聊聊LettucePoolingConnectionProvider

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本文主要研究一下LettucePoolingConnectionProvider

LettucePoolingConnectionProvider

spring-data-redis-2.0.10.RELEASE-sources.jar!/org/springframework/data/redis/connection/lettuce/LettucePoolingConnectionProvider.java

/*** {@link LettuceConnectionProvider} with connection pooling support. This connection provider holds multiple pools (one* per connection type) for contextualized connection allocation.* <p />* Each allocated connection is tracked and to be returned into the pool which created the connection. Instances of this* class require {@link #destroy() disposal} to de-allocate lingering connections that were not returned to the pool and* to close the pools.** @author Mark Paluch* @author Christoph Strobl* @since 2.0* @see #getConnection(Class)*/ class LettucePoolingConnectionProvider implements LettuceConnectionProvider, RedisClientProvider, DisposableBean {private final static Log log = LogFactory.getLog(LettucePoolingConnectionProvider.class);private final LettuceConnectionProvider connectionProvider;private final GenericObjectPoolConfig poolConfig;private final Map<StatefulConnection<?, ?>, GenericObjectPool<StatefulConnection<?, ?>>> poolRef = new ConcurrentHashMap<>(32);private final Map<Class<?>, GenericObjectPool<StatefulConnection<?, ?>>> pools = new ConcurrentHashMap<>(32);LettucePoolingConnectionProvider(LettuceConnectionProvider connectionProvider,LettucePoolingClientConfiguration clientConfiguration) {Assert.notNull(connectionProvider, "ConnectionProvider must not be null!");Assert.notNull(clientConfiguration, "ClientConfiguration must not be null!");this.connectionProvider = connectionProvider;this.poolConfig = clientConfiguration.getPoolConfig();}/** (non-Javadoc)* @see org.springframework.data.redis.connection.lettuce.LettuceConnectionProvider#getConnection(java.lang.Class)*/@Overridepublic <T extends StatefulConnection<?, ?>> T getConnection(Class<T> connectionType) {GenericObjectPool<StatefulConnection<?, ?>> pool = pools.computeIfAbsent(connectionType, poolType -> {return ConnectionPoolSupport.createGenericObjectPool(() -> connectionProvider.getConnection(connectionType),poolConfig, false);});try {StatefulConnection<?, ?> connection = pool.borrowObject();poolRef.put(connection, pool);return connectionType.cast(connection);} catch (Exception e) {throw new PoolException("Could not get a resource from the pool", e);}}/** (non-Javadoc)* @see org.springframework.data.redis.connection.lettuce.RedisClientProvider#getRedisClient()*/@Overridepublic AbstractRedisClient getRedisClient() {if (connectionProvider instanceof RedisClientProvider) {return ((RedisClientProvider) connectionProvider).getRedisClient();}throw new IllegalStateException(String.format("Underlying connection provider %s does not implement RedisClientProvider!",connectionProvider.getClass().getName()));}/** (non-Javadoc)* @see org.springframework.data.redis.connection.lettuce.LettuceConnectionProvider#release(io.lettuce.core.api.StatefulConnection)*/@Overridepublic void release(StatefulConnection<?, ?> connection) {GenericObjectPool<StatefulConnection<?, ?>> pool = poolRef.remove(connection);if (pool == null) {throw new PoolException("Returned connection " + connection+ " was either previously returned or does not belong to this connection provider");}pool.returnObject(connection);}/** (non-Javadoc)* @see org.springframework.beans.factory.DisposableBean#destroy()*/@Overridepublic void destroy() throws Exception {if (!poolRef.isEmpty()) {log.warn("LettucePoolingConnectionProvider contains unreleased connections");poolRef.forEach((connection, pool) -> pool.returnObject(connection));poolRef.clear();}pools.forEach((type, pool) -> pool.close());pools.clear();} } 复制代码

• 这个provider与普通的连接不同，它区分了不同类型的连接池，因而pools是map结构的，而且还多了poolRef这个map来维护每个连接所在连接池
• pools主要是用于根据连接类型获取对应连接池，用于连接的借用场景，而poolRef主要是用于连接的归还场景
• 这里采用了ConcurrentHashMap的computeIfAbsent方法，对于key不存在的则触发创建并返回，对于key存在的则直接返回

小结

• lettuce 4.0版本引入了StatefulConnection，它会维护登录、事务、所选数据库，读写等状态
• StatefulConnection有几个类型，分别是StatefulRedisConnection(StatefulRedisPubSubConnection、StatefulRedisMasterSlaveConnection)、StatefulRedisSentinelConnection、StatefulRedisClusterConnection
• LettucePoolingConnectionProvider维护了多类型的连接的连接池，因而采用map的数据结构，不然单一类型的连接直接使用GenericObjectPool即可

doc

• Stateful Connections

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