kylin源码走读_kylinConfig

kylin配置文件获取

public class KylinConfig extends KylinConfigBase  KylinConfig继承自KylinConfigBase

 public static KylinConfig getInstanceFromEnv() {
        //同步锁
        synchronized (KylinConfig.class) {
            //获取本地实例的config
            KylinConfig config = THREAD_ENV_INSTANCE.get();
//判断实例中的config是否存在，如果存在则直接返回config
            if (config != null) {
                return config;
            }
            //如果不存在则读本地配置文件
            if (SYS_ENV_INSTANCE == null) {
                try {
                    config = new KylinConfig();
                    config.reloadKylinConfig(buildSiteProperties());

                    logger.info("Initialized a new KylinConfig from getInstanceFromEnv : "
                            + System.identityHashCode(config));
                    SYS_ENV_INSTANCE = config;
                } catch (IllegalArgumentException e) {
                    throw new IllegalStateException("Failed to find KylinConfig ", e);
                }
            }
            return SYS_ENV_INSTANCE;
        }
    }

KylinConfig config =  KylinConfig.getInstanceFromEnv();

getInstanceFromEnv方法的具体实现如下：首先获取从本地实例的THREAD_ENV_INSTANCE中获取kylinConfig，如果不为null则直接返回实例中config，如果为null,则读取本地配置问题，然后调用kylinConfig自身的bulidSiteProperties()方法返回一个Properties 最后通过config.reloadKylinConfig()方法把配置项加载到config中。赋值给SYS_ENV_INSTANCE 返回。

bulidSiteProperties()方法实现如下：

 private static Properties buildSiteProperties() {
        Properties conf = new Properties();

        OrderedProperties orderedProperties = buildSiteOrderedProps();
        for (Map.Entry each : orderedProperties.entrySet()) {
            conf.put(each.getKey(), each.getValue());
        }

        return conf;
    }

bulidSiteOrderedProps()方法实现如下：

    // build kylin properties from site deployment, a.k.a KYLIN_HOME/conf/kylin.properties
    private static OrderedProperties buildSiteOrderedProps() {

        try {
            // 1. load default configurations from classpath. 
            // we have a kylin-defaults.properties in kylin/core-common/src/main/resources 
            URL resource = Thread.currentThread().getContextClassLoader().getResource("kylin-defaults.properties");
            Preconditions.checkNotNull(resource);
            logger.info("Loading kylin-defaults.properties from {}", resource.getPath());
            OrderedProperties orderedProperties = new OrderedProperties();
            loadPropertiesFromInputStream(resource.openStream(), orderedProperties);

            for (int i = 0; i < 10; i++) {
                String fileName = "kylin-defaults" + (i) + ".properties";
                URL additionalResource = Thread.currentThread().getContextClassLoader().getResource(fileName);
                if (additionalResource != null) {
                    logger.info("Loading {} from {} ", fileName, additionalResource.getPath());
                    loadPropertiesFromInputStream(additionalResource.openStream(), orderedProperties);
                }
            }

            // 2. load site conf, to keep backward compatibility it's still named kylin.properties
            // actually it's better to be named kylin-site.properties
            File propFile = getSitePropertiesFile();
            if (propFile == null || !propFile.exists()) {
                logger.error("fail to locate " + KYLIN_CONF_PROPERTIES_FILE);
                throw new RuntimeException("fail to locate " + KYLIN_CONF_PROPERTIES_FILE);
            }
            loadPropertiesFromInputStream(new FileInputStream(propFile), orderedProperties);

            // 3. still support kylin.properties.override as secondary override
            // not suggest to use it anymore
            File propOverrideFile = new File(propFile.getParentFile(), propFile.getName() + ".override");
            if (propOverrideFile.exists()) {
                loadPropertiesFromInputStream(new FileInputStream(propOverrideFile), orderedProperties);
            }
            return orderedProperties;
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

bulidSiteProperties() 方法读取 KYLIN_HOME/conf/kylin.properties 文件，具体逻辑：

1.首先从classpath中读取默认kylin-defaults.properties文件，文件位置：kylin/core-common/src/main/resources
生成URL路径，Preconditions.checkNotNull(resource)判断是否为NULL，如果为null，则抛出空指针异常,不为null则使用url.openStream()返回一个InputSteam对象。调用kylinConfig.loadPropertiesFromInputStream()方法，把配置文件中的配置项通过kv形式赋值给orderedProperties对象，接着循环10次判断是否有额外新增的配置文件命名格式以kylin-defaults" + (i) + ".properties，如果有，则重复上述步骤调用kylinConfig.loadPropertiesFromInputStream()方法获取配置项

2.为了保持向后兼容性，调用kylin.getSitePropertiesFile()  返回一个文件对象，然后判断是否为null,接着同上调用kylin.getSitePropertiesFile()  返回一个文件对象重复上述步骤调用kylinConfig.loadPropertiesFromInputStream()方法获取配置项

3.还支持kylin.properties 的重写这里不再鳌述。

kylinConfig.reloadKylinConfig() 方法主要是通过调用
BackwardCompatibilityConfig.check()方法把key，value强制转化为String类型，类似于格式化