org.apache.flink.cep

Class NonDuplicatingTypeSerializer<T>

java.lang.Object

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

org.apache.flink.cep.NonDuplicatingTypeSerializer<T>

Type Parameters:

T - Type of the element to be serialized

All Implemented Interfaces:

Serializable

public class NonDuplicatingTypeSerializer<T>
extends TypeSerializer<T>

Type serializer which keeps track of the serialized objects so that each object is only serialized once. If the same object shall be serialized again, then a reference handle is written instead. Avoiding duplication is achieved by keeping an internal identity hash map. This map contains all serialized objects. To make the serializer work it is important that the same serializer is used for a coherent serialization run. After the serialization has stopped, the identity hash map should be cleared.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
NonDuplicatingTypeSerializer(TypeSerializer<T> typeSerializer)

Method Summary

Modifier and Type	Method and Description
boolean	canEqual(Object obj) Returns true if the given object can be equaled with this object.
void	clearReferences() Clears the data structures containing the already serialized/deserialized objects.
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) Deserializes an object from the 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.
TypeSerializer<T>	duplicate() Creates a deep copy of this serializer if it is necessary, i.e.
boolean	equals(Object obj)
int	getLength() Gets the length of the data type, if it is a fix length data type.
TypeSerializer<T>	getTypeSerializer()
int	hashCode()
boolean	isImmutableType() Gets whether the type is an immutable type.
void	serialize(T record, DataOutputView target) Serializes the given record.

Methods inherited from class java.lang.Object

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

Constructor Detail

NonDuplicatingTypeSerializer

public NonDuplicatingTypeSerializer(TypeSerializer<T> typeSerializer)

Method Detail

getTypeSerializer

public TypeSerializer<T> getTypeSerializer()

clearReferences

public void clearReferences()

Clears the data structures containing the already serialized/deserialized objects. This effectively resets the type serializer.

isImmutableType

public boolean isImmutableType()

Description copied from class: TypeSerializer

Gets whether the type is an immutable type.

Specified by:

isImmutableType in class TypeSerializer<T>

Returns:

True, if the type is immutable.

duplicate

public TypeSerializer<T> duplicate()

Description copied from class: TypeSerializer

Creates a deep copy of this serializer if it is necessary, i.e. if it is stateful. This can return itself if the serializer is not stateful. We need this because Serializers might be used in several threads. Stateless serializers are inherently thread-safe while stateful serializers might not be thread-safe.

Specified by:

duplicate in class TypeSerializer<T>

createInstance

public T createInstance()

Description copied from class: TypeSerializer

Creates a new instance of the data type.

Specified by:

createInstance in class TypeSerializer<T>

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>

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>

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>

Returns:

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

serialize

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

Serializes the given record.

First a boolean indicating whether a reference handle (true) or the object (false) is written. Then, either the reference handle or the object is written.

Specified by:

serialize in class TypeSerializer<T>

Parameters:

record - The record to serialize.

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

Throws:

IOException

deserialize

public T deserialize(DataInputView source)
              throws IOException

Deserializes an object from the input view.

First it reads a boolean indicating whether a reference handle or a serialized object follows.

Specified by:

deserialize in class TypeSerializer<T>

Parameters:

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

Returns:

The deserialized object

Throws:

IOException

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>

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>

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.

equals

public boolean equals(Object obj)

Specified by:

equals in class TypeSerializer<T>

canEqual

public boolean canEqual(Object obj)

Description copied from class: TypeSerializer

Returns true if the given object can be equaled with this object. If not, it returns false.

Specified by:

canEqual in class TypeSerializer<T>

Parameters:

obj - Object which wants to take part in the equality relation

Returns:

true if obj can be equaled with this, otherwise false

hashCode

public int hashCode()

Specified by:

hashCode in class TypeSerializer<T>