content: /*
   * 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.tools;
  
  import java.io.PrintStream;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Set;
  
  import com.google.common.collect.ArrayListMultimap;
  import com.google.common.collect.Multimap;
  
  import org.apache.cassandra.db.ColumnFamilyStore;
  import org.apache.cassandra.db.Directories;
  import org.apache.cassandra.db.Keyspace;
  import org.apache.cassandra.io.sstable.Component;
  import org.apache.cassandra.io.sstable.Descriptor;
  import org.apache.cassandra.io.sstable.format.SSTableFormat.Components;
  import org.apache.cassandra.io.sstable.format.SSTableReader;
  import org.apache.cassandra.schema.Schema;
  import org.apache.cassandra.schema.TableMetadata;
  import org.apache.cassandra.tcm.ClusterMetadataService;
  
  import static org.apache.cassandra.utils.Clock.Global.currentTimeMillis;
  
  /**
   * During compaction we can drop entire sstables if they only contain expired tombstones and if it is guaranteed
   * to not cover anything in other sstables. An expired sstable can be blocked from getting dropped if its newest
   * timestamp is newer than the oldest data in another sstable.
   *
   * This class outputs all sstables that are blocking other sstables from getting dropped so that a user can
   * figure out why certain sstables are still on disk.
   */
  public class SSTableExpiredBlockers
  {
      public static void main(String[] args)
      {
          PrintStream out = System.out;
          if (args.length < 2)
          {
              out.println("Usage: sstableexpiredblockers <keyspace> <table>");
              System.exit(1);
          }
  
          Util.initDatabaseDescriptor();
          ClusterMetadataService.initializeForTools(false);
          String keyspace = args[args.length - 2];
          String columnfamily = args[args.length - 1];
  
          TableMetadata metadata = Schema.instance.validateTable(keyspace, columnfamily);
  
          Keyspace ks = Keyspace.openWithoutSSTables(keyspace);
          ColumnFamilyStore cfs = ks.getColumnFamilyStore(columnfamily);
          Directories.SSTableLister lister = cfs.getDirectories().sstableLister(Directories.OnTxnErr.THROW).skipTemporary(true);
          Set<SSTableReader> sstables = new HashSet<>();
          for (Map.Entry<Descriptor, Set<Component>> sstable : lister.list().entrySet())
          {
              if (sstable.getKey() != null)
              {
                  try
                  {
                      SSTableReader reader = SSTableReader.open(cfs, sstable.getKey());
                      sstables.add(reader);
                  }
                  catch (Throwable t)
                  {
                      out.println("Couldn't open sstable: " + sstable.getKey().fileFor(Components.DATA) + " (" + t.getMessage() + ")");
                  }
              }
          }
          if (sstables.isEmpty())
          {
              out.println("No sstables for " + keyspace + "." + columnfamily);
              System.exit(1);
          }
  
          long gcBefore = (currentTimeMillis() / 1000) - metadata.params.gcGraceSeconds;
          Multimap<SSTableReader, SSTableReader> blockers = checkForExpiredSSTableBlockers(sstables, gcBefore);
          for (SSTableReader blocker : blockers.keySet())
          {
              out.println(String.format("%s blocks %d expired sstables from getting dropped: %s%n",
                                      formatForExpiryTracing(Collections.singleton(blocker)),
                                      blockers.get(blocker).size(),
                                      formatForExpiryTracing(blockers.get(blocker))));
          }
  
          System.exit(0);
      }
  
      public static Multimap<SSTableReader, SSTableReader> checkForExpiredSSTableBlockers(Iterable<SSTableReader> sstables, long gcBefore)
      {
          Multimap<SSTableReader, SSTableReader> blockers = ArrayListMultimap.create();
          for (SSTableReader sstable : sstables)
          {
              if (sstable.getMaxLocalDeletionTime() < gcBefore)
              {
                  for (SSTableReader potentialBlocker : sstables)
                  {
                      if (!potentialBlocker.equals(sstable) &&
                          potentialBlocker.getMinTimestamp() <= sstable.getMaxTimestamp() &&
                          potentialBlocker.getMaxLocalDeletionTime() > gcBefore)
                          blockers.put(potentialBlocker, sstable);
                  }
              }
          }
          return blockers;
      }
  
      private static String formatForExpiryTracing(Iterable<SSTableReader> sstables)
      {
          StringBuilder sb = new StringBuilder();
  
          for (SSTableReader sstable : sstables)
              sb.append(String.format("[%s (minTS = %d, maxTS = %d, maxLDT = %d)]", sstable, sstable.getMinTimestamp(), sstable.getMaxTimestamp(), sstable.getMaxLocalDeletionTime())).append(", ");
  
          return sb.toString();
      }
  }
  