Showing the changes to java/pkg/javax/swing/text/SegmentCache.java (1 of 18352 files). Show all
Unified · Split
| @@ -0,0 +1,127 @@ | ||
| 1 | +/* | |
| 2 | + * Copyright (c) 2001, 2008, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | +package javax.swing.text; | |
| 26 | + | |
| 27 | +import java.util.ArrayList; | |
| 28 | +import java.util.List; | |
| 29 | + | |
| 30 | +/** | |
| 31 | + * SegmentCache caches <code>Segment</code>s to avoid continually creating | |
| 32 | + * and destroying of <code>Segment</code>s. A common use of this class would | |
| 33 | + * be: | |
| 34 | + * <pre> | |
| 35 | + * Segment segment = segmentCache.getSegment(); | |
| 36 | + * // do something with segment | |
| 37 | + * ... | |
| 38 | + * segmentCache.releaseSegment(segment); | |
| 39 | + * </pre> | |
| 40 | + * | |
| 41 | + */ | |
| 42 | +class SegmentCache { | |
| 43 | + /** | |
| 44 | + * A global cache. | |
| 45 | + */ | |
| 46 | + private static SegmentCache sharedCache = new SegmentCache(); | |
| 47 | + | |
| 48 | + /** | |
| 49 | + * A list of the currently unused Segments. | |
| 50 | + */ | |
| 51 | + private List<Segment> segments; | |
| 52 | + | |
| 53 | + | |
| 54 | + /** | |
| 55 | + * Returns the shared SegmentCache. | |
| 56 | + */ | |
| 57 | + public static SegmentCache getSharedInstance() { | |
| 58 | + return sharedCache; | |
| 59 | + } | |
| 60 | + | |
| 61 | + /** | |
| 62 | + * A convenience method to get a Segment from the shared | |
| 63 | + * <code>SegmentCache</code>. | |
| 64 | + */ | |
| 65 | + public static Segment getSharedSegment() { | |
| 66 | + return getSharedInstance().getSegment(); | |
| 67 | + } | |
| 68 | + | |
| 69 | + /** | |
| 70 | + * A convenience method to release a Segment to the shared | |
| 71 | + * <code>SegmentCache</code>. | |
| 72 | + */ | |
| 73 | + public static void releaseSharedSegment(Segment segment) { | |
| 74 | + getSharedInstance().releaseSegment(segment); | |
| 75 | + } | |
| 76 | + | |
| 77 | + | |
| 78 | + | |
| 79 | + /** | |
| 80 | + * Creates and returns a SegmentCache. | |
| 81 | + */ | |
| 82 | + public SegmentCache() { | |
| 83 | + segments = new ArrayList<Segment>(11); | |
| 84 | + } | |
| 85 | + | |
| 86 | + /** | |
| 87 | + * Returns a <code>Segment</code>. When done, the <code>Segment</code> | |
| 88 | + * should be recycled by invoking <code>releaseSegment</code>. | |
| 89 | + */ | |
| 90 | + public Segment getSegment() { | |
| 91 | + synchronized(this) { | |
| 92 | + int size = segments.size(); | |
| 93 | + | |
| 94 | + if (size > 0) { | |
| 95 | + return segments.remove(size - 1); | |
| 96 | + } | |
| 97 | + } | |
| 98 | + return new CachedSegment(); | |
| 99 | + } | |
| 100 | + | |
| 101 | + /** | |
| 102 | + * Releases a Segment. You should not use a Segment after you release it, | |
| 103 | + * and you should NEVER release the same Segment more than once, eg: | |
| 104 | + * <pre> | |
| 105 | + * segmentCache.releaseSegment(segment); | |
| 106 | + * segmentCache.releaseSegment(segment); | |
| 107 | + * </pre> | |
| 108 | + * Will likely result in very bad things happening! | |
| 109 | + */ | |
| 110 | + public void releaseSegment(Segment segment) { | |
| 111 | + if (segment instanceof CachedSegment) { | |
| 112 | + synchronized(this) { | |
| 113 | + segment.array = null; | |
| 114 | + segment.count = 0; | |
| 115 | + segments.add(segment); | |
| 116 | + } | |
| 117 | + } | |
| 118 | + } | |
| 119 | + | |
| 120 | + | |
| 121 | + /** | |
| 122 | + * CachedSegment is used as a tagging interface to determine if | |
| 123 | + * a Segment can successfully be shared. | |
| 124 | + */ | |
| 125 | + private static class CachedSegment extends Segment { | |
| 126 | + } | |
| 127 | +} | |