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
class PCB:
def __init__(self, parent, index, priority):
self.ready = True
self.parent = parent
self.chilren = LinkedList()
self.resources = LinkedList()
self.index = index
self.prio = priority
if not parent == None:
parent.AddChild(self)
def Block(self):
self.ready = False
def Unblock(self):
self.ready = True
def AddChild(self, child):
self.chilren.Add(child)
def AddResource(self, resource):
self.resources.Add(resource)
def ReleaseResources(self):
pcbs = []
for resource in self.resources.GetList():
pcb = resource.ConditionalRelease(self)
resource.TakeOffWaitlist(self)
if not pcb == None:
pcbs.append(pcb)
return pcbs
def RemoveResource(self, index):
self.resources.RemoveIndex(index)
def Remove(self):
self.parent.RemoveChild(self.index)
def RemoveChild(self, index):
self.chilren.RemoveIndex(index)
def __str__(self):
return str(self.index)
def __repr__(self):
return str(self)
