discrete event simulation

Author: gvwilson

requirements.txt

@@ -3,6 +3,8 @@ greenlet
 kaleido
 pandas
 plotly
+prettytable
+py-des-lib
 pydot
 pyfakefs
 pytest

src/eventsim/Makefile

@@ -0,0 +1,7 @@
+TARGETS=\
+  multiprocess.out \
+  wait_and_work.out \
+  wait_event.out \
+  wait_work_record.out
+
+include ../../examples.mk

src/eventsim/index.md

@@ -1,9 +1,17 @@
 ---
-title: "Discrete Event Simulator"
+title: "Discrete Event Simulation"
 abstract: >
     FIXME
 syllabus:
 -   FIXME
 ---
 
 [%fixme "create discrete event simulator" %] [%issue 56 %]
+
+-   Basic ideas of discrete event simulation
+-   `wait_and_work.py`: work a fixed time, wait a fixed time
+-   `wait_work_record.py`: record events and display table of results
+-   `multiprocess.py`: two independent processes
+-   `wait_event.py`: one waits for the other to finish
+    -   But events happen once
+-   `producer_consumer.py`: eventually producer can only run as fast as consumer

src/eventsim/multiprocess.out

@@ -0,0 +1,10 @@
+| time | component | message    |
+|----: | :---------| :----------|
+|    0 | Worker.0  | start work |
+|    0 | Worker.1  | start work |
+|    2 | Worker.0  | start work |
+|    2 | Worker.1  | start work |
+|    4 | Worker.0  | start work |
+|    4 | Worker.1  | start work |
+|    6 | Worker.0  | finished   |
+|    6 | Worker.1  | finished   |

src/eventsim/multiprocess.py

@@ -0,0 +1,28 @@
+from pydes import Component, Simulator
+from util import format_log
+
+
+class Worker(Component):
+    NUM_STEPS = 3
+    WORK_TIME = 2
+
+    def __init__(self, sim):
+        self._sim = sim
+
+    def main(self):
+        for i in range(self.NUM_STEPS):
+            self._sim.record(self, "start work")
+            self._sim.sleep(self.WORK_TIME)
+        self._sim.record(self, "finished")
+
+
+def simulate():
+    sim = Simulator(trace=False)
+    sim.schedule(Worker(sim))
+    sim.schedule(Worker(sim))
+    sim.run()
+    print(format_log(sim.records()))
+
+
+if __name__ == "__main__":
+    simulate()

src/eventsim/producer_consumer.py

@@ -0,0 +1,47 @@
+from pydes import Component, Queue, Simulator
+from util import format_log
+
+
+NUM_ITEMS = 10
+QUEUE_SIZE = 3
+
+
+class Producer(Component):
+    WORK_TIME = 2
+
+    def __init__(self, sim, queue):
+        self._sim = sim
+        self._queue = queue
+
+    def main(self):
+        for i in range(NUM_ITEMS):
+            self._sim.sleep(self.WORK_TIME)
+            self._sim.record(self, f"produce={i} queue@{self._queue.size()}")
+            self._queue.put(i)
+
+
+class Consumer(Component):
+    WORK_TIME = 4
+
+    def __init__(self, sim, queue):
+        self._sim = sim
+        self._queue = queue
+
+    def main(self):
+        for i in range(NUM_ITEMS):
+            value = self._queue.get()
+            self._sim.record(self, f"consume={i}")
+            self._sim.sleep(self.WORK_TIME)
+
+
+def simulate():
+    sim = Simulator(trace=False)
+    queue = Queue(sim, QUEUE_SIZE)
+    sim.schedule(Producer(sim, queue))
+    sim.schedule(Consumer(sim, queue))
+    sim.run()
+    print(format_log(sim.records()))
+
+
+if __name__ == "__main__":
+    simulate()

src/eventsim/util.py

@@ -0,0 +1,18 @@
+from prettytable import MARKDOWN, PrettyTable
+
+
+FIELDS = {
+    "time": "r",
+    "component": "l",
+    "message": "l",
+}
+
+
+def format_log(records):
+    table = PrettyTable(field_names=FIELDS.keys())
+    table.set_style(MARKDOWN)
+    for field, align in FIELDS.items():
+        table.align[field] = align
+    for rec in records:
+        table.add_row([rec.time, str(rec.component), rec.value])
+    return table

src/eventsim/wait_and_work.out

@@ -0,0 +1,4 @@
+start to work at 0
+start to work at 2
+start to work at 4
+finished working at 6

src/eventsim/wait_and_work.py

@@ -0,0 +1,26 @@
+from pydes import Component, Simulator
+
+
+class Worker(Component):
+    NUM_STEPS = 3
+    WORK_TIME = 2
+
+    def __init__(self, sim):
+        self._sim = sim
+
+    def main(self):
+        for i in range(self.NUM_STEPS):
+            print(f"start to work at {self._sim.now()}")
+            self._sim.sleep(self.WORK_TIME)
+        print(f"finished working at {self._sim.now()}")
+
+
+def simulate():
+    sim = Simulator()
+    worker = Worker(sim)
+    sim.schedule(worker)
+    sim.run()
+
+
+if __name__ == "__main__":
+    simulate()

src/eventsim/wait_event.out

@@ -0,0 +1,11 @@
+| time | component | message    |
+|----: | :---------| :----------|
+|    0 | Worker.0  | start work |
+|    0 | Worker.1  | start work |
+|    2 | Worker.1  | start work |
+|    4 | Worker.1  | start work |
+|    6 | Worker.1  | finished   |
+|    6 | Worker.0  | start work |
+|    8 | Worker.0  | start work |
+|   10 | Worker.0  | start work |
+|   12 | Worker.0  | finished   |

src/eventsim/wait_event.py

@@ -0,0 +1,36 @@
+from pydes import Component, Event, Simulator
+from util import format_log
+
+
+class Worker(Component):
+    NUM_STEPS = 3
+    WORK_TIME = 2
+
+    def __init__(self, sim, event, wait_at_start):
+        self._sim = sim
+        self._event = event
+        self._wait_at_start = wait_at_start
+
+    def main(self):
+        if self._wait_at_start:
+            self._sim.record(self, "start work")
+            self._event.wait()
+        for i in range(self.NUM_STEPS):
+            self._sim.record(self, "start work")
+            self._sim.sleep(self.WORK_TIME)
+        self._sim.record(self, "finished")
+        if not self._wait_at_start:
+            self._event.set()
+
+
+def simulate():
+    sim = Simulator(trace=False)
+    event = Event(sim)
+    sim.schedule(Worker(sim, event, True))
+    sim.schedule(Worker(sim, event, False))
+    sim.run()
+    print(format_log(sim.records()))
+
+
+if __name__ == "__main__":
+    simulate()

src/eventsim/wait_work_record.out

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

src/eventsim/wait_work_record.py

@@ -0,0 +1,28 @@
+from pydes import Component, Simulator
+from util import format_log
+
+
+class Worker(Component):
+    NUM_STEPS = 3
+    WORK_TIME = 2
+
+    def __init__(self, sim):
+        self._sim = sim
+
+    def main(self):
+        for i in range(self.NUM_STEPS):
+            self._sim.record(self, "start work")
+            self._sim.sleep(self.WORK_TIME)
+        self._sim.record(self, "finished")
+
+
+def simulate():
+    sim = Simulator(trace=False)
+    worker = Worker(sim)
+    sim.schedule(worker)
+    sim.run()
+    print(format_log(sim.records()))
+
+
+if __name__ == "__main__":
+    simulate()