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| 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 | } | ||