org.rocksdb.WBWIRocksIterator Maven / Gradle / Ivy
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// 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.rocksdb;
import java.nio.ByteBuffer;
public class WBWIRocksIterator
extends AbstractRocksIterator {
private final WriteEntry entry = new WriteEntry();
protected WBWIRocksIterator(final WriteBatchWithIndex wbwi,
final long nativeHandle) {
super(wbwi, nativeHandle);
}
/**
* Get the current entry
*
* The WriteEntry is only valid
* until the iterator is repositioned.
* If you want to keep the WriteEntry across iterator
* movements, you must make a copy of its data!
*
* Note - This method is not thread-safe with respect to the WriteEntry
* as it performs a non-atomic update across the fields of the WriteEntry
*
* @return The WriteEntry of the current entry
*/
public WriteEntry entry() {
assert(isOwningHandle());
final long[] ptrs = entry1(nativeHandle_);
entry.type = WriteType.fromId((byte)ptrs[0]);
entry.key.resetNativeHandle(ptrs[1], ptrs[1] != 0);
entry.value.resetNativeHandle(ptrs[2], ptrs[2] != 0);
return entry;
}
@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(final 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(
final long handle, final ByteBuffer target, final int targetOffset, final int targetLen);
@Override
final native void seekForPrevDirect0(
final long handle, final ByteBuffer target, final int targetOffset, final 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 long[] entry1(final long handle);
/**
* Enumeration of the Write operation
* that created the record in the Write Batch
*/
public enum WriteType {
PUT((byte)0x0),
MERGE((byte)0x1),
DELETE((byte)0x2),
SINGLE_DELETE((byte)0x3),
DELETE_RANGE((byte)0x4),
LOG((byte)0x5),
XID((byte)0x6);
final byte id;
WriteType(final byte id) {
this.id = id;
}
public static WriteType fromId(final byte id) {
for(final WriteType wt : WriteType.values()) {
if(id == wt.id) {
return wt;
}
}
throw new IllegalArgumentException("No WriteType with id=" + id);
}
}
@Override
public void close() {
entry.close();
super.close();
}
/**
* Represents an entry returned by
* {@link org.rocksdb.WBWIRocksIterator#entry()}
*
* It is worth noting that a WriteEntry with
* the type {@link org.rocksdb.WBWIRocksIterator.WriteType#DELETE}
* or {@link org.rocksdb.WBWIRocksIterator.WriteType#LOG}
* will not have a value.
*/
public static class WriteEntry implements AutoCloseable {
WriteType type = null;
final DirectSlice key;
final DirectSlice value;
/**
* Intentionally private as this
* should only be instantiated in
* this manner by the outer WBWIRocksIterator
* class; The class members are then modified
* by calling {@link org.rocksdb.WBWIRocksIterator#entry()}
*/
private WriteEntry() {
key = new DirectSlice();
value = new DirectSlice();
}
public WriteEntry(final WriteType type, final DirectSlice key,
final DirectSlice value) {
this.type = type;
this.key = key;
this.value = value;
}
/**
* Returns the type of the Write Entry
*
* @return the WriteType of the WriteEntry
*/
public WriteType getType() {
return type;
}
/**
* Returns the key of the Write Entry
*
* @return The slice containing the key
* of the WriteEntry
*/
public DirectSlice getKey() {
return key;
}
/**
* Returns the value of the Write Entry
*
* @return The slice containing the value of
* the WriteEntry or null if the WriteEntry has
* no value
*/
public DirectSlice getValue() {
if (value.isOwningHandle()) {
return value;
} else {
return null; // TODO(AR) migrate to JDK8 java.util.Optional#empty()
}
}
/**
* Generates a hash code for the Write Entry. NOTE: The hash code is based
* on the string representation of the key, so it may not work correctly
* with exotic custom comparators.
*
* @return The hash code for the Write Entry
*/
@Override
public int hashCode() {
return (key == null) ? 0 : key.hashCode();
}
@SuppressWarnings("PMD.CloseResource")
@Override
public boolean equals(final Object other) {
if(other == null) {
return false;
} else if (this == other) {
return true;
} else if(other instanceof WriteEntry) {
final WriteEntry otherWriteEntry = (WriteEntry)other;
return type.equals(otherWriteEntry.type)
&& key.equals(otherWriteEntry.key)
&& value.equals(otherWriteEntry.value);
} else {
return false;
}
}
@Override
public void close() {
value.close();
key.close();
}
}
}