private void doPut(Keyspace keyspace, CacheKey key, Integer dataOffset, Point d)
throws ConnectionException {
keyspace
.prepareQuery(columnFamily)
.withCql(CQL_STMT)
.asPreparedStatement()
.withByteBufferValue(key, cacheKeySerializer)
.withIntegerValue(dataOffset)
.withDoubleValue(d.getValue())
.execute();
}
@Override
public CacheBackendPutResult call() throws Exception {
final Keyspace keyspace = ctx.getClient();
final AggregationInstance aggregation = key.getAggregation();
final long size = aggregation.cadence();
final long columnWidth = size * Cassandra2AggregationCacheBackend.WIDTH;
for (final Point d : datapoints) {
final double value = d.getValue();
if (!Double.isFinite(value)) {
continue;
}
final int index = (int) ((d.getTimestamp() % columnWidth) / size);
final long base = d.getTimestamp() - d.getTimestamp() % columnWidth;
final CacheKey key =
new CacheKey(
CacheKey.VERSION, this.key.getFilter(), this.key.getGroup(), aggregation, base);
doPut(keyspace, key, index, d);
}
return new CacheBackendPutResult();
}
@Override
public void updatePoint(Map<String, String> tags, Point d) {
final double value = d.getValue();
while (true) {
final Cell c = cell.get();
final long count = c.count + 1;
final double delta = value - c.mean;
final double mean = c.mean + delta / count;
final double s = c.s + delta * (value - mean);
final Cell n = new Cell(mean, s, count);
if (cell.compareAndSet(c, n)) {
break;
}
}
}