com.gemstone.gemfire.CopyHelper Maven / Gradle / Ivy
/*
* Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you
* may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License. See accompanying
* LICENSE file.
*/
package com.gemstone.gemfire;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.Serializable;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.UUID;
import com.gemstone.gemfire.internal.HeapDataOutputStream;
import com.gemstone.gemfire.internal.cache.CachedDeserializable;
import com.gemstone.gemfire.internal.cache.Token;
import com.gemstone.gemfire.internal.i18n.LocalizedStrings;
import com.gemstone.gemfire.internal.shared.Version;
import com.gemstone.gemfire.pdx.PdxInstance;
import com.gemstone.gemfire.pdx.WritablePdxInstance;
import com.gemstone.gemfire.pdx.internal.PdxUnreadData;
/**
* A static helper for optimally creating copies. Creating copies
* of cache values provides improved concurrency as well as isolation.
* For transactions, creating a copy is the guaranteed way to enforce
* "Read Committed" isolation on changes to cache
* Entries.
* Here is a simple example of how to use CopyHelper.copy
*
* Object o = r.get("stringBuf");
* StringBuffer s = (StringBuffer) CopyHelper.copy(o);
* s.append("... and they lived happily ever after. The End.");
* r.put("stringBuf", s);
*
*
* @see Cloneable
* @see Serializable
* @see DataSerializer
* @see com.gemstone.gemfire.cache.Cache#setCopyOnRead
* @see com.gemstone.gemfire.cache.CacheTransactionManager
*
* @author Mitch Thomas
* @since 4.0
*/
public final class CopyHelper {
// no instances allowed
private CopyHelper() {
}
/** for tests only */
static boolean isWellKnownImmutableInstance(Object o) {
return isWellKnownImmutableInstance(o, o.getClass());
}
/**
* Return true if the given object is an instance of a well known
* immutable class.
* The well known classes are:
*
* - String
*
- Byte
*
- Character
*
- Short
*
- Integer
*
- Long
*
- Float
*
- Double
*
- BigInteger
*
- BigDecimal
*
- UUID
*
- PdxInstance but not WritablePdxInstance
*
* @param o the object to check
* @return true if o is an instance of a well known immutable class.
* @since 6.6.2
*/
public static boolean isWellKnownImmutableInstance(Object o, Class c) {
if (c == String.class) {
return true;
}
if (o instanceof Number) {
if (c == Integer.class) return true;
if (c == Long.class) return true;
if (c == Byte.class) return true;
if (c == Short.class) return true;
if (c == Float.class) return true;
if (c == Double.class) return true;
// subclasses of non-final classes may be mutable
if (c == BigInteger.class) return true;
if (c == BigDecimal.class) return true;
}
if (o instanceof PdxInstance && !(o instanceof WritablePdxInstance)) {
// no need to copy since it is immutable
return true;
}
if (c == Character.class) return true;
if (o instanceof UUID) return true;
return false;
}
/**
* Makes a copy of the specified object.
* Copies can only be made if the original is Cloneable or serializable by GemFire.
* If o is a {@link #isWellKnownImmutableInstance(Object, Class) well known
* immutable instance} then it will be returned without copying it.
*
* @param o the original object that a copy is needed of
* @return the new instance that is a copy of of the original
* @throws CopyException if copying fails because a class could not
* be found or could not be serialized.
* @since 4.0
*/
@SuppressWarnings("unchecked")
public static T copy(T o) {
T copy = null;
try {
if (o == null) {
return null;
} else if (o instanceof Token) {
return o;
} else {
final Class c = o.getClass();
if (c == byte[].class) {
copy = (T)((byte[])o).clone();
return copy;
}
if (c == byte[][].class) {
byte[][] byteArrays = (byte[][])o;
byte[][] arraysCopy = new byte[byteArrays.length][];
for (int index = 0; index < byteArrays.length; ++index) {
arraysCopy[index] = byteArrays[index].clone();
}
copy = (T)arraysCopy;
return copy;
}
if (isWellKnownImmutableInstance(o, c)) return o;
if (o instanceof Cloneable) {
try {
// Note that Object.clone is protected so we need to use reflection
// to call clone even though this guy implements Cloneable
// By convention, the user should make the clone method public.
// But even if they don't, let's go ahead and use it.
// The other problem is that if the class is private, we still
// need to make the method accessible even if the method is public,
// because Object.clone is protected.
Method m = c.getDeclaredMethod("clone", new Class[0]);
m.setAccessible(true);
copy = (T)m.invoke(o, (Object[])null);
return copy;
} catch (NoSuchMethodException ignore) {
// try using Serialization
} catch (IllegalAccessException ignore) {
// try using Serialization
} catch (SecurityException ignore) {
// try using Serialization
} catch (InvocationTargetException ex) {
Throwable cause = ex.getTargetException();
if (cause instanceof CloneNotSupportedException) {
// try using Serialization
} else {
throw new CopyException(LocalizedStrings.CopyHelper_CLONE_FAILED.toLocalizedString(), cause != null ? cause : ex);
}
}
} else if (o instanceof CachedDeserializable) {
return (T) ((CachedDeserializable) o).getDeserializedWritableCopy(null, null);
} else if (o.getClass().isArray() && o.getClass().getComponentType().isPrimitive()) {
if (o instanceof byte[]) {
byte[] a = (byte[])o;
return (T) Arrays.copyOf(a, a.length);
} else if (o instanceof boolean[]) {
boolean[] a = (boolean[])o;
return (T) Arrays.copyOf(a, a.length);
} else if (o instanceof char[]) {
char[] a = (char[])o;
return (T) Arrays.copyOf(a, a.length);
} else if (o instanceof int[]) {
int[] a = (int[])o;
return (T) Arrays.copyOf(a, a.length);
} else if (o instanceof long[]) {
long[] a = (long[])o;
return (T) Arrays.copyOf(a, a.length);
} else if (o instanceof short[]) {
short[] a = (short[])o;
return (T) Arrays.copyOf(a, a.length);
} else if (o instanceof float[]) {
float[] a = (float[])o;
return (T) Arrays.copyOf(a, a.length);
} else if (o instanceof double[]) {
double[] a = (double[])o;
return (T) Arrays.copyOf(a, a.length);
}
}
try {
HeapDataOutputStream hdos = new HeapDataOutputStream(Version.CURRENT);
DataSerializer.writeObject(o, hdos);
copy = (T)DataSerializer.readObject(new DataInputStream(hdos.getInputStream()));
return copy;
} catch (ClassNotFoundException ex) {
throw new CopyException(LocalizedStrings.CopyHelper_COPY_FAILED_ON_INSTANCE_OF_0.toLocalizedString(o.getClass()), ex);
} catch (IOException ex) {
throw new CopyException(LocalizedStrings.CopyHelper_COPY_FAILED_ON_INSTANCE_OF_0.toLocalizedString(o.getClass()), ex);
}
}
} finally {
if (copy != null) {
PdxUnreadData.copy(o, copy);
}
}
}
}