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6640532: Graphics.getFontMetrics() throws NullPointerException

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NIO usage needs to be robust against Thread.interrupt()

Reviewed-by: tdv
This commit is contained in:
Phil Race 2008-03-07 12:13:17 -08:00
parent 1fd0bb2370
commit a15c780502
2 changed files with 124 additions and 21 deletions
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56
jdk/src/share/classes/sun/font/FontManager.java
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@ -93,7 +93,6 @@ public final class FontManager {
*/
private static final int CHANNELPOOLSIZE = 20;
private static int lastPoolIndex = 0;
private static int poolSize = 0;
private static FileFont fontFileCache[] = new FileFont[CHANNELPOOLSIZE];
/* Need to implement a simple linked list scheme for fast
@ -283,29 +282,32 @@ public final class FontManager {
private static native void initIDs();
public static void addToPool(FileFont font) {
boolean added = false;
FileFont fontFileToClose = null;
int freeSlot = -1;
synchronized (fontFileCache) {
/* use poolSize to quickly detect if there's any free slots.
* This is a performance tweak based on the assumption that
* if this is executed at all often, its because there are many
* fonts being used and the pool will be full, and we will save
* a fruitless iteration
/* Avoid duplicate entries in the pool, and don't close() it,
* since this method is called only from within open().
* Seeing a duplicate is most likely to happen if the thread
* was interrupted during a read, forcing perhaps repeated
* close and open calls and it eventually it ends up pointing
* at the same slot.
*/
if (poolSize < CHANNELPOOLSIZE) {
for (int i=0; i<CHANNELPOOLSIZE; i++) {
if (fontFileCache[i] == null) {
fontFileCache[i] = font;
poolSize++;
added = true;
break;
}
for (int i=0;i<CHANNELPOOLSIZE;i++) {
if (fontFileCache[i] == font) {
return;
}
assert added;
if (fontFileCache[i] == null && freeSlot < 0) {
freeSlot = i;
}
}
if (freeSlot >= 0) {
fontFileCache[freeSlot] = font;
return;
} else {
// is it possible for this to be the same font?
assert fontFileCache[lastPoolIndex] != font;
/* replace with new font, poolSize is unchanged. */
fontFileCache[lastPoolIndex].close();
/* replace with new font. */
fontFileToClose = fontFileCache[lastPoolIndex];
fontFileCache[lastPoolIndex] = font;
/* lastPoolIndex is updated so that the least recently opened
* file will be closed next.
@ -313,6 +315,19 @@ public final class FontManager {
lastPoolIndex = (lastPoolIndex+1) % CHANNELPOOLSIZE;
}
}
/* Need to close the font file outside of the synchronized block,
* since its possible some other thread is in an open() call on
* this font file, and could be holding its lock and the pool lock.
* Releasing the pool lock allows that thread to continue, so it can
* then release the lock on this font, allowing the close() call
* below to proceed.
* Also, calling close() is safe because any other thread using
* the font we are closing() synchronizes all reading, so we
* will not close the file while its in use.
*/
if (fontFileToClose != null) {
fontFileToClose.close();
}
}
/*
@ -334,7 +349,6 @@ public final class FontManager {
for (int i=0; i<CHANNELPOOLSIZE; i++) {
if (fontFileCache[i] == font) {
fontFileCache[i] = null;
poolSize--;
}
}
}

89
jdk/test/java/awt/font/Threads/FontThread.java Normal file
View File

@ -0,0 +1,89 @@
/*
* Copyright 2007 Sun Microsystems, Inc. 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.
*
* 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
/* @test
* @summary verify thread interruption doesn't affect font file reading.
* @bug 6640532
*/
import java.awt.*;
public class FontThread extends Thread {
String fontName = "Dialog";
static FontThread thread1;
static FontThread thread2;
static FontThread thread3;
public static void main(String args[]) throws Exception {
thread1 = new FontThread("SansSerif");
thread2 = new FontThread("Serif");
thread3 = new FontThread("Monospaced");
thread1.dometrics(60); // load classes first
thread1.start();
thread2.start();
thread3.start();
InterruptThread ithread = new InterruptThread();
ithread.setDaemon(true);
ithread.start();
thread1.join();
thread2.join();
thread3.join();
}
FontThread(String font) {
super();
this.fontName = font;
}
public void run() {
System.out.println("started "+fontName); System.out.flush();
dometrics(4000);
System.out.println("done "+fontName); System.out.flush();
}
private void dometrics(int max) {
Font f = new Font(fontName, Font.PLAIN, 12);
FontMetrics fm = Toolkit.getDefaultToolkit().getFontMetrics(f);
for (char i=0;i<max;i++) {
if (f.canDisplay(i)) fm.charWidth(i);
}
}
static class InterruptThread extends Thread {
public void run() {
while (true) {
try {
Thread.sleep(1);
} catch (InterruptedException e) {
}
thread1.interrupt();
thread2.interrupt();
thread3.interrupt();
}
}
}
}