org.threadly.concurrent.future

Interface ListenableFuture<T>

Type Parameters:

T - The result object type returned by this future

All Superinterfaces:

java.util.concurrent.Future<T>

All Known Subinterfaces:

ListenableRunnableFuture<T>, ListenableScheduledFuture<T>

All Known Implementing Classes:

CancelDebuggingListenableFuture, ExecuteOnGetFutureTask, ImmediateFailureListenableFuture, ImmediateResultListenableFuture, ListenableFutureAdapterTask, ListenableFutureTask, SettableListenableFuture

public interface ListenableFuture<T>
extends java.util.concurrent.Future<T>

Future where you can add a listener which is called once the future has completed. The runnable will be called once the future completes either as a cancel, with result, or with an exception.

Since:

1.0.0

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ListenableFuture.ListenerOptimizationStrategy Strategy to use for optimizing listener execution.

Method Summary

Modifier and Type	Method and Description
default ListenableFuture<T>	callback(FutureCallback<? super T> callback) Add a FutureCallback to be called once the future has completed.
default ListenableFuture<T>	callback(FutureCallback<? super T> callback, java.util.concurrent.Executor executor) Add a FutureCallback to be called once the future has completed.
default ListenableFuture<T>	callback(FutureCallback<? super T> callback, java.util.concurrent.Executor executor, ListenableFuture.ListenerOptimizationStrategy optimizeExecution) Add a FutureCallback to be called once the future has completed.
default ListenableFuture<T>	failureCallback(java.util.function.Consumer<java.lang.Throwable> callback) Add a Consumer to be called once the future has completed.
default ListenableFuture<T>	failureCallback(java.util.function.Consumer<java.lang.Throwable> callback, java.util.concurrent.Executor executor) Add a Consumer to be called once the future has completed.
default ListenableFuture<T>	failureCallback(java.util.function.Consumer<java.lang.Throwable> callback, java.util.concurrent.Executor executor, ListenableFuture.ListenerOptimizationStrategy optimizeExecution) Add a Consumer to be called once the future has completed.
default <R> ListenableFuture<R>	flatMap(java.util.function.Function<? super T,ListenableFuture<R>> mapper) Similar to map(Function), in that this will apply a mapper function once the applied to future completes.
default <R> ListenableFuture<R>	flatMap(java.util.function.Function<? super T,ListenableFuture<R>> mapper, java.util.concurrent.Executor executor) Similar to map(Function, Executor), in that this will apply a mapper function once the applied to future completes.
default <R> ListenableFuture<R>	flatMap(java.util.function.Function<? super T,ListenableFuture<R>> mapper, java.util.concurrent.Executor executor, ListenableFuture.ListenerOptimizationStrategy optimizeExecution) Similar to map(Function, Executor), in that this will apply a mapper function once the applied to future completes.
default <R> ListenableFuture<R>	flatMap(ListenableFuture<R> future) Convenience function for mapping this future in with an existing future, ignoring the result of this current future.
default <TT extends java.lang.Throwable> ListenableFuture<T>	flatMapFailure(java.lang.Class<TT> throwableType, java.util.function.Function<? super TT,ListenableFuture<T>> mapper) Similar to mapFailure(Class, Function) except that this mapper function returns a ListenableFuture if it needs to map the Throwable / failure into a result or another failure.
default <TT extends java.lang.Throwable> ListenableFuture<T>	flatMapFailure(java.lang.Class<TT> throwableType, java.util.function.Function<? super TT,ListenableFuture<T>> mapper, java.util.concurrent.Executor executor) Similar to mapFailure(Class, Function, Executor) except that this mapper function returns a ListenableFuture if it needs to map the Throwable / failure into a result or another failure.
default <TT extends java.lang.Throwable> ListenableFuture<T>	flatMapFailure(java.lang.Class<TT> throwableType, java.util.function.Function<? super TT,ListenableFuture<T>> mapper, java.util.concurrent.Executor executor, ListenableFuture.ListenerOptimizationStrategy optimizeExecution) Similar to mapFailure(Class, Function, Executor, ListenerOptimizationStrategy) except that this mapper function returns a ListenableFuture if it needs to map the Throwable into a result or another failure.
java.lang.Throwable	getFailure() Similar to Future.get() except instead of providing a result, this will provide a thrown exception if isCompletedExceptionally() returns true.
java.lang.Throwable	getFailure(long timeout, java.util.concurrent.TimeUnit unit) Similar to Future.get(long, TimeUnit) except instead of providing a result, this will provide a thrown exception if isCompletedExceptionally() returns true.
java.lang.StackTraceElement[]	getRunningStackTrace() A best effort to return the stack trace for for the executing thread of either this future, or a future which this depends on through the use of map(Function) or similar functions.
boolean	isCompletedExceptionally() Returns true if the future is both done and has completed with an error or was canceled.
default ListenableFuture<T>	listener(java.lang.Runnable listener) Add a listener to be called once the future has completed.
default ListenableFuture<T>	listener(java.lang.Runnable listener, java.util.concurrent.Executor executor) Add a listener to be called once the future has completed.
ListenableFuture<T>	listener(java.lang.Runnable listener, java.util.concurrent.Executor executor, ListenableFuture.ListenerOptimizationStrategy optimizeExecution) Add a listener to be called once the future has completed.
default <R> ListenableFuture<R>	map(java.util.function.Function<? super T,? extends R> mapper) Transform this future's result into another result by applying the provided mapper function.
default <R> ListenableFuture<R>	map(java.util.function.Function<? super T,? extends R> mapper, java.util.concurrent.Executor executor) Transform this future's result into another result by applying the provided mapper function.
default <R> ListenableFuture<R>	map(java.util.function.Function<? super T,? extends R> mapper, java.util.concurrent.Executor executor, ListenableFuture.ListenerOptimizationStrategy optimizeExecution) Transform this future's result into another result by applying the provided mapper function.
default <TT extends java.lang.Throwable> ListenableFuture<T>	mapFailure(java.lang.Class<TT> throwableType, java.util.function.Function<? super TT,? extends T> mapper) Similar to throwMap(Function) except this mapper will only be invoked when the future is in a failure state (from either the original computation or an earlier mapper throwing an exception).
default <TT extends java.lang.Throwable> ListenableFuture<T>	mapFailure(java.lang.Class<TT> throwableType, java.util.function.Function<? super TT,? extends T> mapper, java.util.concurrent.Executor executor) Similar to throwMap(Function, Executor) except this mapper will only be invoked when the future is in a failure state (from either the original computation or an earlier mapper throwing an exception).
default <TT extends java.lang.Throwable> ListenableFuture<T>	mapFailure(java.lang.Class<TT> throwableType, java.util.function.Function<? super TT,? extends T> mapper, java.util.concurrent.Executor executor, ListenableFuture.ListenerOptimizationStrategy optimizeExecution) Similar to throwMap(Function, Executor, ListenerOptimizationStrategy) except this mapper will only be invoked when the future is in a failure state (from either the original computation or an earlier mapper throwing an exception).
default ListenableFuture<T>	resultCallback(java.util.function.Consumer<? super T> callback) Add a Consumer to be called once the future has completed.
default ListenableFuture<T>	resultCallback(java.util.function.Consumer<? super T> callback, java.util.concurrent.Executor executor) Add a Consumer to be called once the future has completed.
default ListenableFuture<T>	resultCallback(java.util.function.Consumer<? super T> callback, java.util.concurrent.Executor executor, ListenableFuture.ListenerOptimizationStrategy optimizeExecution) Add a Consumer to be called once the future has completed.
default <R> ListenableFuture<R>	throwMap(java.util.function.Function<? super T,? extends R> mapper) Transform this future's result into another result by applying the provided mapper function.
default <R> ListenableFuture<R>	throwMap(java.util.function.Function<? super T,? extends R> mapper, java.util.concurrent.Executor executor) Transform this future's result into another result by applying the provided mapper function.
default <R> ListenableFuture<R>	throwMap(java.util.function.Function<? super T,? extends R> mapper, java.util.concurrent.Executor executor, ListenableFuture.ListenerOptimizationStrategy optimizeExecution) Transform this future's result into another result by applying the provided mapper function.

Methods inherited from interface java.util.concurrent.Future

cancel, get, get, isCancelled, isDone

Method Detail

isCompletedExceptionally

boolean isCompletedExceptionally()

Returns true if the future is both done and has completed with an error or was canceled. If this returns true the Throwable responsible for the error can be retrieved using getFailure();

Returns:

true if this ListenableFuture completed by a thrown Exception or was canceled

getFailure

java.lang.Throwable getFailure()
                        throws java.lang.InterruptedException

Similar to Future.get() except instead of providing a result, this will provide a thrown exception if isCompletedExceptionally() returns true. If the future has not completed yet this function will block until completion. If the future completed normally, this will return null.

Returns:

Throwable thrown in computing the future or null if completed normally

Throws:

java.lang.InterruptedException - If the current thread was interrupted while blocking

getFailure

java.lang.Throwable getFailure(long timeout,
                               java.util.concurrent.TimeUnit unit)
                        throws java.lang.InterruptedException,
                               java.util.concurrent.TimeoutException

Similar to Future.get(long, TimeUnit) except instead of providing a result, this will provide a thrown exception if isCompletedExceptionally() returns true. If the future has not completed yet this function will block until completion. If the future completed normally, this will return null.

Parameters:

timeout - The maximum time to wait

unit - The time unit of the timeout argument

Returns:

Throwable thrown in computing the future or null if completed normally

Throws:

java.lang.InterruptedException - If the current thread was interrupted while blocking

java.util.concurrent.TimeoutException - If the timeout was reached before the future completed

map

default <R> ListenableFuture<R> map(java.util.function.Function<? super T,? extends R> mapper)

Transform this future's result into another result by applying the provided mapper function. If this future completed in error, then the mapper will not be invoked, and instead the returned future will be completed in the same error state this future resulted in. If the mapper function itself throws an Exception, then the returned future will result in the error thrown from the mapper and ExceptionUtils.handleException(Throwable) will be invoked. If you don't want mapped exceptions to be treated as unexpected / uncaught please see throwMap(Function).

This can be easily used to chain together a series of operations, happening async (or in calling thread if already complete) until the final result is actually needed. map(Function, Executor) can be used if transformation mapper is expensive and thus async execution is absolutely required.

If the future is complete already, the function may be invoked on the invoking thread. If the future is not complete then the function will be invoked on the thread which completes the future (immediately after it completes).

If your function returns a future, consider using flatMap(Function) as an alternative.

Example use:

 
   public Integer countSomething(String value);
   
   public ListenableFuture<String> lookupSomething();
   
   ListenableFuture<Integer> count = lookupSomething().map((s) -> countSomething(s));
 

Type Parameters:

R - The type for the object returned from the mapper

Parameters:

mapper - Function to invoke in order to transform the futures result

Returns:

A new ListenableFuture with the specified result type

Since:

5.0

map

default <R> ListenableFuture<R> map(java.util.function.Function<? super T,? extends R> mapper,
                                    java.util.concurrent.Executor executor)

Transform this future's result into another result by applying the provided mapper function. If this future completed in error, then the mapper will not be invoked, and instead the returned future will be completed in the same error state this future resulted in. If the mapper function itself throws an Exception, then the returned future will result in the error thrown from the mapper and ExceptionUtils.handleException(Throwable) will be invoked. If you don't want mapped exceptions to be treated as unexpected / uncaught please see throwMap(Function, Executor).

This can be easily used to chain together a series of operations, happening async until the final result is actually needed. Once the future completes the mapper function will be invoked on the executor (if provided). Because of that providing an executor can ensure this will never block. If an executor is not provided then the mapper may be invoked on the calling thread (if the future is already complete), or on the same thread which the future completes on. If the mapper function is very fast and cheap to run then map(Function) or providing null for the executor can allow more efficient operation.

If your function returns a future, consider using flatMap(Function, Executor) as an alternative.

Type Parameters:

R - The type for the object returned from the mapper

Parameters:

mapper - Function to invoke in order to transform the futures result

executor - Executor to invoke mapper function on, or null to invoke on this thread or future complete thread (depending on future state)

Returns:

A new ListenableFuture with the specified result type

Since:

5.0

map

default <R> ListenableFuture<R> map(java.util.function.Function<? super T,? extends R> mapper,
                                    java.util.concurrent.Executor executor,
                                    ListenableFuture.ListenerOptimizationStrategy optimizeExecution)

Transform this future's result into another result by applying the provided mapper function. If this future completed in error, then the mapper will not be invoked, and instead the returned future will be completed in the same error state this future resulted in. If the mapper function itself throws an Exception, then the returned future will result in the error thrown from the mapper and ExceptionUtils.handleException(Throwable) will be invoked. If you don't want mapped exceptions to be treated as unexpected / uncaught please see throwMap(Function, Executor, ListenerOptimizationStrategy).

This can be easily used to chain together a series of operations, happening async until the final result is actually needed. Once the future completes the mapper function will be invoked on the executor (if provided). Because of that providing an executor can ensure this will never block. If an executor is not provided then the mapper may be invoked on the calling thread (if the future is already complete), or on the same thread which the future completes on. If the mapper function is very fast and cheap to run then map(Function) or providing null for the executor can allow more efficient operation.

If your function returns a future, consider using flatMap(Function, Executor) as an alternative.

Caution should be used when choosing to optimize the listener execution. If the listener is complex, or wanting to be run concurrent, this optimization could prevent that. In addition it will prevent other listeners from potentially being invoked until it completes. However if the listener is small / fast, this can provide significant performance gains. It should also be known that not all ListenableFuture implementations may be able to do such an optimization. Please see ListenableFuture.ListenerOptimizationStrategy javadocs for more specific details of what optimizations are available.

Type Parameters:

R - The type for the object returned from the mapper

Parameters:

mapper - Function to invoke in order to transform the futures result

executor - Executor to invoke mapper function on, or null to invoke on this thread or future complete thread (depending on future state)

optimizeExecution - true to avoid listener queuing for execution if already on the desired pool

Returns:

A new ListenableFuture with the specified result type

Since:

5.10

throwMap

default <R> ListenableFuture<R> throwMap(java.util.function.Function<? super T,? extends R> mapper)

Transform this future's result into another result by applying the provided mapper function. If this future completed in error, then the mapper will not be invoked, and instead the returned future will be completed in the same error state this future resulted in.

This function differs from map(Function) only in how exceptions thrown from the mapper function are handled. Please see map(Function) for a general understanding for the behavior of this operation. This is to be used when the mapper function throwing an exception is EXPECTED. Used to avoid treating mapping an exception as an unexpected behavior.

Say for example you wanted to use FutureUtils.scheduleWhile() to retry an operation as long as it kept throwing an exception. You might put the result and exception into a Pair so it can be checked for a maximum number of times like this:

 
   ListenableFuture<Pair<ResultType, RetryException>> exceptionConvertingLoop =
        FutureUtils.scheduleWhile(scheduler, retryDelayMillis, true, () -> {
          try {
            return new Pair<>(makeResultOrThrow(), null);
          } catch (RetryException e) {
            // we can't throw or we will break the loop
           return new Pair<>(null, e);
          }
        }, new Predicate<Pair<?, RetryException>>() {
          private int selfRetryCount = 0;

          public boolean test(Pair<?, RetryException> p) {
            return p.getLeft() == null && ++selfRetryCount <= maxRetryCount;
          }
        });
 

You would then need to use throwMap(Function) in order to convert that Pair back into a ListenableFuture with either a result, or the contained failure. For example:

 
 ListenableFuture<ResultType> resultFuture =
     exceptionConvertingLoop.throwMap((p) -> {
       if (p.getLeft() != null) {
         return p.getLeft();
       } else {
         throw p.getRight();
       }
     });
 

Type Parameters:

R - The type for the object returned from the mapper

Parameters:

mapper - Function to invoke in order to transform the futures result

Returns:

A new ListenableFuture with the specified result type

Since:

5.11

throwMap

default <R> ListenableFuture<R> throwMap(java.util.function.Function<? super T,? extends R> mapper,
                                         java.util.concurrent.Executor executor)

Transform this future's result into another result by applying the provided mapper function. If this future completed in error, then the mapper will not be invoked, and instead the returned future will be completed in the same error state this future resulted in.

This function differs from map(Function, Executor) only in how exceptions thrown from the mapper function are handled. Please see map(Function, Executor) for a general understanding for the behavior of this operation. This is to be used when the mapper function throwing an exception is EXPECTED. Used to avoid treating mapping an exception as an unexpected behavior. Please see throwMap(Function) for more usage examples.

Once the future completes the mapper function will be invoked on the executor (if provided). Because of that providing an executor can ensure this will never block. If an executor is not provided then the mapper may be invoked on the calling thread (if the future is already complete), or on the same thread which the future completes on. If the mapper function is very fast and cheap to run then throwMap(Function) or providing null for the executor can allow more efficient operation.

Type Parameters:

R - The type for the object returned from the mapper

Parameters:

mapper - Function to invoke in order to transform the futures result

executor - Executor to invoke mapper function on, or null to invoke on this thread or future complete thread (depending on future state)

Returns:

A new ListenableFuture with the specified result type

Since:

5.11

throwMap

default <R> ListenableFuture<R> throwMap(java.util.function.Function<? super T,? extends R> mapper,
                                         java.util.concurrent.Executor executor,
                                         ListenableFuture.ListenerOptimizationStrategy optimizeExecution)

Transform this future's result into another result by applying the provided mapper function. If this future completed in error, then the mapper will not be invoked, and instead the returned future will be completed in the same error state this future resulted in. If the mapper function itself throws an Exception, then the returned future will result in the error thrown from the mapper.

This can be easily used to chain together a series of operations, happening async until the final result is actually needed. Once the future completes the mapper function will be invoked on the executor (if provided). Because of that providing an executor can ensure this will never block. If an executor is not provided then the mapper may be invoked on the calling thread (if the future is already complete), or on the same thread which the future completes on. If the mapper function is very fast and cheap to run then throwMap(Function) or providing null for the executor can allow more efficient operation.

Caution should be used when choosing to optimize the listener execution. If the listener is complex, or wanting to be run concurrent, this optimization could prevent that. In addition it will prevent other listeners from potentially being invoked until it completes. However if the listener is small / fast, this can provide significant performance gains. It should also be known that not all ListenableFuture implementations may be able to do such an optimization. Please see ListenableFuture.ListenerOptimizationStrategy javadocs for more specific details of what optimizations are available.

Type Parameters:

R - The type for the object returned from the mapper

Parameters:

mapper - Function to invoke in order to transform the futures result

executor - Executor to invoke mapper function on, or null to invoke on this thread or future complete thread (depending on future state)

optimizeExecution - true to avoid listener queuing for execution if already on the desired pool

Returns:

A new ListenableFuture with the specified result type

Since:

5.11

flatMap

default <R> ListenableFuture<R> flatMap(ListenableFuture<R> future)

Convenience function for mapping this future in with an existing future, ignoring the result of this current future. This is equivalent to flatMap((ignored) -> future), and conceptually the same as FutureUtils.makeFailurePropagatingCompleteFuture(Iterable) with both futures being provided (though this allows us to capture the result of the provided future).

Please be aware that flatMap(futureProducer.get()) is NOT equivalent to flatMap((ignored) -> futureProducer.get()). As the second version would delay starting the future generation until this future completes. By calling into this with a future you will be starting its execution immediately.

Type Parameters:

R - The type of result returned from the provided future

Parameters:

future - The future to flat mpa against this one

Returns:

A new ListenableFuture that will complete when both this and the provided future does

flatMap

default <R> ListenableFuture<R> flatMap(java.util.function.Function<? super T,ListenableFuture<R>> mapper)

Similar to map(Function), in that this will apply a mapper function once the applied to future completes. Once this future resolves it will provide the result into the provided function. Unlike map(Function), this will then unwrap a future provided from the function so that instead of having ListenableFuture<ListenableFuture<R>> you can simply extract the final value. The returned future will only resolve once the future of the provided function completes.

If the future is complete already, the function may be invoked on the invoking thread. If the future is not complete then the function will be invoked on the thread which completes the future (immediately after it completes).

Example use:

 
   public ListenableFuture<Integer> countSomething(String value);
   
   public ListenableFuture<String> lookupSomething();
   
   ListenableFuture<Integer> count = lookupSomething().flatMap((s) -> countSomething(s));
 

Type Parameters:

R - The type for the object contained in the future which is returned from the mapper

Parameters:

mapper - Function to invoke in order to transform the futures result

Returns:

A new ListenableFuture with the specified result type

Since:

5.0

flatMap

default <R> ListenableFuture<R> flatMap(java.util.function.Function<? super T,ListenableFuture<R>> mapper,
                                        java.util.concurrent.Executor executor)

Similar to map(Function, Executor), in that this will apply a mapper function once the applied to future completes. Once this future resolves it will provide the result into the provided function. Unlike map(Function, Executor), this will then unwrap a future provided from the function so that instead of having ListenableFuture<ListenableFuture<R>> you can simply extract the final value. The returned future will only resolve once the future of the provided function completes.

Once the future completes the mapper function will be invoked on the executor (if provided). Because of that providing an executor can ensure this will never block. If an executor is not provided then the mapper may be invoked on the calling thread (if the future is already complete), or on the same thread which the future completes on. If the mapper function is very fast and cheap to run then flatMap(Function) or providing null for the executor can allow more efficient operation.

Type Parameters:

R - The type for the object contained in the future which is returned from the mapper

Parameters:

mapper - Function to invoke in order to transform the futures result

executor - Executor to invoke mapper function on, or null to invoke on this thread or future complete thread (depending on future state)

Returns:

A new ListenableFuture with the specified result type

Since:

5.0

flatMap

default <R> ListenableFuture<R> flatMap(java.util.function.Function<? super T,ListenableFuture<R>> mapper,
                                        java.util.concurrent.Executor executor,
                                        ListenableFuture.ListenerOptimizationStrategy optimizeExecution)

Similar to map(Function, Executor), in that this will apply a mapper function once the applied to future completes. Once this future resolves it will provide the result into the provided function. Unlike map(Function, Executor), this will then unwrap a future provided from the function so that instead of having ListenableFuture<ListenableFuture<R>> you can simply extract the final value. The returned future will only resolve once the future of the provided function completes.

Once the future completes the mapper function will be invoked on the executor (if provided). Because of that providing an executor can ensure this will never block. If an executor is not provided then the mapper may be invoked on the calling thread (if the future is already complete), or on the same thread which the future completes on. If the mapper function is very fast and cheap to run then flatMap(Function) or providing null for the executor can allow more efficient operation.

Caution should be used when choosing to optimize the listener execution. If the listener is complex, or wanting to be run concurrent, this optimization could prevent that. In addition it will prevent other listeners from potentially being invoked until it completes. However if the listener is small / fast, this can provide significant performance gains. It should also be known that not all ListenableFuture implementations may be able to do such an optimization. Please see ListenableFuture.ListenerOptimizationStrategy javadocs for more specific details of what optimizations are available.

Type Parameters:

R - The type for the object contained in the future which is returned from the mapper

Parameters:

mapper - Function to invoke in order to transform the futures result

executor - Executor to invoke mapper function on, or null to invoke on this thread or future complete thread (depending on future state)

optimizeExecution - true to avoid listener queuing for execution if already on the desired pool

Returns:

A new ListenableFuture with the specified result type

Since:

5.10

mapFailure

default <TT extends java.lang.Throwable> ListenableFuture<T> mapFailure(java.lang.Class<TT> throwableType,
                                                                        java.util.function.Function<? super TT,? extends T> mapper)

Similar to throwMap(Function) except this mapper will only be invoked when the future is in a failure state (from either the original computation or an earlier mapper throwing an exception). If this future does resolve in a failure state, and that exception class matches the one provided here. The mapper function will then be provided that throwable, it can then map that throwable back into a result (perhaps an Optional), or re-throw either the same or a different exception keep the future in a failure state. If the future completes with a normal result, this mapper will be ignored, and the result will be forwarded on without invoking this mapper.

Type Parameters:

TT - The type of throwable that should be handled

Parameters:

throwableType - The class referencing to the type of throwable this mapper handles

mapper - The mapper to convert a thrown exception to either a result or thrown exception

Returns:

A ListenableFuture that will resolve after the mapper is considered

Since:

5.17

mapFailure

default <TT extends java.lang.Throwable> ListenableFuture<T> mapFailure(java.lang.Class<TT> throwableType,
                                                                        java.util.function.Function<? super TT,? extends T> mapper,
                                                                        java.util.concurrent.Executor executor)

Similar to throwMap(Function, Executor) except this mapper will only be invoked when the future is in a failure state (from either the original computation or an earlier mapper throwing an exception). If this future does resolve in a failure state, and that exception class matches the one provided here. The mapper function will then be provided that throwable, it can then map that throwable back into a result (perhaps an Optional), or re-throw either the same or a different exception keep the future in a failure state. If the future completes with a normal result, this mapper will be ignored, and the result will be forwarded on without invoking this mapper.

Type Parameters:

TT - The type of throwable that should be handled

Parameters:

throwableType - The class referencing to the type of throwable this mapper handles

mapper - The mapper to convert a thrown exception to either a result or thrown exception

executor - Executor to invoke mapper function on, or null to invoke on this thread or future complete thread (depending on future state)

Returns:

A ListenableFuture that will resolve after the mapper is considered

Since:

5.17

mapFailure

default <TT extends java.lang.Throwable> ListenableFuture<T> mapFailure(java.lang.Class<TT> throwableType,
                                                                        java.util.function.Function<? super TT,? extends T> mapper,
                                                                        java.util.concurrent.Executor executor,
                                                                        ListenableFuture.ListenerOptimizationStrategy optimizeExecution)

Similar to throwMap(Function, Executor, ListenerOptimizationStrategy) except this mapper will only be invoked when the future is in a failure state (from either the original computation or an earlier mapper throwing an exception). If this future does resolve in a failure state, and that exception class matches the one provided here. The mapper function will then be provided that throwable, it can then map that throwable back into a result perhaps an Optional), or re-throw either the same or a different exception keep the future in a failure state. If the future completes with a normal result, this mapper will be ignored, and the result will be forwarded on without invoking this mapper.

Type Parameters:

TT - The type of throwable that should be handled

Parameters:

throwableType - The class referencing to the type of throwable this mapper handles

mapper - The mapper to convert a thrown exception to either a result or thrown exception

executor - Executor to invoke mapper function on, or null to invoke on this thread or future complete thread (depending on future state)

optimizeExecution - true to avoid listener queuing for execution if already on the desired pool

Returns:

A ListenableFuture that will resolve after the mapper is considered

Since:

5.17

flatMapFailure

default <TT extends java.lang.Throwable> ListenableFuture<T> flatMapFailure(java.lang.Class<TT> throwableType,
                                                                            java.util.function.Function<? super TT,ListenableFuture<T>> mapper)

Similar to mapFailure(Class, Function) except that this mapper function returns a ListenableFuture if it needs to map the Throwable / failure into a result or another failure. The mapper function can return a Future that will (or may) provide a result, or it can provide a future that will result in the same or another failure. Similar to mapFailure(Class, Function) the mapper can also throw an exception directly.

Type Parameters:

TT - The type of throwable that should be handled

Parameters:

throwableType - The class referencing to the type of throwable this mapper handles

mapper - Function to invoke in order to transform the futures result

Returns:

A ListenableFuture that will resolve after the mapper is considered

Since:

5.17

flatMapFailure

default <TT extends java.lang.Throwable> ListenableFuture<T> flatMapFailure(java.lang.Class<TT> throwableType,
                                                                            java.util.function.Function<? super TT,ListenableFuture<T>> mapper,
                                                                            java.util.concurrent.Executor executor)

Similar to mapFailure(Class, Function, Executor) except that this mapper function returns a ListenableFuture if it needs to map the Throwable / failure into a result or another failure. The mapper function can return a Future that will (or may) provide a result, or it can provide a future that will result in the same or another failure. Similar to mapFailure(Class, Function, Executor) the mapper can also throw an exception directly.

Type Parameters:

TT - The type of throwable that should be handled

Parameters:

throwableType - The class referencing to the type of throwable this mapper handles

mapper - Function to invoke in order to transform the futures result

executor - Executor to invoke mapper function on, or null to invoke on this thread or future complete thread (depending on future state)

Returns:

A ListenableFuture that will resolve after the mapper is considered

Since:

5.17

flatMapFailure

default <TT extends java.lang.Throwable> ListenableFuture<T> flatMapFailure(java.lang.Class<TT> throwableType,
                                                                            java.util.function.Function<? super TT,ListenableFuture<T>> mapper,
                                                                            java.util.concurrent.Executor executor,
                                                                            ListenableFuture.ListenerOptimizationStrategy optimizeExecution)

Similar to mapFailure(Class, Function, Executor, ListenerOptimizationStrategy) except that this mapper function returns a ListenableFuture if it needs to map the Throwable into a result or another failure. The mapper function can return a Future that will (or may) provide a result, or it can provide a future that will result in the same or another failure. Similar to mapFailure(Class, Function, Executor, ListenerOptimizationStrategy) the mapper can also throw an exception directly.

Type Parameters:

TT - The type of throwable that should be handled

Parameters:

throwableType - The class referencing to the type of throwable this mapper handles

mapper - Function to invoke in order to transform the futures result

executor - Executor to invoke mapper function on, or null to invoke on this thread or future complete thread (depending on future state)

optimizeExecution - true to avoid listener queuing for execution if already on the desired pool

Returns:

A ListenableFuture that will resolve after the mapper is considered

Since:

5.17

listener

default ListenableFuture<T> listener(java.lang.Runnable listener)

Add a listener to be called once the future has completed. If the future has already finished, this will be called immediately.

The listener from this call will execute on the same thread the result was produced on, or on the adding thread if the future is already complete. If the runnable has high complexity, consider using listener(Runnable, Executor).

Parameters:

listener - the listener to run when the computation is complete

Returns:

Exactly this instance to add more listeners or other functional operations

Since:

5.34

listener

default ListenableFuture<T> listener(java.lang.Runnable listener,
                                     java.util.concurrent.Executor executor)

Add a listener to be called once the future has completed. If the future has already finished, this will be called immediately.

If the provided Executor is null, the listener will execute on the thread which computed the original future (once it is done). If the future has already completed, the listener will execute immediately on the thread which is adding the listener.

Parameters:

listener - the listener to run when the computation is complete

executor - Executor the listener should be ran on, or null

Returns:

Exactly this instance to add more listeners or other functional operations

Since:

5.34

listener

ListenableFuture<T> listener(java.lang.Runnable listener,
                             java.util.concurrent.Executor executor,
                             ListenableFuture.ListenerOptimizationStrategy optimizeExecution)

Add a listener to be called once the future has completed. If the future has already finished, this will be called immediately.

If the provided Executor is null, the listener will execute on the thread which computed the original future (once it is done). If the future has already completed, the listener will execute immediately on the thread which is adding the listener.

Caution should be used when choosing to optimize the listener execution. If the listener is complex, or wanting to be run concurrent, this optimization could prevent that. In addition it will prevent other listeners from potentially being invoked until it completes. However if the listener is small / fast, this can provide significant performance gains. It should also be known that not all ListenableFuture implementations may be able to do such an optimization. Please see ListenableFuture.ListenerOptimizationStrategy javadocs for more specific details of what optimizations are available.

Parameters:

listener - the listener to run when the computation is complete

executor - Executor the listener should be ran on, or null

optimizeExecution - true to avoid listener queuing for execution if already on the desired pool

Returns:

Exactly this instance to add more listeners or other functional operations

Since:

5.34

callback

default ListenableFuture<T> callback(FutureCallback<? super T> callback)

Add a FutureCallback to be called once the future has completed. If the future has already finished, this will be called immediately.

The callback from this call will execute on the same thread the result was produced on, or on the adding thread if the future is already complete. If the callback has high complexity, consider passing an executor in for it to be called on.

If you only care about the success result case please see resultCallback(Consumer) or conversely if you only want to be invoked for failure cases please see failureCallback(Consumer).

Parameters:

callback - to be invoked when the computation is complete

Returns:

Exactly this instance to add more callbacks or other functional operations

Since:

5.34

callback

default ListenableFuture<T> callback(FutureCallback<? super T> callback,
                                     java.util.concurrent.Executor executor)

Add a FutureCallback to be called once the future has completed. If the future has already finished, this will be called immediately.

If the provided Executor is null, the callback will execute on the thread which computed the original future (once it is done). If the future has already completed, the callback will execute immediately on the thread which is adding the callback.

If you only care about the success result case please see resultCallback(Consumer, Executor) or conversely if you only want to be invoked for failure cases please see failureCallback(Consumer, Executor).

Parameters:

callback - to be invoked when the computation is complete

executor - Executor the callback should be ran on, or null

Returns:

Exactly this instance to add more callbacks or other functional operations

Since:

5.34

callback

default ListenableFuture<T> callback(FutureCallback<? super T> callback,
                                     java.util.concurrent.Executor executor,
                                     ListenableFuture.ListenerOptimizationStrategy optimizeExecution)

Add a FutureCallback to be called once the future has completed. If the future has already finished, this will be called immediately.

If the provided Executor is null, the callback will execute on the thread which computed the original future (once it is done). If the future has already completed, the callback will execute immediately on the thread which is adding the callback.

Caution should be used when choosing to optimize the listener execution. If the listener is complex, or wanting to be run concurrent, this optimization could prevent that. In addition it will prevent other listeners from potentially being invoked until it completes. However if the listener is small / fast, this can provide significant performance gains. It should also be known that not all ListenableFuture implementations may be able to do such an optimization. Please see ListenableFuture.ListenerOptimizationStrategy javadocs for more specific details of what optimizations are available.

If you only care about the success result case please see resultCallback(Consumer, Executor, ListenerOptimizationStrategy) or conversely if you only want to be invoked for failure cases please see failureCallback(Consumer, Executor, ListenerOptimizationStrategy).

Parameters:

callback - to be invoked when the computation is complete

executor - Executor the callback should be ran on, or null

optimizeExecution - true to avoid listener queuing for execution if already on the desired pool

Returns:

Exactly this instance to add more callbacks or other functional operations

Since:

5.34

resultCallback

default ListenableFuture<T> resultCallback(java.util.function.Consumer<? super T> callback)

Add a Consumer to be called once the future has completed. If the future has already finished, this will be called immediately. Assuming the future has completed without error, the result will be provided to the Consumer, otherwise it will go un-invoked.

The callback from this call will execute on the same thread the result was produced on, or on the adding thread if the future is already complete. If the callback has high complexity, consider passing an executor in for it to be called on.

Parameters:

callback - to be invoked when the computation is complete

Returns:

Exactly this instance to add more callbacks or other functional operations

Since:

5.34

resultCallback

default ListenableFuture<T> resultCallback(java.util.function.Consumer<? super T> callback,
                                           java.util.concurrent.Executor executor)

Add a Consumer to be called once the future has completed. If the future has already finished, this will be called immediately. Assuming the future has completed without error, the result will be provided to the Consumer, otherwise it will go un-invoked.

If the provided Executor is null, the callback will execute on the thread which computed the original future (once it is done). If the future has already completed, the callback will execute immediately on the thread which is adding the callback.

Parameters:

callback - to be invoked when the computation is complete

executor - Executor the callback should be ran on, or null

Returns:

Exactly this instance to add more callbacks or other functional operations

Since:

5.34

resultCallback

default ListenableFuture<T> resultCallback(java.util.function.Consumer<? super T> callback,
                                           java.util.concurrent.Executor executor,
                                           ListenableFuture.ListenerOptimizationStrategy optimizeExecution)

Add a Consumer to be called once the future has completed. If the future has already finished, this will be called immediately. Assuming the future has completed without error, the result will be provided to the Consumer, otherwise it will go un-invoked.

If the provided Executor is null, the callback will execute on the thread which computed the original future (once it is done). If the future has already completed, the callback will execute immediately on the thread which is adding the callback.

Caution should be used when choosing to optimize the listener execution. If the listener is complex, or wanting to be run concurrent, this optimization could prevent that. In addition it will prevent other listeners from potentially being invoked until it completes. However if the listener is small / fast, this can provide significant performance gains. It should also be known that not all ListenableFuture implementations may be able to do such an optimization. Please see ListenableFuture.ListenerOptimizationStrategy javadocs for more specific details of what optimizations are available.

Parameters:

callback - to be invoked when the computation is complete

executor - Executor the callback should be ran on, or null

optimizeExecution - true to avoid listener queuing for execution if already on the desired pool

Returns:

Exactly this instance to add more callbacks or other functional operations

Since:

5.34

failureCallback

default ListenableFuture<T> failureCallback(java.util.function.Consumer<java.lang.Throwable> callback)

Add a Consumer to be called once the future has completed. If the future has already finished, this will be called immediately. Assuming the future has completed with an error, the Throwable will be provided to the Consumer, otherwise if no error occurred, the callback will go un-invoked.

The callback from this call will execute on the same thread the result was produced on, or on the adding thread if the future is already complete. If the callback has high complexity, consider passing an executor in for it to be called on.

Parameters:

callback - to be invoked when the computation is complete

Returns:

Exactly this instance to add more callbacks or other functional operations

Since:

5.34

failureCallback

default ListenableFuture<T> failureCallback(java.util.function.Consumer<java.lang.Throwable> callback,
                                            java.util.concurrent.Executor executor)

Add a Consumer to be called once the future has completed. If the future has already finished, this will be called immediately. Assuming the future has completed with an error, the Throwable will be provided to the Consumer, otherwise if no error occurred, the callback will go un-invoked.

If the provided Executor is null, the callback will execute on the thread which computed the original future (once it is done). If the future has already completed, the callback will execute immediately on the thread which is adding the callback.

Parameters:

callback - to be invoked when the computation is complete

executor - Executor the callback should be ran on, or null

Returns:

Exactly this instance to add more callbacks or other functional operations

Since:

5.34

failureCallback

default ListenableFuture<T> failureCallback(java.util.function.Consumer<java.lang.Throwable> callback,
                                            java.util.concurrent.Executor executor,
                                            ListenableFuture.ListenerOptimizationStrategy optimizeExecution)

Add a Consumer to be called once the future has completed. If the future has already finished, this will be called immediately. Assuming the future has completed with an error, the Throwable will be provided to the Consumer, otherwise if no error occurred, the callback will go un-invoked.

If the provided Executor is null, the callback will execute on the thread which computed the original future (once it is done). If the future has already completed, the callback will execute immediately on the thread which is adding the callback.

Caution should be used when choosing to optimize the listener execution. If the listener is complex, or wanting to be run concurrent, this optimization could prevent that. In addition it will prevent other listeners from potentially being invoked until it completes. However if the listener is small / fast, this can provide significant performance gains. It should also be known that not all ListenableFuture implementations may be able to do such an optimization. Please see ListenableFuture.ListenerOptimizationStrategy javadocs for more specific details of what optimizations are available.

Parameters:

callback - to be invoked when the computation is complete

executor - Executor the callback should be ran on, or null

optimizeExecution - true to avoid listener queuing for execution if already on the desired pool

Returns:

Exactly this instance to add more callbacks or other functional operations

Since:

5.34

getRunningStackTrace

java.lang.StackTraceElement[] getRunningStackTrace()

A best effort to return the stack trace for for the executing thread of either this future, or a future which this depends on through the use of map(Function) or similar functions. If there is no thread executing the future yet, or the future has already completed, then this will return null.

This is done without locking (though generating a stack trace still requires a JVM safe point), so the resulting stack trace is NOT guaranteed to be accurate. In most cases (particularly when blocking) this should be accurate though.

Returns:

The stack trace currently executing the future, or null if unavailable