alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (CreatedFontTracker.java)

This example Java source code file (CreatedFontTracker.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

appcontext, awt, createdfonttracker, hashmap, interruptedexception, max_file_size, max_total_bytes, object, outputstream, runnable, semaphore, tempfiledeletionhook, threadgroup, threading, threads, util

The CreatedFontTracker.java Java example source code

/*
 * Copyright (c) 2008, 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 sun.font;

import java.io.File;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;

import sun.awt.AppContext;

public class CreatedFontTracker {

    public static final int MAX_FILE_SIZE = 32 * 1024 * 1024;
    public static final int MAX_TOTAL_BYTES = 10 * MAX_FILE_SIZE;

    static CreatedFontTracker tracker;
    int numBytes;

    public static synchronized CreatedFontTracker getTracker() {
        if (tracker == null) {
            tracker = new CreatedFontTracker();
        }
        return tracker;
    }

    private CreatedFontTracker() {
        numBytes = 0;
    }

    public synchronized int getNumBytes() {
        return numBytes;
    }

    public synchronized void addBytes(int sz) {
        numBytes += sz;
    }

    public synchronized void subBytes(int sz) {
        numBytes -= sz;
    }

    /**
     * Returns an AppContext-specific counting semaphore.
     */
    private static synchronized Semaphore getCS() {
        final AppContext appContext = AppContext.getAppContext();
        Semaphore cs = (Semaphore) appContext.get(CreatedFontTracker.class);
        if (cs == null) {
            // Make a semaphore with 5 permits that obeys the first-in first-out
            // granting of permits.
            cs = new Semaphore(5, true);
            appContext.put(CreatedFontTracker.class, cs);
        }
        return cs;
    }

    public boolean acquirePermit() throws InterruptedException {
        // This does a timed-out wait.
        return getCS().tryAcquire(120, TimeUnit.SECONDS);
    }

    public void releasePermit() {
        getCS().release();
    }

    public void add(File file) {
        TempFileDeletionHook.add(file);
    }

    public void set(File file, OutputStream os) {
        TempFileDeletionHook.set(file, os);
    }

    public void remove(File file) {
        TempFileDeletionHook.remove(file);
    }

    /**
     * Helper class for cleanup of temp files created while processing fonts.
     * Note that this only applies to createFont() from an InputStream object.
     */
    private static class TempFileDeletionHook {
        private static HashMap<File, OutputStream> files = new HashMap<>();

        private static Thread t = null;
        static void init() {
            if (t == null) {
                // Add a shutdown hook to remove the temp file.
                java.security.AccessController.doPrivileged(
                   new java.security.PrivilegedAction() {
                      public Object run() {
                          /* The thread must be a member of a thread group
                           * which will not get GCed before VM exit.
                           * Make its parent the top-level thread group.
                           */
                          ThreadGroup tg =
                              Thread.currentThread().getThreadGroup();
                          for (ThreadGroup tgn = tg;
                               tgn != null;
                               tg = tgn, tgn = tg.getParent());
                          t = new Thread(tg, new Runnable() {
                              public void run() {
                                  runHooks();
                              }
                          });
                          t.setContextClassLoader(null);
                          Runtime.getRuntime().addShutdownHook(t);
                          return null;
                      }
                   });
            }
        }

        private TempFileDeletionHook() {}

        static synchronized void add(File file) {
            init();
            files.put(file, null);
        }

        static synchronized void set(File file, OutputStream os) {
            files.put(file, os);
        }

        static synchronized void remove(File file) {
            files.remove(file);
        }

        static synchronized void runHooks() {
            if (files.isEmpty()) {
                return;
            }

            for (Map.Entry<File, OutputStream> entry : files.entrySet()) {
                // Close the associated output stream, and then delete the file.
                try {
                    if (entry.getValue() != null) {
                        entry.getValue().close();
                    }
                } catch (Exception e) {}
                entry.getKey().delete();
            }
        }
    }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java CreatedFontTracker.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2024 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.