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   * Licensed to the Apache Software Foundation (ASF) under one
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   * 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.
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  package org.apache.cassandra.tools.nodetool;
  
  import java.io.PrintStream;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  import com.google.common.collect.HashMultimap;
  import com.google.common.collect.Multimap;
  import org.apache.commons.lang3.ArrayUtils;
  
  import org.apache.cassandra.db.ColumnFamilyStoreMBean;
  import org.apache.cassandra.metrics.CassandraMetricsRegistry;
  import org.apache.cassandra.tools.NodeProbe;
  import org.apache.cassandra.tools.nodetool.layout.CassandraUsage;
  import org.apache.cassandra.utils.EstimatedHistogram;
  import org.apache.cassandra.utils.Pair;
  import picocli.CommandLine.Command;
  import picocli.CommandLine.Parameters;
  
  import static com.google.common.base.Preconditions.checkArgument;
  import static java.lang.String.format;
  import static org.apache.cassandra.tools.nodetool.CommandUtils.concatArgs;
  
  @Command(name = "tablehistograms", description = "Print statistic histograms for a given table")
  public class TableHistograms extends AbstractCommand
  {
      @CassandraUsage(usage = "[<keyspace> <table> | <keyspace.table>]", description = "The keyspace and table name")
      private List<String> args = new ArrayList<>();
  
      @Parameters(index = "0", description = "The keyspace name or keyspace and table name", arity = "0..1")
      private String keyspaceTable = null;
  
      @Parameters(index = "1", description = "The table name", arity = "0..1")
      private String table = null;
  
      @Override
      public void execute(NodeProbe probe)
      {
          args = concatArgs(keyspaceTable, table);
          PrintStream out = probe.output().out;
          Multimap<String, String> tablesList = HashMultimap.create();
  
          // a <keyspace, set<table>> mapping for verification or as reference if none provided
          Multimap<String, String> allTables = HashMultimap.create();
          Iterator<Map.Entry<String, ColumnFamilyStoreMBean>> tableMBeans = probe.getColumnFamilyStoreMBeanProxies();
          while (tableMBeans.hasNext())
          {
              Map.Entry<String, ColumnFamilyStoreMBean> entry = tableMBeans.next();
              allTables.put(entry.getKey(), entry.getValue().getTableName());
          }
  
          if (args.size() == 2 && args.stream().noneMatch(arg -> arg.contains(".")))
          {
              tablesList.put(args.get(0), args.get(1));
          }
          else if (args.size() == 1)
          {
              Pair<String, String> ksTbPair = parseTheKsTbPair(args.get(0));
              tablesList.put(ksTbPair.left, ksTbPair.right);
          }
          else if (args.size() == 0)
          {
              // use all tables
              tablesList = allTables;
          }
          else
          {
              throw new IllegalArgumentException("tablehistograms requires <keyspace> <table> or <keyspace.table> format argument.");
          }
  
          // verify that all tables to list exist
          for (String keyspace : tablesList.keys())
          {
              for (String table : tablesList.get(keyspace))
              {
                  if (!allTables.containsEntry(keyspace, table))
                      throw new IllegalArgumentException("Unknown table " + keyspace + '.' + table);
              }
          }
  
          for (String keyspace : tablesList.keys().elementSet())
          {
              for (String table : tablesList.get(keyspace))
              {
                  // calculate percentile of row size and column count
                  long[] estimatedPartitionSize = (long[]) probe.getColumnFamilyMetric(keyspace, table, "EstimatedPartitionSizeHistogram");
                  long[] estimatedColumnCount = (long[]) probe.getColumnFamilyMetric(keyspace, table, "EstimatedColumnCountHistogram");
  
                  // build arrays to store percentile values
                  double[] estimatedRowSizePercentiles = new double[7];
                  double[] estimatedColumnCountPercentiles = new double[7];
                  double[] offsetPercentiles = new double[]{0.5, 0.75, 0.95, 0.98, 0.99};
  
                  if (ArrayUtils.isEmpty(estimatedPartitionSize) || ArrayUtils.isEmpty(estimatedColumnCount))
                  {
                      out.println("No SSTables exists, unable to calculate 'Partition Size' and 'Cell Count' percentiles");
  
                      for (int i = 0; i < 7; i++)
                      {
                          estimatedRowSizePercentiles[i] = Double.NaN;
                          estimatedColumnCountPercentiles[i] = Double.NaN;
                      }
                  }
                  else
                  {
                      EstimatedHistogram partitionSizeHist = new EstimatedHistogram(estimatedPartitionSize);
                      EstimatedHistogram columnCountHist = new EstimatedHistogram(estimatedColumnCount);
  
                      if (partitionSizeHist.isOverflowed())
                      {
                          out.println(String.format("Row sizes are larger than %s, unable to calculate percentiles", partitionSizeHist.getLargestBucketOffset()));
                          for (int i = 0; i < offsetPercentiles.length; i++)
                              estimatedRowSizePercentiles[i] = Double.NaN;
                      }
                      else
                      {
                          for (int i = 0; i < offsetPercentiles.length; i++)
                              estimatedRowSizePercentiles[i] = partitionSizeHist.percentile(offsetPercentiles[i]);
                      }
  
                      if (columnCountHist.isOverflowed())
                      {
                          out.println(String.format("Column counts are larger than %s, unable to calculate percentiles", columnCountHist.getLargestBucketOffset()));
                          for (int i = 0; i < estimatedColumnCountPercentiles.length; i++)
                              estimatedColumnCountPercentiles[i] = Double.NaN;
                      }
                      else
                      {
                          for (int i = 0; i < offsetPercentiles.length; i++)
                              estimatedColumnCountPercentiles[i] = columnCountHist.percentile(offsetPercentiles[i]);
                      }
  
                      // min value
                      estimatedRowSizePercentiles[5] = partitionSizeHist.min();
                      estimatedColumnCountPercentiles[5] = columnCountHist.min();
                      // max value
                      estimatedRowSizePercentiles[6] = partitionSizeHist.max();
                      estimatedColumnCountPercentiles[6] = columnCountHist.max();
                  }
  
                  String[] percentiles = new String[]{"50%", "75%", "95%", "98%", "99%", "Min", "Max"};
                  Double[] readLatency = probe.metricPercentilesAsArray((CassandraMetricsRegistry.JmxTimerMBean) probe.getColumnFamilyMetric(keyspace, table, "ReadLatency"));
                  Double[] writeLatency = probe.metricPercentilesAsArray((CassandraMetricsRegistry.JmxTimerMBean) probe.getColumnFamilyMetric(keyspace, table, "WriteLatency"));
                  Double[] sstablesPerRead = probe.metricPercentilesAsArray((CassandraMetricsRegistry.JmxHistogramMBean) probe.getColumnFamilyMetric(keyspace, table, "SSTablesPerReadHistogram"));
  
                  out.println(format("%s/%s histograms", keyspace, table));
                  out.println(format("%-10s%18s%18s%18s%18s%18s",
                          "Percentile", "Read Latency", "Write Latency", "SSTables", "Partition Size", "Cell Count"));
                  out.println(format("%-10s%18s%18s%18s%18s%18s",
                          "", "(micros)", "(micros)", "", "(bytes)", ""));
  
                  for (int i = 0; i < percentiles.length; i++)
                  {
                      out.println(format("%-10s%18.2f%18.2f%18.2f%18.0f%18.0f",
                              percentiles[i],
                              readLatency[i],
                              writeLatency[i],
                              sstablesPerRead[i],
                              estimatedRowSizePercentiles[i],
                              estimatedColumnCountPercentiles[i]));
                  }
                  out.println();
              }
          }
      }
  
      private Pair<String, String> parseTheKsTbPair(String ksAndTb)
      {
          String[] input = args.get(0).split("\\.");
          checkArgument(input.length == 2, "tablehistograms requires keyspace and table name arguments");
          return Pair.create(input[0], input[1]);
      }
  }
  