Apache-Ignite入门实战之三 - 分布式锁

﹏ヽ暗。殇╰゛Y 2021-09-16 03:54 376阅读 0赞

[https://blog.csdn.net/kongxx/article/details/78918257][https_blog.csdn.net_kongxx_article_details_78918257]

在 Ignite 的分布式缓存中还有一种常见应用场景是分布式锁，利用分布式锁我们可以实现简单的集群master选举功能。

下面是一个使用分布式锁的例子：

package my.ignitestudy.datagrid;
    
    import org.apache.ignite.Ignite;
    import org.apache.ignite.IgniteCache;
    import org.apache.ignite.Ignition;
    import org.apache.ignite.cache.CacheAtomicityMode;
    import org.apache.ignite.configuration.CacheConfiguration;
    import org.apache.ignite.configuration.IgniteConfiguration;
    import org.apache.ignite.spi.discovery.tcp.TcpDiscoverySpi;
    import org.apache.ignite.spi.discovery.tcp.ipfinder.vm.TcpDiscoveryVmIpFinder;
    
    import java.util.Arrays;
    import java.util.concurrent.locks.Lock;
    
    public class DistributedLockExample {
    
        public static void main( String[] args ) throws Exception {
            test();
        }
    
        private static Ignite getIgnite() {
            TcpDiscoverySpi spi = new TcpDiscoverySpi();
            TcpDiscoveryVmIpFinder ipFinder = new TcpDiscoveryVmIpFinder();
            ipFinder.setAddresses(Arrays.asList("192.168.0.192:47500..47509"));
            spi.setIpFinder(ipFinder);
    
            IgniteConfiguration igniteCfg = new IgniteConfiguration();
            igniteCfg.setDiscoverySpi(spi);
            igniteCfg.setClientMode(true);
    
            Ignite ignite = Ignition.start(igniteCfg);
            return ignite;
        }
    
        private static void test() throws Exception {
            CacheConfiguration cacheCfg = new CacheConfiguration();
            cacheCfg.setName("default");
            cacheCfg.setBackups(1);
            IgniteCache<String, String> cache = getIgnite().getOrCreateCache(cacheCfg);
    
            String mylock = "mylock";
    
            new Thread(new Runnable() {
                @Override
                public void run() {
                    System.out.println("Thread 1: before lock");
                    Lock lock = cache.lock(mylock);
                    lock.lock();
                    System.out.println("Thread 1: after lock");
    
                    try {
                        cache.put(mylock, "Thread 1");
                        Thread.currentThread().sleep(10 * 1000);
                    } catch (Exception ex) {
                        ex.printStackTrace();
                    } finally {
                        System.out.println("Thread 1: before unlock");
                        lock.unlock();
                        System.out.println("Thread 1: after unlock");
                    }
                }
            }).start();
    
            Thread.currentThread().sleep(2 * 1000);
    
            new Thread(new Runnable() {
                @Override
                public void run() {
                    System.out.println("Thread 2: before lock");
                    Lock lock = cache.lock(mylock);
                    lock.lock();
                    System.out.println("Thread 2: after lock");
    
                    try {
                        cache.put(mylock, "Thread 2");
                    } catch (Exception ex) {
                        ex.printStackTrace();
                    } finally {
                        System.out.println("Thread 2: before unlock");
                        lock.unlock();
                        System.out.println("Thread 2: after unlock");
                    }
                }
            }).start();
        }
    
    }

*  例子中使用两个线程来模拟抢占锁的场景。
 *  为了测试方便，第一个线程先启动，在获取锁后先sleep一会，等待第二个线程启动。
 *  第二个线程启动后也试着去获取锁，此时由于第一个线程已经获取了锁，所以第二个线程会等待。
 *  第一个线程sleep一会后，把锁释放，这时第二个线程就会立即获取锁，然后执行自己的逻辑。

[https_blog.csdn.net_kongxx_article_details_78918257]: https://blog.csdn.net/kongxx/article/details/78918257