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* SciJava library facilitating consistent parallel processing.
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package org.scijava.concurrent;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.function.Consumer;
import java.util.function.Function;
/**
* {@link TaskExecutor} is recommended to be used in image processing algorithms
* instead of {@link ExecutorService}. It's simpler to use, and allows single
* threaded execution.
*
*
*
* {@code
*
* // Example of a multi threaded method that fills an image with ones.
* public void fillWithOnes( RandomAccessibleInterval< IntType > image, TaskExecutor taskExecutor )
* {
* int numTasks = taskExecutor.suggestNumberOfTasks();
* List< RandomAccessibleInterval< IntType > > chunks = splitImageIntoChunks( image, numTasks );
*
* // The TaskExecutor executes the forEach method in multi threads, if requested.
* taskExecutor.forEach( chunks, chunk -> {
* for ( IntType pixel : Views.iterable( chunk ) )
* pixel.setOne();
* } );
* }
*
* // The method can be run multi threaded or single threaded
* fillWithOnes( image, TaskExecutors.singleThreaded() );
* fillWithOnes( image, TaskExecutors.multiThreaded() );
* }
*
*/
public interface TaskExecutor extends AutoCloseable {
/**
* Get the number of threads that are used for execution.
*/
int getParallelism();
/**
* If there is a big task that could be split into sub tasks for
* parallelization, this method gives you a reasonable number of sub tasks.
*
* A single threaded {@link TaskExecutor} will return 1. A multi threaded
* {@link TaskExecutor} will usually return 4 times the number of threads.
*/
int suggestNumberOfTasks();
/**
* This method will execute the given list of tasks. A single threaded
* {@link TaskExecutor} will execute the tasks one after the other. A multi
* threaded {@link TaskExecutor} will distribute the tasks to the threads. The
* method blocks until all tasks are completed.
*/
void runAll(List tasks);
/**
* Like {@link #runAll(List)} but - instead of a list of tasks - it takes a
* list of parameters and a function that is called for each of the
* parameters.
*/
void forEach(List parameters, Consumer task);
/**
* Like {@link #forEach(List, Consumer)} but collects the results.
*/
List forEachApply(List parameters,
Function task);
/**
* Get the underlying {@link ExecutorService}. This is not always a fully
* functional {@link ExecutorService}: Especially the methods
* {@link ExecutorService#shutdown()} and
* {@link ExecutorService#awaitTermination(long, TimeUnit)} must not be used.
*/
ExecutorService getExecutorService();
@Override
void close();
}