curator-client/src/main/java/org/apache/curator/utils/ZKPaths.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.curator.utils;

import com.google.common.base.Splitter;
import com.google.common.collect.Lists;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.ACL;
import java.util.Collections;
import java.util.List;

public class ZKPaths
{
    /**
     * Apply the namespace to the given path
     *
     * @param namespace namespace (can be null)
     * @param path      path
     * @return adjusted path
     */
    public static String fixForNamespace(String namespace, String path)
    {
        // Child path must be valid in and of itself.
        PathUtils.validatePath(path);

        if ( namespace != null )
        {
            return makePath(namespace, path);
        }
        return path;
    }

    /**
     * Given a full path, return the node name. i.e. "/one/two/three" will return "three"
     *
     * @param path the path
     * @return the node
     */
    public static String getNodeFromPath(String path)
    {
        PathUtils.validatePath(path);
        int i = path.lastIndexOf('/');
        if ( i < 0 )
        {
            return path;
        }
        if ( (i + 1) >= path.length() )
        {
            return "";
        }
        return path.substring(i + 1);
    }

    public static class PathAndNode
    {
        private final String path;
        private final String node;

        public PathAndNode(String path, String node)
        {
            this.path = path;
            this.node = node;
        }

        public String getPath()
        {
            return path;
        }

        public String getNode()
        {
            return node;
        }
    }

    /**
     * Given a full path, return the node name and its path. i.e. "/one/two/three" will return {"/one/two", "three"}
     *
     * @param path the path
     * @return the node
     */
    public static PathAndNode getPathAndNode(String path)
    {
        PathUtils.validatePath(path);
        int i = path.lastIndexOf('/');
        if ( i < 0 )
        {
            return new PathAndNode(path, "");
        }
        if ( (i + 1) >= path.length() )
        {
            return new PathAndNode("/", "");
        }
        String node = path.substring(i + 1);
        String parentPath = (i > 0) ? path.substring(0, i) : "/";
        return new PathAndNode(parentPath, node);
    }

    private static final Splitter PATH_SPLITTER = Splitter.on('/').omitEmptyStrings();

    /**
     * Given a full path, return the the individual parts, without slashes.
     * The root path will return an empty list.
     *
     * @param path the path
     * @return an array of parts
     */
    public static List<String> split(String path)
    {
        PathUtils.validatePath(path);
        return PATH_SPLITTER.splitToList(path);
    }

    /**
     * Make sure all the nodes in the path are created. NOTE: Unlike File.mkdirs(), Zookeeper doesn't distinguish
     * between directories and files. So, every node in the path is created. The data for each node is an empty blob
     *
     * @param zookeeper the client
     * @param path      path to ensure
     * @throws InterruptedException                 thread interruption
     * @throws org.apache.zookeeper.KeeperException Zookeeper errors
     */
    public static void mkdirs(ZooKeeper zookeeper, String path) throws InterruptedException, KeeperException
    {
        mkdirs(zookeeper, path, true, null);
    }

    /**
     * Make sure all the nodes in the path are created. NOTE: Unlike File.mkdirs(), Zookeeper doesn't distinguish
     * between directories and files. So, every node in the path is created. The data for each node is an empty blob
     *
     * @param zookeeper    the client
     * @param path         path to ensure
     * @param makeLastNode if true, all nodes are created. If false, only the parent nodes are created
     * @throws InterruptedException                 thread interruption
     * @throws org.apache.zookeeper.KeeperException Zookeeper errors
     */
    public static void mkdirs(ZooKeeper zookeeper, String path, boolean makeLastNode) throws InterruptedException, KeeperException
    {
        mkdirs(zookeeper, path, makeLastNode, null);
    }

    /**
     * Make sure all the nodes in the path are created. NOTE: Unlike File.mkdirs(), Zookeeper doesn't distinguish
     * between directories and files. So, every node in the path is created. The data for each node is an empty blob
     *
     * @param zookeeper    the client
     * @param path         path to ensure
     * @param makeLastNode if true, all nodes are created. If false, only the parent nodes are created
     * @param aclProvider  if not null, the ACL provider to use when creating parent nodes
     * @throws InterruptedException                 thread interruption
     * @throws org.apache.zookeeper.KeeperException Zookeeper errors
     */
    public static void mkdirs(ZooKeeper zookeeper, String path, boolean makeLastNode, InternalACLProvider aclProvider) throws InterruptedException, KeeperException
    {
        PathUtils.validatePath(path);

        int pos = 1; // skip first slash, root is guaranteed to exist
        do
        {
            pos = path.indexOf('/', pos + 1);

            if ( pos == -1 )
            {
                if ( makeLastNode )
                {
                    pos = path.length();
                }
                else
                {
                    break;
                }
            }

            String subPath = path.substring(0, pos);
            if ( zookeeper.exists(subPath, false) == null )
            {
                try
                {
                    List<ACL> acl = null;
                    if ( aclProvider != null )
                    {
                        acl = aclProvider.getAclForPath(path);
                        if ( acl == null )
                        {
                            acl = aclProvider.getDefaultAcl();
                        }
                    }
                    if ( acl == null )
                    {
                        acl = ZooDefs.Ids.OPEN_ACL_UNSAFE;
                    }
                    zookeeper.create(subPath, new byte[0], acl, CreateMode.PERSISTENT);
                }
                catch ( KeeperException.NodeExistsException e )
                {
                    // ignore... someone else has created it since we checked
                }
            }

        }
        while ( pos < path.length() );
    }

    /**
     * Recursively deletes children of a node.
     *
     * @param zookeeper  the client
     * @param path       path of the node to delete
     * @param deleteSelf flag that indicates that the node should also get deleted
     * @throws InterruptedException
     * @throws KeeperException
     */
    public static void deleteChildren(ZooKeeper zookeeper, String path, boolean deleteSelf) throws InterruptedException, KeeperException
    {
        PathUtils.validatePath(path);

        List<String> children = zookeeper.getChildren(path, null);
        for ( String child : children )
        {
            String fullPath = makePath(path, child);
            deleteChildren(zookeeper, fullPath, true);
        }

        if ( deleteSelf )
        {
            try
            {
                zookeeper.delete(path, -1);
            }
            catch ( KeeperException.NotEmptyException e )
            {
                //someone has created a new child since we checked ... delete again.
                deleteChildren(zookeeper, path, true);
            }
            catch ( KeeperException.NoNodeException e )
            {
                // ignore... someone else has deleted the node it since we checked
            }
        }
    }

    /**
     * Return the children of the given path sorted by sequence number
     *
     * @param zookeeper the client
     * @param path      the path
     * @return sorted list of children
     * @throws InterruptedException                 thread interruption
     * @throws org.apache.zookeeper.KeeperException zookeeper errors
     */
    public static List<String> getSortedChildren(ZooKeeper zookeeper, String path) throws InterruptedException, KeeperException
    {
        List<String> children = zookeeper.getChildren(path, false);
        List<String> sortedList = Lists.newArrayList(children);
        Collections.sort(sortedList);
        return sortedList;
    }

    /**
     * Given a parent path and a child node, create a combined full path
     *
     * @param parent the parent
     * @param child  the child
     * @return full path
     */
    public static String makePath(String parent, String child)
    {
        StringBuilder path = new StringBuilder();

        // Add parent piece, with no trailing slash.
        if ( (parent != null) && (parent.length() > 0) )
        {
            if ( !parent.startsWith("/") )
            {
                path.append('/');
            }
            if ( parent.endsWith("/") )
            {
                path.append(parent.substring(0, parent.length() - 1));
            }
            else
            {
                path.append(parent);
            }
        }

        if ( (child == null) || (child.length() == 0) || (child.equals("/")) )
        {
            // Special case, empty parent and child
            if ( path.length() == 0 )
            {
                return "/";
            }
            return path.toString();
        }

        // Now add the separator between parent and child.
        path.append('/');

        // Finally, add the child.
        if ( child.startsWith("/") )
        {
            path.append(child.substring(1));
        }
        else
        {
            path.append(child);
        }

        return path.toString();
    }

    private ZKPaths()
    {
    }
}