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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.je.log;

import java.nio.ByteBuffer;

import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.dbi.EnvironmentImpl;

/**
 * CheckpointFileReader searches for root and checkpoint entries.
 */
public class CheckpointFileReader extends FileReader {
    /* Status about the last entry. */
    private boolean isDbTree;
    private boolean isCheckpointEnd;
    private boolean isCheckpointStart;

    /**
     * Create this reader to start at a given LSN.
     */
    public CheckpointFileReader(EnvironmentImpl env,
                                int readBufferSize,
                                boolean forward,
                                long startLsn,
                                long finishLsn,
                                long endOfFileLsn)
        throws DatabaseException {

        super(env, readBufferSize, forward, startLsn,
              null, endOfFileLsn, finishLsn);
    }

    /**
     * @return true if this is a targeted entry.
     */
    @Override
    protected boolean isTargetEntry() {
        byte logEntryTypeNumber = currentEntryHeader.getType();
        boolean isTarget = false;
        isDbTree = false;
        isCheckpointEnd = false;
        isCheckpointStart = false;
        if (LogEntryType.LOG_CKPT_END.equalsType(logEntryTypeNumber)) {
            isTarget = true;
            isCheckpointEnd = true;
        } else if (LogEntryType.LOG_CKPT_START.equalsType
            (logEntryTypeNumber)) {
            isTarget = true;
            isCheckpointStart = true;
        } else if (LogEntryType.LOG_DBTREE.equalsType
                (logEntryTypeNumber)) {
            isTarget = true;
            isDbTree = true;
        }
        return isTarget;
    }

    /**
     * This reader instantiates the first object of a given log entry
     */
    @Override
    protected boolean processEntry(ByteBuffer entryBuffer) {
        /* Don't need to read the entry, since we just use the LSN. */
        return true;
    }

    /**
     * @return true if last entry was a DbTree entry.
     */
    public boolean isDbTree() {
        return isDbTree;
    }

    /**
     * @return true if last entry was a checkpoint end entry.
     */
    public boolean isCheckpointEnd() {
        return isCheckpointEnd;
    }

    /**
     * @return true if last entry was a checkpoint start entry.
     */
    public boolean isCheckpointStart() {
        return isCheckpointStart;
    }
}