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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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,
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package org.apache.cassandra.tools.nodetool;
import static com.google.common.base.Preconditions.checkArgument;
import static org.apache.commons.lang3.StringUtils.join;
import io.airlift.command.Arguments;
import io.airlift.command.Command;
import io.airlift.command.Option;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import javax.management.openmbean.CompositeData;
import javax.management.openmbean.OpenDataException;
import javax.management.openmbean.TabularDataSupport;
import org.apache.cassandra.metrics.TableMetrics;
import org.apache.cassandra.metrics.TableMetrics.Sampler;
import org.apache.cassandra.tools.NodeProbe;
import org.apache.cassandra.tools.NodeTool.NodeToolCmd;
import com.google.common.collect.Lists;
import com.google.common.collect.Ordering;
@Command(name = "toppartitions", description = "Sample and print the most active partitions for a given column family")
public class TopPartitions extends NodeToolCmd
{
@Arguments(usage = " ", description = "The keyspace, column family name, and duration in milliseconds")
private List args = new ArrayList<>();
@Option(name = "-s", description = "Capacity of stream summary, closer to the actual cardinality of partitions will yield more accurate results (Default: 256)")
private int size = 256;
@Option(name = "-k", description = "Number of the top partitions to list (Default: 10)")
private int topCount = 10;
@Option(name = "-a", description = "Comma separated list of samplers to use (Default: all)")
private String samplers = join(TableMetrics.Sampler.values(), ',');
@Override
public void execute(NodeProbe probe)
{
checkArgument(args.size() == 3, "toppartitions requires keyspace, column family name, and duration");
checkArgument(topCount < size, "TopK count (-k) option must be smaller then the summary capacity (-s)");
PrintStream out = probe.output().out;
String keyspace = args.get(0);
String cfname = args.get(1);
Integer duration = Integer.valueOf(args.get(2));
// generate the list of samplers
List targets = Lists.newArrayList();
for (String s : samplers.split(","))
{
try
{
targets.add(Sampler.valueOf(s.toUpperCase()));
} catch (Exception e)
{
throw new IllegalArgumentException(s + " is not a valid sampler, choose one of: " + join(Sampler.values(), ", "));
}
}
Map results;
try
{
results = probe.getPartitionSample(keyspace, cfname, size, duration, topCount, targets);
} catch (OpenDataException e)
{
throw new RuntimeException(e);
}
boolean first = true;
for(Entry result : results.entrySet())
{
CompositeData sampling = result.getValue();
// weird casting for http://bugs.sun.com/view_bug.do?bug_id=6548436
List topk = (List) (Object) Lists.newArrayList(((TabularDataSupport) sampling.get("partitions")).values());
Collections.sort(topk, new Ordering()
{
public int compare(CompositeData left, CompositeData right)
{
return Long.compare((long) right.get("count"), (long) left.get("count"));
}
});
if(!first)
out.println();
out.println(result.getKey().toString()+ " Sampler:");
out.printf(" Cardinality: ~%d (%d capacity)%n", sampling.get("cardinality"), size);
out.printf(" Top %d partitions:%n", topCount);
if (topk.size() == 0)
{
out.println("\tNothing recorded during sampling period...");
} else
{
int offset = 0;
for (CompositeData entry : topk)
offset = Math.max(offset, entry.get("string").toString().length());
out.printf("\t%-" + offset + "s%10s%10s%n", "Partition", "Count", "+/-");
for (CompositeData entry : topk)
out.printf("\t%-" + offset + "s%10d%10d%n", entry.get("string").toString(), entry.get("count"), entry.get("error"));
}
first = false;
}
}
}