/**
* Purge expired entries. Expiration entries are stored in a single key (expirationKey) within a
* specific ColumnFamily (set by configuration). The entries are grouped by expiration timestamp
* in SuperColumns within which each entry's key is mapped to a column
*/
@Override
protected void purgeInternal() throws CacheLoaderException {
if (trace) log.trace("purgeInternal");
Cassandra.Client cassandraClient = null;
try {
cassandraClient = dataSource.getConnection();
// We need to get all supercolumns from the beginning of time until
// now, in SLICE_SIZE chunks
SlicePredicate predicate = new SlicePredicate();
predicate.setSlice_range(
new SliceRange(
ByteBufferUtil.EMPTY_BYTE_BUFFER,
ByteBufferUtil.bytes(System.currentTimeMillis()),
false,
SLICE_SIZE));
Map<ByteBuffer, Map<String, List<Mutation>>> mutationMap =
new HashMap<ByteBuffer, Map<String, List<Mutation>>>();
for (boolean complete = false; !complete; ) {
// Get all columns
List<ColumnOrSuperColumn> slice =
cassandraClient.get_slice(
expirationKey, expirationColumnParent, predicate, readConsistencyLevel);
complete = slice.size() < SLICE_SIZE;
// Delete all keys returned by the slice
for (ColumnOrSuperColumn crumb : slice) {
SuperColumn scol = crumb.getSuper_column();
for (Iterator<Column> i = scol.getColumnsIterator(); i.hasNext(); ) {
Column col = i.next();
// Remove the entry row
remove0(ByteBuffer.wrap(col.getName()), mutationMap);
}
// Remove the expiration supercolumn
addMutation(
mutationMap,
expirationKey,
config.expirationColumnFamily,
ByteBuffer.wrap(scol.getName()),
null,
null);
}
}
cassandraClient.batch_mutate(mutationMap, writeConsistencyLevel);
} catch (Exception e) {
throw new CacheLoaderException(e);
} finally {
dataSource.releaseConnection(cassandraClient);
}
}
