From aab95f0bd68cb09738ef4c836ea8925a97652f26 Mon Sep 17 00:00:00 2001
From: zkhut16 <zkhut16@freeuni.edu.ge>
Date: Wed, 24 Feb 2021 13:31:44 +0400
Subject: [PATCH] implemented my version of CountDownLatch using Semaphore

---
 Java2020/src/homework/MyCountDownLatch.java   | 28 +++++++++++++++++
 .../src/homework/MyCountDownLatchExample.java | 30 +++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 Java2020/src/homework/MyCountDownLatch.java
 create mode 100644 Java2020/src/homework/MyCountDownLatchExample.java

diff --git a/Java2020/src/homework/MyCountDownLatch.java b/Java2020/src/homework/MyCountDownLatch.java
new file mode 100644
index 0000000..874c9cb
--- /dev/null
+++ b/Java2020/src/homework/MyCountDownLatch.java
@@ -0,0 +1,28 @@
+package homework;
+
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class MyCountDownLatch {
+    private AtomicInteger count;
+    Semaphore blocker;
+    public  MyCountDownLatch(int count){
+        this.count = new AtomicInteger(count);
+        blocker = new Semaphore(0);
+    }
+
+    public void await(){
+        if(count.get() > 0)
+            blocker.acquireUninterruptibly();
+    }
+
+    public void countDown(){
+        if(count.decrementAndGet() == 0) {
+            blocker.release(2 * blocker.getQueueLength());
+        }
+    }
+
+    public long getCount(){
+        return count.get();
+    }
+}
diff --git a/Java2020/src/homework/MyCountDownLatchExample.java b/Java2020/src/homework/MyCountDownLatchExample.java
new file mode 100644
index 0000000..80b428e
--- /dev/null
+++ b/Java2020/src/homework/MyCountDownLatchExample.java
@@ -0,0 +1,30 @@
+package homework;
+
+
+public class MyCountDownLatchExample {
+    public static void main(String[] args) {
+        MyCountDownLatch mcdl = new MyCountDownLatch(5);
+        for(int i = 10; i > 0; i--){
+            new Thread(()->{
+                    mcdl.await();
+                    System.out.println("do something" + Thread.currentThread());
+            }).start();
+        }
+        for(int i = 0; i < 6; i++){
+            try {
+                Thread.sleep(1000);
+                mcdl.countDown();
+                System.out.println("iteration #"+(i+1));
+                System.out.println("count : "+mcdl.getCount());
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }
+        for(int i = 10; i > 0; i--){
+            new Thread(()->{
+                    mcdl.await();
+                    System.out.println("do something" + Thread.currentThread());
+            }).start();
+        }
+    }
+}