[HBZ sharing] principle of semaphore and countdownlatch

principle ：

Both are based on AQS Realized

Semaphore Introduction to semaphore principle and function

1. utilize Semaphore The semaphore can be used as a current limiting interface , That is, after configuring the maximum semaphore .
2. Every call acquire() Method , The semaphore will -1, When it comes to 0 when , In the call of the acquire The thread will enter the blocking state
3. Every call release() Method , The semaphore will +1, At this point, the thread in the blocking queue will be awakened for execution , And make the semaphore -1, Until the blocking queue is empty

Semaphore Semaphore API And usage

//  Create semaphore object , And the maximum semaphore is given 5 individual 
Semaphore semaphore = new Semaphore(5);
for(int i =0; i < 10; i++){
	//  Acquisition semaphore , And count the two remaining signals  - 1
	semaphore.acquire();
	System.out.println(" Perform logical ");
	//  Return the semaphore 
	semaphore.release();
}

CountDownLatch Principle and function introduction

1. Block the current thread
2. CountDownLatch countDownLatch = new CountDownLatch(2); It means that every time countDownLatch.await(), It needs to be executed twice countDownLatch.countDown(); To continue executing the current thread

CountDownLatch Of API And usage

CountDownLatch countDownLatch = new CountDownLatch(2);
new Thread(()->{
	System.out.println(" Thread start ");
	//  Block the thread 
	countDownLatch.await();
	System.out.println(" Thread end ");
}).start();

//  For the first time , It does not release the lock , because  new CountDownLatch(2); When parameters are 2, No printing at this time 【 Thread end 】
countDownLatct.countDown();
//  Carry out the second , Can be completely released , And then , Print 【 Thread end 】
countDownLatct.countDown();