jnirrdstrategy.java

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//
// This file is part of the OpenNMS(R) Application.
//
// OpenNMS(R) is Copyright (C) 2002-2005 The OpenNMS Group, Inc.  All rights reserved.
// OpenNMS(R) is a derivative work, containing both original code, included code and modified
// code that was published under the GNU General Public License. Copyrights for modified 
// and included code are below.
//
// OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
//
// Modifications:
//
// Jul 8, 2004: Created this file.
//
// Original code base Copyright (C) 1999-2001 Oculan Corp.  All rights reserved.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License for more details.                                                            
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//       
// For more information contact: 
//      OpenNMS Licensing       <[e-mail]>
//      http://www.opennms.org/
//      http://www.opennms.com/
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package org.opennms.netmgt.rrd;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Iterator;
import java.util.List;

import org.apache.log4j.Category;
import org.apache.log4j.Priority;
import org.opennms.core.utils.ThreadCategory;
import org.opennms.web.Util;

/**
 * Provides an rrdtool based implementation of RrdStrategy. It uses the existing
 * JNI based single-threaded interface to write the rrdtool compatibile RRD
 * files.
 * 
 * The JNI interface takes command-like arguments and doesn't provide open files
 * so the the Objects used to represent open files are really partial command
 * strings
 * 
 * See the individual methods for more details
 */
class JniRrdStrategy implements RrdStrategy {

    boolean initialized = false;

    boolean graphicsInitialized = false;

    /**
     * The 'closes' the rrd file. This is where the actual work of writing the
     * RRD files takes place. The passed in rrd is actually an rrd command
     * string containing updates. This method executes this command.
     */
    public void closeFile(Object rrd) throws Exception {
        checkState("closeFile");
        String[] results = Interface.launch(rrd.toString());
        if (results[0] != null) {
            throw new Exception(results[0]);
        }
    }

    /**
     * Ensures that the initialize method has been called.
     * 
     * @param methodName
     *            the name of the method we are called from
     * @throws IllegalState
     *             exception of intialize has not been called.
     */
    private void checkState(String methodName) {
        if (!initialized)
            throw new IllegalStateException("the " + methodName + " method cannot be called before initialize");
    }

    /**
     * Constructs an rrdtool create command string that can be used to create
     * the rrd file and returns it as the rrdDefinition object.
     * 
     */
    public Object createDefinition(String creator, String directory, String dsName, int step, String dsType, int dsHeartbeat, String dsMin, String dsMax, List rraList) throws Exception {

        checkState("createDefinition");

        File f = new File(directory);
        f.mkdirs();

        String fileName = directory + File.separator + dsName + ".rrd";

        StringBuffer createCmd = new StringBuffer("create");

        createCmd.append(' ' + fileName);

        createCmd.append(" --start=" + (System.currentTimeMillis() / 1000L - 10L));

        createCmd.append(" --step=" + step);

        createCmd.append(" DS:" + dsName + ":" + dsType + ":" + dsHeartbeat + ':' + dsMin + ':' + dsMax);

        for (Iterator it = rraList.iterator(); it.hasNext();) {
            String rra = (String) it.next();
            createCmd.append(' ');
            createCmd.append(rra);
        }

        return createCmd.toString();
    }

    /**
     * Creates a the rrd file from the rrdDefinition. Since this definition is
     * really just the create command string it just executes it.
     */
    public void createFile(Object rrdDef) throws Exception {
        checkState("createFile");
        Interface.launch((String) rrdDef);
    }

    /**
     * The 'opens' the given rrd file. In actuality since the JNI interface does
     * not provide files that may be open, this constructs the beginning portion
     * of the rrd command to update the file.
     */
    public Object openFile(String fileName) throws Exception {
        checkState("openFile");
        return new StringBuffer("update " + fileName);
    }

    /**
     * This 'updates' the given rrd file by providing data. Since the JNI
     * interface does not provide files that can be open, this just appends the
     * data to the command string constructed so far. The data is not
     * immediately written to the file since this would eliminate the
     * possibility of getting performance benefit by doing more than one write
     * per open. The updates are all performed at once in the closeFile method.
     */
    public void updateFile(Object rrd, String data) throws Exception {
        checkState("updateFile");
        StringBuffer cmd = (StringBuffer) rrd;
        cmd.append(' ');
        cmd.append(data);
    }

    /**
     * Initialized the JNI Interface
     */
    public void initialize() throws Exception {
        Interface.init();
        initialized = true;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.opennms.netmgt.rrd.RrdStrategy#graphicsInitialize()
     */
    public void graphicsInitialize() throws Exception {
        // nothing to do here
    }

    /**
     * Fetches the last value directly from the rrd file using the JNI
     * Interface.
     */
    public Double fetchLastValue(String rrdFile, int interval) throws NumberFormatException, RrdException {
        checkState("fetchLastValue");
        // Log4j category
        //
        Category log = ThreadCategory.getInstance(getClass());

        // Generate rrd_fetch() command through jrrd JNI interface in order to
        // retrieve
        // LAST pdp for the datasource stored in the specified RRD file
        //
        // String array returned from launch() native method format:
        // String[0] - If success is null, otherwise contains reason for failure
        // String[1] - All data source names contained in the RRD (space
        // delimited)
        // String[2]...String[n] - RRD fetch data in the following format:
        // <timestamp> <value1> <value2> ... <valueX> where X is
        // the total number of data sources
        //
        // NOTE: Specifying start time of 'now-<interval>' and
        // end time of 'now-<interval>' where <interval> is the
        // configured thresholding interval (and should be the