K
- The type of the keys in the map.V
- The type of the values in the map.@Internal public final class MapSerializer<K,V> extends TypeSerializer<Map<K,V>>
Map
. The serializer relies on a key serializer and a value serializer
for the serialization of the map's key-value pairs.
The serialization format for the map is as follows: four bytes for the length of the map, followed by the serialized representation of each key-value pair. To allow null values, each value is prefixed by a null marker.
Constructor and Description |
---|
MapSerializer(TypeSerializer<K> keySerializer,
TypeSerializer<V> valueSerializer)
Creates a map serializer that uses the given serializers to serialize the key-value pairs in
the map.
|
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.
|
Map<K,V> |
copy(Map<K,V> from)
Creates a deep copy of the given element in a new element.
|
Map<K,V> |
copy(Map<K,V> from,
Map<K,V> reuse)
Creates a copy from the given element.
|
Map<K,V> |
createInstance()
Creates a new instance of the data type.
|
Map<K,V> |
deserialize(DataInputView source)
De-serializes a record from the given source input view.
|
Map<K,V> |
deserialize(Map<K,V> reuse,
DataInputView source)
De-serializes a record from the given source input view into the given reuse record instance
if mutable.
|
TypeSerializer<Map<K,V>> |
duplicate()
Creates a deep copy of this serializer if it is necessary, i.e.
|
boolean |
equals(Object obj) |
TypeSerializer<K> |
getKeySerializer() |
int |
getLength()
Gets the length of the data type, if it is a fix length data type.
|
TypeSerializer<V> |
getValueSerializer() |
int |
hashCode() |
boolean |
isImmutableType()
Gets whether the type is an immutable type.
|
void |
serialize(Map<K,V> map,
DataOutputView target)
Serializes the given record to the given target output view.
|
TypeSerializerSnapshot<Map<K,V>> |
snapshotConfiguration()
Snapshots the configuration of this TypeSerializer.
|
public MapSerializer(TypeSerializer<K> keySerializer, TypeSerializer<V> valueSerializer)
keySerializer
- The serializer for the keys in the mapvalueSerializer
- The serializer for the values in the mappublic TypeSerializer<K> getKeySerializer()
public TypeSerializer<V> getValueSerializer()
public boolean isImmutableType()
TypeSerializer
isImmutableType
in class TypeSerializer<Map<K,V>>
public TypeSerializer<Map<K,V>> duplicate()
TypeSerializer
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.
duplicate
in class TypeSerializer<Map<K,V>>
public Map<K,V> createInstance()
TypeSerializer
createInstance
in class TypeSerializer<Map<K,V>>
public Map<K,V> copy(Map<K,V> from)
TypeSerializer
copy
in class TypeSerializer<Map<K,V>>
from
- The element reuse be copied.public Map<K,V> copy(Map<K,V> from, Map<K,V> reuse)
TypeSerializer
copy
in class TypeSerializer<Map<K,V>>
from
- The element to be copied.reuse
- The element to be reused. May or may not be used.public int getLength()
TypeSerializer
getLength
in class TypeSerializer<Map<K,V>>
-1
for variable length data types.public void serialize(Map<K,V> map, DataOutputView target) throws IOException
TypeSerializer
serialize
in class TypeSerializer<Map<K,V>>
map
- The record to serialize.target
- The output view to write the serialized data to.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.public Map<K,V> deserialize(DataInputView source) throws IOException
TypeSerializer
deserialize
in class TypeSerializer<Map<K,V>>
source
- The input view from which to read the data.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.public Map<K,V> deserialize(Map<K,V> reuse, DataInputView source) throws IOException
TypeSerializer
deserialize
in class TypeSerializer<Map<K,V>>
reuse
- The record instance into which to de-serialize the data.source
- The input view from which to read the data.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.public void copy(DataInputView source, DataOutputView target) throws IOException
TypeSerializer
target.write(source, 8);
.copy
in class TypeSerializer<Map<K,V>>
source
- The input view from which to read the record.target
- The target output view to which to write the record.IOException
- Thrown if any of the two views raises an exception.public int hashCode()
hashCode
in class TypeSerializer<Map<K,V>>
public TypeSerializerSnapshot<Map<K,V>> snapshotConfiguration()
TypeSerializer
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.
snapshotConfiguration
in class TypeSerializer<Map<K,V>>
null
).TypeSerializerSnapshot.resolveSchemaCompatibility(TypeSerializer)
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