之前我们分析了Apollo获取配置的源码解析，下面我们来分析配置刷新的源码。
快速回顾一下创建过程。加上@EnableApolloConfig注解。
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(ApolloConfigRegistrar.class)
public @interface EnableApolloConfig {
.............
}public class ApolloConfigRegistrar implements ImportBeanDefinitionRegistrar {
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
AnnotationAttributes attributes = AnnotationAttributes.fromMap(importingClassMetadata
.getAnnotationAttributes(EnableApolloConfig.class.getName()));
String[] namespaces = attributes.getStringArray("value");
int order = attributes.getNumber("order");
PropertySourcesProcessor.addNamespaces(Lists.newArrayList(namespaces), order);
Map<String, Object> propertySourcesPlaceholderPropertyValues = new HashMap<>();
// to make sure the default PropertySourcesPlaceholderConfigurer's priority is higher than PropertyPlaceholderConfigurer
propertySourcesPlaceholderPropertyValues.put("order", 0);
BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, PropertySourcesPlaceholderConfigurer.class.getName(),
PropertySourcesPlaceholderConfigurer.class, propertySourcesPlaceholderPropertyValues);
BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, PropertySourcesProcessor.class.getName(),
PropertySourcesProcessor.class);
BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, ApolloAnnotationProcessor.class.getName(),
ApolloAnnotationProcessor.class);
BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, SpringValueProcessor.class.getName(), SpringValueProcessor.class);
BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, SpringValueDefinitionProcessor.class.getName(), SpringValueDefinitionProcessor.class);
BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, ApolloJsonValueProcessor.class.getName(),
ApolloJsonValueProcessor.class);
}
}进入PropertySourcesProcessor类。
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
initializePropertySources();
initializeAutoUpdatePropertiesFeature(beanFactory);
}
private void initializePropertySources() {
if (environment.getPropertySources().contains(PropertySourcesConstants.APOLLO_PROPERTY_SOURCE_NAME)) {
//already initialized
return;
}
CompositePropertySource composite = new CompositePropertySource(PropertySourcesConstants.APOLLO_PROPERTY_SOURCE_NAME);
//sort by order asc
ImmutableSortedSet<Integer> orders = ImmutableSortedSet.copyOf(NAMESPACE_NAMES.keySet());
Iterator<Integer> iterator = orders.iterator();
while (iterator.hasNext()) {
int order = iterator.next();
for (String namespace : NAMESPACE_NAMES.get(order)) {
Config config = ConfigService.getConfig(namespace);
composite.addPropertySource(configPropertySourceFactory.getConfigPropertySource(namespace, config));
}
}
}进入到 ConfigService.getConfig(namespace)方法。最后会进入到这里，之前获取配置篇的时候已经分析过。
public Config create(String namespace) {
DefaultConfig defaultConfig =
new DefaultConfig(namespace, createLocalConfigRepository(namespace));
return defaultConfig;
}LocalFileConfigRepository createLocalConfigRepository(String namespace) {
if (m_configUtil.isInLocalMode()) {
logger.warn(
"==== Apollo is in local mode! Won't pull configs from remote server for namespace {} ! ====",
namespace);
return new LocalFileConfigRepository(namespace);
}
return new LocalFileConfigRepository(namespace, createRemoteConfigRepository(namespace));
}进入createRemoteConfigRepository方法会创建RemoteConfigRepository对象。
public RemoteConfigRepository(String namespace) {
m_namespace = namespace;
m_configCache = new AtomicReference<>();
m_configUtil = ApolloInjector.getInstance(ConfigUtil.class);
m_httpUtil = ApolloInjector.getInstance(HttpUtil.class);
m_serviceLocator = ApolloInjector.getInstance(ConfigServiceLocator.class);
remoteConfigLongPollService = ApolloInjector.getInstance(RemoteConfigLongPollService.class);
m_longPollServiceDto = new AtomicReference<>();
m_remoteMessages = new AtomicReference<>();
m_loadConfigRateLimiter = RateLimiter.create(m_configUtil.getLoadConfigQPS());
m_configNeedForceRefresh = new AtomicBoolean(true);
m_loadConfigFailSchedulePolicy = new ExponentialSchedulePolicy(m_configUtil.getOnErrorRetryInterval(),
m_configUtil.getOnErrorRetryInterval() * 8);
gson = new Gson();
this.trySync();
this.schedulePeriodicRefresh();
this.scheduleLongPollingRefresh();
}之前我们只分析到了trySync进行获取配置。现在分析下面两个方法。
schedulePeriodicRefresh()：用来定时从Apollo服务器获取配置信息，延时5分钟执行，每5分钟获取一次。里面依旧是调用trySync()方法。
private void schedulePeriodicRefresh() {
logger.debug("Schedule periodic refresh with interval: {} {}",
m_configUtil.getRefreshInterval(), m_configUtil.getRefreshIntervalTimeUnit());
m_executorService.scheduleAtFixedRate(
new Runnable() {
@Override
public void run() {
Tracer.logEvent("Apollo.ConfigService", String.format("periodicRefresh: %s", m_namespace));
logger.debug("refresh config for namespace: {}", m_namespace);
trySync();
Tracer.logEvent("Apollo.Client.Version", Apollo.VERSION);
}
}, m_configUtil.getRefreshInterval(), m_configUtil.getRefreshInterval(),
m_configUtil.getRefreshIntervalTimeUnit());
}
private int refreshInterval = 5;
private TimeUnit refreshIntervalTimeUnit = TimeUnit.MINUTES;scheduleLongPollingRefresh()：轮询从apollo服务器主动拉取配置信息，每5秒执行一次，每次超时时间90s。
private void scheduleLongPollingRefresh() {
remoteConfigLongPollService.submit(m_namespace, this);
}
public boolean submit(String namespace, RemoteConfigRepository remoteConfigRepository) {
boolean added = m_longPollNamespaces.put(namespace, remoteConfigRepository);
m_notifications.putIfAbsent(namespace, INIT_NOTIFICATION_ID);
if (!m_longPollStarted.get()) {
startLongPolling();
}
return added;
}
private void startLongPolling() {
..............
doLongPollingRefresh(appId, cluster, dataCenter);
...............
}
private void doLongPollingRefresh(String appId, String cluster, String dataCenter) {
final Random random = new Random();
ServiceDTO lastServiceDto = null;
while (!m_longPollingStopped.get() && !Thread.currentThread().isInterrupted()) {
.............
HttpRequest request = new HttpRequest(url);
request.setReadTimeout(LONG_POLLING_READ_TIMEOUT); // private static final int LONG_POLLING_READ_TIMEOUT = 90 * 1000;
transaction.addData("Url", url);
final HttpResponse<List<ApolloConfigNotification>> response =
m_httpUtil.doGet(request, m_responseType);
if (response.getStatusCode() == 200 && response.getBody() != null) {
updateNotifications(response.getBody());
updateRemoteNotifications(response.getBody());
transaction.addData("Result", response.getBody().toString());
notify(lastServiceDto, response.getBody());
}
.............
}
}在notify方法中
private void notify(ServiceDTO lastServiceDto, List<ApolloConfigNotification> notifications) {
if (notifications == null || notifications.isEmpty()) {
return;
}
for (ApolloConfigNotification notification : notifications) {
String namespaceName = notification.getNamespaceName();
//create a new list to avoid ConcurrentModificationException
List<RemoteConfigRepository> toBeNotified =
Lists.newArrayList(m_longPollNamespaces.get(namespaceName));
.....................
for (RemoteConfigRepository remoteConfigRepository : toBeNotified) {
try {
remoteConfigRepository.onLongPollNotified(lastServiceDto, remoteMessages);
} catch (Throwable ex) {
Tracer.logError(ex);
}
}
}
}
public void onLongPollNotified(ServiceDTO longPollNotifiedServiceDto, ApolloNotificationMessages remoteMessages) {
m_longPollServiceDto.set(longPollNotifiedServiceDto);
m_remoteMessages.set(remoteMessages);
m_executorService.submit(new Runnable() {
@Override
public void run() {
m_configNeedForceRefresh.set(true);
trySync();
}
});
}可以看到还是调用trySync()方法。回顾trySync方法
protected synchronized void sync() {
Transaction transaction = Tracer.newTransaction("Apollo.ConfigService", "syncRemoteConfig");
try {
ApolloConfig previous = m_configCache.get();
ApolloConfig current = loadApolloConfig();
//reference equals means HTTP 304
if (previous != current) {
logger.debug("Remote Config refreshed!");
m_configCache.set(current);
this.fireRepositoryChange(m_namespace, this.getConfig());
}
............
}可以看到先从 m_configCache.get() 获取之前的配置项信息，接着调用loadApolloConfig获取当前的。
判断如果不等，则说明有内容更新，之后调用 fireRepositoryChange。
protected void fireRepositoryChange(String namespace, Properties newProperties) {
for (RepositoryChangeListener listener : m_listeners) {
try {
listener.onRepositoryChange(namespace, newProperties);
} catch (Throwable ex) {
Tracer.logError(ex);
logger.error("Failed to invoke repository change listener {}", listener.getClass(), ex);
}
}
}这里的listener是LocalFileConfigRepository。进入LocalFileConfigRepository.onRepositoryChange方法。
public void onRepositoryChange(String namespace, Properties newProperties) {
if (newProperties.equals(m_fileProperties)) {
return;
}
Properties newFileProperties = new Properties();
newFileProperties.putAll(newProperties);
updateFileProperties(newFileProperties, m_upstream.getSourceType());
this.fireRepositoryChange(namespace, newProperties);
}
protected void fireRepositoryChange(String namespace, Properties newProperties) {
for (RepositoryChangeListener listener : m_listeners) {
try {
listener.onRepositoryChange(namespace, newProperties);
} catch (Throwable ex) {
Tracer.logError(ex);
logger.error("Failed to invoke repository change listener {}", listener.getClass(), ex);
}
}
}这里的 listener是DefaultConfig，进入DefaultConfig.onRepositoryChange方法。
public synchronized void onRepositoryChange(String namespace, Properties newProperties) {
if (newProperties.equals(m_configProperties.get())) {
return;
}
ConfigSourceType sourceType = m_configRepository.getSourceType();
Properties newConfigProperties = new Properties();
newConfigProperties.putAll(newProperties);
Map<String, ConfigChange> actualChanges = updateAndCalcConfigChanges(newConfigProperties, sourceType);
//check double checked result
if (actualChanges.isEmpty()) {
return;
}
this.fireConfigChange(new ConfigChangeEvent(m_namespace, actualChanges));
Tracer.logEvent("Apollo.Client.ConfigChanges", m_namespace);
}进入fireConfigChange
protected void fireConfigChange(final ConfigChangeEvent changeEvent) {
for (final ConfigChangeListener listener : m_listeners) {
// check whether the listener is interested in this change event
if (!isConfigChangeListenerInterested(listener, changeEvent)) {
continue;
}
m_executorService.submit(new Runnable() {
@Override
public void run() {
String listenerName = listener.getClass().getName();
Transaction transaction = Tracer.newTransaction("Apollo.ConfigChangeListener", listenerName);
try {
listener.onChange(changeEvent);
transaction.setStatus(Transaction.SUCCESS);
} catch (Throwable ex) {
transaction.setStatus(ex);
Tracer.logError(ex);
logger.error("Failed to invoke config change listener {}", listenerName, ex);
} finally {
transaction.complete();
}
}
});
}这里的listener是AutoUpdateConfigChangeListener。
public void onChange(ConfigChangeEvent changeEvent) {
Set<String> keys = changeEvent.changedKeys();
if (CollectionUtils.isEmpty(keys)) {
return;
}
for (String key : keys) {
// 1. check whether the changed key is relevant
Collection<SpringValue> targetValues = springValueRegistry.get(beanFactory, key);
if (targetValues == null || targetValues.isEmpty()) {
continue;
}
// 2. check whether the value is really changed or not (since spring property sources have hierarchies)
if (!shouldTriggerAutoUpdate(changeEvent, key)) {
continue;
}
// 3. update the value
for (SpringValue val : targetValues) {
updateSpringValue(val);
}
}
}最后通过updateSpringValue更新该Bean的值。
private void updateSpringValue(SpringValue springValue) {
try {
Object value = resolvePropertyValue(springValue);
springValue.update(value);
logger.info("Auto update apollo changed value successfully, new value: {}, {}", value,
springValue);
} catch (Throwable ex) {
logger.error("Auto update apollo changed value failed, {}", springValue.toString(), ex);
}
}
public void update(Object newVal) throws IllegalAccessException, InvocationTargetException {
if (isField()) {
injectField(newVal);
} else {
injectMethod(newVal);
}
}
private void injectField(Object newVal) throws IllegalAccessException {
boolean accessible = field.isAccessible();
field.setAccessible(true);
field.set(bean, newVal);
field.setAccessible(accessible);
}这里要说一下类的继承关系。在之前创建createLocalConfigRepository时
LocalFileConfigRepository createLocalConfigRepository(String namespace) {
if (m_configUtil.isInLocalMode()) {
logger.warn(
"==== Apollo is in local mode! Won't pull configs from remote server for namespace {} ! ====",
namespace);
return new LocalFileConfigRepository(namespace);
}
return new LocalFileConfigRepository(namespace, createRemoteConfigRepository(namespace));
}
public LocalFileConfigRepository(String namespace, ConfigRepository upstream) {
m_namespace = namespace;
m_configUtil = ApolloInjector.getInstance(ConfigUtil.class);
this.setLocalCacheDir(findLocalCacheDir(), false);
this.setUpstreamRepository(upstream);
this.trySync();
}在创建完RemoteConfigRepository对象后，会创建LocalFileConfigRepository对象，LocalFileConfigRepository构造方法中，setUpstreamRepository方法
public void setUpstreamRepository(ConfigRepository upstreamConfigRepository) {
if (upstreamConfigRepository == null) {
return;
}
//clear previous listener
if (m_upstream != null) {
m_upstream.removeChangeListener(this);
}
m_upstream = upstreamConfigRepository;
trySyncFromUpstream();
upstreamConfigRepository.addChangeListener(this);
}这里可以知道upstreamConfigRepository对象是RemoteConfigRepository。
AbstractConfigRepository类有两个子类RemoteConfigRepository和LocalFileConfigRepository类。
创建完LocalFileConfigRepository后，开始创建DefaultConfig对象。
public Config create(String namespace) {
DefaultConfig defaultConfig =
new DefaultConfig(namespace, createLocalConfigRepository(namespace));
return defaultConfig;
}
public DefaultConfig(String namespace, ConfigRepository configRepository) {
m_namespace = namespace;
m_resourceProperties = loadFromResource(m_namespace);
m_configRepository = configRepository;
m_configProperties = new AtomicReference<>();
m_warnLogRateLimiter = RateLimiter.create(0.017); // 1 warning log output per minute
initialize();
}
private void initialize() {
try {
updateConfig(m_configRepository.getConfig(), m_configRepository.getSourceType());
} catch (Throwable ex) {
Tracer.logError(ex);
logger.warn("Init Apollo Local Config failed - namespace: {}, reason: {}.",
m_namespace, ExceptionUtil.getDetailMessage(ex));
} finally {
//register the change listener no matter config repository is working or not
//so that whenever config repository is recovered, config could get changed
m_configRepository.addChangeListener(this);
}
}构造方法中最后initialize方法，m_configRepository.addChangeListener(this)。m_configRepository就是LocalFileConfigRepository对象。给LocalFileConfigRepository增加监听者DefaultConfig。
继续回到PropertySourcesProcessor类，
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
initializePropertySources();
initializeAutoUpdatePropertiesFeature(beanFactory);
}
private void initializePropertySources() {
...................
while (iterator.hasNext()) {
int order = iterator.next();
for (String namespace : NAMESPACE_NAMES.get(order)) {
Config config = ConfigService.getConfig(namespace);
composite.addPropertySource(configPropertySourceFactory.getConfigPropertySource(namespace, config));
}
}
..................
}在通过ConfigService.getConfig(namespace)创建DefaultConfig后，下一行会执行configPropertySourceFactory.getConfigPropertySource(namespace, config)方法。会调用ConfigPropertySourceFactory.getConfigPropertySource方法。
public ConfigPropertySource getConfigPropertySource(String name, Config source) {
ConfigPropertySource configPropertySource = new ConfigPropertySource(name, source);
configPropertySources.add(configPropertySource);
return configPropertySource;
}initializePropertySources()执行完毕，接着执行initializeAutoUpdatePropertiesFeature(beanFactory)方法。
private void initializeAutoUpdatePropertiesFeature(ConfigurableListableBeanFactory beanFactory) {
AutoUpdateConfigChangeListener autoUpdateConfigChangeListener = new AutoUpdateConfigChangeListener(
environment, beanFactory);
List<ConfigPropertySource> configPropertySources = configPropertySourceFactory.getAllConfigPropertySources();
for (ConfigPropertySource configPropertySource : configPropertySources) {
configPropertySource.addChangeListener(autoUpdateConfigChangeListener);
}
}
public List<ConfigPropertySource> getAllConfigPropertySources() {
return Lists.newLinkedList(configPropertySources);
}initializeAutoUpdatePropertiesFeature方法会从ConfigPropertySourceFactory.getAllConfigPropertySources方法中获取需要的添
加监听的DefaultConfig。也就是我们刚刚add进去的DefaultConfig对象。最后执行configPropertySource.addChangeListener(autoUpdateConfigChangeListener)。给DefaultConfig对象添加监听者AutoUpdateConfigChangeListener。
总结创建监听的步骤：
1、创建RemoteConfigRepository对象
2、创建LocalFileConfigRepository对象时，RemoteConfigRepository.addChangeListener方法将LocalFileConfigRepository对象作为自己的监听对象。
3、创建DefaultConfig对象，并设置LocalFileConfigRepository的监听者为DefaultConfig。
4、创建AutoUpdateConfigChangeListener对象，并设置DefaultConfig的监听者为AutoUpdateConfigChangeListener。
总结：
1、Apollo客户端每隔5分钟从服务器同步一次配置信息。
2、Apollo客户端会启动一个线程不停调用Apollo服务器获取配置信息，每次调用超时时间为90s。
3、同步内容都是RemoteConfigRepository对象的trySync方法，之后触发监听。
4、监听顺序为RemoteConfigRepository ← LocalFileConfigRepository ← DefaultConfig ← AutoUpdateConfigChangeListener
5、最后执行AutoUpdateConfigChangeListener.onChange方法刷新Bean中的配置。
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