src/edu/berkeley/fleet/InboxPort.java

   1 package edu.berkeley.fleet;
   2
   3 import static edu.berkeley.fleet.Instruction.IgnoreCopyTake.*;
   4 import java.util.*;
   5
   6 public class InboxPort extends InstructionPort {
   7
   8     public InboxPort(Ship ship, String name) {
   9         super(ship, name);
  10
  11         // default standing move
  12         addInstruction(new Instruction(null,
  13                                        null,
  14                                        Integer.MAX_VALUE,
  15                                        TAKE,
  16                                        false,
  17                                        false,
  18                                        true
  19                                        ));
  20     }
  21
  22     // data in from the switch fabric
  23     private Queue<Integer> dataIn = new LinkedList<Integer>();
  24     public void addData(int data) { dataIn.add(data); }
  25     public void addToken() { throw new RuntimeException("inboxes do not accept tokens!"); }
  26
  27     // data out to the ship
  28     private boolean empty = true;
  29     private int dataOut;
  30     private Port tokenDestination;
  31
  32     public boolean empty() { return empty; }
  33     public int remove() {
  34         if (empty)
  35             throw new RuntimeException("called remove() on an empty() inbox");
  36         empty = true;
  37         if (tokenDestination != null) {
  38             Log.token(this, tokenDestination);
  39             tokenDestination.addToken();
  40         }
  41         return dataOut;
  42     }
  43
  44     public boolean service(Instruction instruction) {
  45
  46         // if data is stuck on dataOut, wait for it to go somewhere
  47         if (!empty) return false;
  48
  49         // if no instruction waiting, do nothing
  50         if (instruction == null) return false;
  51
  52         // check firing conditions
  53         if (instruction.trigger)
  54             throw new RuntimeException("you cannot send a triggered instruction to an inbox!");
  55         if (instruction.dataIn != IGNORE && dataIn.size()==0) return false;
  56
  57         // consume inbound data+token
  58         int data = 0;
  59         switch(instruction.dataIn) {
  60             case COPY:
  61                 dataOut = dataIn.peek();
  62                 break;
  63             case TAKE:
  64                 dataOut = dataIn.remove();
  65                 break;
  66         }
  67
  68         if (instruction.dataOut) {
  69             empty = false;
  70             if (instruction.ack)
  71                 tokenDestination = instruction.destination.resolve(getShip().getFleet());
  72
  73         } else if (instruction.ack) {
  74             Port p = instruction.destination.resolve(getShip().getFleet());
  75             Log.token(this, p);
  76             p.addToken();
  77         }
  78         return true;
  79     }
  80 }