SimPy 版本迁移：SimPy 2 -> SimPy 3 -> SimPy 4
SimPy 2 to 3
Imports
SimPy 3 的 import 被简化。SimPy 2 需要根据模拟环境选择需要导入的模块，SimPy 3 大部分情况下只用导入 simpy
Simulation* classes
SimPy 3 的 Environment 替换 Simulation，RealtimeEnvironment 替换 SimulationRT。
# SimPy 2
# Procedural API
from SimPy.Simulation import initialize, simulate
initialize()
# Start processes
simulate(until=10)
# Object-oriented API
from SimPy.Simulation import Simulation
sim = Simulation()
# Start processes
sim.simulate(until=10)Defining a Process
SimPy 3 中的 Process 是一个封装在进程实例中的 Python 生成器（无论它是在模块级定义的还是作为实例方法定义的）。生成器通常需要对环境的引用才能与之交互，但这是可选的。
进程可以通过创建一个进程实例并将生成器传递给它来启动。环境为此提供了一个快捷方式：process()。
# SimPy 2
# Procedural API
from Simpy.Simulation import Process
class MyProcess(Process):
def __init__(self, another_param):
super().__init__()
self.another_param = another_param
def generator_function(self):
"""Implement the process' behavior."""
yield something
initialize()
proc = Process('Spam')
activate(proc, proc.generator_function())
# Object-oriented API
from SimPy.Simulation import Simulation, Process
class MyProcess(Process):
def __init__(self, sim, another_param):
super().__init__(sim=sim)
self.another_param = another_param
def generator_function(self):
"""Implement the process' behaviour."""
yield something
sim = Simulation()
proc = Process(sim, 'Spam')
sim.activate(proc, proc.generator_function())# SimPy 3
import simpy
def generator_function(env, another_param):
"""Implement the process' behavior."""
yield something
env = simpy.Environment()
proc = env.process(generator_function(env, 'Spam'))SimPy Keywords
SimPy 3中，可以直接生成事件。可以直接实例化事件，也可以使用 Environment 提供的快捷方式。
通常，每当一个进程产生一个事件时，该进程的执行都会被挂起，并在事件被触发后重新开始。为了激发这种理解，一些活动被重新命名。例如，hold 关键字意味着等待一段时间。就事件而言，这意味着发生了超时。因此，hold 已被 Timeout 事件取代。
# SimPy 2
yield hold, self, duration
yield passivate, self
yield request, self, resource
yield release, self, resource
yield waitevent, self, event
yield waitevent, self, [event_a, event_b, event_c]
yield queueevent, self, event_list
yield get, self, level, amount
yield put, self, level, amount# SimPy 3
yield env.timeout(duration) # hold: renamed
yield env.event() # passivate: renamed
yield resource.request() # Request is now bound to class Resource
resource.release() # Release no longer needs to be yielded
yield event # waitevent: just yield the event
yield env.all_of([event_a, event_b, event_c]) # waitevent
yield env.any_of([event_a, event_b, event_c]) # queuevent
yield container.get(amount) # Level is now called Container
yield container.put(amount)
yield event_a | event_b # Wait for either a or b. This is new.
yield event_a & event_b # Wait for a and b. This is new.
yield env.process(calculation(env)) # Wait for the process calculation to
# to finish.Interrupts
SimPy 3 中，可以对进程调用 interrupt()。一个中断被抛出到进程中，进程必须通过 try...except simpy.Interrupt 处理中断。
# SimPy 2
class Interrupter(Process):
def __init__(self, victim):
super().__init__()
self.victim = victim
def run(self):
yield hold, self, 1
self.interrupt(self.victim_proc)
self.victim_proc.interruptCause = 'Spam'
class Victim(Process):
def run(self):
yield hold, self, 10
if self.interrupted:
cause = self.interruptCause
self.interruptReset()SimPy 3 to 4
Python >= 3.6
Environment Subclasses
BaseEnvironment 类已在 SimPy 4 中移除。Environment 类现在是最基本的类。任何从 BaseEnvironment 继承的代码都应该修改为从 Environment 继承。
Returning from Process Generators
在下面的示例中，Environment.exit() 用于返回 the first needle。当将 SimPy 3 与 Python 2 一起使用时，这是从流程生成器返回值的唯一方法。
# SimPy 3 + Python 2
def find_first_needle(env, store):
while True:
item = yield store.get()
if is_needle(item):
env.exit(item) # Python2 generators cannot use return
def proc(env, store):
needle = yield env.process(find_first_needle(env, store))在 SimPy 4 与 Python 3 下，可以写为：
def find_first_needle(env, store):
while True:
item = yield store.get()
if is_needle(item):
return item # A Python3 generator can return
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