org.apache.flink.runtime.checkpoint

Class StateObjectCollection<T extends StateObject>

java.lang.Object

org.apache.flink.runtime.checkpoint.StateObjectCollection<T>

Type Parameters:

T - type of the contained state objects.

All Implemented Interfaces:

Serializable, Iterable<T>, Collection<T>, StateObject

public class StateObjectCollection<T extends StateObject>
extends Object
implements Collection<T>, StateObject

This class represents a generic collection for StateObjects. Being a state object itself, it delegates discardState() to all contained state objects and computes getStateSize() as sum of the state sizes of all contained objects.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
StateObjectCollection() Creates a new StateObjectCollection that is backed by an ArrayList.
StateObjectCollection(Collection<T> stateObjects) Creates a new StateObjectCollection wraps the given collection and delegates to it.

Method Summary

Modifier and Type	Method and Description
boolean	add(T t)
boolean	addAll(Collection<? extends T> c)
List<T>	asList()
void	clear()
boolean	contains(Object o)
boolean	containsAll(Collection<?> c)
void	discardState() Discards the state referred to and solemnly owned by this handle, to free up resources in the persistent storage.
static <T extends StateObject> StateObjectCollection<T>	empty()
boolean	equals(Object o)
long	getStateSize() Returns the size of the state in bytes.
int	hashCode()
boolean	hasState() Returns true if this contains at least one StateObject.
boolean	isEmpty()
Iterator<T>	iterator()
boolean	remove(Object o)
boolean	removeAll(Collection<?> c)
boolean	removeIf(java.util.function.Predicate<? super T> filter)
boolean	retainAll(Collection<?> c)
static <T extends StateObject> StateObjectCollection<T>	singleton(T stateObject)
int	size()
Object[]	toArray()
<T1> T1[]	toArray(T1[] a)
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

parallelStream, spliterator, stream

Methods inherited from interface java.lang.Iterable

forEach

Constructor Detail

StateObjectCollection

public StateObjectCollection()

Creates a new StateObjectCollection that is backed by an ArrayList.

StateObjectCollection

public StateObjectCollection(Collection<T> stateObjects)

Creates a new StateObjectCollection wraps the given collection and delegates to it.

Parameters:

stateObjects - collection of state objects to wrap.

Method Detail

size

public int size()

Specified by:

size in interface Collection<T extends StateObject>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<T extends StateObject>

contains

public boolean contains(Object o)

Specified by:

contains in interface Collection<T extends StateObject>

iterator

public Iterator<T> iterator()

Specified by:

iterator in interface Iterable<T extends StateObject>

Specified by:

iterator in interface Collection<T extends StateObject>

toArray

public Object[] toArray()

Specified by:

toArray in interface Collection<T extends StateObject>

toArray

public <T1> T1[] toArray(T1[] a)

Specified by:

toArray in interface Collection<T extends StateObject>

add

public boolean add(T t)

Specified by:

add in interface Collection<T extends StateObject>

remove

public boolean remove(Object o)

Specified by:

remove in interface Collection<T extends StateObject>

containsAll

public boolean containsAll(Collection<?> c)

Specified by:

containsAll in interface Collection<T extends StateObject>

addAll

public boolean addAll(Collection<? extends T> c)

Specified by:

addAll in interface Collection<T extends StateObject>

removeAll

public boolean removeAll(Collection<?> c)

Specified by:

removeAll in interface Collection<T extends StateObject>

removeIf

public boolean removeIf(java.util.function.Predicate<? super T> filter)

Specified by:

removeIf in interface Collection<T extends StateObject>

retainAll

public boolean retainAll(Collection<?> c)

Specified by:

retainAll in interface Collection<T extends StateObject>

clear

public void clear()

Specified by:

clear in interface Collection<T extends StateObject>

discardState

public void discardState()
                  throws Exception

Description copied from interface: StateObject

Discards the state referred to and solemnly owned by this handle, to free up resources in the persistent storage. This method is called when the state represented by this object will not be used any more.

Specified by:

discardState in interface StateObject

Throws:

Exception

getStateSize

public long getStateSize()

Description copied from interface: StateObject

Returns the size of the state in bytes. If the size is not known, this method should return 0.

The values produced by this method are only used for informational purposes and for metrics/monitoring. If this method returns wrong values, the checkpoints and recovery will still behave correctly. However, efficiency may be impacted (wrong space pre-allocation) and functionality that depends on metrics (like monitoring) will be impacted.

Note for implementors: This method should not perform any I/O operations while obtaining the state size (hence it does not declare throwing an IOException). Instead, the state size should be stored in the state object, or should be computable from the state stored in this object. The reason is that this method is called frequently by several parts of the checkpointing and issuing I/O requests from this method accumulates a heavy I/O load on the storage system at higher scale.

Specified by:

getStateSize in interface StateObject

Returns:

Size of the state in bytes.

hasState

public boolean hasState()

Returns true if this contains at least one StateObject.

equals

public boolean equals(Object o)

Specified by:

equals in interface Collection<T extends StateObject>

Overrides:

equals in class Object

hashCode

public int hashCode()

Specified by:

hashCode in interface Collection<T extends StateObject>

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object

asList

public List<T> asList()

empty

public static <T extends StateObject> StateObjectCollection<T> empty()

singleton

public static <T extends StateObject> StateObjectCollection<T> singleton(T stateObject)