[TIJ4] [diff] Dining Philisophers problem

=== modified file 'concurrency/DeadlockingDiningPhilosophers.java'
--- concurrency/DeadlockingDiningPhilosophers.java  2012-12-04 05:49:42 +0000
+++ concurrency/DeadlockingDiningPhilosophers.java  2012-12-08 13:48:47 +0000
@@ -15,11 +15,12 @@
       size = Integer.parseInt(args[1]);
     ExecutorService exec = Executors.newCachedThreadPool();
     Chopstick[] sticks = new Chopstick[size];
+   LinkedBlockingQueue<Chopstick> bin = new LinkedBlockingQueue<Chopstick>();
     for(int i = 0; i < size; i++)
       sticks[i] = new Chopstick();
     for(int i = 0; i < size; i++)
-      exec.execute(new Philosopher(
-        sticks[i], sticks[(i+1) % size], i, ponder));
+       exec.execute(new Philosopher(
+         sticks[i], sticks[(i+1) % size], bin, i, ponder));
     if(args.length == 3 && args[2].equals("timeout"))
       TimeUnit.SECONDS.sleep(5);
     else {
@@ -29,3 +30,12 @@
     exec.shutdownNow();
   }
 } /* (Execute to see output) *///:~
+
+/**
+ * Ex21(page1229): When the Philosopher puts only one chopstick in the
+ * bin, then the dealock does occur. If the Philosopher puts two
+ * chopsticks the bin -- we end having 10 chopsticks in the queue --
+ * every chopstick is shared by two Philosopher, so in this case
+ * (though it is erroneus, we don't reach Deadlock.)
+ */
+

=== modified file 'concurrency/Philosopher.java'
--- concurrency/Philosopher.java    2012-12-04 05:49:42 +0000
+++ concurrency/Philosopher.java    2012-12-08 13:48:47 +0000
@@ -7,6 +7,7 @@
 import static util.Print.*;

 public class Philosopher implements Runnable {
+   private BlockingQueue<Chopstick> bin;
   private Chopstick left;
   private Chopstick right;
   private final int id;
@@ -17,16 +18,16 @@
     TimeUnit.MILLISECONDS.sleep(
       rand.nextInt(ponderFactor * 250));
   }
-  public Philosopher(Chopstick left, Chopstick right,
+   public Philosopher(Chopstick left, Chopstick right, BlockingQueue<Chopstick> bin,
     int ident, int ponder) {
     this.left = left;
     this.right = right;
+   this.bin = bin;
     id = ident;
     ponderFactor = ponder;
   }
   public void run() {
     try {
-      while(!Thread.interrupted()) {
         print(this + " " + "thinking");
         pause();
         // Philosopher becomes hungry
@@ -36,9 +37,22 @@
         left.take();
         print(this + " " + "eating");
         pause();
-        right.drop();
+        right.drop();
         left.drop();
-      }
+       print("putting left to bin."); bin.put(left);
+       while(!Thread.interrupted()) {
+           print(this + " " + "thinking");
+           pause();
+           // Philosopher becomes hungry
+           print(this + " " + "grabbing right from bin");
+           right = bin.take();
+           print(this + " " + "grabbing left from bin");
+           left = bin.take();
+           print(this + " " + "eating");
+           pause();
+           print(this + " " + "putting right to bin "); bin.put(right);
+           print(this + " " + "putting left to bin "); bin.put(left);
+       }
     } catch(InterruptedException e) {
       print(this + " " + "exiting via interrupt");
     }