package org.hotswap.agent.plugin.logback;
import org.hotswap.agent.annotation.FileEvent;
import org.hotswap.agent.annotation.Init;
import org.hotswap.agent.annotation.OnClassLoadEvent;
import org.hotswap.agent.annotation.Plugin;
import org.hotswap.agent.javassist.*;
import org.hotswap.agent.logging.AgentLogger;
import org.hotswap.agent.util.IOUtils;
import org.hotswap.agent.util.PluginManagerInvoker;
import org.hotswap.agent.watch.WatchFileEvent;
import org.hotswap.agent.watch.WatchEventListener;
import org.hotswap.agent.watch.Watcher;
import java.net.URI;
import java.net.URL;
import java.util.HashSet;
import java.util.Set;
/**
* Logback configuration file reload.
*
* @author Jiri Bubnik
*/
@Plugin(name = "Logback", description = "Logback configuration reload.",
testedVersions = {"1.0.6"}
)
public class LogbackPlugin {
private static AgentLogger LOGGER = AgentLogger.getLogger(LogbackPlugin.class);
@Init
Watcher watcher;
@Init
ClassLoader appClassLoader;
// ensure uri registered only once
Set<URI> registeredURIs = new HashSet<URI>();
/**
* Callback method from ch.qos.logback.core.joran.GenericConfigurator.
*
* @param configurator the configurator object
* @param url configuration file url
*/
public void initLogback(final Object configurator, final URL url) {
try {
final URI uri = url.toURI();
// skip double registration on reload
if (registeredURIs.contains(uri))
return;
LOGGER.debug("Watching '{}' URL for Logback configuration changes.", url);
registeredURIs.add(uri);
watcher.addEventListener(appClassLoader, uri, new WatchEventListener() {
@Override
public void onEvent(WatchFileEvent event) {
if (event.getEventType() != FileEvent.DELETE)
reload(configurator, url);
}
});
} catch (Exception e) {
LOGGER.error("Exception initializing logback configurator {} on url {}.", e, configurator, url);
}
}
/**
* Do the reload using logback configurator.
*
* @param configurator ch.qos.logback.core.joran.GenericConfigurator instance
* @param url URL with configuration file
*/
protected void reload(Object configurator, URL url) {
try {
IOUtils.toByteArray(url.toURI());
} catch (Exception e) {
LOGGER.warning("Unable to open logback configuration file {}, is it deleted?", url);
return;
}
try {
//noinspection SynchronizationOnLocalVariableOrMethodParameter
synchronized (configurator) {
ClassLoader classLoader = configurator.getClass().getClassLoader();
Class<?> configuratorClass = classLoader.loadClass("ch.qos.logback.core.joran.GenericConfigurator");
Class<?> contextAwareBaseClass = classLoader.loadClass("ch.qos.logback.core.spi.ContextAwareBase");
Class<?> contextClass = classLoader.loadClass("ch.qos.logback.classic.LoggerContext");
// reset current context
Object context = contextAwareBaseClass.getDeclaredMethod("getContext").invoke(configurator);
contextClass.getDeclaredMethod("reset").invoke(context);
// configure the URL
configuratorClass.getDeclaredMethod("doConfigure", URL.class).invoke(configurator, url);
LOGGER.reload("Logback configuration reloaded from url '{}'.", url);
}
} catch (Exception e) {
LOGGER.error("Unable to reload {} with logback configurator {}", e, url, configurator);
}
}
/**
* Transform configurator class to register logback config URL.
*/
@OnClassLoadEvent(classNameRegexp = "ch.qos.logback.core.joran.GenericConfigurator")
public static void registerConfigurator(ClassPool classPool, CtClass ctClass) throws NotFoundException, CannotCompileException {
CtMethod m = ctClass.getDeclaredMethod("doConfigure", new CtClass[]{classPool.get("java.net.URL")});
m.insertAfter(PluginManagerInvoker.buildInitializePlugin(LogbackPlugin.class));
m.insertAfter(PluginManagerInvoker.buildCallPluginMethod(LogbackPlugin.class, "initLogback",
"this", "java.lang.Object",
"url", "java.net.URL"));
}
}