class RCB:
def __init__(self, index):
self.curPCB = None
self.waitlist = LinkedList()
self.index = index
def Request(self, PCB):
PCB.AddResource(self)
if self.Free():
self.curPCB = PCB
else:
self.waitlist.Add(PCB)
PCB.Block()
def Release(self):
self.curPCB.RemoveResource(self.index)
self.curPCB = self.waitlist.Pop()
if not self.Free():
self.curPCB.Unblock()
return self.curPCB
def ConditionalRelease(self, PCB):
if self.curPCB == PCB:
return self.Release()
return None
def TakeOffWaitlist(self, PCB):
PCB.RemoveResource(self.index)
self.waitlist.RemoveIndex(PCB.index)
def Free(self):
return self.curPCB == None
