io.pravega.common.util

Class OrderedItemProcessor<ItemType,ResultType>

java.lang.Object

io.pravega.common.util.OrderedItemProcessor<ItemType,ResultType>

All Implemented Interfaces:

java.lang.AutoCloseable

public class OrderedItemProcessor<ItemType,ResultType>
extends java.lang.Object
implements java.lang.AutoCloseable

Processes items in order, subject to capacity constraints.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	OrderedItemProcessor.ProcessingException

Constructor Summary

Constructors

Constructor and Description
OrderedItemProcessor(int capacity, java.util.function.Function<ItemType,java.util.concurrent.CompletableFuture<ResultType>> processor, java.util.concurrent.Executor executor) Creates a new instance of the OrderedItemProcessor class.

Method Summary

Modifier and Type	Method and Description
void	close()
protected void	executionComplete(java.lang.Throwable exception) Callback that is invoked when an item has completed execution.
java.util.concurrent.CompletableFuture<ResultType>	process(ItemType item) Processes the given item.

Methods inherited from class java.lang.Object

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

Constructor Detail

OrderedItemProcessor

public OrderedItemProcessor(int capacity,
                            java.util.function.Function<ItemType,java.util.concurrent.CompletableFuture<ResultType>> processor,
                            java.util.concurrent.Executor executor)

Creates a new instance of the OrderedItemProcessor class.

Parameters:

capacity - The maximum number of concurrent executions.

processor - A Function that, given an Item, returns a CompletableFuture that indicates when the item has been processed (successfully or not).

executor - An Executor for async invocations.

Method Detail

close

public void close()

Specified by:

close in interface java.lang.AutoCloseable

process

public java.util.concurrent.CompletableFuture<ResultType> process(ItemType item)

Processes the given item. * If the OrderedItemProcessor is below capacity, then the item will be processed immediately and the returned future is the actual result from the Processor. * If the max capacity is exceeded, the item will be queued up and it will be processed when capacity allows, after all the items added before it have been processed. * If an item before this one failed to process and this item is still in the queue (it has not yet been processed), the returned future will be cancelled with a ProcessingException to prevent out-of-order executions. * This method guarantees ordered execution as long as its invocations are serial. That is, it only guarantees that the item has begun processing or an order assigned if the method returned successfully. * If an item failed to execute, this class will auto-close and will not be usable anymore.

Parameters:

item - The item to process.

Returns:

A CompletableFuture that, when completed, will indicate that the item has been processed. This will contain the result of the processing function applied to this item.

executionComplete

protected void executionComplete(java.lang.Throwable exception)

Callback that is invoked when an item has completed execution.

Parameters:

exception - (Optional) An exception from the execution. If set, it indicates the item has not been processed successfully.