org.apache.flink.runtime.state

Class JavaSerializer<T extends Serializable>

java.lang.Object

org.apache.flink.api.common.typeutils.TypeSerializer<T>

org.apache.flink.api.common.typeutils.base.TypeSerializerSingleton<T>

org.apache.flink.runtime.state.JavaSerializer<T>

All Implemented Interfaces:

Serializable

@Internal
 @VisibleForTesting
public final class JavaSerializer<T extends Serializable>
extends TypeSerializerSingleton<T>

A TypeSerializer that uses Java serialization. This should not be used for anything.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	JavaSerializer.JavaSerializerSnapshot<T extends Serializable> Serializer configuration snapshot for compatibility and format evolution.

Constructor Summary

Constructors

Constructor and Description
JavaSerializer()

Method Summary

Modifier and Type	Method and Description
void	copy(DataInputView source, DataOutputView target) Copies exactly one record from the source input view to the target output view.
T	copy(T from) Creates a deep copy of the given element in a new element.
T	copy(T from, T reuse) Creates a copy from the given element.
T	createInstance() Creates a new instance of the data type.
T	deserialize(DataInputView source) De-serializes a record from the given source input view.
T	deserialize(T reuse, DataInputView source) De-serializes a record from the given source input view into the given reuse record instance if mutable.
int	getLength() Gets the length of the data type, if it is a fix length data type.
boolean	isImmutableType() Gets whether the type is an immutable type.
void	serialize(T record, DataOutputView target) Serializes the given record to the given target output view.
TypeSerializerSnapshot<T>	snapshotConfiguration() Snapshots the configuration of this TypeSerializer.

Methods inherited from class org.apache.flink.api.common.typeutils.base.TypeSerializerSingleton

duplicate, equals, hashCode

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JavaSerializer

public JavaSerializer()

Method Detail

isImmutableType

public boolean isImmutableType()

Description copied from class: TypeSerializer

Gets whether the type is an immutable type.

Specified by:

isImmutableType in class TypeSerializer<T extends Serializable>

Returns:

True, if the type is immutable.

createInstance

public T createInstance()

Description copied from class: TypeSerializer

Creates a new instance of the data type.

Specified by:

createInstance in class TypeSerializer<T extends Serializable>

Returns:

A new instance of the data type.

copy

public T copy(T from)

Description copied from class: TypeSerializer

Creates a deep copy of the given element in a new element.

Specified by:

copy in class TypeSerializer<T extends Serializable>

Parameters:

from - The element reuse be copied.

Returns:

A deep copy of the element.

copy

public T copy(T from,
              T reuse)

Description copied from class: TypeSerializer

Creates a copy from the given element. The method makes an attempt to store the copy in the given reuse element, if the type is mutable. This is, however, not guaranteed.

Specified by:

copy in class TypeSerializer<T extends Serializable>

Parameters:

from - The element to be copied.

reuse - The element to be reused. May or may not be used.

Returns:

A deep copy of the element.

getLength

public int getLength()

Description copied from class: TypeSerializer

Gets the length of the data type, if it is a fix length data type.

Specified by:

getLength in class TypeSerializer<T extends Serializable>

Returns:

The length of the data type, or -1 for variable length data types.

serialize

public void serialize(T record,
                      DataOutputView target)
               throws IOException

Description copied from class: TypeSerializer

Serializes the given record to the given target output view.

Specified by:

serialize in class TypeSerializer<T extends Serializable>

Parameters:

record - The record to serialize.

target - The output view to write the serialized data to.

Throws:

IOException - Thrown, if the serialization encountered an I/O related error. Typically raised by the output view, which may have an underlying I/O channel to which it delegates.

deserialize

public T deserialize(DataInputView source)
              throws IOException

Description copied from class: TypeSerializer

De-serializes a record from the given source input view.

Specified by:

deserialize in class TypeSerializer<T extends Serializable>

Parameters:

source - The input view from which to read the data.

Returns:

The deserialized element.

Throws:

IOException - Thrown, if the de-serialization encountered an I/O related error. Typically raised by the input view, which may have an underlying I/O channel from which it reads.

deserialize

public T deserialize(T reuse,
                     DataInputView source)
              throws IOException

Description copied from class: TypeSerializer

De-serializes a record from the given source input view into the given reuse record instance if mutable.

Specified by:

deserialize in class TypeSerializer<T extends Serializable>

Parameters:

reuse - The record instance into which to de-serialize the data.

source - The input view from which to read the data.

Returns:

The deserialized element.

Throws:

IOException - Thrown, if the de-serialization encountered an I/O related error. Typically raised by the input view, which may have an underlying I/O channel from which it reads.

copy

public void copy(DataInputView source,
                 DataOutputView target)
          throws IOException

Description copied from class: TypeSerializer

Copies exactly one record from the source input view to the target output view. Whether this operation works on binary data or partially de-serializes the record to determine its length (such as for records of variable length) is up to the implementer. Binary copies are typically faster. A copy of a record containing two integer numbers (8 bytes total) is most efficiently implemented as target.write(source, 8);.

Specified by:

copy in class TypeSerializer<T extends Serializable>

Parameters:

source - The input view from which to read the record.

target - The target output view to which to write the record.

Throws:

IOException - Thrown if any of the two views raises an exception.

snapshotConfiguration

public TypeSerializerSnapshot<T> snapshotConfiguration()

Description copied from class: TypeSerializer

Snapshots the configuration of this TypeSerializer. This method is only relevant if the serializer is used to state stored in checkpoints/savepoints.

The snapshot of the TypeSerializer is supposed to contain all information that affects the serialization format of the serializer. The snapshot serves two purposes: First, to reproduce the serializer when the checkpoint/savepoint is restored, and second, to check whether the serialization format is compatible with the serializer used in the restored program.

IMPORTANT: TypeSerializerSnapshots changed after Flink 1.6. Serializers implemented against Flink versions up to 1.6 should still work, but adjust to new model to enable state evolution and be future-proof. See the class-level comments, section "Upgrading TypeSerializers to the new TypeSerializerSnapshot model" for details.

Specified by:

snapshotConfiguration in class TypeSerializer<T extends Serializable>

Returns:

snapshot of the serializer's current configuration (cannot be null).

See Also:

TypeSerializerSnapshot.resolveSchemaCompatibility(TypeSerializerSnapshot)