countdown latch

last-saiyan · last-saiyan · commit cd86341b573c · 2020-09-14T08:27:18.000+05:30
diff --git a/src/main/java/barrier/CountDownLatch.java b/src/main/java/barrier/CountDownLatch.java
@@ -0,0 +1,21 @@
+package barrier;
+
+public class CountDownLatch {
+    private int count;
+    public CountDownLatch(int count){
+        this.count = count;
+    }
+    public synchronized void countDown(){
+        count--;
+        notifyAll();
+    }
+
+    public synchronized int getCount(){return this.count;}
+
+    public synchronized void await() throws InterruptedException {
+        while (count > 0) {
+            wait();
+        }
+    }
+
+}
diff --git a/src/main/java/barrier/CyclicBarrier.java b/src/main/java/barrier/CyclicBarrier.java
@@ -0,0 +1,4 @@
+package barrier;
+
+public class CyclicBarrier {
+}
diff --git a/src/test/java/barrier/TestCountDownLatch.java b/src/test/java/barrier/TestCountDownLatch.java
@@ -0,0 +1,79 @@
+package barrier;
+
+import org.junit.Test;
+import org.junit.jupiter.api.Assertions;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class TestCountDownLatch {
+
+    @Test
+    public void testCountDown() throws InterruptedException {
+        int threadCount = 10,  diff = 4;
+        CountDownLatch latchSingleThread = new CountDownLatch(threadCount);
+        Assertions.assertEquals(threadCount, latchSingleThread.getCount());
+        latchSingleThread.countDown();
+        latchSingleThread.countDown();
+        Assertions.assertEquals(threadCount-2, latchSingleThread.getCount());
+        CountDownLatch latch = new CountDownLatch(threadCount);
+        java.util.concurrent.CountDownLatch realLatch = new
+                java.util.concurrent.CountDownLatch(threadCount - diff);
+        ExecutorService service = Executors.newFixedThreadPool(10);
+        for (int i = 0; i < threadCount; i++) {
+            service.submit(() -> {
+                try {
+                    Thread.sleep(1000);
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+                latch.countDown();
+                realLatch.countDown();
+            });
+        }
+        realLatch.await();
+        Assertions.assertEquals(diff, latch.getCount());
+    }
+
+
+    @Test
+    public void testAwait() throws InterruptedException {
+        CountDownLatch latch = new CountDownLatch(3);
+        Thread t1 = new Thread(() -> {
+            try {
+                Thread.sleep(1000);
+                latch.countDown();
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        });
+        Thread t2 = new Thread(() -> {
+            try {
+                Thread.sleep(1000);
+                latch.countDown();
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        });
+        Thread t3 = new Thread(() -> {
+            try {
+                Thread.sleep(1000);
+                latch.countDown();
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        });
+        t1.start();
+        t2.start();
+        t3.start();
+
+        latch.await();
+        Assertions.assertEquals(0, latch.getCount());
+        Assertions.assertEquals(Thread.State.TERMINATED, t1.getState());
+        Assertions.assertEquals(Thread.State.TERMINATED, t2.getState());
+        Assertions.assertEquals(Thread.State.TERMINATED, t3.getState());
+
+    }
+
+
+}

-Original file line number
+Diff line change
@@ @@ -0,0 +1,4 @@ @@
 +package barrier;
++
 +public class CyclicBarrier {
 +}