fix: resolve content problem and close #77

docs/SpringBoot/SpringBoot-LogSystem.md

@@ -1,109 +1,456 @@
-该文所涉及的 netty 源码版本为 4.1.6。
+# SpringBoot 日志系统
 
-## Netty 中的 ByteBuf 为什么会发生内存泄漏
+- Author: [HuiFer](https://github.com/huifer)
+- 源码阅读仓库: [SourceHot-spring-boot](https://github.com/SourceHot/spring-boot-read)
 
-在 Netty 中，ByetBuf 并不是只采用可达性分析来对 ByteBuf 底层的 byte[]数组来进行垃圾回收，而同时采用引用计数法来进行回收，来保证堆外内存的准确时机的释放。  
+- 包路径: `org.springframework.boot.logging`
-在每个 ByteBuf 中都维护着一个 refCnt 用来对 ByteBuf 的被引用数进行记录，当 ByteBuf 的 retain()方法被调用时，将会增加 refCnt 的计数，而其 release()方法被调用时将会减少其被引用数计数。
+
+## 日志级别
+
+- 日志级别: `org.springframework.boot.logging.LogLevel`
 
 ```java
-private boolean release0(int decrement) {
+public enum LogLevel {
-    for (;;) {
+	TRACE, DEBUG, INFO, WARN, ERROR, FATAL, OFF
-        int refCnt = this.refCnt;
+}
-        if (refCnt < decrement) {
+```
-            throw new IllegalReferenceCountException(refCnt, -decrement);
+
+## java 日志实现
+
+- `org.springframework.boot.logging.java.JavaLoggingSystem`
+
+![image-20200323144523848](../../images/SpringBoot/image-20200323144523848.png)
+
+```JAVA
+	static {
+	    // KEY :  springBoot 定义的日志级别, value: jdk 定义的日志级别
+		LEVELS.map(LogLevel.TRACE, Level.FINEST);
+		LEVELS.map(LogLevel.DEBUG, Level.FINE);
+		LEVELS.map(LogLevel.INFO, Level.INFO);
+		LEVELS.map(LogLevel.WARN, Level.WARNING);
+		LEVELS.map(LogLevel.ERROR, Level.SEVERE);
+		LEVELS.map(LogLevel.FATAL, Level.SEVERE);
+		LEVELS.map(LogLevel.OFF, Level.OFF);
+	}
+```
+
+- LEVELS 对象
+
+  ```java
+  	protected static class LogLevels<T> {
+
+        /**
+         * key ： SpringBoot 中定义的日志级别, value: 其他日志框架的日志级别
+         */
+  		private final Map<LogLevel, T> systemToNative;
+
+        /**
+         * key : 其他日志框架的日志级别 , value: springBoot 中定义中定义的日志级别
+         */
+  		private final Map<T, LogLevel> nativeToSystem;
+      }
+  ```
+
+## LoggingSystem
+
+- 抽象类
+- `org.springframework.boot.logging.LoggingSystem`
+
+- 一个 map 对象: `SYSTEMS`
+
+```JAVA
+	/**
+	 * key: 第三方日志框架的类 value: springBoot 中的处理类
+	 */
+	private static final Map<String, String> SYSTEMS;
+
+	static {
+		Map<String, String> systems = new LinkedHashMap<>();
+		systems.put("ch.qos.logback.core.Appender", "org.springframework.boot.logging.logback.LogbackLoggingSystem");
+		systems.put("org.apache.logging.log4j.core.impl.Log4jContextFactory",
+				"org.springframework.boot.logging.log4j2.Log4J2LoggingSystem");
+		systems.put("java.util.logging.LogManager", "org.springframework.boot.logging.java.JavaLoggingSystem");
+		SYSTEMS = Collections.unmodifiableMap(systems);
 	}
-        if (refCntUpdater.compareAndSet(this, refCnt, refCnt - decrement)) {
+
-            if (refCnt == decrement) {
+```
-                deallocate();
+
-                return true;
+- 各个抽象方法
+
+| 方法名称                | 作用                               |
+| ----------------------- | ---------------------------------- |
+| beforeInitialize        | 初始化之前调用，目的是减少日志输出 |
+| initialize              | 初始化日志                         |
+| cleanUp                 | 清除日志                           |
+| getShutdownHandler      |                                    |
+| getSupportedLogLevels   | 获取支持的日志级别                 |
+| setLogLevel             | 设置日志级别                       |
+| getLoggerConfigurations | 获取日志配置                       |
+
+### get
+
+```java
+public static LoggingSystem get(ClassLoader classLoader) {
+	    // 获取系统属性
+		String loggingSystem = System.getProperty(SYSTEM_PROPERTY);
+
+		if (StringUtils.hasLength(loggingSystem)) {
+		    // 是不是NONE
+			if (NONE.equals(loggingSystem)) {
+			    // 空的日志系统
+				return new NoOpLoggingSystem();
 			}
-            return false;
+			return get(classLoader, loggingSystem);
 		}
+		// 循环所有日志,
+		return SYSTEMS.entrySet().stream().filter((entry) -> ClassUtils.isPresent(entry.getKey(), classLoader))
+				.map((entry) ->
+				// 实例化具体日志
+				 get(classLoader, entry.getValue())).findFirst()
+				.orElseThrow(() -> new IllegalStateException("No suitable logging system located"));
 	}
-}
 ```
 
-当调用了 ByteBuf 的 release()方法的时候，最后在上方的 release0()方法中将会为 ByteBuf 的引用计数减一，当引用计数归于 0 的时候，将会调用 deallocate()方法对其对应的底层存储数组进行释放(在池化的 ByteBuf 中，在 deallocate()方法里会把该 ByteBuf 的 byte[]回收到底层内存池中，以确保 byte[]可以重复利用)。  
+- 实例化日志系统
-由于 Netty 中的 ByteBuf 并不是随着申请之后会马上使其引用计数归 0 而进行释放，往往在这两个操作之间还有许多操作，如果在这其中如果发生异常抛出导致引用没有及时释放，在使用池化 ByetBuffer 的情况下内存泄漏的问题就会产生。  
-当采用了池化的 ByteBuffer 的时候，比如 PooledHeapByteBuf 和 PooledDirectByteBuf，其 deallocate()方法一共主要分为两个步骤。
 
 ```java
-@Override
+	private static LoggingSystem get(ClassLoader classLoader, String loggingSystemClass) {
-protected final void deallocate() {
+		try {
-	if (handle >= 0) {
+			Class<?> systemClass = ClassUtils.forName(loggingSystemClass, classLoader);
-		final long handle = this.handle;
+			Constructor<?> constructor = systemClass.getDeclaredConstructor(ClassLoader.class);
-		this.handle = -1;
+			constructor.setAccessible(true);
-		memory = null;
+			return (LoggingSystem) constructor.newInstance(classLoader);
-		chunk.arena.free(chunk, handle, maxLength);
-		recycle();
 		}
-}
+		catch (Exception ex) {
+			throw new IllegalStateException(ex);
+		}
+	}
+
 ```
 
-- 将其底层的 byte[]通过 free()方法回收到内存池中等待下一次使用。
+![image-20200323151409473](../../images/SpringBoot/image-20200323151409473.png)
-- 通过 recycle()方法将其本身回收到对象池中等待下一次使用。  
+
-  关键在第一步的内存回收到池中，如果其引用计数未能在 ByteBuf 对象被回收之前归 0，将会导致其底层占用 byte[]无法回收到内存池 PoolArena 中，导致该部分无法被重复利用，下一次将会申请新的内存进行操作，从而产生内存泄漏。  
+- 默认日志: `org.springframework.boot.logging.logback.LogbackLoggingSystem`
-  而非池化的 ByteBuffer 即使引用计数没有在对象被回收的时候被归 0，因为其使用的是单独一块 byte[]内存，因此也会随着 java 对象被回收使得底层 byte[]被释放（由 JDK 的 Cleaner 来保证）。
 
-## Netty 进行内存泄漏检测的原理
+### beforeInitialize
 
-在 Netty 对于 ByteBuf 的检测中，一共包含 4 个级别。
+- 初始化之前
+
+  ![image-20200323154205484](../../images/SpringBoot/image-20200323154205484.png)
+
+  - 链路
+    1. `org.springframework.boot.context.logging.LoggingApplicationListener#onApplicationEvent`
+    2. `org.springframework.boot.context.logging.LoggingApplicationListener#onApplicationStartingEvent`
+    3. `org.springframework.boot.logging.LoggingSystem#beforeInitialize`
+
+- 因为前文中我们已知对象是：`org.springframework.boot.logging.logback.LogbackLoggingSystem` 直接看这个类的**`beforeInitialize`**方法
+
+  ```JAVA
+  	@Override
+  	public void beforeInitialize() {
+  	    // 日志上下文
+  		LoggerContext loggerContext = getLoggerContext();
+  		// 是否初始化
+  		if (isAlreadyInitialized(loggerContext)) {
+  			return;
+  		}
+  		// 父类方法
+  		super.beforeInitialize();
+  		// 添加过滤器
+  		loggerContext.getTurboFilterList().add(FILTER);
+  	}
+
+  ```
+
+- 初始化之前的的操作完成了初始化方法开始
+
+### initialize
+
+- `org.springframework.boot.context.logging.LoggingApplicationListener#onApplicationEnvironmentPreparedEvent`
+
+  ```JAVA
+  	private void onApplicationEnvironmentPreparedEvent(ApplicationEnvironmentPreparedEvent event) {
+  		if (this.loggingSystem == null) {
+  			this.loggingSystem = LoggingSystem.get(event.getSpringApplication().getClassLoader());
+  		}
+  		initialize(event.getEnvironment(), event.getSpringApplication().getClassLoader());
+  	}
+
+  ```
+
+- `org.springframework.boot.context.logging.LoggingApplicationListener#initializeSystem`
+
+  ```JAVA
+  	protected void initialize(ConfigurableEnvironment environment, ClassLoader classLoader) {
+  		new LoggingSystemProperties(environment).apply();
+  		this.logFile = LogFile.get(environment);
+  		if (this.logFile != null) {
+  			this.logFile.applyToSystemProperties();
+  		}
+  		this.loggerGroups = new LoggerGroups(DEFAULT_GROUP_LOGGERS);
+  		// 早期 的日志级别
+  		initializeEarlyLoggingLevel(environment);
+  		// 初始化日志系统
+  		initializeSystem(environment, this.loggingSystem, this.logFile);
+  		// 初始化日志级别
+  		initializeFinalLoggingLevels(environment, this.loggingSystem);
+  		registerShutdownHookIfNecessary(environment, this.loggingSystem);
+  	}
+
+  ```
+
+  ```JAVA
+  	private void initializeSystem(ConfigurableEnvironment environment, LoggingSystem system, LogFile logFile) {
+  		LoggingInitializationContext initializationContext = new LoggingInitializationContext(environment);
+  		String logConfig = environment.getProperty(CONFIG_PROPERTY);
+  		if (ignoreLogConfig(logConfig)) {
+  		    // 日志系统初始化
+  			system.initialize(initializationContext, null, logFile);
+  		}
+  		else {
+  			try {
+  				ResourceUtils.getURL(logConfig).openStream().close();
+  				system.initialize(initializationContext, logConfig, logFile);
+  			}
+  			catch (Exception ex) {
+  				// NOTE: We can't use the logger here to report the problem
+  				System.err.println("Logging system failed to initialize using configuration from '" + logConfig + "'");
+  				ex.printStackTrace(System.err);
+  				throw new IllegalStateException(ex);
+  			}
+  		}
+  	}
+
+  ```
+
+- `org.springframework.boot.logging.logback.LogbackLoggingSystem#initialize`
 
 ```java
-if (level.ordinal() < Level.PARANOID.ordinal()) {
+	@Override
-	if (leakCheckCnt ++ % samplingInterval == 0) {
+	public void initialize(LoggingInitializationContext initializationContext, String configLocation, LogFile logFile) {
-		reportLeak(level);
+		LoggerContext loggerContext = getLoggerContext();
-		return new DefaultResourceLeak(obj);
+		if (isAlreadyInitialized(loggerContext)) {
-	} else {
+			return;
-		return null;
 		}
-}
+		// 日志初始化
+		super.initialize(initializationContext, configLocation, logFile);
+		loggerContext.getTurboFilterList().remove(FILTER);
+		markAsInitialized(loggerContext);
+		if (StringUtils.hasText(System.getProperty(CONFIGURATION_FILE_PROPERTY))) {
+			getLogger(LogbackLoggingSystem.class.getName()).warn("Ignoring '" + CONFIGURATION_FILE_PROPERTY
+					+ "' system property. Please use 'logging.config' instead.");
+		}
+	}
+
 ```
 
-以默认的 SIMPLE 级别为例，在这个级别下，Netty 将会根据以 ByteBuf 创建的序列号与 113 进行取模来判断是否需要进行内存泄漏的检测追踪。当取模成功的时候，将会为这个 ByteBuf 产生一个对应的 DefaultResourceLeak 对象，DefaultResourceLeak 是一个 PhantomReference 虚引用的子类，并有其对应的 ReferenceQueue。之后通过 SimpleLeakAwareByteBuf 类来将被追踪的 ByteBuf 和 DefaultResourceLeak 包装起来。
+- `org.springframework.boot.logging.AbstractLoggingSystem#initializeWithConventions`
 
-```java
+  ```JAVA
-@Override
+  	private void initializeWithConventions(LoggingInitializationContext initializationContext, LogFile logFile) {
-public boolean release(int decrement) {
+  		String config = getSelfInitializationConfig();
-	boolean deallocated = super.release(decrement);
+  		if (config != null && logFile == null) {
-	if (deallocated) {
+  			// self initialization has occurred, reinitialize in case of property changes
-		leak.close();
+  			reinitialize(initializationContext);
+  			return;
   		}
-	return deallocated;
+  		if (config == null) {
-}
+  			config = getSpringInitializationConfig();
+  		}
+  		if (config != null) {
+  			loadConfiguration(initializationContext, config, logFile);
+  			return;
+  		}
+  		// 加载默认配置
+  		loadDefaults(initializationContext, logFile);
+  	}
+
+  ```
+
+  - `org.springframework.boot.logging.logback.LogbackLoggingSystem#loadDefaults`
+
+    ```JAVA
+    	@Override
+    	protected void loadDefaults(LoggingInitializationContext initializationContext, LogFile logFile) {
+    		LoggerContext context = getLoggerContext();
+    		stopAndReset(context);
+    		boolean debug = Boolean.getBoolean("logback.debug");
+    		if (debug) {
+    			StatusListenerConfigHelper.addOnConsoleListenerInstance(context, new OnConsoleStatusListener());
+    		}
+    		LogbackConfigurator configurator = debug ? new DebugLogbackConfigurator(context)
+    				: new LogbackConfigurator(context);
+    		Environment environment = initializationContext.getEnvironment();
+    		context.putProperty(LoggingSystemProperties.LOG_LEVEL_PATTERN,
+    				environment.resolvePlaceholders("${logging.pattern.level:${LOG_LEVEL_PATTERN:%5p}}"));
+    		context.putProperty(LoggingSystemProperties.LOG_DATEFORMAT_PATTERN, environment.resolvePlaceholders(
+    				"${logging.pattern.dateformat:${LOG_DATEFORMAT_PATTERN:yyyy-MM-dd HH:mm:ss.SSS}}"));
+    		context.putProperty(LoggingSystemProperties.ROLLING_FILE_NAME_PATTERN, environment
+    				.resolvePlaceholders("${logging.pattern.rolling-file-name:${LOG_FILE}.%d{yyyy-MM-dd}.%i.gz}"));
+    		new DefaultLogbackConfiguration(initializationContext, logFile).apply(configurator);
+    		context.setPackagingDataEnabled(true);
+    	}
+
+    ```
+
+```JAVA
+	@Override
+	public void initialize(LoggingInitializationContext initializationContext, String configLocation, LogFile logFile) {
+		LoggerContext loggerContext = getLoggerContext();
+		// 是否加载过
+		if (isAlreadyInitialized(loggerContext)) {
+			return;
+		}
+		// 日志初始化
+		super.initialize(initializationContext, configLocation, logFile);
+		// 删除 FILTER
+		loggerContext.getTurboFilterList().remove(FILTER);
+		// 初始化标记
+		markAsInitialized(loggerContext);
+		if (StringUtils.hasText(System.getProperty(CONFIGURATION_FILE_PROPERTY))) {
+			getLogger(LogbackLoggingSystem.class.getName()).warn("Ignoring '" + CONFIGURATION_FILE_PROPERTY
+					+ "' system property. Please use 'logging.config' instead.");
+		}
+	}
+```
+
+标记`markAsInitialized`
+
+```JAVA
+	private void markAsInitialized(LoggerContext loggerContext) {
+		loggerContext.putObject(LoggingSystem.class.getName(), new Object());
+	}
+
 ```
 
-在包装类中，如果该 ByteBuf 成功 deallocated 释放掉了其持有的 byte[]数组将会调用 DefaultResourceLeak 的 close()方法来已通知当前 ByteBuf 已经释放了其持有的内存。  
+此时日志初始化完成
-正是这个虚引用使得该 DefaultResourceLeak 对象被回收的时候将会被放入到与这个虚引用所对应的 ReferenceQueue 中。
+
+### 默认配置文件
+
+- `getStandardConfigLocations` 这个方法定义了默认配置文件有哪些
 
 ```java
-DefaultResourceLeak ref = (DefaultResourceLeak) refQueue.poll();
+	@Override
-if (ref == null) {
+	protected String[] getStandardConfigLocations() {
-	break;
+		return new String[] { "logback-test.groovy", "logback-test.xml", "logback.groovy", "logback.xml" };
-}
+	}
+
+```
 
-ref.clear();
+- 切回`org.springframework.boot.logging.AbstractLoggingSystem#initializeWithConventions`方法
 
-if (!ref.close()) {
+- 添加依赖
-	continue;
-}
 
-String records = ref.toString();
+```XML
-if (reportedLeaks.putIfAbsent(records, Boolean.TRUE) == null) {
+		<dependency>
-	if (records.isEmpty()) {
+			<groupId>org.springframework.boot</groupId>
-		logger.error("LEAK: {}.release() was not called before it's garbage-collected. " +
+			<artifactId>spring-boot-starter-logging</artifactId>
-				"Enable advanced leak reporting to find out where the leak occurred. " +
+			<version>${revision}</version>
-				"To enable advanced leak reporting, " +
+		</dependency>
-				"specify the JVM option '-D{}={}' or call {}.setLevel()",
+
-				resourceType, PROP_LEVEL, Level.ADVANCED.name().toLowerCase(), simpleClassName(this));
+```
-	} else {
+
-		logger.error(
+- 添加配置文件
-				"LEAK: {}.release() was not called before it's garbage-collected.{}",
+
-				resourceType, records);
+![image-20200323161442058](../../images/SpringBoot/image-20200323161442058.png)
+
+![image-20200323161522570](../../images/SpringBoot/image-20200323161522570.png)
+
+- 此时配置文件地址出现了
+
+```JAVA
+	protected String getSelfInitializationConfig() {
+	    // 寻找配置文件
+		return findConfig(getStandardConfigLocations());
 	}
-}
+
+```
+
+```JAVA
+	@Override
+	protected String[] getStandardConfigLocations() {
+		return new String[] { "logback-test.groovy", "logback-test.xml", "logback.groovy", "logback.xml" };
+	}
+
 ```
 
-Netty 会在下一次 ByteBuf 的采样中通过 reportLeak()方法将 ReferenceQueue 中的 DefaultResourceLeak 取出并判断其对应的 ByteBuf 是否已经在其回收前调用过其 close()方法，如果没有，显然在池化 ByteBuf 的场景下内存泄漏已经产生，将会以 ERROR 日志的方式进行日志打印。
+```JAVA
+	private String findConfig(String[] locations) {
+		for (String location : locations) {
+			ClassPathResource resource = new ClassPathResource(location, this.classLoader);
+			if (resource.exists()) {
+				return "classpath:" + location;
+			}
+		}
+		return null;
+	}
+
+```
+
+- 此时自定义配置文件如何获取的已经明了
+
+#### reinitialize
+
+```JAVA
+	@Override
+	protected void reinitialize(LoggingInitializationContext initializationContext) {
+		// 日志上下文重新设置
+		getLoggerContext().reset();
+		getLoggerContext().getStatusManager().clear();
+		// 加载配置文件
+		loadConfiguration(initializationContext, getSelfInitializationConfig(), null);
+	}
+
+```
+
+```JAVA
+	@Override
+	protected void loadConfiguration(LoggingInitializationContext initializationContext, String location,
+			LogFile logFile) {
+	    // 父类方法
+		super.loadConfiguration(initializationContext, location, logFile);
+		// 获取上下文
+		LoggerContext loggerContext = getLoggerContext();
+		// 停止并且重启
+		stopAndReset(loggerContext);
+		try {
+		    // 配置文件加载
+			configureByResourceUrl(initializationContext, loggerContext, ResourceUtils.getURL(location));
+		}
+		catch (Exception ex) {
+			throw new IllegalStateException("Could not initialize Logback logging from " + location, ex);
+		}
+		List<Status> statuses = loggerContext.getStatusManager().getCopyOfStatusList();
+		StringBuilder errors = new StringBuilder();
+		for (Status status : statuses) {
+			if (status.getLevel() == Status.ERROR) {
+				errors.append((errors.length() > 0) ? String.format("%n") : "");
+				errors.append(status.toString());
+			}
+		}
+		if (errors.length() > 0) {
+			throw new IllegalStateException(String.format("Logback configuration error detected: %n%s", errors));
+		}
+	}
+
+```
+
+```java
+	private void configureByResourceUrl(LoggingInitializationContext initializationContext, LoggerContext loggerContext,
+			URL url) throws JoranException {
+		if (url.toString().endsWith("xml")) {
+		    // logback 日志操作
+			JoranConfigurator configurator = new SpringBootJoranConfigurator(initializationContext);
+			// 设置上下文
+			configurator.setContext(loggerContext);
+			// 执行配置
+			configurator.doConfigure(url);
+		}
+		else {
+			new ContextInitializer(loggerContext).configureByResource(url);
+		}
+	}
+
+```
 
-以上内容可以结合 JVM 堆外内存的资料进行阅读。
+- 执行配置属于 logback 操作源码不在此进行分析