __init__(self, sim, queue):
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self._sim = sim
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self._queue = queue
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def main(self):
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for i in range(NUM_ITEMS):
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self._sim.sleep(self.WORK_TIME)
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self._sim.record(self, f"produce={i} queue@{self._queue.size()}")
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self._queue.put(i)
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class Consumer(Component):
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WORK_TIME = 4
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def __init__(self, sim, queue):
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self._sim = sim
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self._queue = queue
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def main(self):
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for i in range(NUM_ITEMS):
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value = self._queue.get()
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self._sim.record(self, f"consume={i}")
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self._sim.sleep(self.WORK_TIME)
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def simulate():
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sim = Simulator(trace=False)
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queue = Queue(sim, QUEUE_SIZE)
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sim.schedule(Producer(sim, queue))
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sim.schedule(Consumer(sim, queue))
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sim.run()
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print(format_log(sim.records()))
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if __name__ == "__main__":
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simulate()

‎src/eventsim/util.py

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from prettytable import MARKDOWN, PrettyTable
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FIELDS = {
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"time": "r",
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"component": "l",
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"message": "l",
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}
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def format_log(records):
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table = PrettyTable(field_names=FIELDS.keys())
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table.set_style(MARKDOWN)
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for field, align in FIELDS.items():
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table.align[field] = align
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for rec in records:
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table.add_row([rec.time, str(rec.component), rec.value])
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return table

‎src/eventsim/wait_and_work.out

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start to work at 0
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start to work at 2
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start to work at 4
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finished working at 6

‎src/eventsim/wait_and_work.py

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from pydes import Component, Simulator
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class Worker(Component):
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NUM_STEPS = 3
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WORK_TIME = 2
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def __init__(self, sim):
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self._sim = sim
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def main(self):
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for i in range(self.NUM_STEPS):
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print(f"start to work at {self._sim.now()}")
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self._sim.sleep(self.WORK_TIME)
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print(f"finished working at {self._sim.now()}")
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def simulate():
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sim = Simulator()
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worker = Worker(sim)
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sim.schedule(worker)
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sim.run()
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if __name__ == "__main__":
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simulate()

‎src/eventsim/wait_event.out

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| time | component | message |
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|----: | :---------| :----------|
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| 0 | Worker.0 | start work |
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| 0 | Worker.1 | start work |
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| 2 | Worker.1 | start work |
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| 4 | Worker.1 | start work |
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| 6 | Worker.1 | finished |
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| 6 | Worker.0 | start work |
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| 8 | Worker.0 | start work |
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| 10 | Worker.0 | start work |
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| 12 | Worker.0 | finished |

‎src/eventsim/wait_event.py

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from pydes import Component, Event, Simulator
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from util import format_log
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class Worker(Component):
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NUM_STEPS = 3
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WORK_TIME = 2
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def __init__(self, sim, event, wait_at_start):
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self._sim = sim
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self._event = event
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self._wait_at_start = wait_at_start
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def main(self):
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if self._wait_at_start:
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self._sim.record(self, "start work")
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self._event.wait()
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for i in range(self.NUM_STEPS):
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self._sim.record(self, "start work")
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self._sim.sleep(self.WORK_TIME)
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self._sim.record(self, "finished")
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if not self._wait_at_start:
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self._event.set()
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def simulate():
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sim = Simulator(trace=False)
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event = Event(sim)
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sim.schedule(Worker(sim, event, True))
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sim.schedule(Worker(sim, event, False))
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sim.run()
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print(format_log(sim.records()))
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if __name__ == "__main__":
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simulate()

‎src/eventsim/wait_work_record.out

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| time | component | message |
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|----: | :---------| :----------|
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| 0 | Worker.0 | start work |
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| 2 | Worker.0 | start work |
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| 4 | Worker.0 | start work |
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| 6 | Worker.0 | finished |

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