Job Processing

[kevin]

 Job Processing

  This snippet looks into the idea of  job processing.   Sometimes in our programs we'll want to limit the amount of the time our code spends doing some calculation.   The reason for this is that sometimes a particular  calculation might take a very long time  to compute.   Which will halt our program until the calc is complete.     So one way around this is, is to build routines that have the ability to exit early and continue from where they left off.  So we're effectively controlling how much time this process takes, if it takes longer than we're willing to accept this frame, we halt it and exit.  Then fire it up again next frame.

  I tend to use this type of approach whenever I need my program to keep running while performing tasks of an unknown length. One that comes to mind is the assembler in the Kyruss tech demo..   Kyruss



 Anyway, this example is more to show the theory, rather than a practical application.

 Required PB1.64k2 or higher

PlayBASIC Code: [Select]

   Constant JobState_Complete       =ac(1)
   Constant JobState_InitialData       =ac(1)
   Constant JobState_Sorting          =ac(1)

   Type tJobs
      State         ; 0 = job done, 1 sorting
      ArrayHandle      
      ArraySize   ; size of the array
      DataRangeLow   ; lowest value in the array
      DataRangeHi      ; higest value in the array
      PassCount      ; The number of sort passes
      DeleteTime      ; Time when this job should be deleted
   EndType

   Dim Job as tJobs list


   // Set up a bunch of the jobs for the routine to do
   Setfps 30
      
   Do
      Cls 0
      ink rgb(255,0,0)
      print fps()
      ink rgb(255,0,255)
      print "Jobs="+str$(Getlistsize(job()) )
      ink $ffffff


      ; Add a random sorting job to the handle
      if rnd(100)>25  
         AddNewJob(rndrange(50,500),10,1000)
      endif

      ; run through and display all the arrays
      for each Job()

         if Job.ArrayHandle
            makearray ThisArray()
            ThisArray()=Job.ArrayHandle
            print ShowArray(ThisArray())
         endif   
         if Job.state=JobState_Complete      
            if Timer()>   Job.deleteTime
               DeleteJob()
            endif
         endif
         if GetCursorY()>GetScreenHeight() then exit
      next


      ; Process all the jobs 
      ProcessSortJobs()


      Sync
   loop



Function  ShowArray(me())
      Size=getarrayelements(me())
      if Size>40 then Size=30
      for lp=0 to Size
         s$=s$+str$(me(lp))+","      
      next
EndFunction s$



Function DeleteJob()
   MakeArray ThisArray()
   
   ThisArray()=Job.ArrayHandle
   Undim ThisArray()
   Job = null
EndFunction



Function AddNewJob(Size,Lowest,Highest)
   Job = new tJobs
   Job.State   = JobState_InitialData   

   Job.ArraySize =Size
   Job.PassCount=0
   Job.DataRangeLow=lowest
   Job.DataRangehi=highest
   

EndFunction




Function ProcessSortJobs()

      CurrentTime=Timer()

      ; The max time this can take is 15 milliseconds
      EndOfProcessTime=CurrentTime+15
      makeArray ThisArray()

      repeat

         ActiveThreads=0

         ; runt through all the jobs and update them
         for each job()
            Select Job.State

                  case JobState_InitialData   
                     ; this job was added, but has not be initialized
                     Size=Job.ArraySize
                     Job.ArrayHandle=NewArray(Size)
                     ThisArray()=Job.ArrayHandle
                     for lp=0 to size
                           ThisArray(lp)=RndRange(Job.DataRangeLow,Job.DataRangeHi)                  
                     next
                     Job.state=JobState_Sorting                              

                  case  JobState_Sorting      
                     ; this job is sorting pass over the array

                     ; move the this jobs array handle into our array stub
                     ThisArray()=Job.ArrayHandle

                     ; Get the number of passes this jobs has already had
                     PassCount=Job.PassCount

                     ;  Do a sort pass of the array data
                     Sorted=BubbleSortPass(ThisArray(),PassCount)

                     ; is this array sorted ?
                     if Sorted =0
                        Job.State=JobState_Complete         
                        Job.DeleteTime=CurrentTime
                     endif
                     Job.PassCount=Passcount+1
                     ActiveThreads++                     

            endselect

            
            if Thread_Jobs =true 
               if Timer()>EndOfProcessTime then exit
            endif
                        

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[Adaz]

Superb, possibly this is the materialization of this older topic:

http://www.underwaredesign.com/forums/index.php?topic=1782.msg12771#msg12771

[kevin]

no..