"""bank19: Using priorities to increase the  clerks for long queues"""
tracing=0
if tracing:
    from SimPy.SimulationTrace  import *                          
else:
    from SimPy.Simulation  import *                              

from random import *

class Source(Process):                                        
    """ Source generates customers randomly"""
    def generate(self,number,rate):       
        for i in range(number):
            c = Customer(name = "Customer%02d"%(i,))
            activate(c,c.visit(timeInBank=12.0))
            yield hold,self,expovariate(rate)

class Customer(Process):                                      
    """ Customer arrives, is served and leaves """
    def visit(self,timeInBank):       
        print "%8.4f %s: Arrived     "%(now(),self.name)

        yield request,self,counter                            
        print "%8.4f %s: Got counter "%(now(),self.name)
        tib = expovariate(1.0/timeInBank)
        yield hold,self,tib
        yield release,self,counter
 
        print "%8.4f %s: Finished    "%(now(),self.name)


class ClerkProcess(Process):                                 
    """ This process removes a clerk from the counter
    immediately."""
    def serverProc(self):                                    
        while True:                                          
            # immediately grab the clerk
            yield request,self,counter,100                   
            print "%8.4f %s: leaves.  Free:"\
                  "%d, %d waiting"%(now(),self.name,counter.n,len(counter.waitQ))
           
            yield waituntil,self, queuelong                  

            yield release,self,counter                       
            print "%8.4f %s: needed .  Free:"\
                  "%d, %d waiting"%(now(),self.name,counter.n,len(counter.waitQ))

            yield waituntil,self,queueshort                   

# The counter is a Priority Queue but is not preemptive
counter = Resource(2,name="Clerk",qType=PriorityQ)            

def queuelong():                                              
    return len(counter.waitQ)> 2

def queueshort():                                             
    return len(counter.waitQ)== 0

def model(SEED=393939):                                        
    seed(SEED)

    initialize()
    clerk1 = ClerkProcess('Clerk')                            
    activate(clerk1, clerk1.serverProc())                     
    source = Source('Source')                                                         
    activate(source,source.generate(number=20,rate=0.1),0.0)    
    simulate(until=200.0)                                     

model()                      
