org.forstdb.SstFileReaderIterator Maven / Gradle / Ivy
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
package org.forstdb;
import java.nio.ByteBuffer;
/**
* An iterator that yields a sequence of key/value pairs from a source.
* Multiple implementations are provided by this library.
* In particular, iterators are provided
* to access the contents of a Table or a DB.
*
* Multiple threads can invoke const methods on an RocksIterator without
* external synchronization, but if any of the threads may call a
* non-const method, all threads accessing the same RocksIterator must use
* external synchronization.
*
* @see RocksObject
*/
public class SstFileReaderIterator extends AbstractRocksIterator {
protected SstFileReaderIterator(final SstFileReader reader, final long nativeHandle) {
super(reader, nativeHandle);
}
/**
* Return the key for the current entry. The underlying storage for
* the returned slice is valid only until the next modification of
* the iterator.
*
* REQUIRES: {@link #isValid()}
*
* @return key for the current entry.
*/
public byte[] key() {
assert (isOwningHandle());
return key0(nativeHandle_);
}
/**
* Return the key for the current entry. The underlying storage for
* the returned slice is valid only until the next modification of
* the iterator.
*
* REQUIRES: {@link #isValid()}
*
* @param key the out-value to receive the retrieved key.
* It is using position and limit. Limit is set according to key size.
* Supports direct buffer only.
* @return The size of the actual key. If the return key is greater than the
* length of {@code key}, then it indicates that the size of the
* input buffer {@code key} is insufficient and partial result will
* be returned.
*/
public int key(final ByteBuffer key) {
assert (isOwningHandle());
final int result;
if (key.isDirect()) {
result = keyDirect0(nativeHandle_, key, key.position(), key.remaining());
} else {
result = keyByteArray0(
nativeHandle_, key.array(), key.arrayOffset() + key.position(), key.remaining());
}
key.limit(Math.min(key.position() + result, key.limit()));
return result;
}
/**
* Return the value for the current entry. The underlying storage for
* the returned slice is valid only until the next modification of
* the iterator.
*
* REQUIRES: !AtEnd() && !AtStart()
* @return value for the current entry.
*/
public byte[] value() {
assert (isOwningHandle());
return value0(nativeHandle_);
}
/**
* Return the value for the current entry. The underlying storage for
* the returned slice is valid only until the next modification of
* the iterator.
*
* REQUIRES: {@link #isValid()}
*
* @param value the out-value to receive the retrieved value.
* It is using position and limit. Limit is set according to value size.
* Supports direct buffer only.
* @return The size of the actual value. If the return value is greater than the
* length of {@code value}, then it indicates that the size of the
* input buffer {@code value} is insufficient and partial result will
* be returned.
*/
public int value(final ByteBuffer value) {
assert (isOwningHandle());
final int result;
if (value.isDirect()) {
result = valueDirect0(nativeHandle_, value, value.position(), value.remaining());
} else {
result = valueByteArray0(
nativeHandle_, value.array(), value.arrayOffset() + value.position(), value.remaining());
}
value.limit(Math.min(value.position() + result, value.limit()));
return result;
}
@Override protected final native void disposeInternal(final long handle);
@Override final native boolean isValid0(long handle);
@Override final native void seekToFirst0(long handle);
@Override final native void seekToLast0(long handle);
@Override final native void next0(long handle);
@Override final native void prev0(long handle);
@Override final native void refresh0(long handle) throws RocksDBException;
@Override final native void seek0(long handle, byte[] target, int targetLen);
@Override final native void seekForPrev0(long handle, byte[] target, int targetLen);
@Override final native void status0(long handle) throws RocksDBException;
@Override
final native void seekDirect0(long handle, ByteBuffer target, int targetOffset, int targetLen);
@Override
final native void seekForPrevDirect0(
long handle, ByteBuffer target, int targetOffset, int targetLen);
@Override
final native void seekByteArray0(
final long handle, final byte[] target, final int targetOffset, final int targetLen);
@Override
final native void seekForPrevByteArray0(
final long handle, final byte[] target, final int targetOffset, final int targetLen);
private native byte[] key0(long handle);
private native byte[] value0(long handle);
private native int keyDirect0(long handle, ByteBuffer buffer, int bufferOffset, int bufferLen);
private native int keyByteArray0(long handle, byte[] buffer, int bufferOffset, int bufferLen);
private native int valueDirect0(long handle, ByteBuffer buffer, int bufferOffset, int bufferLen);
private native int valueByteArray0(long handle, byte[] buffer, int bufferOffset, int bufferLen);
}