uk.gov.gchq.gaffer.parquetstore.serialisation.impl

Class FreqMapParquetSerialiser

java.lang.Object

uk.gov.gchq.gaffer.parquetstore.serialisation.impl.FreqMapParquetSerialiser

All Implemented Interfaces:

Serializable, ParquetSerialiser<FreqMap>, Serialiser<FreqMap,Object[]>

public class FreqMapParquetSerialiser
extends Object
implements ParquetSerialiser<FreqMap>

This class is used to serialise and de-serialise a FreqMap value for use by the ParquetStore.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
FreqMapParquetSerialiser()

Method Summary

Modifier and Type	Method and Description
boolean	canHandle(Class clazz) Check whether the serialiser can serialise a particular class.
FreqMap	deserialise(Object[] objects) This method provides the user a way of specifying how to recreate the Plain Old Java Object (POJO) from the Parquet primitive types.
FreqMap	deserialiseEmpty() Handle an empty OUTPUT and reconstruct an appropriate representation in Object form.
String	getParquetSchema(String colName) This method provides the user a way of specifying the Parquet schema for this object.
boolean	isConsistent() Indicates whether the serialisation process produces a predictable, consistent OUTPUT, from a given INPUT, ie the same object should always serialise in the same way for this to be true.
boolean	preservesObjectOrdering() Indicates whether the serialisation process preserves the ordering of the INPUT, i.e.
Object[]	serialise(FreqMap object) This method provides the user a way of specifying how to convert a Plain Old Java Object (POJO) into the Parquet primitive types.
Object[]	serialiseNull() Handle an incoming null value and generate an appropriate OUTPUT representation.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FreqMapParquetSerialiser

public FreqMapParquetSerialiser()

Method Detail

getParquetSchema

public String getParquetSchema(String colName)

Description copied from interface: ParquetSerialiser

This method provides the user a way of specifying the Parquet schema for this object. Note that the root of this schema must have the same name as the input colName.

Specified by:

getParquetSchema in interface ParquetSerialiser<FreqMap>

Parameters:

colName - The column name as a String as seen in the Gaffer schema that this object is from

Returns:

A String representation of the part of the Parquet schema that this object will be stored as

serialise

public Object[] serialise(FreqMap object)
                   throws SerialisationException

Description copied from interface: ParquetSerialiser

This method provides the user a way of specifying how to convert a Plain Old Java Object (POJO) into the Parquet primitive types.

Specified by:

serialise in interface ParquetSerialiser<FreqMap>

Specified by:

serialise in interface Serialiser<FreqMap,Object[]>

Parameters:

object - The POJO that you will convert to Parquet primitives

Returns:

An object array of Parquet primitives, if this serialiser is used as the vertex serialiser then the order of the objects will determine the sorting order

Throws:

SerialisationException - If the POJO fails to be converted to ParquetObjects then this will be thrown

deserialise

public FreqMap deserialise(Object[] objects)
                    throws SerialisationException

Description copied from interface: ParquetSerialiser

This method provides the user a way of specifying how to recreate the Plain Old Java Object (POJO) from the Parquet primitive types.

Specified by:

deserialise in interface ParquetSerialiser<FreqMap>

Specified by:

deserialise in interface Serialiser<FreqMap,Object[]>

Parameters:

objects - An object array of Parquet primitives

Returns:

The POJO that you have recreated from the Parquet primitives

Throws:

SerialisationException - If the ParquetObjects fails to be converted to a POJO then this will be thrown

deserialiseEmpty

public FreqMap deserialiseEmpty()
                         throws SerialisationException

Description copied from interface: Serialiser

Handle an empty OUTPUT and reconstruct an appropriate representation in Object form.

Specified by:

deserialiseEmpty in interface Serialiser<FreqMap,Object[]>

Returns:

INPUT the deserialised object

Throws:

SerialisationException - if the object fails to deserialise

preservesObjectOrdering

public boolean preservesObjectOrdering()

Description copied from interface: Serialiser

Indicates whether the serialisation process preserves the ordering of the INPUT, i.e. if x and y are objects of class INPUT, and x is less than y, then this method should return true if the serialised form of x is guaranteed to be less than the serialised form of y (using the standard ordering of OUTPUT). If INPUT is not Comparable then this test makes no sense and false should be returned.

Specified by:

preservesObjectOrdering in interface Serialiser<FreqMap,Object[]>

Returns:

true if the serialisation will preserve the order of the INPUT, otherwise false.

isConsistent

public boolean isConsistent()

Description copied from interface: Serialiser

Indicates whether the serialisation process produces a predictable, consistent OUTPUT, from a given INPUT, ie the same object should always serialise in the same way for this to be true.

Specified by:

isConsistent in interface Serialiser<FreqMap,Object[]>

Returns:

true if serialisation is consistent for a given object, otherwise false.

serialiseNull

public Object[] serialiseNull()

Description copied from interface: Serialiser

Handle an incoming null value and generate an appropriate OUTPUT representation.

Specified by:

serialiseNull in interface Serialiser<FreqMap,Object[]>

Returns:

OUTPUT the serialised output

canHandle

public boolean canHandle(Class clazz)

Description copied from interface: Serialiser

Check whether the serialiser can serialise a particular class.

//Warning: Due to erasure you may get false positives. e.g.

 
 Set<Foo> set = Sets.newHashSet();
 boolean b = new Serialiser<Set<Bar>, byte[]>().canHandle(set.getClass());
 b will incorrectly be true because of type erasure between Set<Foo> Set<Bar>
 
 

Specified by:

canHandle in interface Serialiser<FreqMap,Object[]>

Parameters:

clazz - the object class to serialise

Returns:

boolean true if it can be handled