RepositoryCacheConfig.java

/*
 * Copyright (C) 2016 Ericsson 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.lib;

import java.util.concurrent.TimeUnit;

/**
 * Configuration parameters for JVM-wide repository cache used by JGit.
 *
 * @since 4.4
 */
public class RepositoryCacheConfig {

    /**
     * Set cleanupDelayMillis to this value in order to switch off time-based
     * cache eviction. Expired cache entries will only be evicted when
     * RepositoryCache.clearExpired or RepositoryCache.clear are called.
     */
    public static final long NO_CLEANUP = 0;

    /**
     * Set cleanupDelayMillis to this value in order to auto-set it to minimum
     * of 1/10 of expireAfterMillis and 10 minutes
     */
    public static final long AUTO_CLEANUP_DELAY = -1;

    private long expireAfterMillis;

    private long cleanupDelayMillis;

    /**
     * Create a default configuration.
     */
    public RepositoryCacheConfig() {
        expireAfterMillis = TimeUnit.HOURS.toMillis(1);
        cleanupDelayMillis = AUTO_CLEANUP_DELAY;
    }

    /**
     * Get the time an unused repository should be expired and be evicted from
     * the RepositoryCache in milliseconds.
     *
     * @return the time an unused repository should be expired and be evicted
     *         from the RepositoryCache in milliseconds. <b>Default is 1
     *         hour.</b>
     */
    public long getExpireAfter() {
        return expireAfterMillis;
    }

    /**
     * Set the time an unused repository should be expired and be evicted from
     * the RepositoryCache in milliseconds.
     *
     * @param expireAfterMillis
     *            the time an unused repository should be expired and be evicted
     *            from the RepositoryCache in milliseconds.
     */
    public void setExpireAfter(long expireAfterMillis) {
        this.expireAfterMillis = expireAfterMillis;
    }

    /**
     * Get the delay between the periodic cleanup of expired repository in
     * milliseconds.
     *
     * @return the delay between the periodic cleanup of expired repository in
     *         milliseconds. <b>Default is minimum of 1/10 of expireAfterMillis
     *         and 10 minutes</b>
     */
    public long getCleanupDelay() {
        if (cleanupDelayMillis < 0) {
            return Math.min(expireAfterMillis / 10,
                    TimeUnit.MINUTES.toMillis(10));
        }
        return cleanupDelayMillis;
    }

    /**
     * Set the delay between the periodic cleanup of expired repository in
     * milliseconds.
     *
     * @param cleanupDelayMillis
     *            the delay between the periodic cleanup of expired repository
     *            in milliseconds. Set it to {@link #AUTO_CLEANUP_DELAY} to
     *            automatically derive cleanup delay from expireAfterMillis.
     *            <p>
     *            Set it to {@link #NO_CLEANUP} in order to switch off cache
     *            expiration.
     *            <p>
     *            If cache expiration is switched off the JVM still can evict
     *            cache entries when the JVM is running low on available heap
     *            memory.
     */
    public void setCleanupDelay(long cleanupDelayMillis) {
        this.cleanupDelayMillis = cleanupDelayMillis;
    }

    /**
     * Update properties by setting fields from the configuration.
     * <p>
     * If a property is not defined in the configuration, then it is left
     * unmodified.
     *
     * @param config
     *            configuration to read properties from.
     * @return {@code this}.
     */
    public RepositoryCacheConfig fromConfig(Config config) {
        setExpireAfter(
                config.getTimeUnit("core", null, "repositoryCacheExpireAfter", //$NON-NLS-1$//$NON-NLS-2$
                        getExpireAfter(), TimeUnit.MILLISECONDS));
        setCleanupDelay(
                config.getTimeUnit("core", null, "repositoryCacheCleanupDelay", //$NON-NLS-1$ //$NON-NLS-2$
                        AUTO_CLEANUP_DELAY, TimeUnit.MILLISECONDS));
        return this;
    }

    /**
     * Install this configuration as the live settings.
     * <p>
     * The new configuration is applied immediately.
     */
    public void install() {
        RepositoryCache.reconfigure(this);
    }
}