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.beam.runners.direct;
  
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.hamcrest.Matchers.containsInAnyOrder;
  import static org.hamcrest.Matchers.emptyIterable;
  import static org.hamcrest.Matchers.equalTo;
  import static org.hamcrest.Matchers.is;
  import static org.hamcrest.Matchers.nullValue;
  import static org.hamcrest.Matchers.theInstance;
  import static org.junit.Assert.assertNull;
  import static org.mockito.Mockito.never;
  import static org.mockito.Mockito.spy;
  import static org.mockito.Mockito.verify;
  
  import org.apache.beam.runners.core.StateNamespace;
  import org.apache.beam.runners.core.StateNamespaceForTest;
  import org.apache.beam.runners.core.StateNamespaces;
  import org.apache.beam.runners.core.StateTag;
  import org.apache.beam.runners.core.StateTags;
  import org.apache.beam.sdk.coders.CannotProvideCoderException;
  import org.apache.beam.sdk.coders.CoderRegistry;
  import org.apache.beam.sdk.coders.StringUtf8Coder;
  import org.apache.beam.sdk.coders.VarIntCoder;
  import org.apache.beam.sdk.state.BagState;
  import org.apache.beam.sdk.state.CombiningState;
  import org.apache.beam.sdk.state.GroupingState;
  import org.apache.beam.sdk.state.MapState;
  import org.apache.beam.sdk.state.SetState;
  import org.apache.beam.sdk.state.ValueState;
  import org.apache.beam.sdk.state.WatermarkHoldState;
  import org.apache.beam.sdk.testing.TestPipeline;
  import org.apache.beam.sdk.transforms.Combine.CombineFn;
  import org.apache.beam.sdk.transforms.Sum;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.transforms.windowing.TimestampCombiner;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Lists;
  import org.joda.time.Instant;
  import org.junit.Rule;
  import org.junit.Test;
  import org.junit.rules.ExpectedException;
  import org.junit.runner.RunWith;
  import org.junit.runners.JUnit4;
  
  /** Tests for {@link CopyOnAccessInMemoryStateInternals}. */
  @RunWith(JUnit4.class)
  public class CopyOnAccessInMemoryStateInternalsTest {
  
    @Rule public final TestPipeline pipeline = TestPipeline.create();
    @Rule public ExpectedException thrown = ExpectedException.none();
    private String key = "foo";
  
    @Test
    public void testGetWithEmpty() {
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
      BagState<String> stringBag = internals.state(namespace, bagTag);
      assertThat(stringBag.read(), emptyIterable());
  
      stringBag.add("bar");
      stringBag.add("baz");
      assertThat(stringBag.read(), containsInAnyOrder("baz", "bar"));
  
      BagState<String> reReadStringBag = internals.state(namespace, bagTag);
      assertThat(reReadStringBag.read(), containsInAnyOrder("baz", "bar"));
    }
  
    @Test
    public void testGetWithAbsentInUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
      BagState<String> stringBag = internals.state(namespace, bagTag);
      assertThat(stringBag.read(), emptyIterable());
  
      stringBag.add("bar");
      stringBag.add("baz");
      assertThat(stringBag.read(), containsInAnyOrder("baz", "bar"));
  
      BagState<String> reReadVoidBag = internals.state(namespace, bagTag);
      assertThat(reReadVoidBag.read(), containsInAnyOrder("baz", "bar"));
  
      BagState<String> underlyingState = underlying.state(namespace, bagTag);
      assertThat(underlyingState.read(), emptyIterable());
    }
  
    /**
     * Tests that retrieving state with an underlying StateInternals with an existing value returns a
     * value that initially has equal value to the provided state but can be modified without
     * modifying the existing state.
     */
    @Test
    public void testGetWithPresentInUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<ValueState<String>> valueTag = StateTags.value("foo", StringUtf8Coder.of());
      ValueState<String> underlyingValue = underlying.state(namespace, valueTag);
      assertThat(underlyingValue.read(), nullValue(String.class));
  
      underlyingValue.write("bar");
      assertThat(underlyingValue.read(), equalTo("bar"));
  
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
      ValueState<String> copyOnAccessState = internals.state(namespace, valueTag);
      assertThat(copyOnAccessState.read(), equalTo("bar"));
  
      copyOnAccessState.write("baz");
      assertThat(copyOnAccessState.read(), equalTo("baz"));
      assertThat(underlyingValue.read(), equalTo("bar"));
  
      ValueState<String> reReadUnderlyingValue = underlying.state(namespace, valueTag);
      assertThat(underlyingValue.read(), equalTo(reReadUnderlyingValue.read()));
    }
  
    @Test
    public void testBagStateWithUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<BagState<Integer>> valueTag = StateTags.bag("foo", VarIntCoder.of());
      BagState<Integer> underlyingValue = underlying.state(namespace, valueTag);
      assertThat(underlyingValue.read(), emptyIterable());
  
      underlyingValue.add(1);
      assertThat(underlyingValue.read(), containsInAnyOrder(1));
  
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
      BagState<Integer> copyOnAccessState = internals.state(namespace, valueTag);
      assertThat(copyOnAccessState.read(), containsInAnyOrder(1));
  
      copyOnAccessState.add(4);
      assertThat(copyOnAccessState.read(), containsInAnyOrder(4, 1));
      assertThat(underlyingValue.read(), containsInAnyOrder(1));
  
      BagState<Integer> reReadUnderlyingValue = underlying.state(namespace, valueTag);
      assertThat(
          Lists.newArrayList(underlyingValue.read()),
          equalTo(Lists.newArrayList(reReadUnderlyingValue.read())));
    }
  
    @Test
    public void testSetStateWithUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<SetState<Integer>> valueTag = StateTags.set("foo", VarIntCoder.of());
      SetState<Integer> underlyingValue = underlying.state(namespace, valueTag);
      assertThat(underlyingValue.read(), emptyIterable());
  
      underlyingValue.add(1);
      assertThat(underlyingValue.read(), containsInAnyOrder(1));
  
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
      SetState<Integer> copyOnAccessState = internals.state(namespace, valueTag);
      assertThat(copyOnAccessState.read(), containsInAnyOrder(1));
  
      copyOnAccessState.add(4);
      assertThat(copyOnAccessState.read(), containsInAnyOrder(4, 1));
      assertThat(underlyingValue.read(), containsInAnyOrder(1));
  
      SetState<Integer> reReadUnderlyingValue = underlying.state(namespace, valueTag);
      assertThat(underlyingValue.read(), equalTo(reReadUnderlyingValue.read()));
    }
  
    @Test
    public void testMapStateWithUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<MapState<String, Integer>> valueTag =
          StateTags.map("foo", StringUtf8Coder.of(), VarIntCoder.of());
      MapState<String, Integer> underlyingValue = underlying.state(namespace, valueTag);
      assertThat(underlyingValue.entries().read(), emptyIterable());
  
      underlyingValue.put("hello", 1);
      assertThat(underlyingValue.get("hello").read(), equalTo(1));
  
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
      MapState<String, Integer> copyOnAccessState = internals.state(namespace, valueTag);
      assertThat(copyOnAccessState.get("hello").read(), equalTo(1));
  
      copyOnAccessState.put("world", 4);
      assertThat(copyOnAccessState.get("hello").read(), equalTo(1));
      assertThat(copyOnAccessState.get("world").read(), equalTo(4));
      assertThat(underlyingValue.get("hello").read(), equalTo(1));
      assertNull(underlyingValue.get("world").read());
  
      MapState<String, Integer> reReadUnderlyingValue = underlying.state(namespace, valueTag);
      assertThat(underlyingValue.entries().read(), equalTo(reReadUnderlyingValue.entries().read()));
    }
  
    @Test
    public void testAccumulatorCombiningStateWithUnderlying() throws CannotProvideCoderException {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
      CombineFn<Long, long[], Long> sumLongFn = Sum.ofLongs();
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      CoderRegistry reg = pipeline.getCoderRegistry();
      StateTag<CombiningState<Long, long[], Long>> stateTag =
          StateTags.combiningValue(
              "summer", sumLongFn.getAccumulatorCoder(reg, reg.getCoder(Long.class)), sumLongFn);
      GroupingState<Long, Long> underlyingValue = underlying.state(namespace, stateTag);
      assertThat(underlyingValue.read(), equalTo(0L));
  
      underlyingValue.add(1L);
      assertThat(underlyingValue.read(), equalTo(1L));
  
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
      GroupingState<Long, Long> copyOnAccessState = internals.state(namespace, stateTag);
      assertThat(copyOnAccessState.read(), equalTo(1L));
  
      copyOnAccessState.add(4L);
      assertThat(copyOnAccessState.read(), equalTo(5L));
      assertThat(underlyingValue.read(), equalTo(1L));
  
      GroupingState<Long, Long> reReadUnderlyingValue = underlying.state(namespace, stateTag);
      assertThat(underlyingValue.read(), equalTo(reReadUnderlyingValue.read()));
    }
  
    @Test
    public void testWatermarkHoldStateWithUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
  
      TimestampCombiner timestampCombiner = TimestampCombiner.EARLIEST;
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<WatermarkHoldState> stateTag =
          StateTags.watermarkStateInternal("wmstate", timestampCombiner);
      WatermarkHoldState underlyingValue = underlying.state(namespace, stateTag);
      assertThat(underlyingValue.read(), nullValue());
  
      underlyingValue.add(new Instant(250L));
      assertThat(underlyingValue.read(), equalTo(new Instant(250L)));
  
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
      WatermarkHoldState copyOnAccessState = internals.state(namespace, stateTag);
      assertThat(copyOnAccessState.read(), equalTo(new Instant(250L)));
  
      copyOnAccessState.add(new Instant(100L));
      assertThat(copyOnAccessState.read(), equalTo(new Instant(100L)));
      assertThat(underlyingValue.read(), equalTo(new Instant(250L)));
  
      copyOnAccessState.add(new Instant(500L));
      assertThat(copyOnAccessState.read(), equalTo(new Instant(100L)));
  
      WatermarkHoldState reReadUnderlyingValue = underlying.state(namespace, stateTag);
      assertThat(underlyingValue.read(), equalTo(reReadUnderlyingValue.read()));
    }
  
    @Test
    public void testCommitWithoutUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
      BagState<String> stringBag = internals.state(namespace, bagTag);
      assertThat(stringBag.read(), emptyIterable());
  
      stringBag.add("bar");
      stringBag.add("baz");
      assertThat(stringBag.read(), containsInAnyOrder("baz", "bar"));
  
      internals.commit();
  
      BagState<String> reReadStringBag = internals.state(namespace, bagTag);
      assertThat(reReadStringBag.read(), containsInAnyOrder("baz", "bar"));
      assertThat(internals.isEmpty(), is(false));
    }
  
    @Test
    public void testCommitWithUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
      BagState<String> stringBag = underlying.state(namespace, bagTag);
      assertThat(stringBag.read(), emptyIterable());
  
      stringBag.add("bar");
      stringBag.add("baz");
  
      internals.commit();
      BagState<String> reReadStringBag = internals.state(namespace, bagTag);
      assertThat(reReadStringBag.read(), containsInAnyOrder("baz", "bar"));
  
      reReadStringBag.add("spam");
  
      BagState<String> underlyingState = underlying.state(namespace, bagTag);
      assertThat(underlyingState.read(), containsInAnyOrder("spam", "bar", "baz"));
      assertThat(underlyingState, is(theInstance(stringBag)));
      assertThat(internals.isEmpty(), is(false));
    }
  
    @Test
    public void testCommitWithClearedInUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
      CopyOnAccessInMemoryStateInternals<String> secondUnderlying =
          spy(CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying));
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, secondUnderlying);
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
      BagState<String> stringBag = underlying.state(namespace, bagTag);
      assertThat(stringBag.read(), emptyIterable());
  
      stringBag.add("bar");
      stringBag.add("baz");
      stringBag.clear();
      // We should not read through the cleared bag
      secondUnderlying.commit();
  
      // Should not be visible
      stringBag.add("foo");
  
      internals.commit();
      BagState<String> internalsStringBag = internals.state(namespace, bagTag);
      assertThat(internalsStringBag.read(), emptyIterable());
      verify(secondUnderlying, never()).state(namespace, bagTag);
      assertThat(internals.isEmpty(), is(false));
    }
  
    @Test
    public void testCommitWithOverwrittenUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
      BagState<String> stringBag = underlying.state(namespace, bagTag);
      assertThat(stringBag.read(), emptyIterable());
  
      stringBag.add("bar");
      stringBag.add("baz");
  
      BagState<String> internalsState = internals.state(namespace, bagTag);
      internalsState.add("eggs");
      internalsState.add("ham");
      internalsState.add("0x00ff00");
      internalsState.add("&");
  
      internals.commit();
  
      BagState<String> reReadInternalState = internals.state(namespace, bagTag);
      assertThat(
          reReadInternalState.read(),
          containsInAnyOrder("bar", "baz", "0x00ff00", "eggs", "&", "ham"));
      BagState<String> reReadUnderlyingState = underlying.state(namespace, bagTag);
      assertThat(reReadUnderlyingState.read(), containsInAnyOrder("bar", "baz"));
    }
  
    @Test
    public void testCommitWithAddedUnderlying() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
  
      internals.commit();
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
      BagState<String> stringBag = underlying.state(namespace, bagTag);
      assertThat(stringBag.read(), emptyIterable());
  
      stringBag.add("bar");
      stringBag.add("baz");
  
      BagState<String> internalState = internals.state(namespace, bagTag);
      assertThat(internalState.read(), emptyIterable());
  
      BagState<String> reReadUnderlyingState = underlying.state(namespace, bagTag);
      assertThat(reReadUnderlyingState.read(), containsInAnyOrder("bar", "baz"));
    }
  
    @Test
    public void testCommitWithEmptyTableIsEmpty() {
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
  
      internals.commit();
  
      assertThat(internals.isEmpty(), is(true));
    }
  
    @Test
    public void testCommitWithOnlyClearedValuesIsEmpty() {
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
      BagState<String> stringBag = internals.state(namespace, bagTag);
      assertThat(stringBag.read(), emptyIterable());
  
      stringBag.add("foo");
      stringBag.clear();
  
      internals.commit();
  
      assertThat(internals.isEmpty(), is(true));
    }
  
    @Test
    public void testCommitWithEmptyNewAndFullUnderlyingIsNotEmpty() {
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
  
      StateNamespace namespace = new StateNamespaceForTest("foo");
      StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
      BagState<String> stringBag = underlying.state(namespace, bagTag);
      assertThat(stringBag.read(), emptyIterable());
  
      stringBag.add("bar");
      stringBag.add("baz");
  
      internals.commit();
      assertThat(internals.isEmpty(), is(false));
    }
  
    @Test
    public void testGetEarliestWatermarkHoldAfterCommit() {
      BoundedWindow first =
          new BoundedWindow() {
            @Override
            public Instant maxTimestamp() {
              return new Instant(2048L);
            }
          };
      BoundedWindow second =
          new BoundedWindow() {
            @Override
            public Instant maxTimestamp() {
              return new Instant(689743L);
            }
          };
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying("foo", null);
  
      StateTag<WatermarkHoldState> firstHoldAddress =
          StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
      WatermarkHoldState firstHold =
          internals.state(StateNamespaces.window(null, first), firstHoldAddress);
      firstHold.add(new Instant(22L));
  
      StateTag<WatermarkHoldState> secondHoldAddress =
          StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
      WatermarkHoldState secondHold =
          internals.state(StateNamespaces.window(null, second), secondHoldAddress);
      secondHold.add(new Instant(2L));
  
      internals.commit();
      assertThat(internals.getEarliestWatermarkHold(), equalTo(new Instant(2L)));
    }
  
    @Test
    public void testGetEarliestWatermarkHoldWithEarliestInUnderlyingTable() {
      BoundedWindow first =
          new BoundedWindow() {
            @Override
            public Instant maxTimestamp() {
              return new Instant(2048L);
            }
          };
      BoundedWindow second =
          new BoundedWindow() {
            @Override
            public Instant maxTimestamp() {
              return new Instant(689743L);
            }
          };
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying("foo", null);
      StateTag<WatermarkHoldState> firstHoldAddress =
          StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
      WatermarkHoldState firstHold =
          underlying.state(StateNamespaces.window(null, first), firstHoldAddress);
      firstHold.add(new Instant(22L));
  
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying("foo", underlying.commit());
  
      StateTag<WatermarkHoldState> secondHoldAddress =
          StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
      WatermarkHoldState secondHold =
          internals.state(StateNamespaces.window(null, second), secondHoldAddress);
      secondHold.add(new Instant(244L));
  
      internals.commit();
      assertThat(internals.getEarliestWatermarkHold(), equalTo(new Instant(22L)));
    }
  
    @Test
    public void testGetEarliestWatermarkHoldWithEarliestInNewTable() {
      BoundedWindow first =
          new BoundedWindow() {
            @Override
            public Instant maxTimestamp() {
              return new Instant(2048L);
            }
          };
      BoundedWindow second =
          new BoundedWindow() {
            @Override
            public Instant maxTimestamp() {
              return new Instant(689743L);
            }
          };
      CopyOnAccessInMemoryStateInternals<String> underlying =
          CopyOnAccessInMemoryStateInternals.withUnderlying("foo", null);
      StateTag<WatermarkHoldState> firstHoldAddress =
          StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
      WatermarkHoldState firstHold =
          underlying.state(StateNamespaces.window(null, first), firstHoldAddress);
      firstHold.add(new Instant(224L));
  
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying("foo", underlying.commit());
  
      StateTag<WatermarkHoldState> secondHoldAddress =
          StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
      WatermarkHoldState secondHold =
          internals.state(StateNamespaces.window(null, second), secondHoldAddress);
      secondHold.add(new Instant(24L));
  
      internals.commit();
      assertThat(internals.getEarliestWatermarkHold(), equalTo(new Instant(24L)));
    }
  
    @Test
    public void testGetEarliestHoldBeforeCommit() {
      CopyOnAccessInMemoryStateInternals<String> internals =
          CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
  
      internals
          .state(
              StateNamespaces.global(),
              StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST))
          .add(new Instant(1234L));
  
      thrown.expect(IllegalStateException.class);
      thrown.expectMessage(CopyOnAccessInMemoryStateInternals.class.getSimpleName());
      thrown.expectMessage("Can't get the earliest watermark hold");
      thrown.expectMessage("before it is committed");
  
      internals.getEarliestWatermarkHold();
    }
  }
  