SCALA's synchronization and lock mechanism in the Java class library

The synchronization and lock mechanism of the SCALA concurrent framework in the Java library Introduction: SCALA is a static type programming language running on the Java virtual machine, which combines object -oriented programming and functional programming features.The SCALA concurrent framework provides many built -in synchronization and lock mechanisms to help developers write complicated code.This article will introduce the mechanism used to synchronize and lock the SCALA concurrent framework in the Java library, and provide the necessary Java code examples. 1. Synchronous mechanism: In concurrent programming, the synchronization mechanism is a technology used to access shared resources between threads.SCALA provides several synchronous mechanisms, including synchronization blocks, condition variables and atomic operations. 1.1 synchronous block: Synchronous blocks are one of the basic mechanisms for synchronous access to shared resources in SCALA.In the synchronous block, there is only one thread that can access shared resources at the same time.The following is an example of Java code that uses synchronous blocks to achieve synchronization: import scala.concurrent.Lock; class Counter { private var count = 0 private val lock = new Lock() def increment(): Unit = { lock.acquire() try { count += 1 } finally { lock.release() } } def getCount(): Int = count } // Use the example of the synchronous block val counter = new Counter() val thread1 = new Thread(() => { for (i <- 1 to 1000) { counter.increment() } }) val thread2 = new Thread(() => { for (i <- 1 to 1000) { counter.increment() } }) thread1.start() thread2.start() thread1.join() thread2.join() Println (counter.getCount ()) // The output result should be 2000 The Counter class in the above example uses the Scala Lock class to create a lock object.In the increment method, we get lock.acquire () to get locks and release locks through lock.release () after the operation is completed.This can ensure that there is only one thread at a time that can modify the count variables, thereby ensuring thread security. 1.2 Condition variables: Condition variables are a mechanism for thread communication, which allows threads to wait for the satisfaction of a certain condition.Condition variables in SCALA can be used with locks to achieve more complicated synchronization mechanisms.The following is an example of Java code using condition variables: import scala.concurrent.SyncVar; class ProducerConsumer { private val container = new SyncVar[Option[String]]() def produce(data: String): Unit = { container.put(Some(data)) } def consume(): String = { container.take().getOrElse("") } } // Examples to use condition variables val producerConsumer = new ProducerConsumer() val producer = new Thread(() => { for (i <- 1 to 10) { val data = s"Data $i" producerConsumer.produce(data) println(s"Produced: $data") Thread.sleep(1000) } }) val consumer = new Thread(() => { for (_ <- 1 to 10) { val data = producerConsumer.consume() println(s"Consumed: $data") Thread.sleep(2000) } }) producer.start() consumer.start() producer.join() consumer.join() The Producerconsumer class in the above example uses the SCALA Syncvar class to create a condition variable object.In the Produce method, we use Container.put (SOME (DATA)) to put the data into the container.In the consume method, we use the data to take out the data in the container.take ().If the container is empty, the thread will be blocked until there is data available.Through this mechanism, producers and consumer threads can safely produce data production and consumption. 2. Lock mechanism: Locking is a mechanism to control the access of shared resources.The SCALA concurrent framework provides several locking mechanisms, including ReentrantLock, ReadWritelock, and StampedLock. 2.1 ReentrantLock： ReentrantLock is a implementation of the lock in SCALA.It allows threads to obtain locks in a recursion, that is, one thread can obtain the same lock multiple times.The following is an example of Java code that uses RENTRANTLOCK to achieve synchronization: import scala.concurrent.locks.ReentrantLock; class Counter { private var count = 0 private val lock = new ReentrantLock() def increment(): Unit = { lock.lock() try { count += 1 } finally { lock.unlock() } } def getCount(): Int = count } // Example of using ReentrantLock val counter = new Counter() val thread1 = new Thread(() => { for (i <- 1 to 1000) { counter.increment() } }) val thread2 = new Thread(() => { for (i <- 1 to 1000) { counter.increment() } }) thread1.start() thread2.start() thread1.join() thread2.join() Println (counter.getCount ()) // The output result should be 2000 The Counter class in the above example uses the Scala's RENTRANTLOCK class to create a recurring lock object.In the INCREMENT method, we get lock.lock () by calling lock.lock (), and release locks through lock.unlock () after the operation is completed.This can ensure that there is only one thread at a time that can modify the count variables, thereby ensuring thread security. 2.2 ReadWriteLock： Readwritelock is a mechanism for reading and writing access control.It allows multiple threads to read operations at the same time, and only one thread can write operations.The following is a synchronous Java code example using ReadWritelock: import scala.concurrent.locks.ReentrantReadWriteLock; class DataContainer { private var data = "" private val lock = new ReentrantReadWriteLock() def writeData(data: String): Unit = { lock.writeLock().lock() try { this.data = data } finally { lock.writeLock().unlock() } } def readData(): String = { lock.readLock().lock() try { this.data } finally { lock.readLock().unlock() } } } // Example of using ReadWritelock val dataContainer = new DataContainer() val writer = new Thread(() => { for (i <- 1 to 10) { val data = s"Data $i" dataContainer.writeData(data) println(s"Data written: $data") Thread.sleep(1000) } }) val reader = new Thread(() => { for (_ <- 1 to 10) { val data = dataContainer.readData() println(s"Data read: $data") Thread.sleep(2000) } }) writer.start() reader.start() writer.join() reader.join() In the above example, the DataContainer class uses scalantrantreamwritelock class to create a read -write lock object.In the WRITEDATA method, we obtain the writing lock by calling lock.writelock (). Lock (), and release the lock lock through lock.writelock (). Unlock () after the operation is completed.In the ReadData method, we obtain the read lock by calling lock.reamLock (). LOCK (), and release the lock lock through lock.readlock (). Unlock () after the operation is completed.This can ensure that there is only one thread that can be written, and multiple threads can be read at the same time. Summarize: The SCALA concurrent framework provides a variety of mechanisms that synchronize and lock in the Java library, including synchronous blocks, condition variables, ReentrantLock and ReadWriteLock.By using these mechanisms, we can easily write complicated and secure code to ensure the correct access to shared resources in the multi -threaded environment.