org.hibernate.search.engine.backend.orchestration.spi

Class BatchingExecutor<W extends BatchingExecutor.WorkSet<? super P>,P extends BatchingExecutor.WorkProcessor>

java.lang.Object

org.hibernate.search.engine.backend.orchestration.spi.BatchingExecutor<W,P>

public final class BatchingExecutor<W extends BatchingExecutor.WorkSet<? super P>,P extends BatchingExecutor.WorkProcessor>
extends Object

An executor of works that accepts works from multiple threads, puts them in a queue, and processes them in batches in a single background thread.

Useful when works can be merged together for optimization purposes (bulking in Elasticsearch), or when they should never be executed in parallel (writes to a Lucene index).

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	BatchingExecutor.WorkProcessor
static interface	BatchingExecutor.WorkSet<P extends BatchingExecutor.WorkProcessor>

Constructor Summary

Constructors

Constructor and Description
BatchingExecutor(String name, P processor, int maxTasksPerBatch, boolean fair, ErrorHandler errorHandler)

Method Summary

Modifier and Type	Method and Description
void	awaitCompletion() Block the current thread until the executor has completed all pending worksets.
void	start() Start the executor, allowing works to be submitted through submit(WorkSet).
void	stop() Stop the executor, no longer allowing works to be submitted through submit(WorkSet).
void	submit(W workset) Submit a set of works for execution.

Methods inherited from class java.lang.Object

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

Constructor Detail

BatchingExecutor

public BatchingExecutor(String name,
                        P processor,
                        int maxTasksPerBatch,
                        boolean fair,
                        ErrorHandler errorHandler)

Parameters:

name - The name of the executor thread (and of this executor when reporting errors)

processor - A task processor. May not be thread-safe.

maxTasksPerBatch - The maximum number of tasks to process in a single batch. Higher values mean more opportunity for the processor to optimize execution, but higher heap consumption.

fair - if true tasks are always submitted to the processor in FIFO order, if false tasks submitted when the internal queue is full may be submitted out of order.

errorHandler - An error handler to report failures of the background thread.

Method Detail

start

public void start()

Start the executor, allowing works to be submitted through submit(WorkSet).

stop

public void stop()

Stop the executor, no longer allowing works to be submitted through submit(WorkSet).

This will attempt to forcibly terminate currently executing works, and will remove pending works from the queue.

submit

public void submit(W workset)
            throws InterruptedException

Submit a set of works for execution.

Must not be called when the executor is stopped.

Parameters:

workset - A set of works to execute.

Throws:

InterruptedException - If the current thread is interrupted while enqueuing the workset.

awaitCompletion

public void awaitCompletion()
                     throws InterruptedException

Block the current thread until the executor has completed all pending worksets.

Tasks submitted to the executor after entering this method may delay the wait. TODO HSEARCH-3576 we should use child executors, sharing the same execution service but each with its own child phaser, allowing each child executor to only wait until all of its *own* worksets are completed. That would however require to register/deregister the phaser for each single workset, instead of for each scheduling of the processing like we do now. Phaser only support up to 65535 parties, so we would may need to use multiple phasers per child executor...

Throws:

InterruptedException - If the current thread is interrupted while waiting.