聊聊jetcache的BroadcastManager

序

本文主要研究一下jetcache的BroadcastManager

BroadcastManager

jetcache-core/src/main/java/com/alicp/jetcache/support/BroadcastManager.java

public abstract class BroadcastManager implements AutoCloseable {
    private static Logger logger = LoggerFactory.getLogger(BroadcastManager.class);

    private final String sourceId = UUID.randomUUID().toString();
    private final CacheManager cacheManager;

    public BroadcastManager(CacheManager cacheManager) {
        this.cacheManager = cacheManager;
    }

    protected void checkConfig(ExternalCacheConfig config) {
        if (config.getBroadcastChannel() == null) {
            throw new CacheConfigException("BroadcastChannel not set");
        }
        if (config.getValueEncoder() == null) {
            throw new CacheConfigException("no value encoder");
        }
        if (config.getValueDecoder() == null) {
            throw new CacheConfigException("no value decoder");
        }
    }

    public abstract CacheResult publish(CacheMessage cacheMessage);

    public abstract void startSubscribe();

    @Override
    public void close() throws Exception {
    }

    //......
}    

BroadcastManager是个抽象类，实现了AutoCloseable接口，其close方法默认为空实现，它定义了publish及startSubscribe两个抽象方法；它主要有MockRemoteCacheBuilder的匿名实现、RedisBroadcastManager、LettuceBroadcastManager、SpringDataBroadcastManager、RedissonBroadcastManager这几个实现

MockRemoteCacheBuilder

jetcache-core/src/main/java/com/alicp/jetcache/external/MockRemoteCacheBuilder.java

    public BroadcastManager createBroadcastManager(CacheManager cacheManager) {
        return new BroadcastManager(cacheManager) {
            @Override
            public CacheResult publish(CacheMessage cacheMessage) {
                lastPublishMessage = cacheMessage;
                return CacheResult.SUCCESS_WITHOUT_MSG;
            }

            @Override
            public void startSubscribe() {
                subscribeStart = true;
            }
        };
    }

MockRemoteCacheBuilder的createBroadcastManager创建了一个匿名的BroadcastManager，其publish返回CacheResult.SUCCESS_WITHOUT_MSG，其startSubscribe设置subscribeStart为true

RedisBroadcastManager

jetcache-support/jetcache-redis/src/main/java/com/alicp/jetcache/redis/RedisBroadcastManager.java

public class RedisBroadcastManager extends BroadcastManager {

    private static final Logger logger = LoggerFactory.getLogger(RedisBroadcastManager.class);

    private final byte[] channel;
    private final String channelStr;
    private final RedisCacheConfig<Object, Object> config;

    private volatile CacheMessagePubSub cacheMessagePubSub;
    private volatile boolean closed;
    private volatile boolean subscribe;
    private boolean subscribeThreadStart;

    public RedisBroadcastManager(CacheManager cacheManager, RedisCacheConfig<Object, Object> config) {
        super(cacheManager);
        this.channelStr = config.getBroadcastChannel();
        this.channel = channelStr.getBytes(StandardCharsets.UTF_8);
        this.config = config;

        checkConfig(config);
        if (config.get