XFORG
diff --git a/‎.idea/workspace.xml‎
Lines changed: 87 additions & 43 deletions b/‎.idea/workspace.xml‎
Lines changed: 87 additions & 43 deletions
diff --git a/‎out/production/Java/com/xforg/concurrency/AtomicityTest.class‎
1.26 KB b/‎out/production/Java/com/xforg/concurrency/AtomicityTest.class‎
1.26 KB
diff --git a/‎out/production/Java/com/xforg/concurrency/CircularSet.class‎
809 Bytes b/‎out/production/Java/com/xforg/concurrency/CircularSet.class‎
809 Bytes
diff --git a/‎out/production/Java/com/xforg/concurrency/SerialNumberChecker$SerialChecker.class‎
1.22 KB b/‎out/production/Java/com/xforg/concurrency/SerialNumberChecker$SerialChecker.class‎
1.22 KB
diff --git a/‎out/production/Java/com/xforg/concurrency/SerialNumberChecker.class‎
1.67 KB b/‎out/production/Java/com/xforg/concurrency/SerialNumberChecker.class‎
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diff --git a/‎out/production/Java/com/xforg/concurrency/SerialNumberGenerator.class‎
496 Bytes b/‎out/production/Java/com/xforg/concurrency/SerialNumberGenerator.class‎
496 Bytes
diff --git a/‎src/com/xforg/concurrency/AtomicityTest.java‎
Lines changed: 1 addition & 1 deletion b/‎src/com/xforg/concurrency/AtomicityTest.java‎
Lines changed: 1 addition & 1 deletion
diff --git a/‎src/com/xforg/concurrency/SerialNumberChecker.java‎
Lines changed: 63 additions & 0 deletions b/‎src/com/xforg/concurrency/SerialNumberChecker.java‎
Lines changed: 63 additions & 0 deletions
diff --git a/‎src/com/xforg/concurrency/SerialNumberGenerator.java‎
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@@ -2,7 +2,7 @@
 import java.util.concurrent.*;
 
 public class AtomicityTest implements Runnable {
-  private int i = 0;
+  private  int i = 0;
   public int getValue() { return i; }
   private synchronized void evenIncrement() {
     i++; i++;
 
@@ -0,0 +1,63 @@
+package com.xforg.concurrency;//: concurrency/SerialNumberChecker.java
+// Operations that may seem safe are not,
+// when threads are present.
+// {Args: 4}
+import java.util.concurrent.*;
+
+// Reuses storage so we don't run out of memory:
+class CircularSet {
+  private int[] array;
+  private int len;
+  private int index = 0;
+  public CircularSet(int size) {
+    array = new int[size];
+    len = size;
+    // Initialize to a value not produced
+    // by the SerialNumberGenerator:
+    for(int i = 0; i < size; i++)
+      array[i] = -1;
+  }
+  public synchronized void add(int i) {
+    array[index] = i;
+    // Wrap index and write over old elements:
+    index = ++index % len;
+  }
+  public synchronized boolean contains(int val) {
+    for(int i = 0; i < len; i++)
+      if(array[i] == val) return true;
+    return false;
+  }
+}
+
+public class SerialNumberChecker {
+  private static final int SIZE = 10;
+  private static CircularSet serials =
+    new CircularSet(1000);
+  private static ExecutorService exec =
+    Executors.newCachedThreadPool();
+  static class SerialChecker implements Runnable {
+    public void run() {
+      while(true) {
+        int serial =
+          SerialNumberGenerator.nextSerialNumber();
+        if(serials.contains(serial)) {
+          System.out.println("Duplicate: " + serial);
+          System.exit(0);
+        }
+        serials.add(serial);
+      }
+    }
+  }
+  public static void main(String[] args) throws Exception {
+    for(int i = 0; i < SIZE; i++)
+      exec.execute(new SerialChecker());
+    // Stop after n seconds if there's an argument:
+    if(args.length > 0) {
+      TimeUnit.SECONDS.sleep(new Integer(args[0]));
+      System.out.println("No duplicates detected");
+      System.exit(0);
+    }
+  }
+} /* Output: (Sample)
+Duplicate: 8468656
+*///:~
@@ -0,0 +1,8 @@
+package com.xforg.concurrency;//: concurrency/SerialNumberGenerator.java
+
+public class SerialNumberGenerator {
+  private static volatile int serialNumber = 0;
+  public static int nextSerialNumber() {/*问题在于nextSerialNumber在没有同步的情况下对共享可变值进行了访问*/
+    return serialNumber++; // Not thread-safe
+  }
+} ///:~