Seata源码笔记（二）

基于incubartor-seata-2.x

配置相关的

ConfigurationFactory

静态代码块

initOriginConfiguration和maybeNeedOriginFileInstance逻辑较为简单，主要看看load

private static final String REGISTRY_CONF_DEFAULT = "registry";
private static final String ENV_SYSTEM_KEY = "SEATA_ENV";
public static final String ENV_PROPERTY_KEY = "seataEnv";private static final String SYSTEM_PROPERTY_SEATA_CONFIG_NAME = "seata.config.name";private static final String ENV_SEATA_CONFIG_NAME = "SEATA_CONFIG_NAME";public static volatile Configuration CURRENT_FILE_INSTANCE;public static volatile FileConfiguration ORIGIN_FILE_INSTANCE_REGISTRY;public static volatile FileConfiguration ORIGIN_FILE_INSTANCE = null;static {// 负责初始化ORIGIN_FILE_INSTANCE_REGISTRY，通过读取registry.conf（<configName>-<envName>.conf）initOriginConfiguration();// 初始化CURRENT_FILE_INSTANCE（判断是否有extConfiguration，没有就用ORIGIN_FILE_INSTANCE_REGISTRY，本来FileConfiguration就是Configuration的实现）// ext默认有个SpringBootConfigurationProvider实现，返回一个代理对象（seata-spring-autoconfigure-core里）load();// 如果CURRENT_FILE_INSTANCE是.conf的（也就是load用的还是registry.conf）// 那原配置文件ORIGIN_FILE_INSTANCE就用的registry.conf里的config.file.name（test中给的file.conf）maybeNeedOriginFileInstance();
}

load()：融入spring获取value的方式

对应上述静态代码块里load部分（主要是通过SPI去找ExtConfigurationProvider的实现然后调用provide方法，目前唯一提供的实现SpringBootConfigurationProvider，它是通过动态代理创建一个Configuration的代理对象，来拦截并设置get方法获取的值）

public class SpringBootConfigurationProvider implements ExtConfigurationProvider {private static final Logger LOGGER = LoggerFactory.getLogger(SpringBootConfigurationProvider.class);private static final String INTERCEPT_METHOD_PREFIX = "get";private static final Map<String, Object> PROPERTY_BEAN_INSTANCE_MAP = new ConcurrentHashMap<>(64);@Overridepublic Configuration provide(Configuration originalConfiguration) {return (Configuration)Enhancer.create(originalConfiguration.getClass(),(MethodInterceptor)(proxy, method, args, methodProxy) -> {if (method.getName().startsWith(INTERCEPT_METHOD_PREFIX) && args.length > 0) {Object result;String rawDataId = (String)args[0];Class<?> dataType = ReflectionUtil.getWrappedClass(method.getReturnType());// 1. Get config value from the system propertyresult = originalConfiguration.getConfigFromSys(rawDataId);if (result == null) {String dataId = convertDataId(rawDataId);// 2. Get config value from the springboot environmentresult = getConfigFromEnvironment(dataId, dataType);if (result != null) {return result;}// 3. Get config defaultValue from the argumentsif (args.length > 1) {result = args[1];if (result != null) {// See Configuration#getConfig(String dataId, long timeoutMills)if (dataType.isAssignableFrom(result.getClass())) {return result;} else {result = null;}}}// 4. Get config defaultValue from the property objecttry {result = getDefaultValueFromPropertyObject(dataId);} catch (Throwable t) {LOGGER.error("Get config '{}' default value from the property object failed:", dataId, t);}}if (result != null) {if (dataType.isAssignableFrom(result.getClass())) {return result;}// Convert typereturn this.convertType(result, dataType);}}return method.invoke(originalConfiguration, args);});}...
}

Configuration的get方法拦截后，value取值优先级

result，也就是get方法的结果读取优先级：

环境变量（步骤1里getenv和getProperty）
ApplicationContext（步骤2里的ObjectHolder，很贴心的做了各种变换去找，下面会去看ObjectHolder怎么来的）
Configuration.getConfig(String dataId, String defaultValue…)（步骤3取默认值）
从PROPERTY_BEAN_MAP获取（步骤4，下面会去看PROPERTY_BEAN_MAP怎么来的）

ObjectHolder

seata-spring-autoconfigure-core的spring.factories配了个自动配置项SeataCoreAutoConfiguration

PROPERTY_BEAN_MAP

同上，seata-spring-autoconfigure-core的spring.factories配了个自动配置项SeataCoreEnvironmentPostProcessor，并且client和server包里也配置了SeataClientEnvironmentPostProcessor和SeataServerEnvironmentPostProcessor

getInstance

buildConfiguration

reload

工作去了，晚点更