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0104 代码方式动态刷新logback日志配置

李福春 2020-01-14 19:56:52 阅读数:48 评论数:0 点赞数:0 收藏数:0

背景

日志是一个系统或者说一个产品技术架构中重要组成部分。
常见的日志框架如下:
日志框架 说明 跟slf4j集成所需依赖
slf4j 日志门面,具体实现由程序决定
jcl commons-logging
jcl-over-slf4j
jul jdk-logging slf4j-api
jul-to-slf4j
slf4j-jdk14
log4j log4j slf4j-api
log4j-over-slf4j
slf4j-log4j12
log4j2 log4j-api,log4j-core slf4j-api
log4j-slf4j-impl
logback logback-core,logback-classic slf4j-api

slf4j-logback的启动过程

一般使用slf4j来操作日志:
 private static final Logger LOGGER =
LoggerFactory.getLogger(LogbackAppenderExample.class);
public static void main(String[] args) {
LOGGER.trace("trace log");
LOGGER.debug("debug log");
LOGGER.info("info log");
LOGGER.warn("warn log");
LOGGER.error("error log");
LOGGER.error("error log xxx");
LOGGER.error("error log yyy");
LOGGER.error("error log zzz");
LOGGER.error("error log aaa");
}
通过这个来跟踪Logger的初始过程;

1 LoggerFactory.getLogger

代码如下:
public static Logger getLogger(Class<?> clazz) {
Logger logger = getLogger(clazz.getName());
if (DETECT_LOGGER_NAME_MISMATCH) {
Class<?> autoComputedCallingClass = Util.getCallingClass();
if (autoComputedCallingClass != null && nonMatchingClasses(clazz, autoComputedCallingClass)) {
Util.report(String.format("Detected logger name mismatch. Given name: \"%s\"; computed name: \"%s\".", logger.getName(),
autoComputedCallingClass.getName()));
Util.report("See " + LOGGER_NAME_MISMATCH_URL + " for an explanation");
}
}
return logger;
}
过程:
步骤 说明
1 获取得到Logger对象
2 如果有设置系统属性 slf4j.detectLoggerNameMismatch=true
则找到调用getLogger方法的类名
如果跟传入的类名不一致,则给出警告,给的类和调用方法的类不一致,并给出文档地址
3 返回Logger对象

2 getLogger(clazz.getName())

通过类名得到Logger
代码如下:
 public static Logger getLogger(String name) {
ILoggerFactory iLoggerFactory = getILoggerFactory();
return iLoggerFactory.getLogger(name);
}
核心步骤
序号 步骤
1 得到ILggerFactory对象
2 通过工厂,传入名字,得到Logger对象

3 getILoggerFactory()

得到日志工厂
代码如下:
 public static ILoggerFactory getILoggerFactory() {
if (INITIALIZATION_STATE == UNINITIALIZED) {
synchronized (LoggerFactory.class) {
if (INITIALIZATION_STATE == UNINITIALIZED) {
INITIALIZATION_STATE = ONGOING_INITIALIZATION;
performInitialization();
}
}
}
switch (INITIALIZATION_STATE) {
case SUCCESSFUL_INITIALIZATION:
return StaticLoggerBinder.getSingleton().getLoggerFactory();
case NOP_FALLBACK_INITIALIZATION:
return NOP_FALLBACK_FACTORY;
case FAILED_INITIALIZATION:
throw new IllegalStateException(UNSUCCESSFUL_INIT_MSG);
case ONGOING_INITIALIZATION:
// support re-entrant behavior.
// See also http://jira.qos.ch/browse/SLF4J-97
return SUBST_FACTORY;
}
throw new IllegalStateException("Unreachable code");
}
核心步骤:
序号 步骤
1 如果初始化状态值为 未初始化
同步加锁 synchronized(LoggerFactory.class)
再次判断 初始化状态值为 未初始化,如果是:
设置初始化状态值为 正在初始化
然后 执行初始化 _performInitialization_()
2 然后根据初始化状态的条件做不同的处理
如果 初始化失败,抛出异常,并提示哪里失败了
如果 正在初始化, 返回替代工厂SubstituteLoggerFactory,日志一般也是委托给NOPLogger
如果 空回退初始化 返回空的工厂 NOPLoggerFactory,不输出日志的空实现
如果 成功初始化,调用StaticLoggerBinder.getLoggerFactory返回工厂
如果不在以上的状态,直接抛出异常,无法抵达的code;

4 _performInitialization_()

执行初始化
代码:
 private final static void performInitialization() {
bind();
if (INITIALIZATION_STATE == SUCCESSFUL_INITIALIZATION) {
versionSanityCheck();
}
}
核心步骤
序号 步骤说明
1 绑定
2 如果初始化成功,则进行版本明智检查

5 bind()

绑定
代码:
 private final static void bind() {
try {
Set<URL> staticLoggerBinderPathSet = findPossibleStaticLoggerBinderPathSet();
reportMultipleBindingAmbiguity(staticLoggerBinderPathSet);
// the next line does the binding
StaticLoggerBinder.getSingleton();
INITIALIZATION_STATE = SUCCESSFUL_INITIALIZATION;
reportActualBinding(staticLoggerBinderPathSet);
fixSubstitutedLoggers();
playRecordedEvents();
SUBST_FACTORY.clear();
} catch (NoClassDefFoundError ncde) {
String msg = ncde.getMessage();
if (messageContainsOrgSlf4jImplStaticLoggerBinder(msg)) {
INITIALIZATION_STATE = NOP_FALLBACK_INITIALIZATION;
Util.report("Failed to load class \"org.slf4j.impl.StaticLoggerBinder\".");
Util.report("Defaulting to no-operation (NOP) logger implementation");
Util.report("See " + NO_STATICLOGGERBINDER_URL + " for further details.");
} else {
failedBinding(ncde);
throw ncde;
}
} catch (java.lang.NoSuchMethodError nsme) {
String msg = nsme.getMessage();
if (msg != null && msg.contains("org.slf4j.impl.StaticLoggerBinder.getSingleton()")) {
INITIALIZATION_STATE = FAILED_INITIALIZATION;
Util.report("slf4j-api 1.6.x (or later) is incompatible with this binding.");
Util.report("Your binding is version 1.5.5 or earlier.");
Util.report("Upgrade your binding to version 1.6.x.");
}
throw nsme;
} catch (Exception e) {
failedBinding(e);
throw new IllegalStateException("Unexpected initialization failure", e);
}
}
关键步骤
序号 步骤
1 找到可能的静态日志绑定器的路径集合findPossibleStaticLoggerBinderPathSet()
2 如果日志有多个绑定器,打印到控制台
如果是android平台,忽略
依次打印出多个日志绑定器,并给出文档提示
3 获得唯一的静态日志绑定器StaticLoggerBinder.getSingleton()
绑定器内部持有LoggerContext和ContextSelectorStaticBinder
4 设置初始化状态为成功
5 打印出实际的日志绑定器 ContextSelectorStaticBinder
6 设置SubstitutedLogger的委托为实际的Logger; _fixSubstitutedLoggers_()
7 播放记录的事件 playRecordedEvents()
8 清空委托工厂 SubstituteLoggerFactory

6 findPossibleStaticLoggerBinderPathSet()

找到可能的静态日志绑定器的路径

代码:
**

static Set<URL> findPossibleStaticLoggerBinderPathSet() {
// use Set instead of list in order to deal with bug #138
// LinkedHashSet appropriate here because it preserves insertion order during iteration
Set<URL> staticLoggerBinderPathSet = new LinkedHashSet<URL>();
try {
ClassLoader loggerFactoryClassLoader = LoggerFactory.class.getClassLoader();
Enumeration<URL> paths;
if (loggerFactoryClassLoader == null) {
paths = ClassLoader.getSystemResources(STATIC_LOGGER_BINDER_PATH);
} else {
paths = loggerFactoryClassLoader.getResources(STATIC_LOGGER_BINDER_PATH);
}
while (paths.hasMoreElements()) {
URL path = paths.nextElement();
staticLoggerBinderPathSet.add(path);
}
} catch (IOException ioe) {
Util.report("Error getting resources from path", ioe);
}
return staticLoggerBinderPathSet;
}

关键步骤:

序号 步骤
1 如果LoggerFactory的类加载器为空,系统类加载器得到
org/slf4j/impl/StaticLoggerBinder.class 这个文件
分布在不同的jar中,可能有多个;
2 如果不为空,则通过LoggerFactoryLoader找到
org/slf4j/impl/StaticLoggerBinder.class 这个文件
3 把这些class对应的url汇总到结合中返回

image.png

image.png

7 playRecordedEvents()

放映记录的事件

代码:

private static void playRecordedEvents() {
List<SubstituteLoggingEvent> events = SUBST_FACTORY.getEventList();
if (events.isEmpty()) {
return;
}
for (int i = 0; i < events.size(); i++) {
SubstituteLoggingEvent event = events.get(i);
SubstituteLogger substLogger = event.getLogger();
if( substLogger.isDelegateNOP()) {
break;
} else if (substLogger.isDelegateEventAware()) {
if (i == 0)
emitReplayWarning(events.size());
substLogger.log(event);
} else {
if(i == 0)
emitSubstitutionWarning();
Util.report(substLogger.getName());
}
}
}
关键步骤:
序号 步骤
1 得到委托日志工厂的事件,如果为空,则结束
2 如果事件不为空,取出来,
如果委托的日志有空日志,中断
如果委托的日志是委托事件, 打印日志,并打印出播放的警告
否则,警告委托的日志不可用,并打印出日志的名称

8 versionSanityCheck()

得到StaticLoggerBinder的版本,并进行判断是否合适。
LoggerFactory放了允许使用的StaticLoggerBinder的版本,如果不合适,会答应出警告。
源码:
 private final static void versionSanityCheck() {
try {
String requested = StaticLoggerBinder.REQUESTED_API_VERSION;
boolean match = false;
for (String aAPI_COMPATIBILITY_LIST : API_COMPATIBILITY_LIST) {
if (requested.startsWith(aAPI_COMPATIBILITY_LIST)) {
match = true;
}
}
if (!match) {
Util.report("The requested version " + requested + " by your slf4j binding is not compatible with "
+ Arrays.asList(API_COMPATIBILITY_LIST).toString());
Util.report("See " + VERSION_MISMATCH + " for further details.");
}
} catch (java.lang.NoSuchFieldError nsfe) {
// given our large user base and SLF4J's commitment to backward
// compatibility, we cannot cry here. Only for implementations
// which willingly declare a REQUESTED_API_VERSION field do we
// emit compatibility warnings.
} catch (Throwable e) {
// we should never reach here
Util.report("Unexpected problem occured during version sanity check", e);
}
}

9 StaticLoggerBinder.init()

静态日志绑定器的初始化

代码:

void init() {
try {
try {
new ContextInitializer(defaultLoggerContext).autoConfig();
} catch (JoranException je) {
Util.report("Failed to auto configure default logger context", je);
}
// logback-292
if (!StatusUtil.contextHasStatusListener(defaultLoggerContext)) {
StatusPrinter.printInCaseOfErrorsOrWarnings(defaultLoggerContext);
}
contextSelectorBinder.init(defaultLoggerContext, KEY);
initialized = true;
} catch (Exception t) { // see LOGBACK-1159
Util.report("Failed to instantiate [" + LoggerContext.class.getName() + "]", t);
}
}

核心过程

序号 步骤
1 新建上下文初始化器,然后自动配置;
new ContextInitializer(defaultLoggerContext).autoConfig();
2 如果没有配置状态监听器,则打印出警告
3 上下文选择绑定器初始化

10 ContextInitializer.autoConfig();

自动配置上下文

代码:

 public void autoConfig() throws JoranException {
StatusListenerConfigHelper.installIfAsked(loggerContext);
URL url = findURLOfDefaultConfigurationFile(true);
if (url != null) {
configureByResource(url);
} else {
Configurator c = EnvUtil.loadFromServiceLoader(Configurator.class);
if (c != null) {
try {
c.setContext(loggerContext);
c.configure(loggerContext);
} catch (Exception e) {
throw new LogbackException(String.format("Failed to initialize Configurator: %s using ServiceLoader", c != null ? c.getClass()
.getCanonicalName() : "null"), e);
}
} else {
BasicConfigurator basicConfigurator = new BasicConfigurator();
basicConfigurator.setContext(loggerContext);
basicConfigurator.configure(loggerContext);
}
}
}

核心步骤

序号 说明
1 如果没有,安装状态监听器
2 找到默认的配置文件或者URL,一次按照系统属性
logback.configurationFile查找
按照logback-test.xml
按照logback.groovy
按照logback.xml
得到配置文件
3 如果找到了,configureByResource(url);
4 否则,按照spi的方式找到Configurator的实现类,设置上下文,进行配置
如果spi方式拿不到,则使用缺省的BasicConfigurator(里面只配置了一个控制台)
设置上下文,进行配置

11 StaticLoggerBinder.getLoggerFactory

通过静态日志绑定器得到日志工厂,实现类是 LoggerContext;

源码:

 public ILoggerFactory getLoggerFactory() {
if (!initialized) {
return defaultLoggerContext;
}
if (contextSelectorBinder.getContextSelector() == null) {
throw new IllegalStateException("contextSelector cannot be null. See also " + NULL_CS_URL);
}
return contextSelectorBinder.getContextSelector().getLoggerContext();
}

核心流程:

序号 步骤
1 如果没有初始化,返回默认的LoggerContext
2 如果ContextSelectBinder不为空,得到ContextSeleter
3 通过ContextSelector得到LoggerContext;

12 iLoggerFactory.getLogger(name)

这是一个接口,直接得到一个Logger实例;
从上面的代码之后,这里的实例应该是一个LoggerContext对象
这个对象是核心,所有的日志动作都在里面;

logback-aliyun-appender

直接把日志接入到阿里云
对于初创企业来说,直接使用阿里云的日志服务非常方便,减少了自己搭建ELK的运维成本,直接按量付费,非常方便,我贴一下我的接入过程;

引入依赖:

 <!--日志-->
<dependency>
<groupId>com.aliyun.openservices</groupId>
<artifactId>aliyun-log-logback-appender</artifactId>
</dependency>
<!--spring日志桥接,使用的commoon-logging-->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
</dependency>
<!--log4j日志桥接,zk使用的log4j-->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>log4j-over-slf4j</artifactId>
</dependency>

然后按照 代码刷新logback日志配置的方法,把日志配置放到apollo,启动的时候就可以接入到阿里云日志了。

贴一下配置:

<configuration>
<!--为了防止进程退出时,内存中的数据丢失,请加上此选项-->
<shutdownHook class="ch.qos.logback.core.hook.DelayingShutdownHook"/>
<appender name="loghubAppender" class="com.aliyun.openservices.log.logback.LoghubAppender">
<!--必选项-->
<!-- 账号及网络配置 -->
<endpoint>cn-xxx.log.aliyuncs.com</endpoint>
<accessKeyId>xxxxx</accessKeyId>
<accessKeySecret>xxxxx</accessKeySecret>
<!-- sls 项目配置 -->
<project>ts-app-xxx</project>
<logStore>ts-app-xxx</logStore>
<!--必选项 (end)-->
<!-- 可选项 -->
<topic>topic2</topic>
<source>source2</source>
<!-- 可选项 详见 '参数说明'-->
<totalSizeInBytes>104857600</totalSizeInBytes>
<maxBlockMs>60</maxBlockMs>
<ioThreadCount>2</ioThreadCount>
<batchSizeThresholdInBytes>524288</batchSizeThresholdInBytes>
<batchCountThreshold>4096</batchCountThreshold>
<lingerMs>2000</lingerMs>
<retries>3</retries>
<baseRetryBackoffMs>100</baseRetryBackoffMs>
<maxRetryBackoffMs>100</maxRetryBackoffMs>
<!-- 可选项 通过配置 encoder 的 pattern 自定义 log 的格式 -->
<encoder>
<pattern>%d %-5level [%thread] %logger{0}: %msg</pattern>
</encoder>
<!-- 可选项 设置时间格式 -->
<timeFormat>yyyy-MM-dd'T'HH:mmZ</timeFormat>
<!-- 可选项 设置时区 -->
<timeZone>Asia/Shanghai</timeZone>
<filter class="ch.qos.logback.classic.filter.ThresholdFilter"><!-- 只打印INFO级别的日志 -->
<level>INFO</level>
<!-- <onMatch>ACCEPT</onMatch>-->
<!-- <onMismatch>DENY</onMismatch>-->
</filter>
<!-- <mdcFields>THREAD_ID,MDC_KEY</mdcFields>-->
</appender>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger - %msg %X{THREAD_ID} %n</pattern>
</encoder>
</appender>
<!-- 可用来获取StatusManager中的状态 -->
<statusListener class="ch.qos.logback.core.status.OnConsoleStatusListener"/>
<!-- 解决debug模式下循环发送的问题 -->
<logger name="org.apache.http.impl.conn.Wire" level="WARN" />
<root>
<level value="DEBUG"/>
<appender-ref ref="loghubAppender"/>
<appender-ref ref="STDOUT"/>
</root>
</configuration>

代码刷新logback日志配置

主要是模仿LogbackLister的实现细节来模仿:
简单的贴一下我的实现代码:
package com.lifesense.opensource.spring;
import ch.qos.logback.classic.BasicConfigurator;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.joran.JoranConfigurator;
import ch.qos.logback.core.joran.spi.JoranException;
import ch.qos.logback.core.util.StatusPrinter;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.LoggerFactory;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;
import javax.servlet.ServletContext;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.lang.reflect.Method;
/**
* @author carter
*/
public class LogbackLoader {
private static final String DEFAULT_LOG_BACK_XML = "<configuration>" +
"<shutdownHook class=\"ch.qos.logback.core.hook.DelayingShutdownHook\"/>" +
"<appender name=\"STDOUT\" class=\"ch.qos.logback.core.ConsoleAppender\">" +
"<encoder><pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger - %msg %X{THREAD_ID} %n</pattern></encoder>" +
"</appender>" +
"<statusListener class=\"ch.qos.logback.core.status.OnConsoleStatusListener\"/>" +
"<logger name=\"org.apache.http.impl.conn.Wire\" level=\"WARN\" />" +
"<root><level value=\"DEBUG\"/><appender-ref ref=\"STDOUT\"/>" +
"</root></configuration>";
/**
* 初始化日志配置
*/
public static void initLogbackWithoutConfigFile(ServletContext servletContext) {
initLogbackConfigFromXmlString(servletContext, DEFAULT_LOG_BACK_XML);
}
public static void initLogbackConfigFromXmlString(ServletContext servletContext, String xmlStr) {
System.out.println("Initializing Logback from [\n" + xmlStr + "\n]");
LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
Assert.notNull(loggerContext, "获取不到LoggerContext");
loggerContext.getStatusManager().clear();
loggerContext.reset();
//安装默认的日志配置
if (StringUtils.isBlank(xmlStr)) {
BasicConfigurator basicConfigurator = new BasicConfigurator();
basicConfigurator.setContext(loggerContext);
basicConfigurator.configure(loggerContext);
return;
}
//按照传入的配置文件来配置
JoranConfigurator configurator = new JoranConfigurator();
configurator.setContext(loggerContext);
InputStream in = new ByteArrayInputStream(xmlStr.getBytes());
try {
configurator.doConfigure(in);
} catch (JoranException e) {
System.out.println("初始化配置logback发生错误");
e.printStackTrace();
}
//If SLF4J's java.util.logging bridge is available in the classpath, install it. This will direct any messages
//from the Java Logging framework into SLF4J. When logging is terminated, the bridge will need to be uninstalled
try {
Class<?> julBridge = ClassUtils.forName("org.slf4j.bridge.SLF4JBridgeHandler", ClassUtils.getDefaultClassLoader());
Method removeHandlers = ReflectionUtils.findMethod(julBridge, "removeHandlersForRootLogger");
if (removeHandlers != null) {
servletContext.log("Removing all previous handlers for JUL to SLF4J bridge");
ReflectionUtils.invokeMethod(removeHandlers, null);
}
Method install = ReflectionUtils.findMethod(julBridge, "install");
if (install != null) {
servletContext.log("Installing JUL to SLF4J bridge");
ReflectionUtils.invokeMethod(install, null);
}
} catch (ClassNotFoundException ignored) {
//Indicates the java.util.logging bridge is not in the classpath. This is not an indication of a problem.
servletContext.log("JUL to SLF4J bridge is not available on the classpath");
}
StatusPrinter.print(loggerContext);
}
}
在springmvc上下文启动的时候,可以使用代码的方式加载默认的日志配置;
启动完成之后,加上apollo的配置监听器,这样就可以在apollo中实时的修改日志的配置文件,代码实时生效。
package com.lifesense.opensource.spring;
import com.ctrip.framework.apollo.Config;
import com.ctrip.framework.apollo.ConfigService;
import com.ctrip.framework.apollo.model.ConfigChange;
import com.google.common.base.Strings;
import com.lifesense.opensource.commons.utils.WebResourceUtils;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.CollectionUtils;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import java.util.Objects;
import java.util.Set;
/**
* @author carter
*/
@Slf4j
public class ContextLoaderListener extends org.springframework.web.context.ContextLoaderListener {
private static final String APOLLO_LOG_BACK_CONFIG_KEY = "log4j2.xml";
@Override
public void contextInitialized(ServletContextEvent event) {
final ServletContext servletContext = event.getServletContext();
final Config configFile = ConfigService.getAppConfig();
String xmlContent = configFile.getProperty(APOLLO_LOG_BACK_CONFIG_KEY, "");
if (!Strings.isNullOrEmpty(xmlContent)) {
LogbackLoader.initLogbackConfigFromXmlString(servletContext, xmlContent);
configFile.addChangeListener(configFileChangeEvent -> {
final Set<String> newValue = configFileChangeEvent.changedKeys();
if (!CollectionUtils.isEmpty(newValue) && newValue.contains(APOLLO_LOG_BACK_CONFIG_KEY)) {
final ConfigChange change = configFileChangeEvent.getChange(APOLLO_LOG_BACK_CONFIG_KEY);
System.out.println(String.format("log4j2.ml changed:old:\n %s , new : \n %s ", change.getOldValue(), change.getNewValue()));
LogbackLoader.initLogbackConfigFromXmlString(servletContext, change.getNewValue());
}
});
}
}
}

小结

今天学会了:

  1. slf4j的日志装配过程,分析了源码;
  2. 学会了使用代码的方式动态刷新logback的日志配置;
  3. 一种接入阿里云日志的实现方式。
  4. 常见的slf4j的日志组合方式的使用;
原创不易,转载请注明出处,欢迎沟通交流。
版权声明
本文为[李福春]所创,转载请带上原文链接,感谢
https://segmentfault.com/a/1190000021583346