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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2000, 2015 Oracle and/or its affiliates. All rights reserved.
*
*/
package com.sleepycat.bind.tuple;
import com.sleepycat.db.DatabaseEntry;
/**
* A base class for tuple bindings and tuple key creators that provides control
* over the allocation of the output buffer.
*
* <p>Tuple bindings and key creators append data to a {@link TupleOutput}
* instance, which is also a {@link com.sleepycat.util.FastOutputStream}
* instance. This object has a byte array buffer that is resized when it is
* full. The reallocation of this buffer can be a performance factor for
* some applications using large objects. To manage this issue, the {@link
* #setTupleBufferSize} method may be used to control the initial size of the
* buffer, and the {@link #getTupleOutput} method may be overridden by
* subclasses to take over creation of the TupleOutput object.</p>
*/
public class TupleBase<E> {
private int outputBufferSize;
/**
* Initializes the initial output buffer size to zero.
*
* <p>Unless {@link #setTupleBufferSize} is called, the default {@link
* com.sleepycat.util.FastOutputStream#DEFAULT_INIT_SIZE} size will be
* used.</p>
*/
public TupleBase() {
outputBufferSize = 0;
}
/**
* Sets the initial byte size of the output buffer that is allocated by the
* default implementation of {@link #getTupleOutput}.
*
* <p>If this property is zero (the default), the default {@link
* com.sleepycat.util.FastOutputStream#DEFAULT_INIT_SIZE} size is used.</p>
*
* @param byteSize the initial byte size of the output buffer, or zero to
* use the default size.
*/
public void setTupleBufferSize(int byteSize) {
outputBufferSize = byteSize;
}
/**
* Returns the initial byte size of the output buffer.
*
* @return the initial byte size of the output buffer.
*
* @see #setTupleBufferSize
*/
public int getTupleBufferSize() {
return outputBufferSize;
}
/**
* Returns an empty TupleOutput instance that will be used by the tuple
* binding or key creator.
*
* <p>The default implementation of this method creates a new TupleOutput
* with an initial buffer size that can be changed using the {@link
* #setTupleBufferSize} method.</p>
*
* <p>This method may be overridden to return a TupleOutput instance. For
* example, an instance per thread could be created and returned by this
* method. If a TupleOutput instance is reused, be sure to call its
* {@link com.sleepycat.util.FastOutputStream#reset} method before each
* use.</p>
*
* @param object is the object to be written to the tuple output, and may
* be used by subclasses to determine the size of the output buffer.
*
* @return an empty TupleOutput instance.
*
* @see #setTupleBufferSize
*/
protected TupleOutput getTupleOutput(E object) {
int byteSize = getTupleBufferSize();
if (byteSize != 0) {
return new TupleOutput(new byte[byteSize]);
} else {
return new TupleOutput();
}
}
/**
* Utility method to set the data in a entry buffer to the data in a tuple
* output object.
*
* @param output is the source tuple output object.
*
* @param entry is the destination entry buffer.
*/
public static void outputToEntry(TupleOutput output, DatabaseEntry entry) {
entry.setData(output.getBufferBytes(), output.getBufferOffset(),
output.getBufferLength());
}
/**
* Utility method to set the data in a entry buffer to the data in a tuple
* input object.
*
* @param input is the source tuple input object.
*
* @param entry is the destination entry buffer.
*/
public static void inputToEntry(TupleInput input, DatabaseEntry entry) {
entry.setData(input.getBufferBytes(), input.getBufferOffset(),
input.getBufferLength());
}
/**
* Utility method to create a new tuple input object for reading the data
* from a given buffer. If an existing input is reused, it is reset before
* returning it.
*
* @param entry is the source entry buffer.
*
* @return the new tuple input object.
*/
public static TupleInput entryToInput(DatabaseEntry entry) {
return new TupleInput(entry.getData(), entry.getOffset(),
entry.getSize());
}
/**
* Utility method for use by bindings to create a tuple output object.
*
* @return a new tuple output object.
*
* @deprecated replaced by {@link #getTupleOutput}
*/
public static TupleOutput newOutput() {
return new TupleOutput();
}
/**
* Utility method for use by bindings to create a tuple output object
* with a specific starting size.
*
* @return a new tuple output object.
*
* @deprecated replaced by {@link #getTupleOutput}
*/
public static TupleOutput newOutput(byte[] buffer) {
return new TupleOutput(buffer);
}
}
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