code: /*
   * Copyright 2012-2018 Chronicle Map Contributors
   *
   * Licensed 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 net.openhft.chronicle.map.fromdocs;
  
  import net.openhft.chronicle.core.values.LongValue;
  import net.openhft.chronicle.hash.ChecksumEntry;
  import net.openhft.chronicle.map.ChronicleMap;
  import net.openhft.chronicle.map.ExternalMapQueryContext;
  import net.openhft.chronicle.map.MapEntry;
  import net.openhft.chronicle.set.Builder;
  import net.openhft.chronicle.values.Values;
  import org.junit.Assert;
  import org.junit.Test;
  
  import java.io.File;
  import java.io.IOException;
  
  public class ChecksumEntryTest {
  
      @Test
      public void testChecksumEntriesWithValueInterface() throws IOException {
          File file = Builder.getPersistenceFile();
  
          try (ChronicleMap<Integer, LongValue> map = ChronicleMap
                  .of(Integer.class, LongValue.class)
                  .entries(1)
                  // Entry checksums make sense only for persisted Chronicle Maps, and are ON by
                  // default for such maps
                  .createPersistedTo(file)) {
  
              LongValue value = Values.newHeapInstance(LongValue.class);
              value.setValue(42);
              map.put(1, value);
  
              try (ExternalMapQueryContext<Integer, LongValue, ?> c = map.queryContext(1)) {
                  // Update lock required for calling ChecksumEntry.checkSum()
                  c.updateLock().lock();
                  MapEntry<Integer, LongValue> entry = c.entry();
                  Assert.assertNotNull(entry);
                  ChecksumEntry checksumEntry = (ChecksumEntry) entry;
                  Assert.assertTrue(checksumEntry.checkSum());
  
                  // to access off-heap bytes, should call value().getUsing() with Native value
                  // provided. Simple get() return Heap value by default
                  LongValue nativeValue =
                          entry.value().getUsing(Values.newNativeReference(LongValue.class));
                  // This value bytes update bypass Chronicle Map internals, so checksum is not
                  // updated automatically
                  nativeValue.setValue(43);
                  Assert.assertFalse(checksumEntry.checkSum());
  
                  // Restore correct checksum
                  checksumEntry.updateChecksum();
                  Assert.assertTrue(checksumEntry.checkSum());
              }
          }
      }
  }
  