优雅挂逼

日志适配

dubbo-common/src/main/java/com/alibaba/dubbo/common/logger/Level.java

@@ -17,7 +17,7 @@
 package com.alibaba.dubbo.common.logger;
 
 /**
- * Level
+ * Level 日志级别
  */
 public enum Level {
 

dubbo-common/src/main/java/com/alibaba/dubbo/common/logger/Logger.java

@@ -18,6 +18,9 @@
 
 /**
  * Logger interface
+ *
+ * Logger 接口
+ *
  * <p>
  * This interface is referred from commons-logging
  */

dubbo-common/src/main/java/com/alibaba/dubbo/common/logger/LoggerAdapter.java

@@ -22,6 +22,8 @@
 
 /**
  * Logger provider
+ *
+ * Logger 适配器接口
  */
 @SPI
 public interface LoggerAdapter {

dubbo-common/src/main/java/com/alibaba/dubbo/common/logger/LoggerFactory.java

@@ -33,12 +33,22 @@
  */
 public class LoggerFactory {
 
+    /**
+     * 已创建的 Logger 对应的映射
+     *
+     * key：类名
+     */
     private static final ConcurrentMap<String, FailsafeLogger> LOGGERS = new ConcurrentHashMap<String, FailsafeLogger>();
+    /**
+     * 当前使用的 LoggerAdapter 日志适配器
+     */
     private static volatile LoggerAdapter LOGGER_ADAPTER;
 
     // search common-used logging frameworks
     static {
+        // 获得 "logger" 配置项
         String logger = System.getProperty("dubbo.application.logger");
+        // 根据配置项，进行对应的 LoggerAdapter 对象
         if ("slf4j".equals(logger)) {
             setLoggerAdapter(new Slf4jLoggerAdapter());
         } else if ("jcl".equals(logger)) {
@@ -48,6 +58,7 @@ public class LoggerFactory {
         } else if ("jdk".equals(logger)) {
             setLoggerAdapter(new JdkLoggerAdapter());
         } else {
+            // 未配置，按照 log4j > slf4j > apache common logger > jdk logger
             try {
                 setLoggerAdapter(new Log4jLoggerAdapter());
             } catch (Throwable e1) {
@@ -80,9 +91,12 @@ public static void setLoggerAdapter(String loggerAdapter) {
      */
     public static void setLoggerAdapter(LoggerAdapter loggerAdapter) {
         if (loggerAdapter != null) {
+            // 获得 Logger 对象，并打印日志，提示设置后的 LoggerAdapter 实现类
             Logger logger = loggerAdapter.getLogger(LoggerFactory.class.getName());
             logger.info("using logger: " + loggerAdapter.getClass().getName());
+            // 设置 LOGGER_ADAPTER 属性
             LoggerFactory.LOGGER_ADAPTER = loggerAdapter;
+            // 循环，将原有已经生成的 LOGGER 缓存对象，全部重新生成替换
             for (Map.Entry<String, FailsafeLogger> entry : LOGGERS.entrySet()) {
                 entry.getValue().setLogger(LOGGER_ADAPTER.getLogger(entry.getKey()));
             }
@@ -96,7 +110,9 @@ public static void setLoggerAdapter(LoggerAdapter loggerAdapter) {
      * @return logger
      */
     public static Logger getLogger(Class<?> key) {
+        // 从缓存中，获得 Logger 对象
         FailsafeLogger logger = LOGGERS.get(key.getName());
+        // 不存在，则进行创建，并进行缓存
         if (logger == null) {
             LOGGERS.putIfAbsent(key.getName(), new FailsafeLogger(LOGGER_ADAPTER.getLogger(key)));
             logger = LOGGERS.get(key.getName());
@@ -111,7 +127,9 @@ public static Logger getLogger(Class<?> key) {
      * @return logger provider
      */
     public static Logger getLogger(String key) {
+        // 从缓存中，获得 Logger 对象
         FailsafeLogger logger = LOGGERS.get(key);
+        // 不存在，则进行创建，并进行缓存
         if (logger == null) {
             LOGGERS.putIfAbsent(key, new FailsafeLogger(LOGGER_ADAPTER.getLogger(key)));
             logger = LOGGERS.get(key);

dubbo-common/src/main/java/com/alibaba/dubbo/common/logger/jcl/JclLoggerAdapter.java

@@ -52,4 +52,4 @@ public void setFile(File file) {
         this.file = file;
     }
 
-}
+}

dubbo-common/src/main/java/com/alibaba/dubbo/common/logger/log4j/Log4jLogger.java

@@ -79,6 +79,7 @@ public void warn(String msg, Throwable e) {
         logger.log(FQCN, Level.WARN, msg, e);
     }
 
+    @Override
     public void error(String msg) {
         logger.log(FQCN, Level.ERROR, msg, null);
     }

dubbo-common/src/main/java/com/alibaba/dubbo/common/logger/log4j/Log4jLoggerAdapter.java

@@ -27,18 +27,27 @@
 import java.io.File;
 import java.util.Enumeration;
 
+/**
+ * Log4j 的 LoggerAdapter 实现类
+ */
 public class Log4jLoggerAdapter implements LoggerAdapter {
 
+    /**
+     * Root Logger 的文件，在构造方法中初始化
+     */
     private File file;
 
     @SuppressWarnings("unchecked")
     public Log4jLoggerAdapter() {
         try {
+            // 获得 Root Logger 对象
             org.apache.log4j.Logger logger = LogManager.getRootLogger();
             if (logger != null) {
+                // 循环每个 Logger 对象的 Appender 对象
                 Enumeration<Appender> appenders = logger.getAllAppenders();
                 if (appenders != null) {
                     while (appenders.hasMoreElements()) {
+                        // 当且仅当 FileAppender 时
                         Appender appender = appenders.nextElement();
                         if (appender instanceof FileAppender) {
                             FileAppender fileAppender = (FileAppender) appender;
@@ -87,28 +96,33 @@ private static Level fromLog4jLevel(org.apache.log4j.Level level) {
         return Level.OFF;
     }
 
+    @Override
     public Logger getLogger(Class<?> key) {
         return new Log4jLogger(LogManager.getLogger(key));
     }
 
+    @Override
     public Logger getLogger(String key) {
         return new Log4jLogger(LogManager.getLogger(key));
     }
 
+    @Override
     public Level getLevel() {
         return fromLog4jLevel(LogManager.getRootLogger().getLevel());
     }
 
+    @Override
     public void setLevel(Level level) {
         LogManager.getRootLogger().setLevel(toLog4jLevel(level));
     }
 
+    @Override
     public File getFile() {
         return file;
     }
 
+    @Override
     public void setFile(File file) {
-
     }
 
 }

dubbo-common/src/main/java/com/alibaba/dubbo/common/logger/slf4j/Slf4jLoggerAdapter.java

@@ -27,28 +27,34 @@ public class Slf4jLoggerAdapter implements LoggerAdapter {
     private Level level;
     private File file;
 
+    @Override
     public Logger getLogger(String key) {
         return new Slf4jLogger(org.slf4j.LoggerFactory.getLogger(key));
     }
 
+    @Override
     public Logger getLogger(Class<?> key) {
         return new Slf4jLogger(org.slf4j.LoggerFactory.getLogger(key));
     }
 
-    public Level getLevel() {
+    @Override
+    public Level getLevel() { // 无用
         return level;
     }
 
-    public void setLevel(Level level) {
+    @Override
+    public void setLevel(Level level) { // 无用
         this.level = level;
     }
 
-    public File getFile() {
+    @Override
+    public File getFile() { // 无用
         return file;
     }
 
-    public void setFile(File file) {
+    @Override
+    public void setFile(File file) { // 无用
         this.file = file;
     }
 
-}
+}

dubbo-common/src/main/java/com/alibaba/dubbo/common/logger/support/FailsafeLogger.java

@@ -22,6 +22,9 @@
 
 public class FailsafeLogger implements Logger {
 
+    /**
+     * Dubbo Logger 对象
+     */
     private Logger logger;
 
     public FailsafeLogger(Logger logger) {
@@ -117,6 +120,7 @@ public void error(String msg, Throwable e) {
         }
     }
 
+    @Override
     public void error(String msg) {
         try {
             logger.error(appendContextMessage(msg));

dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/ConfigUtils.java

@@ -313,13 +313,17 @@ public static int getPid() {
 
     @SuppressWarnings("deprecation")
     public static int getServerShutdownTimeout() {
+        // 默认，10 * 1000 毫秒
         int timeout = Constants.DEFAULT_SERVER_SHUTDOWN_TIMEOUT;
+        // 获得 "dubbo.service.shutdown.wait" 配置项，单位：毫秒
         String value = ConfigUtils.getProperty(Constants.SHUTDOWN_WAIT_KEY);
         if (value != null && value.length() > 0) {
             try {
                 timeout = Integer.parseInt(value);
             } catch (Exception e) {
             }
+        // 若为空，获得 "dubbo.service.shutdown.wait.seconds" 配置项，单位：秒。
+        // ps：目前已经废弃该参数，推荐使用 "dubbo.service.shutdown.wait"
         } else {
             value = ConfigUtils.getProperty(Constants.SHUTDOWN_WAIT_SECONDS_KEY);
             if (value != null && value.length() > 0) {
@@ -329,7 +333,7 @@ public static int getServerShutdownTimeout() {
                 }
             }
         }
-
+        // 返回
         return timeout;
     }
 

dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/ExecutorUtil.java

@@ -28,25 +28,27 @@
 import java.util.concurrent.TimeUnit;
 
 public class ExecutorUtil {
+
     private static final Logger logger = LoggerFactory.getLogger(ExecutorUtil.class);
+
     private static final ThreadPoolExecutor shutdownExecutor = new ThreadPoolExecutor(0, 1,
             0L, TimeUnit.MILLISECONDS,
             new LinkedBlockingQueue<Runnable>(100),
             new NamedThreadFactory("Close-ExecutorService-Timer", true));
 
     public static boolean isShutdown(Executor executor) {
         if (executor instanceof ExecutorService) {
-            if (((ExecutorService) executor).isShutdown()) {
-                return true;
-            }
+            return ((ExecutorService) executor).isShutdown();
         }
         return false;
     }
 
     public static void gracefulShutdown(Executor executor, int timeout) {
+        // 忽略，若不是 ExecutorService ，或者已经关闭
         if (!(executor instanceof ExecutorService) || isShutdown(executor)) {
             return;
         }
+        // 关闭，禁止新的任务提交，将原有任务执行完
         final ExecutorService es = (ExecutorService) executor;
         try {
             es.shutdown(); // Disable new tasks from being submitted
@@ -55,23 +57,28 @@ public static void gracefulShutdown(Executor executor, int timeout) {
         } catch (NullPointerException ex2) {
             return;
         }
+        // 等待原有任务执行完。若等待超时，强制结束所有任务
         try {
             if (!es.awaitTermination(timeout, TimeUnit.MILLISECONDS)) {
                 es.shutdownNow();
             }
         } catch (InterruptedException ex) {
+            // 发生 InterruptedException 异常，也强制结束所有任务
             es.shutdownNow();
             Thread.currentThread().interrupt();
         }
+        // 若未关闭成功，新开线程去关闭
         if (!isShutdown(es)) {
             newThreadToCloseExecutor(es);
         }
     }
 
     public static void shutdownNow(Executor executor, final int timeout) {
+        // 忽略，若不是 ExecutorService ，或者已经关闭
         if (!(executor instanceof ExecutorService) || isShutdown(executor)) {
             return;
         }
+        // 立即关闭，包括原有任务也打断
         final ExecutorService es = (ExecutorService) executor;
         try {
             es.shutdownNow();
@@ -80,11 +87,13 @@ public static void shutdownNow(Executor executor, final int timeout) {
         } catch (NullPointerException ex2) {
             return;
         }
+        // 等待原有任务被打断完成
         try {
             es.awaitTermination(timeout, TimeUnit.MILLISECONDS);
         } catch (InterruptedException ex) {
             Thread.currentThread().interrupt();
         }
+        // 若未关闭成功，新开线程去关闭
         if (!isShutdown(es)) {
             newThreadToCloseExecutor(es);
         }
@@ -95,8 +104,11 @@ private static void newThreadToCloseExecutor(final ExecutorService es) {
             shutdownExecutor.execute(new Runnable() {
                 public void run() {
                     try {
+                        // 循环 1000 次，不断强制结束线程池
                         for (int i = 0; i < 1000; i++) {
+                            // 立即关闭，包括原有任务也打断
                             es.shutdownNow();
+                            // 等待原有任务被打断完成
                             if (es.awaitTermination(10, TimeUnit.MILLISECONDS)) {
                                 break;
                             }

dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/AbstractConfig.java

@@ -93,7 +93,7 @@ public abstract class AbstractConfig implements Serializable {
         legacyProperties.put("dubbo.service.url", "dubbo.service.address");
     }
 
-    static { // TODO 芋艿，注意
+    static {
         Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
             public void run() {
                 if (logger.isInfoEnabled()) {

dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/AbstractInterfaceConfig.java

@@ -238,8 +238,8 @@ protected List<URL> loadRegistries(boolean provider) {
                         url = url.addParameter(Constants.REGISTRY_KEY, url.getProtocol());
                         url = url.setProtocol(Constants.REGISTRY_PROTOCOL);
                         // 添加到结果
-                        if ((provider && url.getParameter(Constants.REGISTER_KEY, true)) // 服务提供者 && 注册
-                                || (!provider && url.getParameter(Constants.SUBSCRIBE_KEY, true))) { // 服务消费者 && 订阅
+                        if ((provider && url.getParameter(Constants.REGISTER_KEY, true)) // 服务提供者 && 注册 https://dubbo.gitbooks.io/dubbo-user-book/demos/subscribe-only.html
+                                || (!provider && url.getParameter(Constants.SUBSCRIBE_KEY, true))) { // 服务消费者 && 订阅 https://dubbo.gitbooks.io/dubbo-user-book/demos/registry-only.html
                             registryList.add(url);
                         }
                     }

dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ApplicationConfig.java

@@ -60,7 +60,7 @@ public class ApplicationConfig extends AbstractConfig {
     private String compiler; // TODO 芋艿
 
     // logger
-    private String logger; // TODO 芋艿
+    private String logger;
 
     // registry centers
     private List<RegistryConfig> registries;
@@ -203,6 +203,7 @@ public String getLogger() {
 
     public void setLogger(String logger) {
         this.logger = logger;
+        // 设置 LoggerAdapter
         LoggerFactory.setLoggerAdapter(logger);
     }