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src/java.xml/share/classes/com/sun/org/apache/bcel/internal/classfile/ConstantUtf8.java
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@@ -1,7 +1,7 @@
/*
- * Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2017, 2020, 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.
@@ -27,187 +27,182 @@
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
/**
- * This class is derived from the abstract {@link Constant}
- * and represents a reference to a Utf8 encoded string.
+ * Extends the abstract {@link Constant} to represent a reference to a UTF-8 encoded string.
*
- * @version $Id$
* @see Constant
- * @LastModified: Jun 2019
+ * @LastModified: Jan 2020
*/
public final class ConstantUtf8 extends Constant {
- private final String bytes;
+ private static class Cache {
- // 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 final int MAX_ENTRIES = 20000;
+ private static final int INITIAL_CAPACITY = (int) (MAX_ENTRIES / 0.75);
+ private static final HashMap<String, ConstantUtf8> CACHE = new LinkedHashMap<String, ConstantUtf8>(
+ INITIAL_CAPACITY, 0.75f, true) {
- 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;
+ return size() > MAX_ENTRIES;
}
};
- }
+ // Set the size to 0 or below to skip caching entirely
+ private static final int MAX_ENTRY_SIZE = 200;
- // 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");
+ static boolean isEnabled() {
+ return Cache.MAX_ENTRIES > 0 && MAX_ENTRY_SIZE > 0;
}
- // 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();
- }
- });
- }
+ /**
+ * Clears the cache.
+ *
+ * @since 6.4.0
+ */
+ public static synchronized void clearCache() {
+ Cache.CACHE.clear();
}
/**
+ * Gets a new or cached instance of the given value.
+ * <p>
+ * See {@link ConstantUtf8} class Javadoc for details.
+ * </p>
+ *
+ * @param value the value.
+ * @return a new or cached instance of the given value.
* @since 6.0
*/
- public static ConstantUtf8 getCachedInstance(final String s) {
- if (s.length() > MAX_CACHED_SIZE) {
- skipped++;
- return new ConstantUtf8(s);
+ public static ConstantUtf8 getCachedInstance(final String value) {
+ if (value.length() > Cache.MAX_ENTRY_SIZE) {
+ return new ConstantUtf8(value);
}
- considered++;
+
synchronized (ConstantUtf8.class) { // might be better with a specific lock object
- ConstantUtf8 result = CACHE_HOLDER.CACHE.get(s);
+ ConstantUtf8 result = Cache.CACHE.get(value);
if (result != null) {
- hits++;
return result;
}
- result = new ConstantUtf8(s);
- CACHE_HOLDER.CACHE.put(s, result);
+ result = new ConstantUtf8(value);
+ Cache.CACHE.put(value, result);
return result;
}
}
/**
+ * Gets a new or cached instance of the given value.
+ * <p>
+ * See {@link ConstantUtf8} class Javadoc for details.
+ * </p>
+ *
+ * @param dataInput the value.
+ * @return a new or cached instance of the given value.
+ * @throws IOException if an I/O error occurs.
* @since 6.0
*/
- public static ConstantUtf8 getInstance(final String s) {
- return new ConstantUtf8(s);
+ public static ConstantUtf8 getInstance(final DataInput dataInput) throws IOException {
+ return getInstance(dataInput.readUTF());
}
/**
+ * Gets a new or cached instance of the given value.
+ * <p>
+ * See {@link ConstantUtf8} class Javadoc for details.
+ * </p>
+ *
+ * @param value the value.
+ * @return a new or cached instance of the given value.
* @since 6.0
*/
- public static ConstantUtf8 getInstance (final DataInput input) throws IOException {
- return getInstance(input.readUTF());
+ public static ConstantUtf8 getInstance(final String value) {
+ return Cache.isEnabled() ? getCachedInstance(value) : new ConstantUtf8(value);
}
+ private final String value;
+
/**
- * Initialize from another object.
+ * Initializes from another object.
+ *
+ * @param constantUtf8 the value.
*/
- public ConstantUtf8(final ConstantUtf8 c) {
- this(c.getBytes());
+ public ConstantUtf8(final ConstantUtf8 constantUtf8) {
+ this(constantUtf8.getBytes());
}
-
/**
- * Initialize instance from file data.
+ * Initializes instance from file data.
*
- * @param file Input stream
+ * @param dataInput Input stream
* @throws IOException
*/
- ConstantUtf8(final DataInput file) throws IOException {
+ ConstantUtf8(final DataInput dataInput) throws IOException {
super(Const.CONSTANT_Utf8);
- bytes = file.readUTF();
- created++;
+ value = dataInput.readUTF();
}
-
/**
- * @param bytes Data
+ * @param value Data
*/
- public ConstantUtf8(final String bytes) {
+ public ConstantUtf8(final String value) {
super(Const.CONSTANT_Utf8);
- if (bytes == null) {
- throw new IllegalArgumentException("bytes must not be null!");
+ if (value == null) {
+ throw new IllegalArgumentException("Value must not be null.");
}
- this.bytes = bytes;
- created++;
+ this.value = value;
}
-
/**
- * 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.
+ * 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
*/
@Override
- public void accept( final Visitor v ) {
+ public void accept(final Visitor v) {
v.visitConstantUtf8(this);
}
-
/**
- * Dump String in Utf8 format to file stream.
+ * Dumps String in Utf8 format to file stream.
*
* @param file Output file stream
* @throws IOException
*/
@Override
- public final void dump( final DataOutputStream file ) throws IOException {
+ public void dump(final DataOutputStream file) throws IOException {
file.writeByte(super.getTag());
- file.writeUTF(bytes);
+ file.writeUTF(value);
}
-
/**
* @return Data converted to string.
*/
- public final String getBytes() {
- return bytes;
+ public String getBytes() {
+ return value;
}
-
/**
- * @param bytes the raw bytes of this Utf-8
+ * @param bytes the raw bytes of this UTF-8
* @deprecated (since 6.0)
*/
@java.lang.Deprecated
- public final void setBytes( final String bytes ) {
+ public void setBytes(final String bytes) {
throw new UnsupportedOperationException();
}
-
/**
* @return String representation
*/
@Override
- public final String toString() {
- return super.toString() + "(\"" + Utility.replace(bytes, "\n", "\\n") + "\")";
+ public String toString() {
+ return super.toString() + "(\"" + Utility.replace(value, "\n", "\\n") + "\")";
}
}
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