Clickhouse负载均衡客户端BalancedClickhouseDataSource源码分析

BalancedClickhouseDataSource源码分析

BalancedClickhouseDataSource的完整路径是ru.yandex.clickhouse.BalancedClickhouseDataSource，源码主要包括三部分，构造方法、获取连接、以及生成可用的地址列表。

BalancedClickhouseDataSource实现了javax.sql.DataSource，参数中allUrls是构造方法中传入的地址列表，enabledUrls是可用的地址列表。

public class BalancedClickhouseDataSource implements javax.sql.DataSource {
   
    private final ThreadLocal<Random> randomThreadLocal = new ThreadLocal<Random>();
    private final List<String> allUrls;
    private volatile List<String> enabledUrls;
}

BalancedClickhouseDataSource的构造方法，有多个，但是最终调用的都是BalancedClickhouseDataSource(final List urls, ClickHouseProperties properties)，如果像jdbc:clickhouse://10.170.4.81:8123,10.170.4.82:8123,10.170.4.83:8123,10.170.4.84:8123/datasets这样配置多个地址，则会先进行切分。拆分成像jdbc:clickhouse://10.170.4.81:8123/datasets、jdbc:clickhouse://10.170.4.82:8123/datasets多个地址。

public BalancedClickhouseDataSource(final String url, Properties properties) {
   
        this(splitUrl(url), new ClickHouseProperties(properties));
    }
    
    static List<String> splitUrl(final String url) {
   
        Matcher m = URL_TEMPLATE.matcher(url);
        if (!m.matches()) {
   
            throw new IllegalArgumentException("Incorrect url");
        }
        String database = m.group(2);
        if (database == null) {
   
            database = "";
        }
        String[] hosts