com.hazelcast.jet.core

Interface Outbox

All Known Implementing Classes:

TestOutbox

public interface Outbox

Data sink for a Processor. The outbox consists of individual output buckets, one per outbound edge of the vertex represented by the associated processor and one for the snapshot state. The processor must deliver its output items separated by destination edge into the outbox by calling offer(int, Object) or offer(Object).

To save its current state to the snapshot, it must call offerToSnapshot(Object, Object) from its implementation of saveToSnapshot().

The outbox has finite capacity and will eventually refuse an item. If one of the offer() methods returns false, the calling processor must return from its callback method and retry delivering the same item when Jet calls its method again.

Thread safety

You must offer to outbox only from the thread that called the processor's methods. For example, you must not offer to outbox from a callback of an asynchronous operation. If you need that, you have to employ a concurrent queue, add to it in the callback and drain it in e.g. Processor.tryProcess().

Since:

Jet 3.0

Method Summary

Modifier and Type	Method and Description
int	bucketCount() Returns the number of buckets in this outbox.
boolean	hasUnfinishedItem() Returns true if this outbox has an unfinished item and the same item must be offered again.
boolean	offer(int[] ordinals, Object item) Offers the item to all supplied edge ordinals.
boolean	offer(int ordinal, Object item) Offers the supplied item to the bucket with the supplied ordinal.
default boolean	offer(Object item) Offers the item to all edges.
boolean	offerToSnapshot(Object key, Object value) Offers the given key and value pair to the processor's snapshot storage.

Method Detail

bucketCount

int bucketCount()

Returns the number of buckets in this outbox. This is equal to the number of output edges of the vertex and does not include the snapshot bucket.

offer

@CheckReturnValue
boolean offer(int ordinal,
                                @Nonnull
                                Object item)

Offers the supplied item to the bucket with the supplied ordinal.

Items offered to outbox should not be subsequently mutated because the same instance might be used by a downstream processor in different thread, causing concurrent access.

Outbox is not thread safe, see Thread safety in its class javadoc.

Parameters:

ordinal - output ordinal number or -1 to offer to all ordinals

Returns:

true if the outbox accepted the item

offer

@CheckReturnValue
boolean offer(@Nonnull
                                int[] ordinals,
                                @Nonnull
                                Object item)

Offers the item to all supplied edge ordinals. See offer(int, Object) for more details.

Outbox is not thread safe, see Thread safety in its class javadoc.

Returns:

true if the outbox accepted the item

offerToSnapshot

@CheckReturnValue
boolean offerToSnapshot(@Nonnull
                                          Object key,
                                          @Nonnull
                                          Object value)

Offers the given key and value pair to the processor's snapshot storage.

The type of the offered key determines which processors receive the key and value pair when it is restored. If the key is of type BroadcastKey, the entry will be restored to all processor instances. Otherwise the key will be distributed according to default partitioning and only a single processor instance will receive the key.

This method must only be called from the Processor.saveToSnapshot() or Processor.snapshotCommitPrepare() methods.

Keys and values offered to snapshot are serialized and can be further mutated as soon as this method returns.

Outbox is not thread safe, see Thread safety in its class javadoc.

Returns:

true if the outbox accepted the item

offer

@CheckReturnValue
default boolean offer(@Nonnull
                                        Object item)

Offers the item to all edges. See offer(int, Object) for more details.

Outbox is not thread safe, see Thread safety in its class javadoc.

Returns:

true if the outbox accepted the item

hasUnfinishedItem

boolean hasUnfinishedItem()

Returns true if this outbox has an unfinished item and the same item must be offered again. If it returns false, it is safe to offer a new item.

Outbox is not thread safe, see Thread safety in its class javadoc.