| /* |
| * Copyright (c) 2002, 2011, 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.io; |
| |
| import java.util.Iterator; |
| import java.util.Map; |
| import java.util.LinkedHashMap; |
| import java.util.Set; |
| |
| class ExpiringCache { |
| private long millisUntilExpiration; |
| private Map<String,Entry> map; |
| // Clear out old entries every few queries |
| private int queryCount; |
| private int queryOverflow = 300; |
| private int MAX_ENTRIES = 200; |
| |
| static class Entry { |
| private long timestamp; |
| private String val; |
| |
| Entry(long timestamp, String val) { |
| this.timestamp = timestamp; |
| this.val = val; |
| } |
| |
| long timestamp() { return timestamp; } |
| void setTimestamp(long timestamp) { this.timestamp = timestamp; } |
| |
| String val() { return val; } |
| void setVal(String val) { this.val = val; } |
| } |
| |
| ExpiringCache() { |
| this(30000); |
| } |
| |
| @SuppressWarnings("serial") |
| ExpiringCache(long millisUntilExpiration) { |
| this.millisUntilExpiration = millisUntilExpiration; |
| map = new LinkedHashMap<String,Entry>() { |
| // Android-changed: Qualified ExpiringCache.Entry to distinguish from Map.Entry. |
| // There seems to be a compiler difference between javac and jack here; |
| // Map.Entry<String,Entry> doesn't work on jack since the latter "Entry" gets |
| // interpreted as referring to Map.Entry rather than ExpiringCache.Entry. |
| // protected boolean removeEldestEntry(Map.Entry<String,Entry> eldest) { |
| protected boolean removeEldestEntry(Map.Entry<String,ExpiringCache.Entry> eldest) { |
| return size() > MAX_ENTRIES; |
| } |
| }; |
| } |
| |
| synchronized String get(String key) { |
| if (++queryCount >= queryOverflow) { |
| cleanup(); |
| } |
| Entry entry = entryFor(key); |
| if (entry != null) { |
| return entry.val(); |
| } |
| return null; |
| } |
| |
| synchronized void put(String key, String val) { |
| if (++queryCount >= queryOverflow) { |
| cleanup(); |
| } |
| Entry entry = entryFor(key); |
| if (entry != null) { |
| entry.setTimestamp(System.currentTimeMillis()); |
| entry.setVal(val); |
| } else { |
| map.put(key, new Entry(System.currentTimeMillis(), val)); |
| } |
| } |
| |
| synchronized void clear() { |
| map.clear(); |
| } |
| |
| private Entry entryFor(String key) { |
| Entry entry = map.get(key); |
| if (entry != null) { |
| long delta = System.currentTimeMillis() - entry.timestamp(); |
| if (delta < 0 || delta >= millisUntilExpiration) { |
| map.remove(key); |
| entry = null; |
| } |
| } |
| return entry; |
| } |
| |
| private void cleanup() { |
| Set<String> keySet = map.keySet(); |
| // Avoid ConcurrentModificationExceptions |
| String[] keys = new String[keySet.size()]; |
| int i = 0; |
| for (String key: keySet) { |
| keys[i++] = key; |
| } |
| for (int j = 0; j < keys.length; j++) { |
| entryFor(keys[j]); |
| } |
| queryCount = 0; |
| } |
| } |