hadoop MetaRecoveryContext 源码

haddop MetaRecoveryContext 代码

文件路径：/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/MetaRecoveryContext.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.hadoop.hdfs.server.namenode;

import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** Context data for an ongoing NameNode metadata recovery process. */
@InterfaceAudience.Private
@InterfaceStability.Evolving
public final class MetaRecoveryContext  {
  public static final Logger LOG =
      LoggerFactory.getLogger(MetaRecoveryContext.class.getName());
  public final static int FORCE_NONE = 0;
  public final static int FORCE_FIRST_CHOICE = 1;
  public final static int FORCE_ALL = 2;
  private int force;
  
  /** Exception thrown when the user has requested processing to stop. */
  static public class RequestStopException extends IOException {
    private static final long serialVersionUID = 1L;
    public RequestStopException(String msg) {
      super(msg);
    }
  }
  
  public MetaRecoveryContext(int force) {
    this.force = force;
  }

  /**
   * Display a prompt to the user and get his or her choice.
   *  
   * @param prompt      The prompt to display
   * @param firstChoice First choice (will be taken if autoChooseDefault is
   *                    true)
   * @param choices     Other choies
   *
   * @return            The choice that was taken
   * @throws IOException
   */
  public String ask(String prompt, String firstChoice, String... choices) 
      throws IOException {
    while (true) {
      System.err.print(prompt);
      if (force > FORCE_NONE) {
        System.out.println("automatically choosing " + firstChoice);
        return firstChoice;
      }
      StringBuilder responseBuilder = new StringBuilder();
      while (true) {
        int c = System.in.read();
        if (c == -1 || c == '\r' || c == '\n') {
          break;
        }
        responseBuilder.append((char)c);
      }
      String response = responseBuilder.toString();
      if (response.equalsIgnoreCase(firstChoice))
        return firstChoice;
      for (String c : choices) {
        if (response.equalsIgnoreCase(c)) {
          return c;
        }
      }
      System.err.print("I'm sorry, I cannot understand your response.\n");
    }
  }

  public static void editLogLoaderPrompt(String prompt,
        MetaRecoveryContext recovery, String contStr)
        throws IOException, RequestStopException
  {
    if (recovery == null) {
      throw new IOException(prompt);
    }
    LOG.error(prompt);
    String answer = recovery.ask("\nEnter 'c' to continue, " + contStr + "\n" +
      "Enter 's' to stop reading the edit log here, abandoning any later " +
        "edits\n" +
      "Enter 'q' to quit without saving\n" +
      "Enter 'a' to always select the first choice in the future " +
      "without prompting. " + 
      "(c/s/q/a)\n", "c", "s", "q", "a");
    if (answer.equals("c")) {
      LOG.info("Continuing");
      return;
    } else if (answer.equals("s")) {
      throw new RequestStopException("user requested stop");
    } else if (answer.equals("q")) {
      recovery.quit();
    } else {
      recovery.setForce(FORCE_FIRST_CHOICE);
      return;
    }
  }

  /** Log a message and quit */
  public void quit() {
    LOG.error("Exiting on user request.");
    System.exit(0);
  }

  public int getForce() {
    return this.force;
  }

  public void setForce(int force) {
    this.force = force;
  }
}

相关信息

hadoop 源码目录

相关文章

hadoop AclEntryStatusFormat 源码

hadoop AclFeature 源码

hadoop AclStorage 源码

hadoop AclTransformation 源码

hadoop AuditLogger 源码

hadoop BackupImage 源码

hadoop BackupJournalManager 源码

hadoop BackupNode 源码

hadoop BackupState 源码

hadoop CacheManager 源码