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src/java.xml/share/classes/com/sun/org/apache/bcel/internal/classfile/ConstantUtf8.java
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@@ -1,8 +1,7 @@
/*
- * reserved comment block
- * DO NOT REMOVE OR ALTER!
+ * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
*/
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
@@ -19,96 +18,195 @@
* limitations under the License.
*/
package com.sun.org.apache.bcel.internal.classfile;
-
-import com.sun.org.apache.bcel.internal.Constants;
-import java.io.*;
+import com.sun.org.apache.bcel.internal.Const;
+import java.io.DataInput;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
/**
- * This class is derived from the abstract
- * <A HREF="com.sun.org.apache.bcel.internal.classfile.Constant.html">Constant</A> class
+ * This class is derived from the abstract {@link Constant}
* and represents a reference to a Utf8 encoded string.
*
- * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
+ * @version $Id: ConstantUtf8.java 1750029 2016-06-23 22:14:38Z sebb $
* @see Constant
*/
public final class ConstantUtf8 extends Constant {
- private String bytes;
+
+ private final String bytes;
+
+ // TODO these should perhaps be AtomicInt?
+ private static volatile int considered = 0;
+ private static volatile int hits = 0;
+ private static volatile int skipped = 0;
+ private static volatile int created = 0;
+
+ // Set the size to 0 or below to skip caching entirely
+ private static final int MAX_CACHED_SIZE = 200;
+ private static final boolean BCEL_STATISTICS = false;
+
+
+ private static class CACHE_HOLDER {
+
+ private static final int MAX_CACHE_ENTRIES = 20000;
+ private static final int INITIAL_CACHE_CAPACITY = (int)(MAX_CACHE_ENTRIES/0.75);
+
+ private static final HashMap<String, ConstantUtf8> CACHE =
+ new LinkedHashMap<String, ConstantUtf8>(INITIAL_CACHE_CAPACITY, 0.75f, true) {
+ private static final long serialVersionUID = -8506975356158971766L;
+
+ @Override
+ protected boolean removeEldestEntry(final Map.Entry<String, ConstantUtf8> eldest) {
+ return size() > MAX_CACHE_ENTRIES;
+ }
+ };
+
+ }
+
+ // for accesss by test code
+ static void printStats() {
+ System.err.println("Cache hit " + hits + "/" + considered +", " + skipped + " skipped");
+ System.err.println("Total of " + created + " ConstantUtf8 objects created");
+ }
+
+ // for accesss by test code
+ static void clearStats() {
+ hits = considered = skipped = created = 0;
+ }
+
+ static {
+ if (BCEL_STATISTICS) {
+ Runtime.getRuntime().addShutdownHook(new Thread() {
+ @Override
+ public void run() {
+ printStats();
+ }
+ });
+ }
+ }
+
+ /**
+ * @since 6.0
+ */
+ public static ConstantUtf8 getCachedInstance(final String s) {
+ if (s.length() > MAX_CACHED_SIZE) {
+ skipped++;
+ return new ConstantUtf8(s);
+ }
+ considered++;
+ synchronized (ConstantUtf8.class) { // might be better with a specific lock object
+ ConstantUtf8 result = CACHE_HOLDER.CACHE.get(s);
+ if (result != null) {
+ hits++;
+ return result;
+ }
+ result = new ConstantUtf8(s);
+ CACHE_HOLDER.CACHE.put(s, result);
+ return result;
+ }
+ }
+
+ /**
+ * @since 6.0
+ */
+ public static ConstantUtf8 getInstance(final String s) {
+ return new ConstantUtf8(s);
+ }
+
+ /**
+ * @since 6.0
+ */
+ public static ConstantUtf8 getInstance (final DataInput input) throws IOException {
+ return getInstance(input.readUTF());
+ }
/**
* Initialize from another object.
*/
- public ConstantUtf8(ConstantUtf8 c) {
+ public ConstantUtf8(final ConstantUtf8 c) {
this(c.getBytes());
}
+
/**
* Initialize instance from file data.
*
* @param file Input stream
* @throws IOException
*/
- ConstantUtf8(DataInputStream file) throws IOException
- {
- super(Constants.CONSTANT_Utf8);
-
+ ConstantUtf8(final DataInput file) throws IOException {
+ super(Const.CONSTANT_Utf8);
bytes = file.readUTF();
+ created++;
}
+
/**
* @param bytes Data
*/
- public ConstantUtf8(String bytes)
- {
- super(Constants.CONSTANT_Utf8);
-
- if(bytes == null)
+ public ConstantUtf8(final String bytes) {
+ super(Const.CONSTANT_Utf8);
+ if (bytes == null) {
throw new IllegalArgumentException("bytes must not be null!");
-
+ }
this.bytes = bytes;
+ created++;
}
+
/**
* Called by objects that are traversing the nodes of the tree implicitely
* defined by the contents of a Java class. I.e., the hierarchy of methods,
* fields, attributes, etc. spawns a tree of objects.
*
* @param v Visitor object
*/
- public void accept(Visitor v) {
+ @Override
+ public void accept( final Visitor v ) {
v.visitConstantUtf8(this);
}
+
/**
* Dump String in Utf8 format to file stream.
*
* @param file Output file stream
* @throws IOException
*/
- public final void dump(DataOutputStream file) throws IOException
- {
- file.writeByte(tag);
+ @Override
+ public final void dump( final DataOutputStream file ) throws IOException {
+ file.writeByte(super.getTag());
file.writeUTF(bytes);
}
+
/**
* @return Data converted to string.
*/
- public final String getBytes() { return bytes; }
+ public final String getBytes() {
+ return bytes;
+ }
+
/**
- * @param bytes.
+ * @param bytes the raw bytes of this Utf-8
+ * @deprecated (since 6.0)
*/
- public final void setBytes(String bytes) {
- this.bytes = bytes;
+ @java.lang.Deprecated
+ public final void setBytes( final String bytes ) {
+ throw new UnsupportedOperationException();
}
+
/**
* @return String representation
*/
- public final String toString()
- {
+ @Override
+ public final String toString() {
return super.toString() + "(\"" + Utility.replace(bytes, "\n", "\\n") + "\")";
}
}
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