io.github.lukehutch.fastclasspathscanner.utils

Class WorkQueue<T>

java.lang.Object

io.github.lukehutch.fastclasspathscanner.utils.WorkQueue<T>

Type Parameters:

T - The work unit type.

All Implemented Interfaces:

AutoCloseable

public class WorkQueue<T>
extends Object
implements AutoCloseable

A parallel work queue.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	WorkQueue.WorkQueuePreStartHook<T> A hook that is called once a WorkQueue is created, inside its try-with-resources block, before the workers are started.
static interface	WorkQueue.WorkUnitProcessor<T> A work unit processor.

Constructor Summary

Constructors

Constructor and Description
WorkQueue(Collection<T> initialWorkUnits, WorkQueue.WorkUnitProcessor<T> workUnitProcessor, InterruptionChecker interruptionChecker, LogNode log) A parallel work queue.

Method Summary

Modifier and Type	Method and Description
void	addWorkUnits(Collection<T> workUnits) Add multiple units of work.
void	close() Ensure that there are no work units still uncompleted.
void	runWorkLoop() Start a worker.
static <U> void	runWorkQueue(Collection<U> elements, ExecutorService executorService, int numParallelTasks, WorkQueue.WorkUnitProcessor<U> workUnitProcessor, InterruptionChecker interruptionChecker, LogNode log) Start a work queue on the elements in the provided collection, blocking until all work units have been completed.
static <U> void	runWorkQueue(Collection<U> elements, ExecutorService executorService, int numParallelTasks, WorkQueue.WorkUnitProcessor<U> workUnitProcessor, WorkQueue.WorkQueuePreStartHook<U> workQueuePreStartHook, InterruptionChecker interruptionChecker, LogNode log) Start a work queue on the elements in the provided collection, blocking until all work units have been completed.
void	startWorkers(ExecutorService executorService, int numWorkers, LogNode log) Start worker threads with a shared log.

Methods inherited from class java.lang.Object

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

Constructor Detail

WorkQueue

public WorkQueue(Collection<T> initialWorkUnits,
                 WorkQueue.WorkUnitProcessor<T> workUnitProcessor,
                 InterruptionChecker interruptionChecker,
                 LogNode log)

A parallel work queue.

Method Detail

runWorkQueue

public static <U> void runWorkQueue(Collection<U> elements,
                                    ExecutorService executorService,
                                    int numParallelTasks,
                                    WorkQueue.WorkUnitProcessor<U> workUnitProcessor,
                                    WorkQueue.WorkQueuePreStartHook<U> workQueuePreStartHook,
                                    InterruptionChecker interruptionChecker,
                                    LogNode log)
                             throws ExecutionException,
                                    InterruptedException

Start a work queue on the elements in the provided collection, blocking until all work units have been completed. Calls workQueuePreStartHook with a ref to the work queue before starting the workers.

Throws:

ExecutionException

InterruptedException

runWorkQueue

public static <U> void runWorkQueue(Collection<U> elements,
                                    ExecutorService executorService,
                                    int numParallelTasks,
                                    WorkQueue.WorkUnitProcessor<U> workUnitProcessor,
                                    InterruptionChecker interruptionChecker,
                                    LogNode log)
                             throws ExecutionException,
                                    InterruptedException

Start a work queue on the elements in the provided collection, blocking until all work units have been completed.

Throws:

ExecutionException

InterruptedException

startWorkers

public void startWorkers(ExecutorService executorService,
                         int numWorkers,
                         LogNode log)

Start worker threads with a shared log.

runWorkLoop

public void runWorkLoop()
                 throws InterruptedException,
                        ExecutionException

Start a worker. Called by startWorkers(), but should also be called by the main thread to do some of the work on that thread, to prevent deadlock in the case that the ExecutorService doesn't have as many threads available as numParallelTasks. When this method returns, either all the work has been completed, or this or some other thread was interrupted. If InterruptedException is thrown, this thread or another was interrupted.

Throws:

InterruptedException

ExecutionException

addWorkUnits

public void addWorkUnits(Collection<T> workUnits)

Add multiple units of work. May be called by workers to add more work units to the tail of the queue.

close

public void close()
           throws ExecutionException

Ensure that there are no work units still uncompleted. This should be called after runWorkLoop() exits on the main thread (e.g. using try-with-resources, since this class is AutoCloseable). If any work units are still uncompleted (e.g. in the case of an exception), will shut down remaining workers.

Specified by:

close in interface AutoCloseable

Throws:

ExecutionException