com.bigdata.btree.raba.MutableValueBuffer Maven / Gradle / Ivy
/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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 for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.bigdata.btree.raba;
import java.io.DataInput;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* A flyweight mutable implementation exposing the backing byte[][], permitting
* nulls and not supporting search. It is assumed that caller
* maintains a dense byte[][] in the sense that all entries in [0:nvalues] are
* defined, even if some of entries are null. The implementation is NOT
* thread-safe for mutation.
*
* @author Bryan Thompson
* @version $Id$
*/
public class MutableValueBuffer implements IRaba {
/**
* The #of entries with valid data.
*/
public int nvalues;
/**
* The backing array.
*/
public final byte[][] values;
/**
* Mutable.
*/
final public boolean isReadOnly() {
return false;
}
/**
* For B+Tree values.
*/
@Override
final public boolean isKeys() {
return false;
}
/**
* Create a new, empty byte[][] of the specified capacity.
*
* @param nvalues
* The capacity of the byte[][].
*/
public MutableValueBuffer(final int nvalues) {
this(0/* size */, new byte[nvalues][]);
}
/**
* Create a view of a byte[][]. All elements in the array are visible in the
* view.
*
* @param nvalues
* The #of entries in the array with valid data.
* @param values
* The backing byte[][].
*/
public MutableValueBuffer(final int nvalues, final byte[][] values) {
if (values == null)
throw new IllegalArgumentException();
if (nvalues < 0 || nvalues >= values.length)
throw new IllegalArgumentException();
this.nvalues = nvalues;
this.values = values;
}
/**
* Builds a mutable value buffer.
*
* @param capacity
* The capacity of the new instance (this is based on the
* branching factor for the B+Tree).
* @param src
* The source data.
*
* @throws IllegalArgumentException
* if the capacity is LT the {@link IRaba#size()} of the
* src.
* @throws IllegalArgumentException
* if the source is null.
*/
public MutableValueBuffer(final int capacity, final IRaba src) {
if (src == null)
throw new IllegalArgumentException();
if (capacity < src.capacity())
throw new IllegalArgumentException();
nvalues = src.size();
assert nvalues >= 0; // allows deficient root.
values = new byte[capacity][];
int i = 0;
for (byte[] a : src) {
values[i++] = a;
}
}
@Override
final public int size() {
return nvalues;
}
@Override
final public boolean isEmpty() {
return nvalues == 0;
}
@Override
final public boolean isFull() {
return nvalues == values.length;
}
@Override
final public int capacity() {
return values.length;
}
final protected boolean rangeCheck(final int index)
throws IndexOutOfBoundsException {
if (index < 0 || index >= nvalues) {
throw new IndexOutOfBoundsException("index=" + index
+ ", capacity=" + nvalues);
}
return true;
}
final public byte[] get(final int index) {
assert rangeCheck(index);
return values[index];
}
@Override
final public int length(final int index) {
assert rangeCheck(index);
final byte[] tmp = values[index];
if (tmp == null)
throw new NullPointerException();
return tmp.length;
}
@Override
final public boolean isNull(final int index) {
assert rangeCheck(index);
return values[index] == null;
}
@Override
final public int copy(final int index, final OutputStream out) {
assert rangeCheck(index);
final byte[] tmp = values[index];
if (tmp == null)
throw new NullPointerException();
try {
out.write(tmp, 0, tmp.length);
} catch (IOException ex) {
throw new RuntimeException(ex);
}
return tmp.length;
}
@Override
final public Iterator iterator() {
return new Iterator() {
int i = 0;
@Override
public boolean hasNext() {
return i < nvalues;
}
@Override
public byte[] next() {
if (!hasNext())
throw new NoSuchElementException();
return values[i++];
}
@Override
public void remove() {
if (isReadOnly())
throw new UnsupportedOperationException();
// @todo support remove on the iterator when mutable.
throw new UnsupportedOperationException();
}
};
}
/**
* @throws IllegalStateException
* unless there is room to store another value.
*/
protected void assertNotFull() {
if (nvalues >= values.length) {
throw new IllegalStateException();
}
}
@Override
public void set(final int index, final byte[] key) {
assert rangeCheck(index);
values[index] = key;
}
@Override
public int add(final byte[] key) {
assertNotFull();
values[nvalues++] = key;
return nvalues;
}
@Override
public int add(final byte[] key, final int off, final int len) {
assertNotFull();
final byte[] b = new byte[len];
System.arraycopy(key, off, b, 0, len);
values[nvalues++] = b;
return nvalues;
}
@Override
public int add(final DataInput in, final int len) throws IOException {
assertNotFull();
final byte[] b = new byte[len];
in.readFully(b, 0, len);
values[nvalues++] = b;
return nvalues;
}
@Override
final public int search(final byte[] searchKey) {
throw new UnsupportedOperationException();
}
@Override
public String toString() {
return AbstractRaba.toString(this);
}
}
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