trunk/oak-core-spi/src/main/java/org/apache/jackrabbit/oak/spi/mount/Mount.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.jackrabbit.oak.spi.mount;

import org.osgi.annotation.versioning.ProviderType;

/**
 * Refers to a set of paths from a {@code ContentRepository}x that are possibly 
 * stored in a separate physical persistent store.
 * 
 * <p>In a default setup all paths belong to a default Mount.</p>
 */
@ProviderType
public interface Mount {
    /**
     * Name of the mount. If this <code>@Mount</code>
     * is the default mount, an empty string is returned
     */
    String getName();

    /**
     * Checks whether the mount is marked as read only.
     *
     * @return true if the mount is read only.
     */
    boolean isReadOnly();

    /**
     * Checks whether current mount is the default mount.
     * 
     * <p>The Default mount includes the root path and all other
     * paths which are not part of any other mount.</p>
     *
     * @return true if this mount represents the
     * default mount
     */
    boolean isDefault();

    /**
     * Returns fragment name which can be used to construct node name
     * used for storing meta content belonging to path under this
     * <code>Mount</code>. 
     * Such a node name would be used by NodeStore
     * to determine the storage for nodes under those paths.
     *
     * <p>Fragment name  is formatted as 'oak:mount-&lt;mount name&gt;'
     *
     * <p>For e.g. for mount name 'private' the fragment name would be
     * <code>oak:mount-private</code>. This can be then used to construct
     * node name like <code>oak:mount-private-index</code> and then any derived
     * content for path under this mount would be stored as child node under
     * <i>oak:mount-private-index</i> like <code>/fooIndex/oak:mount-private-index/foo</code>.
     * Such paths would then be stored in a separate store which would only be
     * storing paths belonging to that mount
     *
     * <p>If this <code>Mount</code> is the default mount, an empty string is returned
     *
     * @return node name prefix which can be used
     */
    String getPathFragmentName();

    /**
     * Checks if this mount supports mounting nodes containing the fragment
     * (see {@link #getPathFragmentName()}) under the given path.
     *
     * @param path ancestor path
     * @return true if the path fragment mounts are supported in the given subtree
     */
    boolean isSupportFragment(String path);

    /**
     * Checks if any path supporting the fragments falls under the specified path.
     *
     * @param path ancestor path
     * @return true if the path fragment mounts are supported under some descendants
     * of the specified path
     */
    boolean isSupportFragmentUnder(String path);

    /**
     * Checks if given path belongs to this <code>Mount</code>
     *
     * <p>A path belongs to a Mount in two scenarios:</p>
     * <ol>
     *   <li>The path is below a fragment-supported path and the path contains a fragment name.</li>
     *   <li>The path of this mount is the most specific ancestor for the specified path.</li>
     * </ol>
     * 
     * <p>The fragment check has a higher priority, and the presence of a fragment name in the path
     * always decides the mount this path belongs to.</p>
     *
     * @param path path to check
     * @return true if path belong to this mount
     * 
     * @see #getPathFragmentName()
     */
    boolean isMounted(String path);

    /**
     * Checks if this mount falls under given path. 
     * 
     * <p>For e.g. if a mount consist of '/etc/config'. Then if path is
     * <ul>
     *     <li>/etc - Then it returns true</li>
     *     <li>/etc/config - Then it returns false</li>
     *     <li>/lib - Then it returns false</li>
     * </ul>
     *
     * @param path path to check
     * @return true if this Mount is rooted under given path
     */
    boolean isUnder(String path);

    /**
     * Checks if this mount directly falls under given path. 
     * 
     * <p>For e.g. if a mount consist of '/etc/my/config'. Then if path is
     * <ul>
     *     <li>/etc - Then it returns false</li>
     *     <li>/etc/my - Then it returns true</li>
     *     <li>/etc/my/config- Then it returns false</li>
     *     <li>/lib - Then it returns false</li>
     * </ul>
     *
     * @param path path to check
     * @return true if this Mount is rooted directly under given path
     */
    boolean isDirectlyUnder(String path);
}