Java tutorial
/** * 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 * <p/> * http://www.apache.org/licenses/LICENSE-2.0 * <p/> * 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.ambari.server.controller.metrics.timeline; import org.apache.ambari.server.controller.internal.URLStreamProvider; import org.apache.commons.httpclient.HttpStatus; import org.apache.hadoop.metrics2.sink.timeline.Precision; import org.apache.http.NameValuePair; import org.apache.hadoop.metrics2.sink.timeline.TimelineMetric; import org.apache.hadoop.metrics2.sink.timeline.TimelineMetrics; import org.apache.http.client.utils.URIBuilder; import org.codehaus.jackson.map.AnnotationIntrospector; import org.codehaus.jackson.map.ObjectMapper; import org.codehaus.jackson.map.ObjectReader; import org.codehaus.jackson.map.annotate.JsonSerialize; import org.codehaus.jackson.xc.JaxbAnnotationIntrospector; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import javax.ws.rs.HttpMethod; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.net.HttpURLConnection; import java.net.SocketTimeoutException; import java.net.URISyntaxException; import java.util.Collections; import java.util.Date; import java.util.Iterator; import java.util.List; /** * Helper class to call AMS backend that is utilized by @AMSPropertyProvider * and @AMSReportPropertyProvider as well as @TimelineMetricCacheEntryFactory */ public class MetricsRequestHelper { private final static Logger LOG = LoggerFactory.getLogger(MetricsRequestHelper.class); private final static ObjectMapper mapper; private final static ObjectReader timelineObjectReader; private final URLStreamProvider streamProvider; static { mapper = new ObjectMapper(); AnnotationIntrospector introspector = new JaxbAnnotationIntrospector(); mapper.setAnnotationIntrospector(introspector); //noinspection deprecation mapper.getSerializationConfig().setSerializationInclusion(JsonSerialize.Inclusion.NON_NULL); timelineObjectReader = mapper.reader(TimelineMetrics.class); } public MetricsRequestHelper(URLStreamProvider streamProvider) { this.streamProvider = streamProvider; } public TimelineMetrics fetchTimelineMetrics(URIBuilder uriBuilder, Long startTime, Long endTime) throws IOException { LOG.debug("Metrics request url = " + uriBuilder.toString()); BufferedReader reader = null; TimelineMetrics timelineMetrics = null; try { HttpURLConnection connection = streamProvider.processURL(uriBuilder.toString(), HttpMethod.GET, (String) null, Collections.<String, List<String>>emptyMap()); if (!checkConnectionForPrecisionException(connection)) { //Try one more time with higher precision String higherPrecision = getHigherPrecision(uriBuilder, startTime, endTime); if (higherPrecision != null) { LOG.debug("Requesting metrics with higher precision : " + higherPrecision); uriBuilder.setParameter("precision", higherPrecision); String newSpec = uriBuilder.toString(); connection = streamProvider.processURL(newSpec, HttpMethod.GET, (String) null, Collections.<String, List<String>>emptyMap()); if (!checkConnectionForPrecisionException(connection)) { throw new IOException( "Encountered Precision exception : Higher precision request also failed."); } } else { throw new IOException("Encountered Precision exception : Unable to request higher precision"); } } InputStream inputStream = connection.getInputStream(); reader = new BufferedReader(new InputStreamReader(inputStream)); timelineMetrics = timelineObjectReader.readValue(reader); if (LOG.isTraceEnabled()) { for (TimelineMetric metric : timelineMetrics.getMetrics()) { LOG.trace("metric: " + metric.getMetricName() + ", size = " + metric.getMetricValues().size() + ", host = " + metric.getHostName() + ", app = " + metric.getAppId() + ", instance = " + metric.getInstanceId() + ", time = " + metric.getTimestamp() + ", startTime = " + new Date(metric.getStartTime())); } } } catch (IOException io) { String errorMsg = "Error getting timeline metrics : " + io.getMessage(); LOG.error(errorMsg); if (LOG.isDebugEnabled()) { LOG.debug(errorMsg, io); } if (io instanceof SocketTimeoutException) { errorMsg += " Can not connect to collector, socket error."; LOG.error(errorMsg); throw io; } } catch (URISyntaxException e) { String errorMsg = "Error getting timeline metrics : " + e.getMessage(); LOG.error(errorMsg); if (LOG.isDebugEnabled()) { LOG.debug(errorMsg, e); } } finally { if (reader != null) { try { reader.close(); } catch (IOException e) { if (LOG.isWarnEnabled()) { if (LOG.isDebugEnabled()) { LOG.warn("Unable to close http input stream : spec=" + uriBuilder.toString(), e); } else { LOG.warn("Unable to close http input stream : spec=" + uriBuilder.toString()); } } } } } return timelineMetrics; } private boolean checkConnectionForPrecisionException(HttpURLConnection connection) throws IOException, URISyntaxException { if (connection != null && connection.getResponseCode() == HttpStatus.SC_BAD_REQUEST) { InputStream errorStream = connection.getErrorStream(); BufferedReader reader = new BufferedReader(new InputStreamReader(errorStream)); String errorMessage = reader.readLine(); if (errorMessage != null && errorMessage.contains("PrecisionLimitExceededException")) { LOG.debug("Encountered Precision exception while requesting metrics : " + errorMessage); return false; } else { throw new IOException(errorMessage); } } return true; } private String getHigherPrecision(URIBuilder uriBuilder, Long startTime, Long endTime) throws URISyntaxException { Precision currentPrecision = null; List<NameValuePair> queryParams = uriBuilder.getQueryParams(); for (Iterator<NameValuePair> it = queryParams.iterator(); it.hasNext();) { NameValuePair nvp = it.next(); if (nvp.getName().equals("precision")) { currentPrecision = Precision.getPrecision(nvp.getValue()); } } if (currentPrecision == null && startTime != null && endTime != null) { currentPrecision = Precision.getPrecision(startTime, endTime); } Precision higherPrecision = Precision.getHigherPrecision(currentPrecision); return (higherPrecision != null) ? higherPrecision.toString() : null; } }