org.apache.hadoop.hdfs.server.namenode.MetaRecoveryContext Maven / Gradle / Ivy
/**
* 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;
}
}