| /* |
| * Copyright (c) 2000, 2019, 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; |
| |
| /** |
| * {@code Handler} that buffers requests in a circular buffer in memory. |
| * <p> |
| * Normally this {@code Handler} simply stores incoming {@code LogRecords} |
| * into its memory buffer and discards earlier records. This buffering |
| * is very cheap and avoids formatting costs. On certain trigger |
| * conditions, the {@code MemoryHandler} will push out its current buffer |
| * contents to a target {@code Handler}, 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 {@code LogRecord} has a type that is greater than |
| * a pre-defined level, the {@code pushLevel}. </li> |
| * <li> |
| * An external class calls the {@code push} method explicitly. </li> |
| * <li> |
| * A subclass overrides the {@code log} method and scans each incoming |
| * {@code LogRecord} and calls {@code push} if a record matches some |
| * desired criteria. </li> |
| * </ul> |
| * <p> |
| * <b>Configuration:</b> |
| * By default each {@code MemoryHandler} is initialized using the following |
| * {@code LogManager} configuration properties where {@code <handler-name>} |
| * 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> <handler-name>.level |
| * specifies the level for the {@code Handler} |
| * (defaults to {@code Level.ALL}). </li> |
| * <li> <handler-name>.filter |
| * specifies the name of a {@code Filter} class to use |
| * (defaults to no {@code Filter}). </li> |
| * <li> <handler-name>.size |
| * defines the buffer size (defaults to 1000). </li> |
| * <li> <handler-name>.push |
| * defines the {@code pushLevel} (defaults to {@code level.SEVERE}). </li> |
| * <li> <handler-name>.target |
| * specifies the name of the target {@code Handler } 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> |
| * |
| * @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; |
| |
| /** |
| * Create a {@code MemoryHandler} and configure it based on |
| * {@code LogManager} configuration properties. |
| */ |
| public MemoryHandler() { |
| // configure with specific defaults for MemoryHandler |
| super(Level.ALL, new SimpleFormatter(), null); |
| |
| 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; |
| } |
| String targetName = manager.getProperty(cname+".target"); |
| if (targetName == null) { |
| throw new RuntimeException("The handler " + cname |
| + " does not specify a target"); |
| } |
| Class<?> clz; |
| try { |
| clz = ClassLoader.getSystemClassLoader().loadClass(targetName); |
| @SuppressWarnings("deprecation") |
| Object o = clz.newInstance(); |
| target = (Handler) o; |
| } catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) { |
| throw new RuntimeException("MemoryHandler can't load handler target \"" + targetName + "\"" , e); |
| } |
| init(); |
| } |
| |
| // Initialize. Size is a count of LogRecords. |
| private void init() { |
| buffer = new LogRecord[size]; |
| start = 0; |
| count = 0; |
| } |
| |
| /** |
| * Create a {@code MemoryHandler}. |
| * <p> |
| * The {@code MemoryHandler} is configured based on {@code LogManager} |
| * properties (or their default values) except that the given {@code pushLevel} |
| * 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) { |
| // configure with specific defaults for MemoryHandler |
| super(Level.ALL, new SimpleFormatter(), null); |
| |
| if (target == null || pushLevel == null) { |
| throw new NullPointerException(); |
| } |
| if (size <= 0) { |
| throw new IllegalArgumentException(); |
| } |
| this.target = target; |
| this.pushLevel = pushLevel; |
| this.size = size; |
| init(); |
| } |
| |
| /** |
| * Store a {@code LogRecord} in an internal buffer. |
| * <p> |
| * If there is a {@code Filter}, its {@code isLoggable} |
| * 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 {@code pushLevel}. If the given level is |
| * greater than or equal to the {@code pushLevel} then {@code push} |
| * is called to write all buffered records to the target output |
| * {@code Handler}. |
| * |
| * @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 {@code Handler}. |
| * <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 {@code Handler}. |
| * <p> |
| * Note that the current contents of the {@code MemoryHandler} |
| * buffer are <b>not</b> written out. That requires a "push". |
| */ |
| @Override |
| public void flush() { |
| target.flush(); |
| } |
| |
| /** |
| * Close the {@code Handler} and free all associated resources. |
| * This will also close the target {@code Handler}. |
| * |
| * @exception SecurityException if a security manager exists and if |
| * the caller does not have {@code LoggingPermission("control")}. |
| */ |
| @Override |
| public void close() throws SecurityException { |
| target.close(); |
| setLevel(Level.OFF); |
| } |
| |
| /** |
| * Set the {@code pushLevel}. After a {@code LogRecord} is copied |
| * into our internal buffer, if its level is greater than or equal to |
| * the {@code pushLevel}, then {@code push} will be called. |
| * |
| * @param newLevel the new value of the {@code pushLevel} |
| * @exception SecurityException if a security manager exists and if |
| * the caller does not have {@code LoggingPermission("control")}. |
| */ |
| public synchronized void setPushLevel(Level newLevel) throws SecurityException { |
| if (newLevel == null) { |
| throw new NullPointerException(); |
| } |
| checkPermission(); |
| pushLevel = newLevel; |
| } |
| |
| /** |
| * Get the {@code pushLevel}. |
| * |
| * @return the value of the {@code pushLevel} |
| */ |
| public Level getPushLevel() { |
| return pushLevel; |
| } |
| |
| /** |
| * Check if this {@code Handler} would actually log a given |
| * {@code LogRecord} into its internal buffer. |
| * <p> |
| * This method checks if the {@code LogRecord} has an appropriate level and |
| * whether it satisfies any {@code Filter}. However it does <b>not</b> |
| * check whether the {@code LogRecord} would result in a "push" of the |
| * buffer contents. It will return false if the {@code LogRecord} is null. |
| * |
| * @param record a {@code LogRecord} (may be null). |
| * @return true if the {@code LogRecord} would be logged. |
| * |
| */ |
| @Override |
| public boolean isLoggable(LogRecord record) { |
| return super.isLoggable(record); |
| } |
| } |
