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   * "License"); you may not use this file except in compliance
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   *
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   * Unless required by applicable law or agreed to in writing, software
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  package org.apache.cassandra.distributed.upgrade;
  
  import java.util.concurrent.TimeUnit;
  
  import org.junit.Test;
  
  import org.apache.cassandra.distributed.api.ConsistencyLevel;
  import org.apache.cassandra.distributed.api.Feature;
  import org.apache.cassandra.distributed.upgrade.MixedModePaxosTestBase.FakePaxosHelper;
  
  import static java.lang.String.format;
  
  public class MixedModePaxosTTLTest extends UpgradeTestBase
  {
      /**
       * Tests the mixed mode paxos loop bug in CASSANDRA-20514
       *
       * CEP-14 changed the ttl behavior of legacy paxos state to expire based off the ballot time of the operation being
       * persisted, not the time a commit is persisted. This eliminated the race addressed by CASSANDRA-12043, and so the
       * check it added to the most recent commit prepare logic was removed.
       *
       * When operating in mixed mode though, this can still be a problem. If a 4.1 or higher node is coordinating a paxos
       * operation with 2 or more replicas on 4.0 or lower, this race becomes a problem again. You need 3 things to make
       * this an infinite loop
       * 1. a 4.1 node coordinating a paxos operation with 2x 4.0 replicas
       * 2. replica A) a 4.0 node returns a most recent commit for a ballot that's could have been ttld
       * 3. replica B) a 4.0 node has ttl'd that mrc AND converted the ttld cells into tombstones
       *
       * The 4.1 coordinator receives the mrc from replica A, but since it no longer disregards missing most recent commits
       * past the ttl window, it sends the "missing" commit to replica B. Since replica B now has a tombstone for that mrc,
       * and tombstones win when reconciled with live cells, even ones with ttls, the commit is a noop and it continues
       * to report nothing for its mrc value when the coordinator restarts the prepare phase. This loops until the query
       * times out.
       */
      @Test
      public void legacyExpiredStateTest() throws Throwable
      {
          String keyspace = "ks";
          String table = "tbl";
          int gcGrace = 60*60*24; // 1 day
          int key = 100;  // hashes to nodes 2 & 3 w/ murmur @ RF=2
          new TestCase()
          .withConfig(c -> c.with(Feature.GOSSIP, Feature.NETWORK).set("cas_contention_timeout", "500ms"))
          .nodes(3)
          .nodesToUpgrade(1)
          .upgradesToCurrentFrom(v40)
          .setup(cluster -> {
              cluster.schemaChange(format("CREATE KEYSPACE %s WITH REPLICATION={'class': 'SimpleStrategy', 'replication_factor': '2'}", keyspace));
              cluster.schemaChange(format("CREATE TABLE %s.%s (k int primary key, v int) " +
                                          "WITH gc_grace_seconds=%s", keyspace, table, gcGrace));
          })
          .runAfterClusterUpgrade(cluster -> {
              // disable compaction to prevent paxos state from being purged
              cluster.forEach(instance -> instance.nodetool("disableautocompaction"));
  
              long ballotMicros = TimeUnit.MILLISECONDS.toMicros(System.currentTimeMillis());
              ballotMicros -= TimeUnit.SECONDS.toMicros(gcGrace + 10);
              FakePaxosHelper helper = FakePaxosHelper.create(cluster.coordinator(1), keyspace, table, key, gcGrace, ballotMicros);
  
              // confirm none of the nodes have paxos state
              for (int i = 1; i <= cluster.size(); i++)
                  helper.assertNoPaxosData(cluster.coordinator(i));
  
              // save a tombstoned commit to one node to simulate expired cells being converted to tombstones
              helper.tombstoneCommit(cluster.coordinator(2));
  
              // insert paxos state and confirm it hasn't ttl'd yet
              helper.saveCommit(cluster.coordinator(3));
              helper.assertPaxosData(cluster.coordinator(3));
  
              // paxos operation should not timeout
              cluster.coordinator(1).execute(format("SELECT * FROM %s.%s WHERE k=%s", keyspace, table, key), ConsistencyLevel.SERIAL);
          })
          .run();
      }
  }
  