80 lines
2.4 KiB
Java
80 lines
2.4 KiB
Java
package io.github.ehlxr.zkrwlock.v1;
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import org.apache.zookeeper.CreateMode;
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import org.apache.zookeeper.ZooDefs;
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import java.util.Collections;
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import java.util.List;
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import java.util.stream.Collectors;
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/**
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* 写锁优先
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*/
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@SuppressWarnings("all")
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public class ReadWriteLock extends ZkLock {
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private static final String READ_WRITE_NODE = "lock_";
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// 有写锁的时候读锁等待，写锁永远都可以插队
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public static String READ = "read_";
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public static String WRITE = "write_";
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// 当前锁的状态
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private String state;
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public ReadWriteLock(String state) throws Exception {
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this.state = state;
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// 1. 创建临时有序节点
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path = zooKeeper.create(READ_WRITE_LOCK_PATH + "/" + READ_WRITE_NODE + state, "".getBytes()
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, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
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// 2. 获得路径下所有节点
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attemptLock(path);
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}
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@Override
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protected void attemptLock(String path) throws Exception {
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List<String> list = zooKeeper.getChildren(READ_WRITE_LOCK_PATH, false);
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List<String> readList = list.stream().filter(data -> data.contains(READ)).collect(Collectors.toList());
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List<String> writeList = list.stream().filter(data -> data.contains(WRITE)).collect(Collectors.toList());
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Collections.sort(readList);
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Collections.sort(writeList);
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if (READ.equals(state)) {
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// 读锁的获取方式必须是前面没有写锁，并且自己是第一个，否则阻塞
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if (writeList.size() == 0) {
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int index = readList.indexOf(path.substring(READ_WRITE_LOCK_PATH.length() + 1));
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if (index == 0) {
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// System.out.println("获取到锁对象");
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return;
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} else {
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cirLock(path, readList, index);
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}
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} else {
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// 有写锁，需要监听最后一个写锁
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cirLock(path, writeList, writeList.size());
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}
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} else {
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// 写锁的获取方式是前面没有写锁
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int index = writeList.indexOf(path.substring(READ_WRITE_LOCK_PATH.length() + 1));
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if (index == 0) {
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// System.out.println("写锁获取到锁对象");
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return;
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} else {
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// 监听上一个读锁
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cirLock(path, writeList, index);
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}
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}
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}
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}
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