MonitorPatternTest++

MonitorPatternTest++

Author: inbravo

README.md

@@ -49,6 +49,7 @@
 -  [Usage of 'Timer' and 'TimerTask'][TimerTest.md]
 -  [Example of failed concurrency][FailedConcurrency.md]
 -  [Example of successful concurrency][SuccessfullConcurrency.md]
+-  [Example of Java Monitor Pattern][MonitorPatternTest.md]
 -  [Example to find number of cores of a processor][AvailableProcessorTest.md]
 -  [Example of blocking array implemented using 'ReentrantLock'][BlockingArray.md]
 -  [Example of fork and join pool class 'ForkJoinPool'][ForkJoinPoolTest.md]
@@ -117,6 +118,7 @@
 [SemaphoreTest.md]: https://github.com/inbravo/java-src/blob/master/src/com/inbravo/concurrency/SemaphoreTest.java
 [FailedConcurrency.md]: https://github.com/inbravo/java-src/blob/master/src/com/inbravo/concurrency/FailedConcurrency.java
 [SuccessfullConcurrency.md]: https://github.com/inbravo/java-src/blob/master/src/com/inbravo/concurrency/SuccessfullConcurrency.java
+[MonitorPatternTest.md]: https://github.com/inbravo/java-src/blob/master/src/com/inbravo/concurrency/MonitorPatternTest.java
 [TimerTest.md]: https://github.com/inbravo/java-src/blob/master/src/com/inbravo/concurrency/TimerTest.java
 [Stack.md]: https://github.com/inbravo/java-src/blob/master/src/com/inbravo/ds.stack/Stack.java
 [ReverseTheWord.md]: https://github.com/inbravo/java-src/blob/master/src/com/inbravo/ds/stack/ReverseTheWord.java

src/com/inbravo/concurrency/MonitorPatternTest.java

@@ -0,0 +1,114 @@
+package com.inbravo.concurrency;
+
+import java.util.concurrent.Semaphore;
+
+
+/**
+ * 
+ * @author amit.dixit
+ *
+ */
+public final class MonitorPatternTest {
+
+  /* Create new Semaphore objects in class */
+  final private Semaphore firstLock = new Semaphore(1);
+  final private Semaphore secondLock = new Semaphore(1);
+
+  /**
+   * 
+   * @param args
+   */
+  public static final void main(final String... args) {
+
+    /* Create new instance of lock test */
+    final MonitorPatternTest lockTest = new MonitorPatternTest();
+
+    /* Number of threads */
+    for (int i = 0; i < 1000; i++) {
+
+      /* Create first anonymous thread */
+      new Thread() {
+
+        public void run() {
+
+          lockTest.threadSafeMethodOne();
+        }
+      }.start();
+
+      /* Create second anonymous thread */
+      new Thread() {
+
+        public void run() {
+
+          lockTest.threadSafeMethodTwo();
+        }
+      }.start();
+    }
+  }
+
+  /**
+   * First thread is still in critical section and second thread also enters
+   * 
+   * Output:
+   * 
+   * First-Thread is inside critical section Second-Thread is inside critical section Second-Thread
+   * is out of critical section First-Thread is out of critical section
+   */
+  private final void threadSafeMethodOne() {
+
+    try {
+
+      /* Acquire the lock */
+      firstLock.acquire();
+
+      /* Print current thread info */
+      System.out.println(Thread.currentThread().getName() + " is inside critical section of object:" + System.identityHashCode(this)
+          + "'s method threadSafeMethodOne at time:[" + System.currentTimeMillis() + "]");
+
+      /* Sleep this thread so that another thread can do the same operation */
+      Thread.sleep(1000);
+
+    } catch (final InterruptedException e) {
+      e.printStackTrace();
+    } finally {
+
+      /* Release the lock */
+      firstLock.release();
+      System.out.println(Thread.currentThread().getName() + " is out of critical section of object:" + System.identityHashCode(this)
+          + "'s method threadSafeMethodOne at time:[" + System.currentTimeMillis() + "]");
+    }
+  }
+
+  /**
+   * Second thread only enters critical section only when first thread is out
+   * 
+   * Output:
+   * 
+   * First-Thread is inside critical section First-Thread is out of critical section Second-Thread
+   * is inside critical section Second-Thread is out of critical section
+   */
+  private final void threadSafeMethodTwo() {
+
+    try {
+
+      /* Acquire the lock */
+      secondLock.acquire();
+
+      /* Print current thread info */
+      System.out.println(Thread.currentThread().getName() + " is inside critical section of object:" + System.identityHashCode(this)
+          + "'s method threadSafeMethodTwo at time:[" + System.currentTimeMillis() + "]");
+
+      /* Sleep this thread so that another thread can do the same operation */
+      Thread.sleep(1000);
+
+    } catch (final InterruptedException e) {
+      e.printStackTrace();
+    } finally {
+
+      /* Release the lock */
+      secondLock.release();
+      System.out.println(Thread.currentThread().getName() + " is out of critical section of object:" + System.identityHashCode(this)
+          + "'s method threadSafeMethodTwo at time:[" + System.currentTimeMillis() + "]");
+    }
+  }
+}