path: root/branches/sca-java-integration/sca/kernel/core/src/main/java/org/apache/tuscany/core/monitor/JavaLoggingMonitorFactory.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.    
 */
package org.apache.tuscany.core.monitor;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.ref.WeakReference;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.MissingResourceException;
import java.util.Properties;
import java.util.ResourceBundle;
import java.util.WeakHashMap;
import java.util.logging.Level;
import java.util.logging.LogRecord;
import java.util.logging.Logger;

import org.osoa.sca.annotations.Service;

import org.apache.tuscany.api.annotation.LogLevel;
import org.apache.tuscany.host.MonitorFactory;
import org.apache.tuscany.host.monitor.ExceptionFormatter;
import org.apache.tuscany.host.monitor.FormatterRegistry;

/**
 * A factory for monitors that forwards events to a {@link java.util.logging.Logger Java Logging (JSR47) Logger}.
 *
 * @version $Rev$ $Date$
 * @see java.util.logging
 */
@Service(interfaces = {MonitorFactory.class, FormatterRegistry.class})
public class JavaLoggingMonitorFactory implements MonitorFactory, FormatterRegistry {
    private String bundleName;
    private Level defaultLevel;
    private Map<String, Level> levels;
    private List<ExceptionFormatter> formatters = new ArrayList<ExceptionFormatter>();
    private ExceptionFormatter defaultFormatter = new DefaultExceptionFormatter();
    private Map<Class<?>, WeakReference<?>> proxies = new WeakHashMap<Class<?>, WeakReference<?>>();

    /**
     * Construct a MonitorFactory that will monitor the specified methods at the specified levels and generate messages
     * using java.util.logging.
     * <p/>
     * The supplied Properties can be used to specify custom log levels for specific monitor methods. The key should be
     * the method name in form returned by <code>Class.getName() + '#' + Method.getName()</code> and the value the log
     * level to use as defined by {@link java.util.logging.Level}.
     *
     * @param levels       definition of custom levels for specific monitored methods, may be null or empty.
     * @param defaultLevel the default log level to use
     * @param bundleName   the name of a resource bundle that will be passed to the logger
     * @see java.util.logging.Logger
     */
    public JavaLoggingMonitorFactory(Properties levels, Level defaultLevel, String bundleName) {
        Map<String, Object> configProperties = new HashMap<String, Object>();
        configProperties.put("levels", levels);
        configProperties.put("defaultLevel", defaultLevel);
        configProperties.put("bundleName", bundleName);
        initInternal(configProperties);
    }

    /**
     * Constructs a MonitorFactory that needs to be subsequently configured via a call to {@link #initialize}.
     */
    public JavaLoggingMonitorFactory() {
    }

    public void initialize(Map<String, Object> configProperties) {
        if (configProperties == null) {
            return;
        }
        initInternal(configProperties);
    }

    private void initInternal(Map<String, Object> configProperties) {
        try {
            this.defaultLevel = (Level) configProperties.get("defaultLevel");
            this.bundleName = (String) configProperties.get("bundleName");
            Properties levels = (Properties) configProperties.get("levels");

            this.levels = new HashMap<String, Level>();
            if (levels != null) {
                for (Map.Entry<Object, Object> entry : levels.entrySet()) {
                    String method = (String) entry.getKey();
                    String level = (String) entry.getValue();
                    try {
                        this.levels.put(method, Level.parse(level));
                    } catch (IllegalArgumentException e) {
                        throw new InvalidLevelException(method, level);
                    }
                }
            }
        } catch (ClassCastException cce) {
            throw new IllegalArgumentException(cce.getLocalizedMessage());
        }
    }

    public synchronized <T> T getMonitor(Class<T> monitorInterface) {
        T proxy = getCachedMonitor(monitorInterface);
        if (proxy == null) {
            proxy = createMonitor(monitorInterface, bundleName);
            proxies.put(monitorInterface, new WeakReference<T>(proxy));
        }
        return proxy;
    }

    private <T> T getCachedMonitor(Class<T> monitorInterface) {
        WeakReference<?> ref = proxies.get(monitorInterface);
        return (ref != null) ? monitorInterface.cast(ref.get()) : null;
    }

    private <T> T createMonitor(Class<T> monitorInterface, String bundleName) {
        String className = monitorInterface.getName();
        Logger logger = Logger.getLogger(className);
        Method[] methods = monitorInterface.getMethods();
        Map<String, Level> levels = new HashMap<String, Level>(methods.length);
        for (Method method : methods) {
            String key = className + '#' + method.getName();
            Level level = null;
            if (this.levels != null) {
                this.levels.get(key);
            }
            // if not specified the in config properties, look for an annotation on the method
            if (level == null) {
                LogLevel annotation = method.getAnnotation(LogLevel.class);
                if (annotation != null && annotation.value() != null) {
                    try {
                        level = Level.parse(annotation.value());
                    } catch (IllegalArgumentException e) {
                        // bad value, just use the default
                        level = defaultLevel;
                    }
                }
            }
            if (level == null) {
                level = defaultLevel;
            }
            levels.put(method.getName(), level);
        }

        ResourceBundle bundle = locateBundle(monitorInterface, bundleName);

        InvocationHandler handler = new LoggingHandler(logger, levels, bundle, formatters, defaultFormatter);
        return monitorInterface
            .cast(Proxy.newProxyInstance(monitorInterface.getClassLoader(), new Class<?>[]{monitorInterface}, handler));
    }

    private static <T> ResourceBundle locateBundle(Class<T> monitorInterface, String bundleName) {
        Locale locale = Locale.getDefault();
        ClassLoader cl = monitorInterface.getClassLoader();
        String packageName = monitorInterface.getPackage().getName();
        while (true) {
            try {
                return ResourceBundle.getBundle(packageName + '.' + bundleName, locale, cl);
            } catch (MissingResourceException e) {
                //ok
            }
            int index = packageName.lastIndexOf('.');
            if (index == -1) {
                break;
            }
            packageName = packageName.substring(0, index);
        }
        try {
            return ResourceBundle.getBundle(bundleName, locale, cl);
        } catch (Exception e) {
            return null;
        }
    }

    public void register(ExceptionFormatter formatter) {
        formatters.add(formatter);
    }

    public void unregister(ExceptionFormatter formatter) {
        formatters.remove(formatter);
    }

    private static final class LoggingHandler implements InvocationHandler {
        private final Logger logger;
        private final Map<String, Level> methodLevels;
        private final ResourceBundle bundle;
        private List<ExceptionFormatter> formatters;
        private ExceptionFormatter defaultFormatter;

        public LoggingHandler(Logger logger,
                              Map<String, Level> methodLevels,
                              ResourceBundle bundle,
                              List<ExceptionFormatter> formatters,
                              ExceptionFormatter defaultFormatter) {
            this.logger = logger;
            this.methodLevels = methodLevels;
            this.bundle = bundle;
            this.formatters = formatters;
            this.defaultFormatter = defaultFormatter;
        }

        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            String sourceMethod = method.getName();
            Level level = methodLevels.get(sourceMethod);
            if (level != null && logger.isLoggable(level)) {
                // construct the key for the resource bundle
                String className = logger.getName();
                String key = className + '#' + sourceMethod;

                LogRecord logRecord = new LogRecord(level, key);
                logRecord.setLoggerName(className);
                logRecord.setSourceClassName(className);
                logRecord.setSourceMethodName(sourceMethod);
                logRecord.setParameters(args);
                if (args != null) {
                    for (Object o : args) {
                        if (o instanceof Throwable) {
                            Throwable e = (Throwable) o;
                            ExceptionFormatter formatter = null;
                            for (ExceptionFormatter candidate : formatters) {
                                if (candidate.canFormat(e.getClass())) {
                                    formatter = candidate;
                                    break;
                                }
                            }
                            StringWriter writer = new StringWriter();
                            PrintWriter pw = new PrintWriter(writer);
                            if (formatter != null) {
                                formatter.write(pw, e);
                            } else {
                                defaultFormatter.write(pw, e);
                            }
                            format(pw, e);
                            pw.close();
                            logRecord.setMessage(writer.toString());
                            break;
                        }
                    }
                }
                logRecord.setResourceBundle(bundle);
                logger.log(logRecord);
            }
            return null;
        }

        private void format(PrintWriter writer, Throwable throwable) {
            writer.println(throwable.getClass().getName());
            StackTraceElement[] trace = throwable.getStackTrace();
            for (StackTraceElement aTrace : trace) {
                writer.println("\tat " + aTrace);
            }
            Throwable ourCause = throwable.getCause();

            if (ourCause != null) {
                printStackTraceAsCause(writer, ourCause, trace);
            }
        }

        private void printStackTraceAsCause(PrintWriter pw,
                                            Throwable throwable,
                                            StackTraceElement[] causedTrace) {

            // Compute number of frames in common between this and caused
            StackTraceElement[] trace = throwable.getStackTrace();
            int m = trace.length - 1;
            int n = causedTrace.length - 1;
            while (m >= 0 && n >= 0 && trace[m].equals(causedTrace[n])) {
                m--;
                n--;
            }
            int framesInCommon = trace.length - 1 - m;

            pw.println("Caused by: " + throwable.getClass().getName());

            ExceptionFormatter formatter = null;
            for (ExceptionFormatter candidate : formatters) {
                if (candidate.canFormat(throwable.getClass())) {
                    formatter = candidate;
                    break;
                }
            }
            if (formatter != null) {
                formatter.write(pw, throwable);
            } else {
                defaultFormatter.write(pw, throwable);
            }


            for (int i = 0; i <= m; i++) {
                pw.println("\tat " + trace[i]);
            }
            if (framesInCommon != 0) {
                pw.println("\t... " + framesInCommon + " more");
            }

            // Recurse if we have a cause
            Throwable ourCause = throwable.getCause();
            if (ourCause != null) {
                printStackTraceAsCause(pw, ourCause, trace);
            }
        }

    }
}