com.hazelcast.jet

Interface Processor

All Known Implementing Classes:

AbstractProcessor, Processors.NoopP

public interface Processor

Does the computation needed to transform zero or more input data streams into zero or more output streams. Each input/output stream corresponds to one edge on the vertex represented by this processor. The correspondence between a stream and an edge is established via the edge's ordinal.

The special case of zero input streams applies to a source vertex, which gets its data from the environment. The special case of zero output streams applies to a sink vertex, which pushes its data to the environment.

The processor accepts input from instances of Inbox and pushes its output to an instance of Outbox.

The processing methods should limit the amount of data they output per invocation because the outbox will not be emptied until the processor yields control back to its caller. Specifically, Outbox has a method isHighWater() that can be tested to see whether it's time to stop pushing more data into it. There is also a finer-grained method isHighWater(ordinal), which tells the state of an individual output bucket.

If this processor declares itself as "cooperative" (isCooperative() returns true, the default), it should also limit the amount of time it spends per call because it will participate in a cooperative multithreading scheme.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	Processor.Context Context passed to the processor in the init() call.

Method Summary

Modifier and Type	Method and Description
default boolean	complete() Called after all the inputs are exhausted.
default boolean	completeEdge(int ordinal) Called after the edge input with the supplied ordinal is exhausted.
default void	init(Outbox outbox, Processor.Context context) Initializes this processor with the outbox that the processing methods must use to deposit their output items.
default boolean	isCooperative() Tells whether this processor is able to participate in cooperative multithreading.
default void	process(int ordinal, Inbox inbox) Processes some items in the supplied inbox.

Method Detail

init

default void init(@Nonnull
                  Outbox outbox,
                  @Nonnull
                  Processor.Context context)

Initializes this processor with the outbox that the processing methods must use to deposit their output items. This method will be called exactly once and strictly before any calls to processing methods (process(int, Inbox), completeEdge(int), complete()).

The default implementation does nothing.

process

default void process(int ordinal,
                     @Nonnull
                     Inbox inbox)

Processes some items in the supplied inbox. Removes the items it's done with. Does not remove an item until it is done with it.

The default implementation does nothing.

Parameters:

ordinal - ordinal of the edge the item comes from

inbox - the inbox containing the pending items

completeEdge

default boolean completeEdge(int ordinal)

Called after the edge input with the supplied ordinal is exhausted. If it returns false, it will be invoked again until it returns true, and until it does, no other methods will be invoked on the processor.

Returns:

true if the processor is now done completing this input, false otherwise.

complete

default boolean complete()

Called after all the inputs are exhausted. If it returns false, it will be invoked again until it returns true. After this method is called, no other processing methods will be called on this processor.

Returns:

true if the completing step is now done, false otherwise.

isCooperative

default boolean isCooperative()

Tells whether this processor is able to participate in cooperative multithreading. This means that each invocation of a processing method will take a reasonably small amount of time (up to a millisecond). A cooperative processor should not attempt any blocking I/O operations.

If this processor declares itself non-cooperative, it will be allocated a dedicated Java thread. Otherwise it will be allocated a tasklet which shares a thread with other tasklets.