/* * Copyright (C) 2012, 2016 higherfrequencytrading.com * Copyright (C) 2016 Roman Leventov * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation, either version 3 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 Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package net.openhft.chronicle.hash.serialization; import net.openhft.chronicle.hash.ChronicleHash; import net.openhft.chronicle.hash.ChronicleHashBuilder; import net.openhft.chronicle.hash.Data; import net.openhft.chronicle.map.ChronicleMapBuilder; import net.openhft.chronicle.wire.Marshallable; import org.jetbrains.annotations.NotNull; import java.nio.ByteBuffer; /** * Strategy of accessing flat byte contents of objects, using a reusable {@link Data} object, cached * inside the {@code DataAccess} instance. This strategy interface is suitable for types of objects, * that are already in fact sequences of bytes ({@code byte[]}, {@link ByteBuffer}, etc.) and * shouldn't be serialized, and allows to avoid extra data copying. Accessed bytes should be later * readable by some {@link BytesReader}. * * <p>Read <a href="https://github.com/OpenHFT/Chronicle-Map#dataaccess-and-sizedreader">{@link * DataAccess} and {@code SizedReader}</a> and * <a href="https://github.com/OpenHFT/Chronicle-Map#custom-serialization-checklist">custom * serialization checklist</a> sections in the Chronicle Map tutorial for more information on this * interface, how to implement and use it properly. * * @param <T> the type of objects accessed * @see ChronicleHashBuilder#keyReaderAndDataAccess(SizedReader, DataAccess) * @see ChronicleMapBuilder#valueReaderAndDataAccess(SizedReader, DataAccess) */ public interface DataAccess<T> extends StatefulCopyable<DataAccess<T>>, Marshallable { /** * Obtain {@code Data} accessor to the bytes of the given object. Typically a {@code Data} * instance should be cached in a field of this {@code DataAccess}, so always the same object * is returned. * * @param instance the object to access bytes (serialized form) of * @return an accessor to the bytes of the given object */ Data<T> getData(@NotNull T instance); /** * Clear references to the accessed object (provided in {@link #getData(Object)} method) in * caching fields of this {@code DataAccess} or the cached {@link Data} object, returned from * {@link #getData(Object)}. * * {@code DataAccess} is cached itself in thread-local variables for {@link ChronicleHash} * instances, this method prevents leaking of accessed objects (they are not eligible for * garbage collection while there are some references). */ void uninit(); }