--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/sun/nio/cs/ThreadLocalCoders.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,137 @@
+/*
+ * Copyright 2001 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.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun 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 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.
+ */
+
+
+package sun.nio.cs;
+
+import java.nio.*;
+import java.nio.charset.*;
+
+
+/**
+ * Utility class for caching per-thread decoders and encoders.
+ */
+
+public class ThreadLocalCoders {
+
+    private static final int CACHE_SIZE = 3;
+
+    private static abstract class Cache {
+
+        // Thread-local reference to array of cached objects, in LRU order
+        private ThreadLocal cache = new ThreadLocal();
+        private final int size;
+
+        Cache(int size) {
+            this.size = size;
+        }
+
+        abstract Object create(Object name);
+
+        private void moveToFront(Object[] oa, int i) {
+            Object ob = oa[i];
+            for (int j = i; j > 0; j--)
+                oa[j] = oa[j - 1];
+            oa[0] = ob;
+        }
+
+        abstract boolean hasName(Object ob, Object name);
+
+        Object forName(Object name) {
+            Object[] oa = (Object[])cache.get();
+            if (oa == null) {
+                oa = new Object[size];
+                cache.set(oa);
+            } else {
+                for (int i = 0; i < oa.length; i++) {
+                    Object ob = oa[i];
+                    if (ob == null)
+                        continue;
+                    if (hasName(ob, name)) {
+                        if (i > 0)
+                            moveToFront(oa, i);
+                        return ob;
+                    }
+                }
+            }
+
+            // Create a new object
+            Object ob = create(name);
+            oa[oa.length - 1] = ob;
+            moveToFront(oa, oa.length - 1);
+            return ob;
+        }
+
+    }
+
+    private static Cache decoderCache = new Cache(CACHE_SIZE) {
+            boolean hasName(Object ob, Object name) {
+                if (name instanceof String)
+                    return (((CharsetDecoder)ob).charset().name().equals(name));
+                if (name instanceof Charset)
+                    return ((CharsetDecoder)ob).charset().equals(name);
+                return false;
+            }
+            Object create(Object name) {
+                if (name instanceof String)
+                    return Charset.forName((String)name).newDecoder();
+                if (name instanceof Charset)
+                    return ((Charset)name).newDecoder();
+                assert false;
+                return null;
+            }
+        };
+
+    public static CharsetDecoder decoderFor(Object name) {
+        CharsetDecoder cd = (CharsetDecoder)decoderCache.forName(name);
+        cd.reset();
+        return cd;
+    }
+
+    private static Cache encoderCache = new Cache(CACHE_SIZE) {
+            boolean hasName(Object ob, Object name) {
+                if (name instanceof String)
+                    return (((CharsetEncoder)ob).charset().name().equals(name));
+                if (name instanceof Charset)
+                    return ((CharsetEncoder)ob).charset().equals(name);
+                return false;
+            }
+            Object create(Object name) {
+                if (name instanceof String)
+                    return Charset.forName((String)name).newEncoder();
+                if (name instanceof Charset)
+                    return ((Charset)name).newEncoder();
+                assert false;
+                return null;
+            }
+        };
+
+    public static CharsetEncoder encoderFor(Object name) {
+        CharsetEncoder ce = (CharsetEncoder)encoderCache.forName(name);
+        ce.reset();
+        return ce;
+    }
+
+}