ReftableConfig.java

/*
 * Copyright (C) 2017, Google Inc. and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.eclipse.jgit.internal.storage.reftable;

import static org.eclipse.jgit.internal.storage.reftable.ReftableConstants.MAX_BLOCK_SIZE;

import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.lib.Repository;

/**
 * Configuration used by a reftable writer when constructing the stream.
 */
public class ReftableConfig {
    private int refBlockSize = 4 << 10;
    private int logBlockSize;
    private int restartInterval;
    private int maxIndexLevels;
    private boolean alignBlocks = true;
    private boolean indexObjects = true;

    /**
     * Create a default configuration.
     */
    public ReftableConfig() {
    }

    /**
     * Create a configuration honoring the repository's settings.
     *
     * @param db
     *            the repository to read settings from. The repository is not
     *            retained by the new configuration, instead its settings are
     *            copied during the constructor.
     */
    public ReftableConfig(Repository db) {
        fromConfig(db.getConfig());
    }

    /**
     * Create a configuration honoring settings in a
     * {@link org.eclipse.jgit.lib.Config}.
     *
     * @param cfg
     *            the source to read settings from. The source is not retained
     *            by the new configuration, instead its settings are copied
     *            during the constructor.
     */
    public ReftableConfig(Config cfg) {
        fromConfig(cfg);
    }

    /**
     * Copy an existing configuration to a new instance.
     *
     * @param cfg
     *            the source configuration to copy from.
     */
    public ReftableConfig(ReftableConfig cfg) {
        this.refBlockSize = cfg.refBlockSize;
        this.logBlockSize = cfg.logBlockSize;
        this.restartInterval = cfg.restartInterval;
        this.maxIndexLevels = cfg.maxIndexLevels;
        this.alignBlocks = cfg.alignBlocks;
        this.indexObjects = cfg.indexObjects;
    }

    /**
     * Get desired output block size for references, in bytes.
     *
     * @return desired output block size for references, in bytes.
     */
    public int getRefBlockSize() {
        return refBlockSize;
    }

    /**
     * Set desired output block size for references, in bytes.
     *
     * @param szBytes
     *            desired output block size for references, in bytes.
     */
    public void setRefBlockSize(int szBytes) {
        if (szBytes > MAX_BLOCK_SIZE) {
            throw new IllegalArgumentException();
        }
        refBlockSize = Math.max(0, szBytes);
    }

    /**
     * Get desired output block size for log entries, in bytes.
     *
     * @return desired output block size for log entries, in bytes. If 0 the
     *         writer will default to {@code 2 * getRefBlockSize()}.
     */
    public int getLogBlockSize() {
        return logBlockSize;
    }

    /**
     * Set desired output block size for log entries, in bytes.
     *
     * @param szBytes
     *            desired output block size for log entries, in bytes. If 0 will
     *            default to {@code 2 * getRefBlockSize()}.
     */
    public void setLogBlockSize(int szBytes) {
        if (szBytes > MAX_BLOCK_SIZE) {
            throw new IllegalArgumentException();
        }
        logBlockSize = Math.max(0, szBytes);
    }

    /**
     * Get number of references between binary search markers.
     *
     * @return number of references between binary search markers.
     */
    public int getRestartInterval() {
        return restartInterval;
    }

    /**
     * <p>Setter for the field <code>restartInterval</code>.</p>
     *
     * @param interval
     *            number of references between binary search markers. If
     *            {@code interval} is 0 (default), the writer will select a
     *            default value based on the block size.
     */
    public void setRestartInterval(int interval) {
        restartInterval = Math.max(0, interval);
    }

    /**
     * Get maximum depth of the index; 0 for unlimited.
     *
     * @return maximum depth of the index; 0 for unlimited.
     */
    public int getMaxIndexLevels() {
        return maxIndexLevels;
    }

    /**
     * Set maximum number of levels to use in indexes.
     *
     * @param levels
     *            maximum number of levels to use in indexes. Lower levels of
     *            the index respect {@link #getRefBlockSize()}, and the highest
     *            level may exceed that if the number of levels is limited.
     */
    public void setMaxIndexLevels(int levels) {
        maxIndexLevels = Math.max(0, levels);
    }

    /**
     * Whether the writer should align blocks.
     *
     * @return {@code true} if the writer should align blocks.
     */
    public boolean isAlignBlocks() {
        return alignBlocks;
    }

    /**
     * Whether blocks are written aligned to multiples of
     * {@link #getRefBlockSize()}.
     *
     * @param align
     *            if {@code true} blocks are written aligned to multiples of
     *            {@link #getRefBlockSize()}. May increase file size due to NUL
     *            padding bytes added between blocks. Default is {@code true}.
     */
    public void setAlignBlocks(boolean align) {
        alignBlocks = align;
    }

    /**
     * Whether the writer should index object to ref.
     *
     * @return {@code true} if the writer should index object to ref.
     */
    public boolean isIndexObjects() {
        return indexObjects;
    }

    /**
     * Whether the reftable may include additional storage to efficiently map
     * from {@code ObjectId} to reference names.
     *
     * @param index
     *            if {@code true} the reftable may include additional storage to
     *            efficiently map from {@code ObjectId} to reference names. By
     *            default, {@code true}.
     */
    public void setIndexObjects(boolean index) {
        indexObjects = index;
    }

    /**
     * Update properties by setting fields from the configuration.
     *
     * If a property's corresponding variable is not defined in the supplied
     * configuration, then it is left unmodified.
     *
     * @param rc
     *            configuration to read properties from.
     */
    public void fromConfig(Config rc) {
        refBlockSize = rc.getInt("reftable", "blockSize", refBlockSize); //$NON-NLS-1$ //$NON-NLS-2$
        logBlockSize = rc.getInt("reftable", "logBlockSize", logBlockSize); //$NON-NLS-1$ //$NON-NLS-2$
        restartInterval = rc.getInt("reftable", "restartInterval", restartInterval); //$NON-NLS-1$ //$NON-NLS-2$
        maxIndexLevels = rc.getInt("reftable", "indexLevels", maxIndexLevels); //$NON-NLS-1$ //$NON-NLS-2$
        alignBlocks = rc.getBoolean("reftable", "alignBlocks", alignBlocks); //$NON-NLS-1$ //$NON-NLS-2$
        indexObjects = rc.getBoolean("reftable", "indexObjects", indexObjects); //$NON-NLS-1$ //$NON-NLS-2$
    }
}