jetbrains.exodus.log.Loggable Maven / Gradle / Ivy
/**
* Copyright 2010 - 2022 JetBrains s.r.o.
*
* 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
*
* https://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.
*/
package jetbrains.exodus.log;
import jetbrains.exodus.ByteIterable;
import org.jetbrains.annotations.NotNull;
/**
* For writing a loggable to log, instance should provide only type, data and its length.
*
* If the instance is read from log, then all its methods return actual data.
*/
public interface Loggable {
long NULL_ADDRESS = -1;
int NO_STRUCTURE_ID = 0;
/**
* Address of the loggable in log. It's available (has non-negative value) only for loggables
* been read from log. Loggables to write return indefinite value.
*
* @return non-negative address of the loggable.
*/
long getAddress();
/**
* Type of loggable.
*
* @return integer int the range [0..127] identifying the loggable.
*/
byte getType();
/**
* Length of the loggable with header and data.
*
* @return length of the loggable with header and data.
*/
int length();
/**
* Loggable data.
*
* @return loggable data.
*/
@NotNull
ByteIterable getData();
/**
* Length of the loggable data.
*
* @return length of the loggable data.
*/
int getDataLength();
/**
* Returns unique id of structure that the loggable belongs to. Basically, structure id is id of a tree
* (BTree or Patricia). Valid structure id is non-zero.
*
* @return unique structure id.
*/
int getStructureId();
}