content: /*
   * Copyright (C) 2014 The Android Open Source Project
   * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package java.util.logging;
  
  /**
   * <tt>Handler</tt> that buffers requests in a circular buffer in memory.
   * <p>
   * Normally this <tt>Handler</tt> simply stores incoming <tt>LogRecords</tt>
   * into its memory buffer and discards earlier records.  This buffering
   * is very cheap and avoids formatting costs.  On certain trigger
   * conditions, the <tt>MemoryHandler</tt> will push out its current buffer
   * contents to a target <tt>Handler</tt>, which will typically publish
   * them to the outside world.
   * <p>
   * There are three main models for triggering a push of the buffer:
   * <ul>
   * <li>
   * An incoming <tt>LogRecord</tt> has a type that is greater than
   * a pre-defined level, the <tt>pushLevel</tt>. </li>
   * <li>
   * An external class calls the <tt>push</tt> method explicitly. </li>
   * <li>
   * A subclass overrides the <tt>log</tt> method and scans each incoming
   * <tt>LogRecord</tt> and calls <tt>push</tt> if a record matches some
   * desired criteria. </li>
   * </ul>
   * <p>
   * <b>Configuration:</b>
   * By default each <tt>MemoryHandler</tt> is initialized using the following
   * <tt>LogManager</tt> configuration properties where <tt>&lt;handler-name&gt;</tt>
   * refers to the fully-qualified class name of the handler.
   * If properties are not defined
   * (or have invalid values) then the specified default values are used.
   * If no default value is defined then a RuntimeException is thrown.
   * <ul>
   * <li>   &lt;handler-name&gt;.level
   *        specifies the level for the <tt>Handler</tt>
   *        (defaults to <tt>Level.ALL</tt>). </li>
   * <li>   &lt;handler-name&gt;.filter
   *        specifies the name of a <tt>Filter</tt> class to use
   *        (defaults to no <tt>Filter</tt>). </li>
   * <li>   &lt;handler-name&gt;.size
   *        defines the buffer size (defaults to 1000). </li>
   * <li>   &lt;handler-name&gt;.push
   *        defines the <tt>pushLevel</tt> (defaults to <tt>level.SEVERE</tt>). </li>
   * <li>   &lt;handler-name&gt;.target
   *        specifies the name of the target <tt>Handler </tt> class.
   *        (no default). </li>
   * </ul>
   * <p>
   * For example, the properties for {@code MemoryHandler} would be:
   * <ul>
   * <li>   java.util.logging.MemoryHandler.level=INFO </li>
   * <li>   java.util.logging.MemoryHandler.formatter=java.util.logging.SimpleFormatter </li>
   * </ul>
   * <p>
   * For a custom handler, e.g. com.foo.MyHandler, the properties would be:
   * <ul>
   * <li>   com.foo.MyHandler.level=INFO </li>
   * <li>   com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter </li>
   * </ul>
   * <p>
   * @since 1.4
   */
  
  public class MemoryHandler extends Handler {
      private final static int DEFAULT_SIZE = 1000;
      private volatile Level pushLevel;
      private int size;
      private Handler target;
      private LogRecord buffer[];
      int start, count;
  
      // Private method to configure a MemoryHandler from LogManager
      // properties and/or default values as specified in the class
      // javadoc.
      private void configure() {
          LogManager manager = LogManager.getLogManager();
          String cname = getClass().getName();
  
          pushLevel = manager.getLevelProperty(cname +".push", Level.SEVERE);
          size = manager.getIntProperty(cname + ".size", DEFAULT_SIZE);
          if (size <= 0) {
              size = DEFAULT_SIZE;
          }
          setLevel(manager.getLevelProperty(cname +".level", Level.ALL));
          setFilter(manager.getFilterProperty(cname +".filter", null));
          setFormatter(manager.getFormatterProperty(cname +".formatter", new SimpleFormatter()));
      }
  
      /**
       * Create a <tt>MemoryHandler</tt> and configure it based on
       * <tt>LogManager</tt> configuration properties.
       */
      public MemoryHandler() {
          sealed = false;
          configure();
          sealed = true;
  
          LogManager manager = LogManager.getLogManager();
          String handlerName = getClass().getName();
          String targetName = manager.getProperty(handlerName+".target");
          if (targetName == null) {
              throw new RuntimeException("The handler " + handlerName
                      + " does not specify a target");
          }
          Class<?> clz;
          try {
              clz = ClassLoader.getSystemClassLoader().loadClass(targetName);
              target = (Handler) clz.newInstance();
          // Android-changed: Fall back to the context classloader before giving up.
          // } catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {
          //     throw new RuntimeException("MemoryHandler can't load handler target \"" + targetName + "\"" , e);
          } catch (Exception e) {
              try {
                  clz = Thread.currentThread().getContextClassLoader()
                          .loadClass(targetName);
                  target = (Handler) clz.newInstance();
              } catch (Exception innerE) {
                  throw new RuntimeException("MemoryHandler can't load handler target \"" +
                          targetName + "\"" , innerE);
              }
          }
          init();
      }
  
      // Initialize.  Size is a count of LogRecords.
      private void init() {
          buffer = new LogRecord[size];
          start = 0;
          count = 0;
      }
  
      /**
       * Create a <tt>MemoryHandler</tt>.
       * <p>
       * The <tt>MemoryHandler</tt> is configured based on <tt>LogManager</tt>
       * properties (or their default values) except that the given <tt>pushLevel</tt>
       * argument and buffer size argument are used.
       *
       * @param target  the Handler to which to publish output.
       * @param size    the number of log records to buffer (must be greater than zero)
       * @param pushLevel  message level to push on
       *
       * @throws IllegalArgumentException if {@code size is <= 0}
       */
      public MemoryHandler(Handler target, int size, Level pushLevel) {
          if (target == null || pushLevel == null) {
              throw new NullPointerException();
          }
          if (size <= 0) {
              throw new IllegalArgumentException();
          }
          sealed = false;
          configure();
          sealed = true;
          this.target = target;
          this.pushLevel = pushLevel;
          this.size = size;
          init();
      }
  
      /**
       * Store a <tt>LogRecord</tt> in an internal buffer.
       * <p>
       * If there is a <tt>Filter</tt>, its <tt>isLoggable</tt>
       * method is called to check if the given log record is loggable.
       * If not we return.  Otherwise the given record is copied into
       * an internal circular buffer.  Then the record's level property is
       * compared with the <tt>pushLevel</tt>. If the given level is
       * greater than or equal to the <tt>pushLevel</tt> then <tt>push</tt>
       * is called to write all buffered records to the target output
       * <tt>Handler</tt>.
       *
       * @param  record  description of the log event. A null record is
       *                 silently ignored and is not published
       */
      @Override
      public synchronized void publish(LogRecord record) {
          if (!isLoggable(record)) {
              return;
          }
          int ix = (start+count)%buffer.length;
          buffer[ix] = record;
          if (count < buffer.length) {
              count++;
          } else {
              start++;
              start %= buffer.length;
          }
          if (record.getLevel().intValue() >= pushLevel.intValue()) {
              push();
          }
      }
  
      /**
       * Push any buffered output to the target <tt>Handler</tt>.
       * <p>
       * The buffer is then cleared.
       */
      public synchronized void push() {
          for (int i = 0; i < count; i++) {
              int ix = (start+i)%buffer.length;
              LogRecord record = buffer[ix];
              target.publish(record);
          }
          // Empty the buffer.
          start = 0;
          count = 0;
      }
  
      /**
       * Causes a flush on the target <tt>Handler</tt>.
       * <p>
       * Note that the current contents of the <tt>MemoryHandler</tt>
       * buffer are <b>not</b> written out.  That requires a "push".
       */
      @Override
      public void flush() {
          target.flush();
      }
  
      /**
       * Close the <tt>Handler</tt> and free all associated resources.
       * This will also close the target <tt>Handler</tt>.
       *
       * @exception  SecurityException  if a security manager exists and if
       *             the caller does not have <tt>LoggingPermission("control")</tt>.
       */
      @Override
      public void close() throws SecurityException {
          target.close();
          setLevel(Level.OFF);
      }
  
      /**
       * Set the <tt>pushLevel</tt>.  After a <tt>LogRecord</tt> is copied
       * into our internal buffer, if its level is greater than or equal to
       * the <tt>pushLevel</tt>, then <tt>push</tt> will be called.
       *
       * @param newLevel the new value of the <tt>pushLevel</tt>
       * @exception  SecurityException  if a security manager exists and if
       *             the caller does not have <tt>LoggingPermission("control")</tt>.
       */
      public synchronized void setPushLevel(Level newLevel) throws SecurityException {
          if (newLevel == null) {
              throw new NullPointerException();
          }
          checkPermission();
          pushLevel = newLevel;
      }
  
      /**
       * Get the <tt>pushLevel</tt>.
       *
       * @return the value of the <tt>pushLevel</tt>
       */
      public Level getPushLevel() {
          return pushLevel;
      }
  
      /**
       * Check if this <tt>Handler</tt> would actually log a given
       * <tt>LogRecord</tt> into its internal buffer.
       * <p>
       * This method checks if the <tt>LogRecord</tt> has an appropriate level and
       * whether it satisfies any <tt>Filter</tt>.  However it does <b>not</b>
       * check whether the <tt>LogRecord</tt> would result in a "push" of the
       * buffer contents. It will return false if the <tt>LogRecord</tt> is null.
       * <p>
       * @param record  a <tt>LogRecord</tt>
       * @return true if the <tt>LogRecord</tt> would be logged.
       *
       */
      @Override
      public boolean isLoggable(LogRecord record) {
          return super.isLoggable(record);
      }
  }
  