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   * Licensed to the Apache Software Foundation (ASF) under one
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   * distributed with this work for additional information
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   * 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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   * See the License for the specific language governing permissions and
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  package org.apache.cassandra.hints;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.file.Files;
  import java.util.UUID;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.TimeUnit;
  
  import com.google.common.collect.ImmutableMap;
  import com.google.common.util.concurrent.Uninterruptibles;
  import org.junit.Assert;
  import org.junit.Before;
  import org.junit.BeforeClass;
  import org.junit.Test;
  
  import org.apache.cassandra.SchemaLoader;
  import org.apache.cassandra.io.util.File;
  import org.apache.cassandra.schema.Schema;
  import org.apache.cassandra.schema.TableMetadata;
  import org.apache.cassandra.db.Mutation;
  import org.apache.cassandra.db.RowUpdateBuilder;
  import org.apache.cassandra.schema.KeyspaceParams;
  import org.apache.cassandra.utils.memory.MemoryUtil;
  import org.hamcrest.Matchers;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertNull;
  import static org.junit.Assert.assertTrue;
  
  import static org.apache.cassandra.utils.ByteBufferUtil.bytes;
  
  public class HintsStoreTest
  {
      private static final String KEYSPACE = "hints_store_test";
      private static final String TABLE = "table";
      private File directory;
      private UUID hostId;
  
      @Before
      public void testSetup() throws IOException
      {
          directory = new File(Files.createTempDirectory(null));
          directory.deleteOnExit();
          hostId = UUID.randomUUID();
      }
  
      @BeforeClass
      public static void setup()
      {
          SchemaLoader.prepareServer();
          SchemaLoader.createKeyspace(KEYSPACE, KeyspaceParams.simple(1), SchemaLoader.standardCFMD(KEYSPACE, TABLE));
      }
  
      @Test
      public void testDeleteAllExpiredHints() throws IOException
      {
          final long now = System.currentTimeMillis();
          // hints to delete
          writeHints(directory, new HintsDescriptor(hostId, now), 100, now);
          writeHints(directory, new HintsDescriptor(hostId, now + 1000), 1, now);
          HintsStore store = HintsCatalog.load(directory, ImmutableMap.of()).get(hostId);
          assertTrue("Hints store should have files", store.hasFiles());
          assertEquals(2, store.getDispatchQueueSize());
  
          // jump to the future and delete.
          store.deleteExpiredHints(now + TimeUnit.SECONDS.toMillis(Hint.maxHintTTL) + 10);
  
          assertFalse("All hints files should be deleted", store.hasFiles());
      }
  
      @Test
      public void testDeleteAllExpiredHintsByHittingExpirationsCache() throws IOException
      {
          final long now = System.currentTimeMillis();
          HintsDescriptor hintsDescriptor = new HintsDescriptor(hostId, now);
          writeHints(directory, hintsDescriptor, 100, now);
  
          HintsStore store = HintsCatalog.load(directory, ImmutableMap.of()).get(hostId);
          assertTrue("Hints store should have files", store.hasFiles());
          assertEquals("Hints store should not have cached expiration yet", 0, store.getHintsExpirationsMapSize());
          assertEquals(1, store.getDispatchQueueSize());
  
          store.deleteExpiredHints(now + 1); // Not expired yet. Wont delete.
          assertEquals("Hint should not be deleted yet", 1, store.getDispatchQueueSize());
          assertEquals("Found no cached hints expiration", 1, store.getHintsExpirationsMapSize());
          // jump to the future and delete. It should not re-read all the file
          store.deleteExpiredHints(now + TimeUnit.SECONDS.toMillis(Hint.maxHintTTL) + 10);
          assertFalse("All hints files should be deleted", store.hasFiles());
      }
  
      /**
       * Test multiple threads delete hints files.
       * It could happen when hint service is running a removal process, meanwhile operator issues a NodeTool command to delete.
       *
       * Thread contends and delete part of the files in the store. The final effect should all files get deleted.
       */
      @Test
      public void testConcurrentDeleteExpiredHints() throws Exception
      {
          final long now = System.currentTimeMillis();
          for (int i = 100; i >= 0; i--)
          {
              writeHints(directory, new HintsDescriptor(hostId, now - i), 100, now);
          }
  
          HintsStore store = HintsCatalog.load(directory, ImmutableMap.of()).get(hostId);
          int concurrency = 3;
          CountDownLatch start = new CountDownLatch(1);
          Runnable removal = () -> {
              Uninterruptibles.awaitUninterruptibly(start);
              store.deleteExpiredHints(now + TimeUnit.SECONDS.toMillis(Hint.maxHintTTL) + 10); // jump to the future and delete
          };
          ExecutorService es = Executors.newFixedThreadPool(concurrency);
          try (Closeable ignored = es::shutdown)
          {
              for (int i = 0; i < concurrency; i++)
                  es.submit(removal);
              start.countDown();
          }
          assertTrue(es.awaitTermination(2, TimeUnit.SECONDS));
          assertFalse("All hints files should be deleted", store.hasFiles());
      }
  
      @Test
      public void testPendingHintsInfo() throws Exception
      {
          HintsStore store = HintsCatalog.load(directory, ImmutableMap.of()).get(hostId);
          assertNull(store.getPendingHintsInfo());
  
          final long t1 = 10;
          HintsDescriptor d1 = new HintsDescriptor(hostId, t1);
          writeHints(directory, d1, 100, t1);
          long d1Size = d1.hintsFileSize(directory);
          store = HintsCatalog.load(directory, ImmutableMap.of()).get(hostId);
          assertEquals(new PendingHintsInfo(store.hostId, 1, t1, t1, d1Size, 0, 0),
                       store.getPendingHintsInfo());
          final long t2 = t1 + 1;
          HintsDescriptor d2 = new HintsDescriptor(hostId, t2);
          writeHints(directory, d2, 100, t2);
          long d2Size = d2.hintsFileSize(directory);
          store = HintsCatalog.load(directory, ImmutableMap.of()).get(hostId);
          assertEquals(new PendingHintsInfo(store.hostId, 2, t1, t2, d1Size + d2Size, 0, 0),
                       store.getPendingHintsInfo());
      }
  
      private long writeHints(File directory, HintsDescriptor descriptor, int hintsCount, long hintCreationTime) throws IOException
      {
          try (HintsWriter writer = HintsWriter.create(directory, descriptor))
          {
              ByteBuffer buffer = ByteBuffer.allocateDirect(256 * 1024);
              try (HintsWriter.Session session = writer.newSession(buffer))
              {
                  for (int i = 0; i < hintsCount; i++)
                      session.append(createHint(i, hintCreationTime));
              }
              MemoryUtil.clean(buffer);
          }
          Assert.assertThat(descriptor.hintsFileSize(directory), Matchers.greaterThan(0L));
          return new File(directory, descriptor.fileName()).lastModified(); // hint file last modified time
      }
  
      private Hint createHint(int idx, long creationTime)
      {
          TableMetadata table = Schema.instance.getTableMetadata(KEYSPACE, TABLE);
          Mutation mutation = new RowUpdateBuilder(table, creationTime, bytes(idx))
                              .clustering(bytes(idx))
                              .add("val", bytes(idx))
                              .build();
  
          return Hint.create(mutation, creationTime, 1);
      }
  }
  