Java tutorial
/******************************************************************************* * This file is part of OpenNMS(R). * * Copyright (C) 2010-2015 The OpenNMS Group, Inc. * OpenNMS(R) is Copyright (C) 1999-2015 The OpenNMS Group, Inc. * * OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc. * * OpenNMS(R) is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as published * by the Free Software Foundation, either version 3 of the License, * or (at your option) any later version. * * OpenNMS(R) is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with OpenNMS(R). If not, see: * http://www.gnu.org/licenses/ * * For more information contact: * OpenNMS(R) Licensing <license@opennms.org> * http://www.opennms.org/ * http://www.opennms.com/ *******************************************************************************/ package org.opennms.web.rest.measurements.fetch; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.StringReader; import java.util.Map; import javax.xml.bind.JAXBContext; import javax.xml.bind.JAXBException; import javax.xml.bind.Unmarshaller; import javax.xml.transform.sax.SAXSource; import org.apache.commons.exec.CommandLine; import org.apache.commons.exec.DefaultExecutor; import org.apache.commons.exec.ExecuteWatchdog; import org.apache.commons.exec.PumpStreamHandler; import org.apache.commons.lang.StringUtils; import org.jrobin.core.RrdException; import org.opennms.netmgt.dao.api.ResourceDao; import org.opennms.netmgt.rrd.model.RrdXport; import org.opennms.netmgt.rrd.model.XRow; import org.opennms.web.rest.measurements.model.Source; import org.xml.sax.InputSource; import org.xml.sax.SAXException; import org.xml.sax.XMLReader; import org.xml.sax.helpers.XMLReaderFactory; import com.google.common.collect.Maps; /** * Used to fetch measurements from RRD files by invoking * rrdtool via exec. * * As of Feb 24th the jrrd library does not support 'xport' commands. * See http://issues.opennms.org/browse/JRRD-3. * * @author Jesse White <jesse@opennms.org> * @author Dustin Frisch <fooker@lab.sh> */ public class RrdtoolXportFetchStrategy extends AbstractRrdBasedFetchStrategy { /** * Maximum runtime of 'rrdtool xport' in milliseconds before failing and * throwing an exception. */ public static final long XPORT_TIMEOUT_MS = 120000; public RrdtoolXportFetchStrategy(final ResourceDao resourceDao) { super(resourceDao); } /** * {@inheritDoc} */ @Override protected FetchResults fetchMeasurements(long start, long end, long step, int maxrows, Map<Source, String> rrdsBySource, Map<String, Object> constants) throws RrdException { String rrdBinary = System.getProperty("rrd.binary"); if (rrdBinary == null) { throw new RrdException("No RRD binary is set."); } final long startInSeconds = (long) Math.floor(start / 1000); final long endInSeconds = (long) Math.floor(end / 1000); long stepInSeconds = (long) Math.floor(step / 1000); // The step must be strictly positive if (stepInSeconds <= 0) { stepInSeconds = 1; } final CommandLine cmdLine = new CommandLine(rrdBinary); cmdLine.addArgument("xport"); cmdLine.addArgument("--step"); cmdLine.addArgument("" + stepInSeconds); cmdLine.addArgument("--start"); cmdLine.addArgument("" + startInSeconds); cmdLine.addArgument("--end"); cmdLine.addArgument("" + endInSeconds); if (maxrows > 0) { cmdLine.addArgument("--maxrows"); cmdLine.addArgument("" + maxrows); } // Use labels without spaces when executing the xport command // These are mapped back to the requested labels in the response final Map<String, String> labelMap = Maps.newHashMap(); int k = 0; for (final Map.Entry<Source, String> entry : rrdsBySource.entrySet()) { final Source source = entry.getKey(); final String rrdFile = entry.getValue(); final String tempLabel = Integer.toString(++k); labelMap.put(tempLabel, source.getLabel()); cmdLine.addArgument(String.format("DEF:%s=%s:%s:%s", tempLabel, rrdFile, source.getAttribute(), source.getAggregation())); cmdLine.addArgument(String.format("XPORT:%s:%s", tempLabel, tempLabel)); } // Use commons-exec to execute rrdtool final DefaultExecutor executor = new DefaultExecutor(); // Capture stdout/stderr final ByteArrayOutputStream stdout = new ByteArrayOutputStream(); final ByteArrayOutputStream stderr = new ByteArrayOutputStream(); executor.setStreamHandler(new PumpStreamHandler(stdout, stderr, null)); // Fail if we get a non-zero exit code executor.setExitValue(0); // Fail if the process takes too long final ExecuteWatchdog watchdog = new ExecuteWatchdog(XPORT_TIMEOUT_MS); executor.setWatchdog(watchdog); // Export RrdXport rrdXport; try { executor.execute(cmdLine); final XMLReader xmlReader = XMLReaderFactory.createXMLReader(); xmlReader.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false); final SAXSource source = new SAXSource(xmlReader, new InputSource(new StringReader(stdout.toString()))); final JAXBContext jc = JAXBContext.newInstance(RrdXport.class); final Unmarshaller u = jc.createUnmarshaller(); rrdXport = (RrdXport) u.unmarshal(source); } catch (IOException e) { throw new RrdException("An error occured while executing '" + StringUtils.join(cmdLine.toStrings(), " ") + "' with stderr: " + stderr.toString(), e); } catch (SAXException | JAXBException e) { throw new RrdException("The output generated by 'rrdtool xport' could not be parsed.", e); } final int numRows = rrdXport.getRows().size(); final int numColumns = rrdXport.getMeta().getLegends().size(); final long timestamps[] = new long[numRows]; final double values[][] = new double[numColumns][numRows]; // Convert rows to columns int i = 0; for (final XRow row : rrdXport.getRows()) { timestamps[i] = row.getTimestamp() * 1000; for (int j = 0; j < numColumns; j++) { if (row.getValues() == null) { // NMS-7710: Avoid NPEs, in certain cases the list of values may be null throw new RrdException( "The output generated by 'rrdtool xport' was not recognized. Try upgrading your rrdtool binaries."); } values[j][i] = row.getValues().get(j); } i++; } // Map the columns by label // The legend entries are in the same order as the column values final Map<String, double[]> columns = Maps.newHashMapWithExpectedSize(numColumns); i = 0; for (String label : rrdXport.getMeta().getLegends()) { columns.put(labelMap.get(label), values[i++]); } return new FetchResults(timestamps, columns, rrdXport.getMeta().getStep() * 1000, constants); } }