Merge remote-tracking branch 'origin/master'

许旸/snowflake/SnowflakeDemo.java

+package cn.xy.snowflake;
+
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.Semaphore;
 
 public class SnowflakeDemo {
-
+    //分割长度
     private final long sequenceLength = 12L;
 
     private final long workerIdLength = 10L;
 
     private final long lastTimeStampLength = 41L;
 
+    //偏移量
     private final long workerIdShift = sequenceLength;
 
     private final long lastTimeStampShift = sequenceLength + workerIdLength;
 
+    //初始化
     private long lastTimeStamp = -1L;
 
-    private long workerId;
+    private long workerId = 0L;
 
     private long sequence = 0L;
 
+    //掩码
     private long mark =  ~(-1L << sequenceLength);
 
-    private static final int loopNum = 1*10000;
+    private static final int loopNum = 10_000;
+
+    //请求总数
+    public static int clientTotal = 5000;
+
+    //同时并发执行的线程数
+    public static int threadTotal = 200;
 
     public synchronized String getId() {
         long timeStamp = System.currentTimeMillis();
@@ -40,16 +53,9 @@ public class SnowflakeDemo {
             sequence = 0;
         }
         lastTimeStamp = timeStamp;
-
-        return Long.toBinaryString(sequence | (workerId << workerIdShift) | (timeStamp << lastTimeStampShift));
-    }
-
-    public synchronized long waitTime(long lastTimeStamp) {
-        long timeStamp = System.currentTimeMillis();
-        while(timeStamp <= lastTimeStamp) {
-            timeStamp = System.currentTimeMillis();
-        }
-        return timeStamp;
+        String res = Thread.currentThread().getName() + " " + Long.toBinaryString(sequence | (workerId << workerIdShift) | (timeStamp << lastTimeStampShift));
+        System.out.println(Thread.currentThread().getName() + " " + res);
+        return res;
     }
 
     private SnowflakeDemo(){}
@@ -65,38 +71,76 @@ public class SnowflakeDemo {
         long currentTime = System.currentTimeMillis();
         SnowflakeDemo snowflakeDemo = new SnowflakeDemo(currentTime, 0, 0);
         for (int index = 0; index < loopNum; index++) {
+            int finalIndex = index;
             Runnable run = new Runnable() {
                 public void run() {
                     try {
                         //new Thread().sleep(1000);  //模拟耗时操作
-                        System.out.println("[1]" + Thread.currentThread().getName() + " " + snowflakeDemo.getId());
+                        //System.out.println(finalIndex + " "+ Thread.currentThread().getName() + " " + snowflakeDemo.getId());
+                        snowflakeDemo.getId();
                     } catch (Exception e) {
                     }
                 }
             };
             pool.execute(run);
         }
-        System.out.println("[1] done!");
         pool.shutdown();
     }
 
+    //模拟并发
+    public void m2() {
+        SnowflakeDemo snowflakeWorker0 = new SnowflakeDemo(System.currentTimeMillis(), 0, 0);
+        ExecutorService executorService = Executors.newCachedThreadPool();
+        //信号量，此处用于控制并发的线程数
+        final Semaphore semaphore = new Semaphore(threadTotal);
+        //闭锁，可实现计数器递减
+        final CountDownLatch countDownLatch = new CountDownLatch(clientTotal);
+        for (int i = 0; i < clientTotal ; i++) {
+            executorService.execute(() -> {
+                try {
+                    //执行此方法用于获取执行许可，当总计未释放的许可数不超过200时，
+                    //允许通行，否则线程阻塞等待，直到获取到许可。
+                    semaphore.acquire();
+                    System.out.println(Thread.currentThread().getName() + ": " + snowflakeWorker0.getId());
+                    //释放许可
+                    semaphore.release();
+                } catch (Exception e) {
+                    //log.error("exception", e);
+                    e.printStackTrace();
+                }
+                //闭锁减一
+                countDownLatch.countDown();
+            });
+        }
+        try {
+            countDownLatch.await();//线程阻塞，直到闭锁值为0时，阻塞才释放，继续往下执行
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        executorService.shutdown();
+    }
+
     public static void main(String[] args) {
         long bt = System.currentTimeMillis();
         SnowflakeDemo snowflakeWorker0 = new SnowflakeDemo(bt, 0, 0);
-        for(int i = 0; i < loopNum; i++) {
-            System.out.println(snowflakeWorker0.getId());
+        /*for(int i = 0; i < loopNum; i++) {
+            snowflakeWorker0.getId();
         }
-        long et = System.currentTimeMillis();
+        long et2 = System.currentTimeMillis();
         System.out.println("耗时:"+(et2 - bt)+ "ms");
-        System.out.println("吞吐量为："+loopNum*1.0/(et - bt));
+        System.out.println("吞吐量为："+loopNum*1.0/(et2 - bt));*/
 
-        /*SnowflakeDemo TestThreadPool = new SnowflakeDemo();
-        long bt = System.currentTimeMillis();
+        SnowflakeDemo TestThreadPool = new SnowflakeDemo();
         TestThreadPool.m1();
+        //TestThreadPool.m2();
         long et2 = System.currentTimeMillis();
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
         System.out.println("耗时:"+(et2 - bt)+ "ms");
-        System.out.println("吞吐量为："+loopNum*1.0/(et2 - bt));*/
-
+        System.out.println("吞吐量为："+loopNum*1.0/(et2 - bt));
     }
 
 }