JAVA-3070: Make CqlVector and CqlDuration serializable (#1676)

Author: hhughes

core/src/main/java/com/datastax/oss/driver/api/core/data/CqlDuration.java

@@ -20,6 +20,7 @@
 import com.datastax.oss.driver.shaded.guava.common.base.Preconditions;
 import com.datastax.oss.driver.shaded.guava.common.collect.ImmutableList;
 import edu.umd.cs.findbugs.annotations.NonNull;
+import java.io.Serializable;
 import java.time.Duration;
 import java.time.Period;
 import java.time.temporal.ChronoUnit;
@@ -42,7 +43,9 @@
  * in time, regardless of the calendar).
  */
 @Immutable
-public final class CqlDuration implements TemporalAmount {
+public final class CqlDuration implements TemporalAmount, Serializable {
+
+  private static final long serialVersionUID = 1L;
 
   @VisibleForTesting static final long NANOS_PER_MICRO = 1000L;
   @VisibleForTesting static final long NANOS_PER_MILLI = 1000 * NANOS_PER_MICRO;
@@ -75,8 +78,11 @@ public final class CqlDuration implements TemporalAmount {
   private static final ImmutableList<TemporalUnit> TEMPORAL_UNITS =
       ImmutableList.of(ChronoUnit.MONTHS, ChronoUnit.DAYS, ChronoUnit.NANOS);
 
+  /** @serial */
   private final int months;
+  /** @serial */
   private final int days;
+  /** @serial */
   private final long nanoseconds;
 
   private CqlDuration(int months, int days, long nanoseconds) {

core/src/main/java/com/datastax/oss/driver/api/core/data/CqlVector.java

@@ -22,6 +22,12 @@
 import com.datastax.oss.driver.shaded.guava.common.collect.Iterables;
 import com.datastax.oss.driver.shaded.guava.common.collect.Streams;
 import edu.umd.cs.findbugs.annotations.NonNull;
+import java.io.IOException;
+import java.io.InvalidObjectException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.ObjectStreamException;
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Iterator;
@@ -44,7 +50,7 @@
  * where possible we've tried to make the API of this class similar to the equivalent methods on
  * {@link List}.
  */
-public class CqlVector<T extends Number> implements Iterable<T> {
+public class CqlVector<T extends Number> implements Iterable<T>, Serializable {
 
   /**
    * Create a new CqlVector containing the specified values.
@@ -190,4 +196,58 @@ public int hashCode() {
   public String toString() {
     return Iterables.toString(this.list);
   }
+
+  /**
+   * Serialization proxy for CqlVector. Allows serialization regardless of implementation of list
+   * field.
+   *
+   * @param <T> inner type of CqlVector, assume Number is always Serializable.
+   */
+  private static class SerializationProxy<T extends Number> implements Serializable {
+
+    private static final long serialVersionUID = 1;
+
+    private transient List<T> list;
+
+    SerializationProxy(CqlVector<T> vector) {
+      this.list = vector.list;
+    }
+
+    // Reconstruct CqlVector's list of elements.
+    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
+      stream.defaultReadObject();
+
+      int size = stream.readInt();
+      list = new ArrayList<>(size);
+      for (int i = 0; i < size; i++) {
+        list.add((T) stream.readObject());
+      }
+    }
+
+    // Return deserialized proxy object as CqlVector.
+    private Object readResolve() throws ObjectStreamException {
+      return new CqlVector(list);
+    }
+
+    // Write size of CqlVector followed by items in order.
+    private void writeObject(ObjectOutputStream stream) throws IOException {
+      stream.defaultWriteObject();
+
+      stream.writeInt(list.size());
+      for (T item : list) {
+        stream.writeObject(item);
+      }
+    }
+  }
+
+  /** @serialData The number of elements in the vector, followed by each element in-order. */
+  private Object writeReplace() {
+    return new SerializationProxy(this);
+  }
+
+  private void readObject(@SuppressWarnings("unused") ObjectInputStream stream)
+      throws InvalidObjectException {
+    // Should never be called since we serialized a proxy
+    throw new InvalidObjectException("Proxy required");
+  }
 }

core/src/test/java/com/datastax/oss/driver/api/core/data/CqlDurationTest.java

@@ -20,6 +20,7 @@
 import static org.assertj.core.api.Assertions.fail;
 
 import com.datastax.oss.driver.TestDataProviders;
+import com.datastax.oss.driver.internal.SerializationHelper;
 import com.tngtech.java.junit.dataprovider.DataProviderRunner;
 import com.tngtech.java.junit.dataprovider.UseDataProvider;
 import java.time.ZonedDateTime;
@@ -190,4 +191,18 @@ public void should_subtract_from_temporal() {
     assertThat(dateTime.minus(CqlDuration.from("1h15s15ns")))
         .isEqualTo("2018-10-03T22:59:44.999999985-07:00[America/Los_Angeles]");
   }
+
+  @Test
+  public void should_serialize_and_deserialize() throws Exception {
+    CqlDuration initial = CqlDuration.from("3mo2d15s");
+    CqlDuration deserialized = SerializationHelper.serializeAndDeserialize(initial);
+    assertThat(deserialized).isEqualTo(initial);
+  }
+
+  @Test
+  public void should_serialize_and_deserialize_negative() throws Exception {
+    CqlDuration initial = CqlDuration.from("-2d15m");
+    CqlDuration deserialized = SerializationHelper.serializeAndDeserialize(initial);
+    assertThat(deserialized).isEqualTo(initial);
+  }
 }

core/src/test/java/com/datastax/oss/driver/api/core/data/CqlVectorTest.java

@@ -19,9 +19,12 @@
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import com.datastax.oss.driver.api.core.type.codec.TypeCodecs;
+import com.datastax.oss.driver.internal.SerializationHelper;
 import com.datastax.oss.driver.shaded.guava.common.collect.Iterators;
+import java.util.AbstractList;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 import org.assertj.core.util.Lists;
@@ -195,4 +198,37 @@ public void should_correctly_compare_vectors() {
     assertThat(vector1).isNotSameAs(vector5);
     assertThat(vector1).isNotEqualTo(vector5);
   }
+
+  @Test
+  public void should_serialize_and_deserialize() throws Exception {
+    CqlVector<Float> initial = CqlVector.newInstance(VECTOR_ARGS);
+    CqlVector<Float> deserialized = SerializationHelper.serializeAndDeserialize(initial);
+    assertThat(deserialized).isEqualTo(initial);
+  }
+
+  @Test
+  public void should_serialize_and_deserialize_empty_vector() throws Exception {
+    CqlVector<Float> initial = CqlVector.newInstance(Collections.emptyList());
+    CqlVector<Float> deserialized = SerializationHelper.serializeAndDeserialize(initial);
+    assertThat(deserialized).isEqualTo(initial);
+  }
+
+  @Test
+  public void should_serialize_and_deserialize_unserializable_list() throws Exception {
+    CqlVector<Float> initial =
+        CqlVector.newInstance(
+            new AbstractList<Float>() {
+              @Override
+              public Float get(int index) {
+                return VECTOR_ARGS[index];
+              }
+
+              @Override
+              public int size() {
+                return VECTOR_ARGS.length;
+              }
+            });
+    CqlVector<Float> deserialized = SerializationHelper.serializeAndDeserialize(initial);
+    assertThat(deserialized).isEqualTo(initial);
+  }
 }