import Process
import Events
class SRTF:
  running = -1
  ReadyQ = []
  IOWaitTime = 10
  preemptTime = -1
  def tick(self):
    if SRTF.running >= 0:
      pr = Process.PT.pt[SRTF.running]
      if pr.time == 0:
        newEv = Events.EventCreate(Events.currentTime,'exit',pr.num,0,0,0)
        Events.AddEvent(newEv)
      elif pr.timetoio == 0:
        newEv = Events.EventCreate(Events.currentTime,'iowait',pr.num,0,0,0)
        Events.AddEvent(newEv)
  
  def HandleEvent(self,ev):
    if ev.type == 'create':
      pr = Process.ProcessCreate(ev.p1,ev.p2,ev.p3,ev.p4)
      pr.statechange(ev.time,'created')
      if pr.iotime > 0:
        pr.timetoio = pr.iotime
      else:
        pr.timetoio = pr.time + 1
      LogEvent(pr,"created")
      
    elif ev.type == 'admit':
      pr = Process.PT.pt[ev.p1]
      pr.statechange(ev.time,'ready')
      self.AddReady(ev.p1)
      LogEvent(pr,"admitted")
      if SRTF.preemptTime != Events.currentTime and SRTF.running > 0:
        curpr = Process.PT.pt[SRTF.running]
        timeToRun = curpr.time
        if timeToRun > 0 and curpr.timetoio > 0:
          if pr.time < timeToRun:
            newEv = Events.EventCreate(Events.currentTime,'interrupt',SRTF.running,0,0,0)
            Events.AddEvent(newEv)
            msg = "preemption forced"
            SRTF.preemptTime = Events.currentTime
          else:
            msg = "no preemption"  
          print "            check preemption: " + \
                "new (%d): %d, current (%d): %d/%d, %s" % \
                (pr.num,pr.time,SRTF.running,timeToRun,curpr.timetoio,msg)
      
      
    elif ev.type == 'dispatch':
      pr = Process.PT.pt[ev.p1]
      pr.statechange(ev.time,'running')
      SRTF.running = pr.num
      LogEvent(pr,"dispatched")
      
    elif ev.type == 'interrupt':
      pr = Process.PT.pt[ev.p1]
      pr.statechange(ev.time,'ready')
      if SRTF.running == pr.num:
        SRTF.running = -1
      self.AddReady(pr.num)
      LogEvent(pr,"interrupted")
      
    elif ev.type == 'iowait':
      pr = Process.PT.pt[ev.p1]
      pr.statechange(ev.time,'waiting')
      SRTF.running = -1
      waitfor = SRTF.IOWaitTime
      etime = Events.currentTime + waitfor
      newEv = Events.EventCreate(etime,'iocomplete',ev.p1,0,0,0)
      Events.AddEvent(newEv)
      LogEvent(pr,"io waits",waitfor)
      
    elif ev.type == 'iocomplete':
      pr = Process.PT.pt[ev.p1]
      pr.statechange(ev.time,'ready')
      if pr.iotime > 0:
        pr.timetoio = pr.iotime
      else:
        pr.timetoio = pr.time + 1
      self.AddReady(ev.p1)
      LogEvent(pr,"completes io")
      if SRTF.preemptTime != Events.currentTime and SRTF.running > 0:
        curpr = Process.PT.pt[SRTF.running]
        timeToRun = curpr.time
        if timeToRun > 0 and curpr.timetoio > 0:
          if pr.time < timeToRun:
            newEv = Events.EventCreate(Events.currentTime,'interrupt',SRTF.running,0,0,0)
            Events.AddEvent(newEv)
            msg = "preemption forced"
            SRTF.preemptTime = Events.currentTime
          else:
            msg = "no preemption"  
          print "            check preemption: " + \
                "new (%d): %d, current (%d): %d/%d, %s" % \
                (pr.num,pr.time,SRTF.running,timeToRun,curpr.timetoio,msg)
      
      
    elif ev.type == 'exit': # terminate
      pr = Process.PT.pt[ev.p1]
      pr.statechange(Events.currentTime,'terminated')
      SRTF.running = -1
      LogEvent(pr,"terminates")
      
    if SRTF.running < 0:
      if len(SRTF.ReadyQ) > 0:
        runP = SRTF.ReadyQ[0]
        SRTF.running = runP
        del SRTF.ReadyQ[0]
        newEv = Events.EventCreate(Events.currentTime,'dispatch',runP,0,0,0)
        Events.AddEvent(newEv)
        
    
  
  def AddReady(self,pnum):
    addp = Process.PT.pt[pnum]
    for i in range(len(self.ReadyQ)):
      pn = self.ReadyQ[i]
      process = Process.PT.pt[pn]
      if (addp.time < process.time):
        self.ReadyQ.insert(i,pnum)
        break
    else:
      self.ReadyQ.append(pnum)
    print "            added process %d to ready queue with time %d, ReadyQ=%s" \
          % (pnum,addp.time,self.ReadyQ)
  
def LogEvent(pr,evname,waitfor=0):
  if waitfor>0:
    msg = ", io wait for %d" % waitfor
  else:
    msg = ""
  print "time:%3d => process %d %s, run time %d, time to io %d%s" % \
        (Events.currentTime,pr.num,evname,pr.time,pr.timetoio,msg)