Java tutorial
/* * 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; } }