Creating custom simpy resources

[Camilla Montonen]

Hi Simpy users, 

I would like to create a custom shared resource that will notify all processes yielding a put request, if they have been put into the queue (something like the below)

resource = simpy.Resource(env, capacity=1)

def user(env, resource):

    req = resource.request()

    result = yield req | resource.resource_capacity_full

    if req in result:

        print 'Place received'

    else:

        print 'Waiting for resource'

in this case resource_capacity_full would be an Event that is triggered as successful once the Resource is at capacity. 

Is there a simple way to do this? perhaps make a subclass of resource and then add a method?

Would really appreciate to hear your ideas/comments.

Kind regards,

Camilla

[jpgr...@gmail.com]

For the particular scenario identified in your code, I think the existing Resource has what you need. You can test resource.count against resource.capacity to determine whether requesting the resource would block (wait).

resource = simpy.Resource(env, capacity=1)
def user(env, resource):

    if resource.count < resource.capacity:
        with resource.request() as req:
            t0 = env.now
            yield req
            assert t0 == env.now
            print 'acquired'
    else:
        print 'would wait'

Are there other scenarios you are thinking about that this technique would not serve?

I've had situations where I have wanted an event when a Resource becomes available or when a Store becomes non-empty, but without also acquiring the Resource or popping an item from the Store. Those scenarios would require a non-standard event.

Cheers,

Pete

[Stefan Scherfke]

Hi Camilla and Pete,

you can also use this guide (http://simpy.readthedocs.io/en/latest/topical_guides/monitoring.html) for inspiration :)

Cheers,
Stefan

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