/**
* Given the time and first element of the sample, see if there are more array elements.
*
* @param stamp Time stamp of the sample
* @param dbl0 Value of the first (maybe only) array element
* @param severity Severity of the sample
* @return Array with given element and maybe more.
* @throws Exception on error, including 'cancel'
*/
private double[] readArrayElements(
final Timestamp stamp, final double dbl0, final AlarmSeverity severity) throws Exception {
// For performance reasons, only look for array data until we hit a scalar sample.
if (is_an_array == false) return new double[] {dbl0};
// See if there are more array elements
if (sel_array_samples == null) { // Lazy initialization
sel_array_samples =
reader.getConnection().prepareStatement(reader.getSQL().sample_sel_array_vals);
}
sel_array_samples.setInt(1, channel_id);
sel_array_samples.setTimestamp(2, TimestampHelper.toSQLTimestamp(stamp));
// MySQL keeps nanoseconds in designated column, not TIMESTAMP
if (!reader.isOracle()) sel_array_samples.setInt(3, stamp.getNanoSec());
// Assemble array of unknown size in ArrayList ....
final ArrayList<Double> vals = new ArrayList<Double>();
reader.addForCancellation(sel_array_samples);
try {
final ResultSet res = sel_array_samples.executeQuery();
vals.add(new Double(dbl0));
while (res.next()) vals.add(res.getDouble(1));
res.close();
} finally {
reader.removeFromCancellation(sel_array_samples);
}
// Convert to plain double array
final int N = vals.size();
final double ret[] = new double[N];
for (int i = 0; i < N; i++) ret[i] = vals.get(i).doubleValue();
// Check if it's in fact just a scalar, and a valid one
if (N == 1 && severity != AlarmSeverity.UNDEFINED) { // Found a perfect non-array sample:
// Assume that the data is scalar, skip the array check from now on
is_an_array = false;
}
return ret;
}