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   * "License"); you may not use this file except in compliance
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   *
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   * See the License for the specific language governing permissions and
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  package org.apache.cassandra.distributed.test;
  
  import java.util.Collection;
  import java.util.concurrent.Callable;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.atomic.AtomicBoolean;
  
  import org.junit.Test;
  
  import com.datastax.driver.core.PreparedStatement;
  import com.datastax.driver.core.Session;
  import net.bytebuddy.ByteBuddy;
  import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
  import net.bytebuddy.implementation.MethodDelegation;
  import net.bytebuddy.implementation.bind.annotation.SuperCall;
  import org.apache.cassandra.cql3.QueryHandler;
  import org.apache.cassandra.cql3.QueryProcessor;
  import org.apache.cassandra.cql3.statements.SelectStatement;
  import org.apache.cassandra.db.Keyspace;
  import org.apache.cassandra.distributed.api.ICluster;
  import org.apache.cassandra.distributed.api.IInvokableInstance;
  import org.apache.cassandra.schema.DistributedSchema;
  import org.apache.cassandra.schema.TableMetadata;
  
  import static net.bytebuddy.matcher.ElementMatchers.named;
  import static net.bytebuddy.matcher.ElementMatchers.takesArguments;
  import static org.apache.cassandra.distributed.api.Feature.GOSSIP;
  import static org.apache.cassandra.distributed.api.Feature.NATIVE_PROTOCOL;
  import static org.apache.cassandra.distributed.api.Feature.NETWORK;
  import static org.junit.Assert.assertEquals;
  
  public class PreparedStatementInvalidationRaceTest extends TestBaseImpl
  {
      @Test
      public void testInvalidationRace() throws Exception
      {
          try (ICluster<IInvokableInstance> c = init(builder().withNodes(1)
                                                              .withConfig(config -> config.with(GOSSIP, NETWORK, NATIVE_PROTOCOL))
                                                              .withInstanceInitializer(BBHelper::install)
                                                              .start()))
          {
              try (com.datastax.driver.core.Cluster cluster = com.datastax.driver.core.Cluster.builder()
                                                                                              .addContactPoint("127.0.0.1")
                                                                                              .build();
                   Session s = cluster.connect())
              {
                  s.execute(withKeyspace("CREATE TABLE %s.tbl (pk int primary key)"));
                  PreparedStatement prepared = s.prepare(withKeyspace("select pk from %s.tbl where pk = ?"));
                  s.execute(prepared.bind(1));
                  c.get(1).runOnInstance(() -> BBHelper.enabled.set(true));
                  Thread t = new Thread(() -> s.execute(withKeyspace("alter table %s.tbl add x int")));
                  t.start();
                  c.get(1).runOnInstance(() -> await(BBHelper.initializeKeyspaceInstancesDone));
                  // This is where the race existed before - we used to invalidate the statement in
                  // initializeKeyspaceInstances, but the schema change is not yet committed so the
                  // next execute would reprepare with the wrong tablemetadata (and keep it forever).
                  // Now we invalidate after committing - so the last execute below will reprepare the
                  // query, with the correct tablemetadata
                  s.execute(prepared.bind(1));
                  c.get(1).runOnInstance(() -> {
                      BBHelper.enabled.set(false);
                      BBHelper.delayCommittingSchemaChange.countDown();
                  });
                  t.join();
                  s.execute(prepared.bind(1));
                  c.get(1).runOnInstance(() -> {
                      TableMetadata tableMetadata = Keyspace.open(KEYSPACE).getColumnFamilyStore("tbl").metadata();
                      Collection<QueryHandler.Prepared> serverSidePrepared = QueryProcessor.instance.getPreparedStatements().values();
                      assertEquals(1, serverSidePrepared.size());
                      for (QueryHandler.Prepared ssp : QueryProcessor.instance.getPreparedStatements().values())
                          assertEquals(tableMetadata.epoch, ((SelectStatement)ssp.statement).table.epoch);
                  });
              }
          }
      }
  
      public static class BBHelper
      {
          static AtomicBoolean enabled = new AtomicBoolean();
          static CountDownLatch delayCommittingSchemaChange = new CountDownLatch(1);
          static CountDownLatch initializeKeyspaceInstancesDone = new CountDownLatch(1);
  
          public static void install(ClassLoader cl, int i)
          {
              new ByteBuddy().rebase(DistributedSchema.class)
                             .method(named("initializeKeyspaceInstances").and(takesArguments(2)))
                             .intercept(MethodDelegation.to(BBHelper.class))
                             .make()
                             .load(cl, ClassLoadingStrategy.Default.INJECTION);
          }
  
          public static void initializeKeyspaceInstances(DistributedSchema prev, boolean loadSSTables, @SuperCall Callable<Void> zuper)
          {
              try
              {
                  zuper.call();
                  if (enabled.get())
                  {
                      initializeKeyspaceInstancesDone.countDown();
                      delayCommittingSchemaChange.await();
                  }
              }
              catch (Exception e)
              {
                  throw new RuntimeException(e);
              }
          }
      }
  
      private static void await(CountDownLatch cdl)
      {
          try
          {
              cdl.await();
          }
          catch (InterruptedException e)
          {
              throw new RuntimeException(e);
          }
      }
  }