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A fork of the Apache Cassandra Project ready to embed Elasticsearch.
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cassandra.db;
import java.util.*;
import java.util.concurrent.TimeUnit;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.db.lifecycle.SSTableIntervalTree;
import org.apache.cassandra.db.lifecycle.SSTableSet;
import org.apache.cassandra.db.lifecycle.View;
import org.apache.cassandra.dht.Range;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.io.sstable.format.SSTableReader;
import org.apache.cassandra.locator.TokenMetadata;
import org.apache.cassandra.service.MigrationListener;
import org.apache.cassandra.service.MigrationManager;
import org.apache.cassandra.service.StorageService;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.Pair;
import org.apache.cassandra.utils.concurrent.Refs;
/**
* A very simplistic/crude partition count/size estimator.
*
* Exposing per-primary-range estimated partitions count and size in CQL form,
* as a direct CQL alternative to Thrift's describe_splits_ex().
*
* Estimates (per primary range) are calculated and dumped into a system table (system.size_estimates) every 5 minutes.
*
* See CASSANDRA-7688.
*/
public class SizeEstimatesRecorder extends MigrationListener implements Runnable
{
private static final Logger logger = LoggerFactory.getLogger(SizeEstimatesRecorder.class);
public static final SizeEstimatesRecorder instance = new SizeEstimatesRecorder();
private SizeEstimatesRecorder()
{
MigrationManager.instance.register(this);
}
public void run()
{
TokenMetadata metadata = StorageService.instance.getTokenMetadata().cloneOnlyTokenMap();
if (!metadata.isMember(FBUtilities.getBroadcastAddress()))
{
logger.debug("Node is not part of the ring; not recording size estimates");
return;
}
logger.trace("Recording size estimates");
for (Keyspace keyspace : Keyspace.nonLocalStrategy())
{
Collection> localRanges = StorageService.instance.getPrimaryRangesForEndpoint(keyspace.getName(),
FBUtilities.getBroadcastAddress());
for (ColumnFamilyStore table : keyspace.getColumnFamilyStores())
{
long start = System.nanoTime();
recordSizeEstimates(table, localRanges);
long passed = System.nanoTime() - start;
logger.trace("Spent {} milliseconds on estimating {}.{} size",
TimeUnit.NANOSECONDS.toMillis(passed),
table.metadata.ksName,
table.metadata.cfName);
}
}
}
@SuppressWarnings("resource")
private void recordSizeEstimates(ColumnFamilyStore table, Collection> localRanges)
{
// for each local primary range, estimate (crudely) mean partition size and partitions count.
Map, Pair> estimates = new HashMap<>(localRanges.size());
for (Range localRange : localRanges)
{
for (Range unwrappedRange : localRange.unwrap())
{
// filter sstables that have partitions in this range.
Refs refs = null;
long partitionsCount, meanPartitionSize;
try
{
while (refs == null)
{
Iterable sstables = table.getTracker().getView().select(SSTableSet.CANONICAL);
SSTableIntervalTree tree = SSTableIntervalTree.build(sstables);
Range r = Range.makeRowRange(unwrappedRange);
Iterable canonicalSSTables = View.sstablesInBounds(r.left, r.right, tree);
refs = Refs.tryRef(canonicalSSTables);
}
// calculate the estimates.
partitionsCount = estimatePartitionsCount(refs, unwrappedRange);
meanPartitionSize = estimateMeanPartitionSize(refs);
}
finally
{
if (refs != null)
refs.release();
}
estimates.put(unwrappedRange, Pair.create(partitionsCount, meanPartitionSize));
}
}
// atomically update the estimates.
SystemKeyspace.updateSizeEstimates(table.metadata.ksName, table.metadata.cfName, estimates);
}
private long estimatePartitionsCount(Collection sstables, Range range)
{
long count = 0;
for (SSTableReader sstable : sstables)
count += sstable.estimatedKeysForRanges(Collections.singleton(range));
return count;
}
private long estimateMeanPartitionSize(Collection sstables)
{
long sum = 0, count = 0;
for (SSTableReader sstable : sstables)
{
long n = sstable.getEstimatedPartitionSize().count();
sum += sstable.getEstimatedPartitionSize().mean() * n;
count += n;
}
return count > 0 ? sum / count : 0;
}
@Override
public void onDropColumnFamily(String keyspace, String table)
{
SystemKeyspace.clearSizeEstimates(keyspace, table);
}
}