org.apache.flink.api.common.typeutils.TypeSerializerSnapshotSerializationUtil Java Examples

@Test
public void testMigrationStrategyForRemovedAvroDependency() throws Exception {
	KryoSerializer<TestClass> kryoSerializerForA = new KryoSerializer<>(TestClass.class, new ExecutionConfig());

	// read configuration again from bytes
	TypeSerializerSnapshot kryoSerializerConfigSnapshot;
	try (InputStream in = getClass().getResourceAsStream("/kryo-serializer-flink1.3-snapshot")) {
		kryoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), kryoSerializerForA);
	}

	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<TestClass> compatResult =
		kryoSerializerConfigSnapshot.resolveSchemaCompatibility(kryoSerializerForA);
	assertTrue(compatResult.isCompatibleAsIs());
}
 

@Test
public void testMigrationStrategyForRemovedAvroDependency() throws Exception {
	KryoSerializer<TestClass> kryoSerializerForA = new KryoSerializer<>(TestClass.class, new ExecutionConfig());

	// read configuration again from bytes
	TypeSerializerSnapshot kryoSerializerConfigSnapshot;
	try (InputStream in = getClass().getResourceAsStream("/kryo-serializer-flink1.3-snapshot")) {
		kryoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), kryoSerializerForA);
	}

	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<TestClass> compatResult =
		kryoSerializerConfigSnapshot.resolveSchemaCompatibility(kryoSerializerForA);
	assertTrue(compatResult.isCompatibleAsIs());
}
 

@Test
public void testMigrationStrategyForRemovedAvroDependency() throws Exception {
	KryoSerializer<TestClass> kryoSerializerForA = new KryoSerializer<>(TestClass.class, new ExecutionConfig());

	// read configuration again from bytes
	TypeSerializerSnapshot kryoSerializerConfigSnapshot;
	try (InputStream in = getClass().getResourceAsStream("/kryo-serializer-flink1.3-snapshot")) {
		kryoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), kryoSerializerForA);
	}

	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<TestClass> compatResult =
		kryoSerializerConfigSnapshot.resolveSchemaCompatibility(kryoSerializerForA);
	assertTrue(compatResult.isCompatibleAsIs());
}
 

@Test
public void testConfigurationSnapshotSerialization() throws Exception {
	EnumSerializer<PublicEnum> serializer = new EnumSerializer<>(PublicEnum.class);

	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), serializer.snapshotConfiguration(), serializer);
		serializedConfig = out.toByteArray();
	}

	TypeSerializerSnapshot<PublicEnum> restoredConfig;
	try (ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		restoredConfig = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), serializer);
	}

	TypeSerializerSchemaCompatibility<PublicEnum> compatResult = restoredConfig.resolveSchemaCompatibility(serializer);
	assertTrue(compatResult.isCompatibleAsIs());

	assertEquals(PublicEnum.FOO.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.FOO).intValue());
	assertEquals(PublicEnum.BAR.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.BAR).intValue());
	assertEquals(PublicEnum.PETER.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.PETER).intValue());
	assertEquals(PublicEnum.NATHANIEL.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.NATHANIEL).intValue());
	assertEquals(PublicEnum.EMMA.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.EMMA).intValue());
	assertEquals(PublicEnum.PAULA.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.PAULA).intValue());
	assertTrue(Arrays.equals(PublicEnum.values(), serializer.getValues()));
}
 

/**
 * Verifies that reconfiguring with a config snapshot of a preceding POJO serializer
 * with different POJO type will result in INCOMPATIBLE.
 */
@Test
public void testReconfigureWithDifferentPojoType() throws Exception {
	PojoSerializer<SubTestUserClassB> pojoSerializer1 = (PojoSerializer<SubTestUserClassB>)
		TypeExtractor.getForClass(SubTestUserClassB.class).createSerializer(new ExecutionConfig());

	// snapshot configuration and serialize to bytes
	TypeSerializerSnapshot pojoSerializerConfigSnapshot = pojoSerializer1.snapshotConfiguration();
	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), pojoSerializerConfigSnapshot, pojoSerializer1);
		serializedConfig = out.toByteArray();
	}

	PojoSerializer<SubTestUserClassA> pojoSerializer2 = (PojoSerializer<SubTestUserClassA>)
		TypeExtractor.getForClass(SubTestUserClassA.class).createSerializer(new ExecutionConfig());

	// read configuration again from bytes
	try(ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		pojoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), pojoSerializer2);
	}

	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<SubTestUserClassA> compatResult =
		pojoSerializerConfigSnapshot.resolveSchemaCompatibility(pojoSerializer2);
	assertTrue(compatResult.isIncompatible());
}
 

/**
 * Snapshot and restore the given serializer. Returns the restored serializer.
 */
public static <T> TypeSerializer<T> snapshotAndReconfigure(
	TypeSerializer<T> serializer, SerializerGetter<T> serializerGetter) throws IOException {
	TypeSerializerSnapshot<T> configSnapshot = serializer.snapshotConfiguration();

	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), configSnapshot, serializer);
		serializedConfig = out.toByteArray();
	}

	TypeSerializerSnapshot<T> restoredConfig;
	try (ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		restoredConfig = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in),
			Thread.currentThread().getContextClassLoader(),
			serializerGetter.getSerializer());
	}

	TypeSerializerSchemaCompatibility<T> strategy =
		restoredConfig.resolveSchemaCompatibility(serializerGetter.getSerializer());
	final TypeSerializer<T> restoredSerializer;
	if (strategy.isCompatibleAsIs()) {
		restoredSerializer = restoredConfig.restoreSerializer();
	}
	else if (strategy.isCompatibleWithReconfiguredSerializer()) {
		restoredSerializer = strategy.getReconfiguredSerializer();
	}
	else {
		throw new AssertionError("Unable to restore serializer with " + strategy);
	}
	assertEquals(serializer.getClass(), restoredSerializer.getClass());

	return restoredSerializer;
}
 

/**
 * Verifies that reconfiguration result is INCOMPATIBLE if data type has changed.
 */
@Test
public void testMigrationStrategyWithDifferentKryoType() throws Exception {
	KryoSerializer<TestClassA> kryoSerializerForA = new KryoSerializer<>(TestClassA.class, new ExecutionConfig());

	// snapshot configuration and serialize to bytes
	TypeSerializerSnapshot kryoSerializerConfigSnapshot = kryoSerializerForA.snapshotConfiguration();
	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), kryoSerializerConfigSnapshot, kryoSerializerForA);
		serializedConfig = out.toByteArray();
	}

	KryoSerializer<TestClassB> kryoSerializerForB = new KryoSerializer<>(TestClassB.class, new ExecutionConfig());

	// read configuration again from bytes
	try (ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		kryoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), kryoSerializerForB);
	}

	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<TestClassB> compatResult =
		kryoSerializerConfigSnapshot.resolveSchemaCompatibility(kryoSerializerForB);
	assertTrue(compatResult.isIncompatible());
}
 

@Override
public void write(DataOutputView out) throws IOException {
	super.write(out);

	// write the compression format used to write each key-group
	out.writeBoolean(usingKeyGroupCompression);

	TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(out, keySerializerSnapshot, keySerializer);

	// write individual registered keyed state metainfos
	out.writeShort(stateMetaInfoSnapshots.size());
	for (StateMetaInfoSnapshot metaInfoSnapshot : stateMetaInfoSnapshots) {
		StateMetaInfoSnapshotReadersWriters.getWriter().writeStateMetaInfoSnapshot(metaInfoSnapshot, out);
	}
}
 

@Nonnull
@Override
public StateMetaInfoSnapshot readStateMetaInfoSnapshot(
	@Nonnull DataInputView inputView,
	@Nonnull ClassLoader userCodeClassLoader) throws IOException {

	final String stateName = inputView.readUTF();
	final StateMetaInfoSnapshot.BackendStateType stateType =
		StateMetaInfoSnapshot.BackendStateType.values()[inputView.readInt()];
	final int numOptions = inputView.readInt();
	HashMap<String, String> optionsMap = new HashMap<>(numOptions);
	for (int i = 0; i < numOptions; ++i) {
		String key = inputView.readUTF();
		String value = inputView.readUTF();
		optionsMap.put(key, value);
	}

	final int numSerializerConfigSnapshots = inputView.readInt();
	final HashMap<String, TypeSerializerSnapshot<?>> serializerConfigsMap = new HashMap<>(numSerializerConfigSnapshots);

	for (int i = 0; i < numSerializerConfigSnapshots; ++i) {
		serializerConfigsMap.put(
			inputView.readUTF(),
			TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
				inputView, userCodeClassLoader, null));
	}

	return new StateMetaInfoSnapshot(stateName, stateType, optionsMap, serializerConfigsMap);
}
 

@Test
public void testConfigurationSnapshotSerialization() throws Exception {
	EnumSerializer<PublicEnum> serializer = new EnumSerializer<>(PublicEnum.class);

	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), serializer.snapshotConfiguration(), serializer);
		serializedConfig = out.toByteArray();
	}

	TypeSerializerSnapshot<PublicEnum> restoredConfig;
	try (ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		restoredConfig = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), serializer);
	}

	TypeSerializerSchemaCompatibility<PublicEnum> compatResult = restoredConfig.resolveSchemaCompatibility(serializer);
	assertTrue(compatResult.isCompatibleAsIs());

	assertEquals(PublicEnum.FOO.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.FOO).intValue());
	assertEquals(PublicEnum.BAR.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.BAR).intValue());
	assertEquals(PublicEnum.PETER.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.PETER).intValue());
	assertEquals(PublicEnum.NATHANIEL.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.NATHANIEL).intValue());
	assertEquals(PublicEnum.EMMA.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.EMMA).intValue());
	assertEquals(PublicEnum.PAULA.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.PAULA).intValue());
	assertTrue(Arrays.equals(PublicEnum.values(), serializer.getValues()));
}
 

@SuppressWarnings("unchecked")
private static TypeSerializerSchemaCompatibility checkCompatibility(String enumSourceA, String enumSourceB)
	throws IOException, ClassNotFoundException {

	ClassLoader classLoader = ClassLoaderUtils.compileAndLoadJava(
		temporaryFolder.newFolder(), ENUM_NAME + ".java", enumSourceA);

	EnumSerializer enumSerializer = new EnumSerializer(classLoader.loadClass(ENUM_NAME));

	TypeSerializerSnapshot snapshot = enumSerializer.snapshotConfiguration();
	byte[] snapshotBytes;
	try (
		ByteArrayOutputStream outBuffer = new ByteArrayOutputStream();
		DataOutputViewStreamWrapper outputViewStreamWrapper = new DataOutputViewStreamWrapper(outBuffer)) {

		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			outputViewStreamWrapper, snapshot, enumSerializer);
		snapshotBytes = outBuffer.toByteArray();
	}

	ClassLoader classLoader2 = ClassLoaderUtils.compileAndLoadJava(
		temporaryFolder.newFolder(), ENUM_NAME + ".java", enumSourceB);

	TypeSerializerSnapshot restoredSnapshot;
	try (
		ByteArrayInputStream inBuffer = new ByteArrayInputStream(snapshotBytes);
		DataInputViewStreamWrapper inputViewStreamWrapper = new DataInputViewStreamWrapper(inBuffer)) {

		restoredSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			inputViewStreamWrapper, classLoader2, enumSerializer);
	}

	EnumSerializer enumSerializer2 = new EnumSerializer(classLoader2.loadClass(ENUM_NAME));
	return restoredSnapshot.resolveSchemaCompatibility(enumSerializer2);
}
 

/**
 * Verifies that reconfiguration result is INCOMPATIBLE if data type has changed.
 */
@Test
public void testMigrationStrategyWithDifferentKryoType() throws Exception {
	KryoSerializer<TestClassA> kryoSerializerForA = new KryoSerializer<>(TestClassA.class, new ExecutionConfig());

	// snapshot configuration and serialize to bytes
	TypeSerializerSnapshot kryoSerializerConfigSnapshot = kryoSerializerForA.snapshotConfiguration();
	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), kryoSerializerConfigSnapshot, kryoSerializerForA);
		serializedConfig = out.toByteArray();
	}

	KryoSerializer<TestClassB> kryoSerializerForB = new KryoSerializer<>(TestClassB.class, new ExecutionConfig());

	// read configuration again from bytes
	try (ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		kryoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), kryoSerializerForB);
	}

	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<TestClassB> compatResult =
		kryoSerializerConfigSnapshot.resolveSchemaCompatibility(kryoSerializerForB);
	assertTrue(compatResult.isIncompatible());
}
 

@SuppressWarnings("unchecked")
private static TypeSerializerSchemaCompatibility checkCompatibility(String enumSourceA, String enumSourceB)
	throws IOException, ClassNotFoundException {

	ClassLoader classLoader = ClassLoaderUtils.compileAndLoadJava(
		temporaryFolder.newFolder(), ENUM_NAME + ".java", enumSourceA);

	EnumSerializer enumSerializer = new EnumSerializer(classLoader.loadClass(ENUM_NAME));

	TypeSerializerSnapshot snapshot = enumSerializer.snapshotConfiguration();
	byte[] snapshotBytes;
	try (
		ByteArrayOutputStream outBuffer = new ByteArrayOutputStream();
		DataOutputViewStreamWrapper outputViewStreamWrapper = new DataOutputViewStreamWrapper(outBuffer)) {

		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			outputViewStreamWrapper, snapshot, enumSerializer);
		snapshotBytes = outBuffer.toByteArray();
	}

	ClassLoader classLoader2 = ClassLoaderUtils.compileAndLoadJava(
		temporaryFolder.newFolder(), ENUM_NAME + ".java", enumSourceB);

	TypeSerializerSnapshot restoredSnapshot;
	try (
		ByteArrayInputStream inBuffer = new ByteArrayInputStream(snapshotBytes);
		DataInputViewStreamWrapper inputViewStreamWrapper = new DataInputViewStreamWrapper(inBuffer)) {

		restoredSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			inputViewStreamWrapper, classLoader2, enumSerializer);
	}

	EnumSerializer enumSerializer2 = new EnumSerializer(classLoader2.loadClass(ENUM_NAME));
	return restoredSnapshot.resolveSchemaCompatibility(enumSerializer2);
}
 

/**
 * Verifies that reconfiguring with a config snapshot of a preceding POJO serializer
 * with different POJO type will result in INCOMPATIBLE.
 */
@Test
public void testReconfigureWithDifferentPojoType() throws Exception {
	PojoSerializer<SubTestUserClassB> pojoSerializer1 = (PojoSerializer<SubTestUserClassB>)
		TypeExtractor.getForClass(SubTestUserClassB.class).createSerializer(new ExecutionConfig());

	// snapshot configuration and serialize to bytes
	TypeSerializerSnapshot pojoSerializerConfigSnapshot = pojoSerializer1.snapshotConfiguration();
	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), pojoSerializerConfigSnapshot, pojoSerializer1);
		serializedConfig = out.toByteArray();
	}

	PojoSerializer<SubTestUserClassA> pojoSerializer2 = (PojoSerializer<SubTestUserClassA>)
		TypeExtractor.getForClass(SubTestUserClassA.class).createSerializer(new ExecutionConfig());

	// read configuration again from bytes
	try(ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		pojoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), pojoSerializer2);
	}

	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<SubTestUserClassA> compatResult =
		pojoSerializerConfigSnapshot.resolveSchemaCompatibility(pojoSerializer2);
	assertTrue(compatResult.isIncompatible());
}
 

/**
 * Snapshot and restore the given serializer. Returns the restored serializer.
 */
public static <T> TypeSerializer<T> snapshotAndReconfigure(
	TypeSerializer<T> serializer, SerializerGetter<T> serializerGetter) throws IOException {
	TypeSerializerSnapshot<T> configSnapshot = serializer.snapshotConfiguration();

	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), configSnapshot, serializer);
		serializedConfig = out.toByteArray();
	}

	TypeSerializerSnapshot<T> restoredConfig;
	try (ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		restoredConfig = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in),
			Thread.currentThread().getContextClassLoader(),
			serializerGetter.getSerializer());
	}

	TypeSerializerSchemaCompatibility<T> strategy =
		restoredConfig.resolveSchemaCompatibility(serializerGetter.getSerializer());
	final TypeSerializer<T> restoredSerializer;
	if (strategy.isCompatibleAsIs()) {
		restoredSerializer = restoredConfig.restoreSerializer();
	}
	else if (strategy.isCompatibleWithReconfiguredSerializer()) {
		restoredSerializer = strategy.getReconfiguredSerializer();
	}
	else {
		throw new AssertionError("Unable to restore serializer with " + strategy);
	}
	assertEquals(serializer.getClass(), restoredSerializer.getClass());

	return restoredSerializer;
}
 

@Nonnull
@Override
public StateMetaInfoSnapshot readStateMetaInfoSnapshot(
	@Nonnull DataInputView inputView,
	@Nonnull ClassLoader userCodeClassLoader) throws IOException {

	final String stateName = inputView.readUTF();
	final StateMetaInfoSnapshot.BackendStateType stateType =
		StateMetaInfoSnapshot.BackendStateType.values()[inputView.readInt()];
	final int numOptions = inputView.readInt();
	HashMap<String, String> optionsMap = new HashMap<>(numOptions);
	for (int i = 0; i < numOptions; ++i) {
		String key = inputView.readUTF();
		String value = inputView.readUTF();
		optionsMap.put(key, value);
	}

	final int numSerializerConfigSnapshots = inputView.readInt();
	final HashMap<String, TypeSerializerSnapshot<?>> serializerConfigsMap = new HashMap<>(numSerializerConfigSnapshots);

	for (int i = 0; i < numSerializerConfigSnapshots; ++i) {
		serializerConfigsMap.put(
			inputView.readUTF(),
			TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
				inputView, userCodeClassLoader, null));
	}

	return new StateMetaInfoSnapshot(stateName, stateType, optionsMap, serializerConfigsMap);
}
 

@Override
public void write(DataOutputView out) throws IOException {
	super.write(out);

	// write the compression format used to write each key-group
	out.writeBoolean(usingKeyGroupCompression);

	TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(out, keySerializerSnapshot, keySerializer);

	// write individual registered keyed state metainfos
	out.writeShort(stateMetaInfoSnapshots.size());
	for (StateMetaInfoSnapshot metaInfoSnapshot : stateMetaInfoSnapshots) {
		StateMetaInfoSnapshotReadersWriters.getWriter().writeStateMetaInfoSnapshot(metaInfoSnapshot, out);
	}
}
 

@Nonnull
@Override
public StateMetaInfoSnapshot readStateMetaInfoSnapshot(
	@Nonnull DataInputView inputView,
	@Nonnull ClassLoader userCodeClassLoader) throws IOException {

	final String stateName = inputView.readUTF();
	final StateMetaInfoSnapshot.BackendStateType stateType =
		StateMetaInfoSnapshot.BackendStateType.values()[inputView.readInt()];
	final int numOptions = inputView.readInt();
	HashMap<String, String> optionsMap = new HashMap<>(numOptions);
	for (int i = 0; i < numOptions; ++i) {
		String key = inputView.readUTF();
		String value = inputView.readUTF();
		optionsMap.put(key, value);
	}

	final int numSerializerConfigSnapshots = inputView.readInt();
	final HashMap<String, TypeSerializerSnapshot<?>> serializerConfigsMap = new HashMap<>(numSerializerConfigSnapshots);

	for (int i = 0; i < numSerializerConfigSnapshots; ++i) {
		serializerConfigsMap.put(
			inputView.readUTF(),
			TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
				inputView, userCodeClassLoader, null));
	}

	return new StateMetaInfoSnapshot(stateName, stateType, optionsMap, serializerConfigsMap);
}
 

@Test
public void testConfigurationSnapshotSerialization() throws Exception {
	EnumSerializer<PublicEnum> serializer = new EnumSerializer<>(PublicEnum.class);

	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), serializer.snapshotConfiguration(), serializer);
		serializedConfig = out.toByteArray();
	}

	TypeSerializerSnapshot<PublicEnum> restoredConfig;
	try (ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		restoredConfig = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), serializer);
	}

	TypeSerializerSchemaCompatibility<PublicEnum> compatResult = restoredConfig.resolveSchemaCompatibility(serializer);
	assertTrue(compatResult.isCompatibleAsIs());

	assertEquals(PublicEnum.FOO.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.FOO).intValue());
	assertEquals(PublicEnum.BAR.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.BAR).intValue());
	assertEquals(PublicEnum.PETER.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.PETER).intValue());
	assertEquals(PublicEnum.NATHANIEL.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.NATHANIEL).intValue());
	assertEquals(PublicEnum.EMMA.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.EMMA).intValue());
	assertEquals(PublicEnum.PAULA.ordinal(), serializer.getValueToOrdinal().get(PublicEnum.PAULA).intValue());
	assertTrue(Arrays.equals(PublicEnum.values(), serializer.getValues()));
}
 

@SuppressWarnings("unchecked")
private static TypeSerializerSchemaCompatibility checkCompatibility(String enumSourceA, String enumSourceB)
	throws IOException, ClassNotFoundException {

	ClassLoader classLoader = ClassLoaderUtils.compileAndLoadJava(
		temporaryFolder.newFolder(), ENUM_NAME + ".java", enumSourceA);

	EnumSerializer enumSerializer = new EnumSerializer(classLoader.loadClass(ENUM_NAME));

	TypeSerializerSnapshot snapshot = enumSerializer.snapshotConfiguration();
	byte[] snapshotBytes;
	try (
		ByteArrayOutputStream outBuffer = new ByteArrayOutputStream();
		DataOutputViewStreamWrapper outputViewStreamWrapper = new DataOutputViewStreamWrapper(outBuffer)) {

		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			outputViewStreamWrapper, snapshot, enumSerializer);
		snapshotBytes = outBuffer.toByteArray();
	}

	ClassLoader classLoader2 = ClassLoaderUtils.compileAndLoadJava(
		temporaryFolder.newFolder(), ENUM_NAME + ".java", enumSourceB);

	TypeSerializerSnapshot restoredSnapshot;
	try (
		ByteArrayInputStream inBuffer = new ByteArrayInputStream(snapshotBytes);
		DataInputViewStreamWrapper inputViewStreamWrapper = new DataInputViewStreamWrapper(inBuffer)) {

		restoredSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			inputViewStreamWrapper, classLoader2, enumSerializer);
	}

	EnumSerializer enumSerializer2 = new EnumSerializer(classLoader2.loadClass(ENUM_NAME));
	return restoredSnapshot.resolveSchemaCompatibility(enumSerializer2);
}
 

/**
 * Verifies that reconfiguration result is INCOMPATIBLE if data type has changed.
 */
@Test
public void testMigrationStrategyWithDifferentKryoType() throws Exception {
	KryoSerializer<TestClassA> kryoSerializerForA = new KryoSerializer<>(TestClassA.class, new ExecutionConfig());

	// snapshot configuration and serialize to bytes
	TypeSerializerSnapshot kryoSerializerConfigSnapshot = kryoSerializerForA.snapshotConfiguration();
	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), kryoSerializerConfigSnapshot, kryoSerializerForA);
		serializedConfig = out.toByteArray();
	}

	KryoSerializer<TestClassB> kryoSerializerForB = new KryoSerializer<>(TestClassB.class, new ExecutionConfig());

	// read configuration again from bytes
	try (ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		kryoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), kryoSerializerForB);
	}

	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<TestClassB> compatResult =
		kryoSerializerConfigSnapshot.resolveSchemaCompatibility(kryoSerializerForB);
	assertTrue(compatResult.isIncompatible());
}
 

@Override
public void write(DataOutputView out) throws IOException {
	super.write(out);

	// write the compression format used to write each key-group
	out.writeBoolean(usingKeyGroupCompression);

	TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(out, keySerializerSnapshot, keySerializer);

	// write individual registered keyed state metainfos
	out.writeShort(stateMetaInfoSnapshots.size());
	for (StateMetaInfoSnapshot metaInfoSnapshot : stateMetaInfoSnapshots) {
		StateMetaInfoSnapshotReadersWriters.getWriter().writeStateMetaInfoSnapshot(metaInfoSnapshot, out);
	}
}
 

/**
 * Verifies that reconfiguring with a config snapshot of a preceding POJO serializer
 * with different POJO type will result in INCOMPATIBLE.
 */
@Test
public void testReconfigureWithDifferentPojoType() throws Exception {
	PojoSerializer<SubTestUserClassB> pojoSerializer1 = (PojoSerializer<SubTestUserClassB>)
		TypeExtractor.getForClass(SubTestUserClassB.class).createSerializer(new ExecutionConfig());

	// snapshot configuration and serialize to bytes
	TypeSerializerSnapshot pojoSerializerConfigSnapshot = pojoSerializer1.snapshotConfiguration();
	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), pojoSerializerConfigSnapshot, pojoSerializer1);
		serializedConfig = out.toByteArray();
	}

	PojoSerializer<SubTestUserClassA> pojoSerializer2 = (PojoSerializer<SubTestUserClassA>)
		TypeExtractor.getForClass(SubTestUserClassA.class).createSerializer(new ExecutionConfig());

	// read configuration again from bytes
	try(ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		pojoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), pojoSerializer2);
	}

	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<SubTestUserClassA> compatResult =
		pojoSerializerConfigSnapshot.resolveSchemaCompatibility(pojoSerializer2);
	assertTrue(compatResult.isIncompatible());
}
 

@SuppressWarnings("unchecked")
@Override
public void read(DataInputView in) throws IOException {
	super.read(in);

	final int readVersion = getReadVersion();

	if (readVersion >= 4) {
		usingKeyGroupCompression = in.readBoolean();
	} else {
		usingKeyGroupCompression = false;
	}

	// only starting from version 3, we have the key serializer and its config snapshot written
	if (readVersion >= 6) {
		this.keySerializerSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			in, userCodeClassLoader, null);
	} else if (readVersion >= 3) {
		Tuple2<TypeSerializer<?>, TypeSerializerSnapshot<?>> keySerializerAndConfig =
				TypeSerializerSerializationUtil.readSerializersAndConfigsWithResilience(in, userCodeClassLoader).get(0);
		this.keySerializerSnapshot = (TypeSerializerSnapshot<K>) keySerializerAndConfig.f1;
	} else {
		this.keySerializerSnapshot = new BackwardsCompatibleSerializerSnapshot<>(
			TypeSerializerSerializationUtil.tryReadSerializer(in, userCodeClassLoader, true));
	}
	this.keySerializer = null;

	Integer metaInfoSnapshotVersion = META_INFO_SNAPSHOT_FORMAT_VERSION_MAPPER.get(readVersion);
	if (metaInfoSnapshotVersion == null) {
		// this should not happen; guard for the future
		throw new IOException("Cannot determine corresponding meta info snapshot version for keyed backend serialization readVersion=" + readVersion);
	}
	final StateMetaInfoReader stateMetaInfoReader = StateMetaInfoSnapshotReadersWriters.getReader(
		metaInfoSnapshotVersion,
		StateMetaInfoSnapshotReadersWriters.StateTypeHint.KEYED_STATE);

	int numKvStates = in.readShort();
	stateMetaInfoSnapshots = new ArrayList<>(numKvStates);
	for (int i = 0; i < numKvStates; i++) {
		StateMetaInfoSnapshot snapshot = stateMetaInfoReader.readStateMetaInfoSnapshot(in, userCodeClassLoader);

		stateMetaInfoSnapshots.add(snapshot);
	}
}
 

/**
 * Tests that:
 *  - Previous Pojo serializer did not have registrations, and created cached serializers for subclasses
 *  - On restore, it had those subclasses registered
 *
 * In this case, after reconfiguration, the cache should be repopulated, and registrations should
 * also exist for the subclasses.
 *
 * Note: the cache still needs to be repopulated because previous data of those subclasses were
 * written with the cached serializers. In this case, the repopulated cache has reconfigured serializers
 * for the subclasses so that previous written data can be read, but the registered serializers
 * for the subclasses do not necessarily need to be reconfigured since they will only be used to
 * write new data.
 */
@Test
public void testReconfigureWithPreviouslyNonregisteredSubclasses() throws Exception {
	// don't register any subclasses at first
	PojoSerializer<TestUserClass> pojoSerializer = (PojoSerializer<TestUserClass>) type.createSerializer(new ExecutionConfig());

	// create cached serializers for SubTestUserClassA and SubTestUserClassB
	pojoSerializer.getSubclassSerializer(SubTestUserClassA.class);
	pojoSerializer.getSubclassSerializer(SubTestUserClassB.class);

	// make sure serializers are in cache
	assertEquals(2, pojoSerializer.getSubclassSerializerCache().size());
	assertTrue(pojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassA.class));
	assertTrue(pojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassB.class));

	// make sure that registrations are empty
	assertTrue(pojoSerializer.getRegisteredClasses().isEmpty());
	assertEquals(0, pojoSerializer.getRegisteredSerializers().length);

	// snapshot configuration and serialize to bytes
	TypeSerializerSnapshot pojoSerializerConfigSnapshot = pojoSerializer.snapshotConfiguration();
	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), pojoSerializerConfigSnapshot, pojoSerializer);
		serializedConfig = out.toByteArray();
	}

	// instantiate new PojoSerializer, with new execution config that has the subclass registrations
	ExecutionConfig newExecutionConfig = new ExecutionConfig();
	newExecutionConfig.registerPojoType(SubTestUserClassA.class);
	newExecutionConfig.registerPojoType(SubTestUserClassB.class);
	pojoSerializer = (PojoSerializer<TestUserClass>) type.createSerializer(newExecutionConfig);

	// read configuration from bytes
	try(ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		pojoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), pojoSerializer);
	}

	// reconfigure - check reconfiguration result and that
	// 1) subclass serializer cache is repopulated
	// 2) registrations also contain the now registered subclasses
	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<TestUserClass> compatResult =
		pojoSerializerConfigSnapshot.resolveSchemaCompatibility(pojoSerializer);
	assertTrue(compatResult.isCompatibleWithReconfiguredSerializer());
	assertTrue(compatResult.getReconfiguredSerializer() instanceof PojoSerializer);

	PojoSerializer<TestUserClass> reconfiguredPojoSerializer = (PojoSerializer<TestUserClass>) compatResult.getReconfiguredSerializer();
	assertEquals(2, reconfiguredPojoSerializer.getSubclassSerializerCache().size());
	assertTrue(reconfiguredPojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassA.class));
	assertTrue(reconfiguredPojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassB.class));
	assertEquals(2, reconfiguredPojoSerializer.getRegisteredClasses().size());
	assertTrue(reconfiguredPojoSerializer.getRegisteredClasses().containsKey(SubTestUserClassA.class));
	assertTrue(reconfiguredPojoSerializer.getRegisteredClasses().containsKey(SubTestUserClassB.class));
}
 

/**
 * Tests that reconfiguration repopulates previously cached subclass serializers.
 */
@Test
public void testReconfigureRepopulateNonregisteredSubclassSerializerCache() throws Exception {
	// don't register any subclasses
	PojoSerializer<TestUserClass> pojoSerializer = (PojoSerializer<TestUserClass>) type.createSerializer(new ExecutionConfig());

	// create cached serializers for SubTestUserClassA and SubTestUserClassB
	pojoSerializer.getSubclassSerializer(SubTestUserClassA.class);
	pojoSerializer.getSubclassSerializer(SubTestUserClassB.class);

	assertEquals(2, pojoSerializer.getSubclassSerializerCache().size());
	assertTrue(pojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassA.class));
	assertTrue(pojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassB.class));

	// snapshot configuration and serialize to bytes
	TypeSerializerSnapshot pojoSerializerConfigSnapshot = pojoSerializer.snapshotConfiguration();
	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), pojoSerializerConfigSnapshot, pojoSerializer);
		serializedConfig = out.toByteArray();
	}

	// instantiate new PojoSerializer

	pojoSerializer = (PojoSerializer<TestUserClass>) type.createSerializer(new ExecutionConfig());

	// read configuration from bytes
	try(ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		pojoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), pojoSerializer);
	}

	// reconfigure - check reconfiguration result and that subclass serializer cache is repopulated
	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<TestUserClass> compatResult =
		pojoSerializerConfigSnapshot.resolveSchemaCompatibility(pojoSerializer);
	assertTrue(compatResult.isCompatibleWithReconfiguredSerializer());
	assertTrue(compatResult.getReconfiguredSerializer() instanceof PojoSerializer);

	PojoSerializer<TestUserClass> reconfiguredPojoSerializer = (PojoSerializer<TestUserClass>) compatResult.getReconfiguredSerializer();
	assertEquals(2, reconfiguredPojoSerializer.getSubclassSerializerCache().size());
	assertTrue(reconfiguredPojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassA.class));
	assertTrue(reconfiguredPojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassB.class));
}
 

@SuppressWarnings("unchecked")
@Override
public void read(DataInputView in) throws IOException {
	super.read(in);

	final int readVersion = getReadVersion();

	if (readVersion >= 4) {
		usingKeyGroupCompression = in.readBoolean();
	} else {
		usingKeyGroupCompression = false;
	}

	// only starting from version 3, we have the key serializer and its config snapshot written
	if (readVersion >= 6) {
		this.keySerializerSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			in, userCodeClassLoader, null);
	} else if (readVersion >= 3) {
		Tuple2<TypeSerializer<?>, TypeSerializerSnapshot<?>> keySerializerAndConfig =
				TypeSerializerSerializationUtil.readSerializersAndConfigsWithResilience(in, userCodeClassLoader).get(0);
		this.keySerializerSnapshot = (TypeSerializerSnapshot<K>) keySerializerAndConfig.f1;
	} else {
		this.keySerializerSnapshot = new BackwardsCompatibleSerializerSnapshot<>(
			TypeSerializerSerializationUtil.tryReadSerializer(in, userCodeClassLoader, true));
	}
	this.keySerializer = null;

	Integer metaInfoSnapshotVersion = META_INFO_SNAPSHOT_FORMAT_VERSION_MAPPER.get(readVersion);
	if (metaInfoSnapshotVersion == null) {
		// this should not happen; guard for the future
		throw new IOException("Cannot determine corresponding meta info snapshot version for keyed backend serialization readVersion=" + readVersion);
	}
	final StateMetaInfoReader stateMetaInfoReader = StateMetaInfoSnapshotReadersWriters.getReader(
		metaInfoSnapshotVersion,
		StateMetaInfoSnapshotReadersWriters.StateTypeHint.KEYED_STATE);

	int numKvStates = in.readShort();
	stateMetaInfoSnapshots = new ArrayList<>(numKvStates);
	for (int i = 0; i < numKvStates; i++) {
		StateMetaInfoSnapshot snapshot = stateMetaInfoReader.readStateMetaInfoSnapshot(in, userCodeClassLoader);

		stateMetaInfoSnapshots.add(snapshot);
	}
}
 

/**
 * Tests that:
 *  - Previous Pojo serializer did not have registrations, and created cached serializers for subclasses
 *  - On restore, it had those subclasses registered
 *
 * In this case, after reconfiguration, the cache should be repopulated, and registrations should
 * also exist for the subclasses.
 *
 * Note: the cache still needs to be repopulated because previous data of those subclasses were
 * written with the cached serializers. In this case, the repopulated cache has reconfigured serializers
 * for the subclasses so that previous written data can be read, but the registered serializers
 * for the subclasses do not necessarily need to be reconfigured since they will only be used to
 * write new data.
 */
@Test
public void testReconfigureWithPreviouslyNonregisteredSubclasses() throws Exception {
	// don't register any subclasses at first
	PojoSerializer<TestUserClass> pojoSerializer = (PojoSerializer<TestUserClass>) type.createSerializer(new ExecutionConfig());

	// create cached serializers for SubTestUserClassA and SubTestUserClassB
	pojoSerializer.getSubclassSerializer(SubTestUserClassA.class);
	pojoSerializer.getSubclassSerializer(SubTestUserClassB.class);

	// make sure serializers are in cache
	assertEquals(2, pojoSerializer.getSubclassSerializerCache().size());
	assertTrue(pojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassA.class));
	assertTrue(pojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassB.class));

	// make sure that registrations are empty
	assertTrue(pojoSerializer.getRegisteredClasses().isEmpty());
	assertEquals(0, pojoSerializer.getRegisteredSerializers().length);

	// snapshot configuration and serialize to bytes
	TypeSerializerSnapshot pojoSerializerConfigSnapshot = pojoSerializer.snapshotConfiguration();
	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), pojoSerializerConfigSnapshot, pojoSerializer);
		serializedConfig = out.toByteArray();
	}

	// instantiate new PojoSerializer, with new execution config that has the subclass registrations
	ExecutionConfig newExecutionConfig = new ExecutionConfig();
	newExecutionConfig.registerPojoType(SubTestUserClassA.class);
	newExecutionConfig.registerPojoType(SubTestUserClassB.class);
	pojoSerializer = (PojoSerializer<TestUserClass>) type.createSerializer(newExecutionConfig);

	// read configuration from bytes
	try(ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		pojoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), pojoSerializer);
	}

	// reconfigure - check reconfiguration result and that
	// 1) subclass serializer cache is repopulated
	// 2) registrations also contain the now registered subclasses
	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<TestUserClass> compatResult =
		pojoSerializerConfigSnapshot.resolveSchemaCompatibility(pojoSerializer);
	assertTrue(compatResult.isCompatibleWithReconfiguredSerializer());
	assertTrue(compatResult.getReconfiguredSerializer() instanceof PojoSerializer);

	PojoSerializer<TestUserClass> reconfiguredPojoSerializer = (PojoSerializer<TestUserClass>) compatResult.getReconfiguredSerializer();
	assertEquals(2, reconfiguredPojoSerializer.getSubclassSerializerCache().size());
	assertTrue(reconfiguredPojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassA.class));
	assertTrue(reconfiguredPojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassB.class));
	assertEquals(2, reconfiguredPojoSerializer.getRegisteredClasses().size());
	assertTrue(reconfiguredPojoSerializer.getRegisteredClasses().containsKey(SubTestUserClassA.class));
	assertTrue(reconfiguredPojoSerializer.getRegisteredClasses().containsKey(SubTestUserClassB.class));
}
 

/**
 * Tests that reconfiguration repopulates previously cached subclass serializers.
 */
@Test
public void testReconfigureRepopulateNonregisteredSubclassSerializerCache() throws Exception {
	// don't register any subclasses
	PojoSerializer<TestUserClass> pojoSerializer = (PojoSerializer<TestUserClass>) type.createSerializer(new ExecutionConfig());

	// create cached serializers for SubTestUserClassA and SubTestUserClassB
	pojoSerializer.getSubclassSerializer(SubTestUserClassA.class);
	pojoSerializer.getSubclassSerializer(SubTestUserClassB.class);

	assertEquals(2, pojoSerializer.getSubclassSerializerCache().size());
	assertTrue(pojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassA.class));
	assertTrue(pojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassB.class));

	// snapshot configuration and serialize to bytes
	TypeSerializerSnapshot pojoSerializerConfigSnapshot = pojoSerializer.snapshotConfiguration();
	byte[] serializedConfig;
	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
		TypeSerializerSnapshotSerializationUtil.writeSerializerSnapshot(
			new DataOutputViewStreamWrapper(out), pojoSerializerConfigSnapshot, pojoSerializer);
		serializedConfig = out.toByteArray();
	}

	// instantiate new PojoSerializer

	pojoSerializer = (PojoSerializer<TestUserClass>) type.createSerializer(new ExecutionConfig());

	// read configuration from bytes
	try(ByteArrayInputStream in = new ByteArrayInputStream(serializedConfig)) {
		pojoSerializerConfigSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			new DataInputViewStreamWrapper(in), Thread.currentThread().getContextClassLoader(), pojoSerializer);
	}

	// reconfigure - check reconfiguration result and that subclass serializer cache is repopulated
	@SuppressWarnings("unchecked")
	TypeSerializerSchemaCompatibility<TestUserClass> compatResult =
		pojoSerializerConfigSnapshot.resolveSchemaCompatibility(pojoSerializer);
	assertTrue(compatResult.isCompatibleWithReconfiguredSerializer());
	assertTrue(compatResult.getReconfiguredSerializer() instanceof PojoSerializer);

	PojoSerializer<TestUserClass> reconfiguredPojoSerializer = (PojoSerializer<TestUserClass>) compatResult.getReconfiguredSerializer();
	assertEquals(2, reconfiguredPojoSerializer.getSubclassSerializerCache().size());
	assertTrue(reconfiguredPojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassA.class));
	assertTrue(reconfiguredPojoSerializer.getSubclassSerializerCache().containsKey(SubTestUserClassB.class));
}
 

@SuppressWarnings("unchecked")
@Override
public void read(DataInputView in) throws IOException {
	super.read(in);

	final int readVersion = getReadVersion();

	if (readVersion >= 4) {
		usingKeyGroupCompression = in.readBoolean();
	} else {
		usingKeyGroupCompression = false;
	}

	// only starting from version 3, we have the key serializer and its config snapshot written
	if (readVersion >= 6) {
		this.keySerializerSnapshot = TypeSerializerSnapshotSerializationUtil.readSerializerSnapshot(
			in, userCodeClassLoader, null);
	} else if (readVersion >= 3) {
		Tuple2<TypeSerializer<?>, TypeSerializerSnapshot<?>> keySerializerAndConfig =
				TypeSerializerSerializationUtil.readSerializersAndConfigsWithResilience(in, userCodeClassLoader).get(0);
		this.keySerializerSnapshot = (TypeSerializerSnapshot<K>) keySerializerAndConfig.f1;
	} else {
		this.keySerializerSnapshot = new BackwardsCompatibleSerializerSnapshot<>(
			TypeSerializerSerializationUtil.tryReadSerializer(in, userCodeClassLoader, true));
	}
	this.keySerializer = null;

	Integer metaInfoSnapshotVersion = META_INFO_SNAPSHOT_FORMAT_VERSION_MAPPER.get(readVersion);
	if (metaInfoSnapshotVersion == null) {
		// this should not happen; guard for the future
		throw new IOException("Cannot determine corresponding meta info snapshot version for keyed backend serialization readVersion=" + readVersion);
	}
	final StateMetaInfoReader stateMetaInfoReader = StateMetaInfoSnapshotReadersWriters.getReader(
		metaInfoSnapshotVersion,
		StateMetaInfoSnapshotReadersWriters.StateTypeHint.KEYED_STATE);

	int numKvStates = in.readShort();
	stateMetaInfoSnapshots = new ArrayList<>(numKvStates);
	for (int i = 0; i < numKvStates; i++) {
		StateMetaInfoSnapshot snapshot = stateMetaInfoReader.readStateMetaInfoSnapshot(in, userCodeClassLoader);

		stateMetaInfoSnapshots.add(snapshot);
	}
}