Slot.java

/*
 * Slot.java
 * Copyright (C) 2011,2012 Wannes De Smet
 * 
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */
package org.xenmaster.monitoring.engine;

import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Objects;
import net.wgr.settings.Settings;
import org.apache.commons.codec.binary.Base64;
import org.apache.log4j.Logger;
import org.xenmaster.api.entity.Host;

/**
 *
 * @created Jan 31, 2012
 *
 * @author double-u
 */
public class Slot implements Comparable<Slot> {

    protected String reference;
    protected boolean connectToUpdates;
    protected boolean busy;
    protected int errorCount = 0;
    protected long lastPolled;
    private URLConnection connection;

    public Slot(Host host) {
        this.reference = host.getReference();
    }

    public String getReference() {
        return reference;
    }

    @Override
    public int compareTo(Slot o) {
        return (int) ( o.lastPolled - lastPolled );
    }

    public boolean isUpdate() {
        return connectToUpdates;
    }

    public boolean isStable() {
        return errorCount == 0;
    }

    public void errorOccurred() {
        switch (errorCount) {
            case 1:
                Logger.getLogger(getClass()).warn("Monitoring for " + reference + " is unstable.");
                break;
            case 5:
                Logger.getLogger(getClass()).error("Monitoring for " + reference + " has been disabled due to multiple errors");
                break;
        }
        errorCount += 1;
    }

    public boolean isBeingProcessed() {
        return busy;
    }

    public boolean startProcessing() {
        if (errorCount > 5) {
            // Too many errors, sorry
        } else if (errorCount != 0 && System.currentTimeMillis() - lastPolled < 60 * 10E3) {
            // Wait a minute until we try again
        } else {
            busy = true;
            errorCount = 0;
        }

        return busy;
    }

    public void processingDone() throws IOException {
        if (busy) {
            busy = false;
            connection.getInputStream().close();
            connection = null;
        }
    }

    public long getLastPollingTime() {
        return lastPolled;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == null || getClass() != obj.getClass()) {
            return false;
        }

        final Slot other = (Slot) obj;
        if (!Objects.equals(this.reference, other.reference)) {
            return false;
        }
        return true;
    }

    @Override
    public int hashCode() {
        int hash = 7;
        hash = 41 * hash + Objects.hashCode(this.reference);
        hash = 41 * hash + (int) ( this.lastPolled ^ ( this.lastPolled >>> 32 ) );
        return hash;
    }

    public URLConnection getConnection() {
        try {
            if (connection == null || connectToUpdates) {
                Host host = new Host(reference);
                URL url;
                if (connectToUpdates) {
                    url = new URL("http://" + host.getAddress().getCanonicalHostName() + "/rrd_updates?start=" + ( ( lastPolled - 5000 ) / 1000 ) + "&host=true");
                } else {
                    url = new URL("http://" + host.getAddress().getCanonicalHostName() + "/host_rrd");
                    connectToUpdates = true;
                }

                URLConnection uc = url.openConnection();
                byte[] auth = ( Settings.getInstance().getString("Xen.User") + ':' + Settings.getInstance().getString("Xen.Password") ).getBytes("UTF-8");
                uc.setRequestProperty("Authorization", "Basic " + new String(Base64.encodeBase64(auth)));
                uc.connect();

                lastPolled = System.currentTimeMillis();
                connection = uc;
            }
        }
        catch (Exception ex) {
            busy = false;
            Logger.getLogger(getClass()).error("Failed to retrieve statistics", ex);
        }

        return connection;
    }
}