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Berkeley DB Java Edition is a open source, transactional storage solution for Java applications. The Direct Persistence Layer (DPL) API is faster and easier to develop, deploy, and manage than serialized object files or ORM-based Java persistence solutions. The Collections API enhances the standard java.util.collections classes allowing them to be persisted to a local file system and accessed concurrently while protected by ACID transactions. Data is stored by serializing objects and managing class and instance data separately so as not to waste space. Berkeley DB Java Edition is the reliable drop-in solution for complex, fast, and scalable storage. Source for this release is in 'je-4.0.92-sources.jar', the Javadoc is located at 'http://download.oracle.com/berkeley-db/docs/je/4.0.92/'.

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/*-
 * Copyright (C) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
 *
 * This file was distributed by Oracle as part of a version of Oracle Berkeley
 * DB Java Edition made available at:
 *
 * http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html
 *
 * Please see the LICENSE file included in the top-level directory of the
 * appropriate version of Oracle Berkeley DB Java Edition for a copy of the
 * license and additional information.
 */

package com.sleepycat.persist.impl;

import com.sleepycat.bind.EntryBinding;
import com.sleepycat.bind.tuple.TupleBase;
import com.sleepycat.compat.DbCompat;
import com.sleepycat.je.DatabaseEntry;

/**
 * A persistence key binding for a given key class.
 *
 * @author Mark Hayes
 */
public class PersistKeyBinding implements EntryBinding {

    /* See Store.refresh for an explanation of the use of volatile fields. */
    volatile Catalog catalog;
    volatile Format keyFormat;
    final boolean rawAccess;

    /**
     * Creates a key binding for a given key class.
     */
    public PersistKeyBinding(Catalog catalogParam,
                             String clsName,
                             boolean rawAccess) {
        catalog = catalogParam;
        try {
            keyFormat = PersistEntityBinding.getOrCreateFormat
                (catalog, clsName, rawAccess);
        } catch (RefreshException e) {
            /* Must assign catalog field in constructor. */
            catalog = e.refresh();
            try {
                keyFormat = PersistEntityBinding.getOrCreateFormat
                    (catalog, clsName, rawAccess);
            } catch (RefreshException e2) {
                throw DbCompat.unexpectedException(e2);
            }
        }
        if (!keyFormat.isSimple() &&
            !keyFormat.isEnum() &&
            !(keyFormat.getClassMetadata() != null &&
              keyFormat.getClassMetadata().getCompositeKeyFields() != null)) {
            throw new IllegalArgumentException
                ("Key class is not a simple type, an enum, or a composite " +
                 "key class (composite keys must include @KeyField " +
                 "annotations): " +
                 clsName);
        }
        this.rawAccess = rawAccess;
    }

    /**
     * Creates a key binding dynamically for use by PersistComparator.  Formats
     * are created from scratch rather than using a shared catalog.
     */
    PersistKeyBinding(final Catalog catalog,
                      final Class cls,
                      final String[] compositeFieldOrder) {
        this.catalog = catalog;
        keyFormat = new CompositeKeyFormat(catalog, cls, compositeFieldOrder);
        keyFormat.initializeIfNeeded(catalog, null /*model*/);
        rawAccess = false;
    }

    /**
     * Binds bytes to an object for use by PersistComparator as well as
     * entryToObject.
     */
    Object bytesToObject(byte[] bytes, int offset, int length)
        throws RefreshException {

        return readKey(keyFormat, catalog, bytes, offset, length, rawAccess);
    }

    /**
     * Binds bytes to an object for use by PersistComparator as well as
     * entryToObject.
     */
    static Object readKey(Format keyFormat,
                          Catalog catalog,
                          byte[] bytes,
                          int offset,
                          int length,
                          boolean rawAccess)
        throws RefreshException {

        EntityInput input = new RecordInput
            (catalog, rawAccess, null, 0, bytes, offset, length);
        return input.readKeyObject(keyFormat);
    }

    public Object entryToObject(DatabaseEntry entry) {
        try {
            return entryToObjectInternal(entry);
        } catch (RefreshException e) {
            e.refresh();
            try {
                return entryToObjectInternal(entry);
            } catch (RefreshException e2) {
                throw DbCompat.unexpectedException(e2);
            }
        }
    }

    private Object entryToObjectInternal(DatabaseEntry entry)
        throws RefreshException {

        return bytesToObject
            (entry.getData(), entry.getOffset(), entry.getSize());
    }

    public void objectToEntry(Object object, DatabaseEntry entry) {
        try {
            objectToEntryInternal(object, entry);
        } catch (RefreshException e) {
            e.refresh();
            try {
                objectToEntryInternal(object, entry);
            } catch (RefreshException e2) {
                throw DbCompat.unexpectedException(e2);
            }
        }
    }

    private void objectToEntryInternal(Object object, DatabaseEntry entry)
        throws RefreshException {

        RecordOutput output = new RecordOutput(catalog, rawAccess);
        output.writeKeyObject(object, keyFormat);
        TupleBase.outputToEntry(output, entry);
    }

    /**
     * See Store.refresh.
     */
    void refresh(final PersistCatalog newCatalog) {
        catalog = newCatalog;
        keyFormat = catalog.getFormat(keyFormat.getClassName());
    }
}