/**
* fetchLastValue
*
* @param latIface a {@link org.opennms.netmgt.threshd.LatencyInterface} object.
* @param latParms a {@link org.opennms.netmgt.threshd.LatencyParameters} object.
* @return a {@link java.lang.Double} object.
* @throws org.opennms.netmgt.threshd.ThresholdingException if any.
*/
public Double fetchLastValue(LatencyInterface latIface, LatencyParameters latParms)
throws ThresholdingException {
// Assume that this only happens on a simple "Threshold", not an "Expression"
// If it is an Expression, then we don't yet know what to do - this will likely just fail with
// some sort of exception.
// perhaps we should figure out how to expand it (or at least use code elsewhere to do so
// sensibly)
String datasource = getDataSourceExpression();
// Use RRD strategy to "fetch" value of the datasource from the RRD file
Double dsValue = null;
try {
if (getDatasourceType().equals("if")) {
if (log().isDebugEnabled()) {
log().debug("Fetching last value from dataSource '" + datasource + "'");
}
File rrdFile = new File(latIface.getLatencyDir(), datasource + RrdUtils.getExtension());
if (!rrdFile.exists()) {
log().info("rrd file " + rrdFile + " does not exist");
return null;
}
if (!rrdFile.canRead()) {
log().error("Unable to read existing rrd file " + rrdFile);
return null;
}
if (latParms.getRange() == 0) {
dsValue =
RrdUtils.fetchLastValue(
rrdFile.getAbsolutePath(), datasource, latParms.getInterval());
} else {
dsValue =
RrdUtils.fetchLastValueInRange(
rrdFile.getAbsolutePath(),
datasource,
latParms.getInterval(),
latParms.getRange());
}
} else {
throw new ThresholdingException(
"expr types not yet implemented", LatencyThresholder.THRESHOLDING_FAILED);
}
if (log().isDebugEnabled()) {
log().debug("Last value from dataSource '" + datasource + "' was " + dsValue);
}
} catch (NumberFormatException nfe) {
log()
.warn(
"Unable to convert retrieved value for datasource '"
+ datasource
+ "' to a double, skipping evaluation.");
} catch (RrdException e) {
log()
.error(
"An error occurred retriving the last value for datasource '"
+ datasource
+ "': "
+ e,
e);
}
return dsValue;
}
