content: /*
   * 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.distributedlog.metadata;
  
  import java.net.URI;
  
  /**
   * Class to represent the layout and metadata of the zookeeper-based log metadata.
   */
  public class LogMetadata {
  
      protected static String getLogComponentPath(URI uri, String logName, String logIdentifier, String component) {
          return String.format("%s/%s/%s%s", uri.getPath(), logName, logIdentifier, component);
      }
  
      /**
       * Get the top stream path for a given log.
       *
       * @param uri namespace to store the log
       * @param logName name of the log
       * @return top stream path
       */
      public static String getLogStreamPath(URI uri, String logName) {
          return String.format("%s/%s", uri.getPath(), logName);
      }
  
      /**
       * Get the log root path for a given log.
       *
       * @param uri
       *          namespace to store the log
       * @param logName
       *          name of the log
       * @param logIdentifier
       *          identifier of the log
       * @return log root path
       */
      public static String getLogRootPath(URI uri, String logName, String logIdentifier) {
          return getLogComponentPath(uri, logName, logIdentifier, "");
      }
  
      /**
       * Get the logsegments root path for a given log.
       *
       * @param uri
       *          namespace to store the log
       * @param logName
       *          name of the log
       * @param logIdentifier
       *          identifier of the log
       * @return logsegments root path
       */
      public static String getLogSegmentsPath(URI uri, String logName, String logIdentifier) {
          return getLogComponentPath(uri, logName, logIdentifier, LOGSEGMENTS_PATH);
      }
  
      public static final int LAYOUT_VERSION = -1;
      public static final  String LOGSEGMENTS_PATH = "/ledgers";
      public static final  String VERSION_PATH = "/version";
      // writer znodes
      public static final  String MAX_TXID_PATH = "/maxtxid";
      public static final  String LOCK_PATH = "/lock";
      public static final  String ALLOCATION_PATH = "/allocation";
      // reader znodes
      public static final  String READ_LOCK_PATH = "/readLock";
  
      protected final URI uri;
      protected final String logName;
      protected final String logIdentifier;
  
      // Root path of the log
      protected final String logRootPath;
      // Components
      protected final String logSegmentsPath;
      protected final String lockPath;
      protected final String maxTxIdPath;
      protected final String allocationPath;
  
      /**
       * metadata representation of a log.
       *
       * @param uri
       *          namespace to store the log
       * @param logName
       *          name of the log
       * @param logIdentifier
       *          identifier of the log
       */
      protected LogMetadata(URI uri,
                            String logName,
                            String logIdentifier) {
          this.uri = uri;
          this.logName = logName;
          this.logIdentifier = logIdentifier;
          this.logRootPath = getLogRootPath(uri, logName, logIdentifier);
          this.logSegmentsPath = logRootPath + LOGSEGMENTS_PATH;
          this.lockPath = logRootPath + LOCK_PATH;
          this.maxTxIdPath = logRootPath + MAX_TXID_PATH;
          this.allocationPath = logRootPath + ALLOCATION_PATH;
      }
  
      public URI getUri() {
          return uri;
      }
  
      public String getLogName() {
          return logName;
      }
  
      /**
       * Get the root path of the log.
       *
       * @return root path of the log.
       */
      public String getLogRootPath() {
          return logRootPath;
      }
  
      /**
       * Get the root path for log segments.
       *
       * @return root path for log segments
       */
      public String getLogSegmentsPath() {
          return this.logSegmentsPath;
      }
  
      /**
       * Get the path for a log segment of the log.
       *
       * @param segmentName
       *          segment name
       * @return path for the log segment
       */
      public String getLogSegmentPath(String segmentName) {
          return this.logSegmentsPath + "/" + segmentName;
      }
  
      public String getLockPath() {
          return lockPath;
      }
  
      public String getMaxTxIdPath() {
          return maxTxIdPath;
      }
  
      public String getAllocationPath() {
          return allocationPath;
      }
  
      /**
       * Get the fully qualified name of the log.
       *
       * @return fully qualified name
       */
      public String getFullyQualifiedName() {
          return String.format("%s:%s", logName, logIdentifier);
      }
  
  }
  