Spring redis批處理 RedisTemplate.executePipelined

使用pipeline可以減少與redis通信次數，在一次通信中執行一系列命令
Spring中通過RedisTemplate.executePipelined使用流水線執行命令

• 函數提供兩種回調方式SessionCalback/RedisCallback
• 與RedisTemplate.execute不同，executePipelined會自動將回調中每個命令的執行結果存入數組中返回，參數回調必須返回null，否則將拋出異常

org.springframework.dao.InvalidDataAccessApiUsageException: Callback cannot return a non-null value as it gets overwritten by the pipeline

• pipeline不是原子操作
• org.springframework.data.redis.core.RedisTemplate

public List<Object> executePipelined(SessionCallback<?> session) {
	return this.executePipelined(session, this.valueSerializer);
}

public List<Object> executePipelined(SessionCallback<?> session, @Nullable RedisSerializer<?> resultSerializer) {
    Assert.isTrue(this.initialized, "template not initialized; call afterPropertiesSet() before using it");
    Assert.notNull(session, "Callback object must not be null");
    RedisConnectionFactory factory = this.getRequiredConnectionFactory();
    RedisConnectionUtils.bindConnection(factory, this.enableTransactionSupport);

    List var4;
    try {
        var4 = (List)this.execute((connection) -> {
            connection.openPipeline();
            boolean pipelinedClosed = false;

            List var7;
            try {
                Object result = this.executeSession(session);
                // 回調
                if (result != null) {
                    throw new InvalidDataAccessApiUsageException("Callback cannot return a non-null value as it gets overwritten by the pipeline");
                }

                List<Object> closePipeline = connection.closePipeline();
                pipelinedClosed = true;
                var7 = this.deserializeMixedResults(closePipeline, resultSerializer, this.hashKeySerializer, this.hashValueSerializer);
            } finally {
                if (!pipelinedClosed) {
                    connection.closePipeline();
                }

            }

            return var7;
        });
    } finally {
        RedisConnectionUtils.unbindConnection(factory);
    }

    return var4;
}

public List<Object> executePipelined(RedisCallback<?> action) {
    return this.executePipelined(action, this.valueSerializer);
}

public List<Object> executePipelined(RedisCallback<?> action, @Nullable RedisSerializer<?> resultSerializer) {
    return (List)this.execute((connection) -> {
        connection.openPipeline();
        boolean pipelinedClosed = false;

        List var7;
        try {
            Object result = action.doInRedis(connection);
            if (result != null) {
                throw new InvalidDataAccessApiUsageException("Callback cannot return a non-null value as it gets overwritten by the pipeline");
            }

            List<Object> closePipeline = connection.closePipeline();
            pipelinedClosed = true;
            var7 = this.deserializeMixedResults(closePipeline, resultSerializer, this.hashKeySerializer, this.hashValueSerializer);
        } finally {
            if (!pipelinedClosed) {
                connection.closePipeline();
            }

        }

        return var7;
    });
}