/**
* 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 javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.hadoop.hdfs.server.namenode.startupprogress.Phase;
import org.apache.hadoop.hdfs.server.namenode.startupprogress.StartupProgress;
import org.apache.hadoop.hdfs.server.namenode.startupprogress.StartupProgressView;
import org.apache.hadoop.hdfs.server.namenode.startupprogress.Step;
import org.apache.hadoop.hdfs.server.namenode.startupprogress.StepType;
import org.apache.hadoop.io.IOUtils;
import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonGenerator;
import org.apache.hadoop.classification.InterfaceAudience;
/**
* Servlet that provides a JSON representation of the namenode's current startup
* progress.
*/
@InterfaceAudience.Private
@SuppressWarnings("serial")
public class StartupProgressServlet extends DfsServlet {
private static final String COUNT = "count";
private static final String ELAPSED_TIME = "elapsedTime";
private static final String FILE = "file";
private static final String NAME = "name";
private static final String PERCENT_COMPLETE = "percentComplete";
private static final String PHASES = "phases";
private static final String SIZE = "size";
private static final String STATUS = "status";
private static final String STEPS = "steps";
private static final String TOTAL = "total";
public static final String PATH_SPEC = "/startupProgress";
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
resp.setContentType("application/json; charset=UTF-8");
StartupProgress prog = NameNodeHttpServer.getStartupProgressFromContext(
getServletContext());
StartupProgressView view = prog.createView();
JsonGenerator json = new JsonFactory().createJsonGenerator(resp.getWriter());
try {
json.writeStartObject();
json.writeNumberField(ELAPSED_TIME, view.getElapsedTime());
json.writeNumberField(PERCENT_COMPLETE, view.getPercentComplete());
json.writeArrayFieldStart(PHASES);
for (Phase phase: view.getPhases()) {
json.writeStartObject();
json.writeStringField(NAME, phase.getName());
json.writeStringField(STATUS, view.getStatus(phase).toString());
json.writeNumberField(PERCENT_COMPLETE, view.getPercentComplete(phase));
json.writeNumberField(ELAPSED_TIME, view.getElapsedTime(phase));
writeStringFieldIfNotNull(json, FILE, view.getFile(phase));
writeNumberFieldIfDefined(json, SIZE, view.getSize(phase));
json.writeArrayFieldStart(STEPS);
for (Step step: view.getSteps(phase)) {
json.writeStartObject();
StepType type = step.getType();
String name = type != null ? type.getName() : null;
writeStringFieldIfNotNull(json, NAME, name);
json.writeNumberField(COUNT, view.getCount(phase, step));
writeStringFieldIfNotNull(json, FILE, step.getFile());
writeNumberFieldIfDefined(json, SIZE, step.getSize());
json.writeNumberField(TOTAL, view.getTotal(phase, step));
json.writeNumberField(PERCENT_COMPLETE, view.getPercentComplete(phase,
step));
json.writeNumberField(ELAPSED_TIME, view.getElapsedTime(phase, step));
json.writeEndObject();
}
json.writeEndArray();
json.writeEndObject();
}
json.writeEndArray();
json.writeEndObject();
} finally {
IOUtils.cleanup(LOG, json);
}
}
/**
* Writes a JSON number field only if the value is defined.
*
* @param json JsonGenerator to receive output
* @param key String key to put
* @param value long value to put
* @throws IOException if there is an I/O error
*/
private static void writeNumberFieldIfDefined(JsonGenerator json, String key,
long value) throws IOException {
if (value != Long.MIN_VALUE) {
json.writeNumberField(key, value);
}
}
/**
* Writes a JSON string field only if the value is non-null.
*
* @param json JsonGenerator to receive output
* @param key String key to put
* @param value String value to put
* @throws IOException if there is an I/O error
*/
private static void writeStringFieldIfNotNull(JsonGenerator json, String key,
String value) throws IOException {
if (value != null) {
json.writeStringField(key, value);
}
}
}