Interface Operation
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public interface Operation
A logical operation.An operation encapsulates a logical piece of work, which will complete some time in the future. It is similar to a
Promise
except that it does not produce a value. It merely succeeds, or throws an exception.The
then(Block)
method allows specifying what should happen after the operation completes. TheonError(Action)
method allows specifying what should happen if the operation fails. LikePromise
, the operation will not start until it is subscribed to, viathen(Block)
orthen()
.It is common for methods that would naturally return
void
to return anOperation
instead, to allow the method implementation to be effectively asynchronous. The caller of the method is then expected to use thethen(Block)
method to specify what should happen after the operation that the method represents finishes.import ratpack.exec.Blocking; import ratpack.exec.Operation; import com.google.common.collect.Lists; import ratpack.test.exec.ExecHarness; import java.util.Arrays; import java.util.List; import static org.junit.Assert.assertEquals; public class Example { public static void main(String... args) throws Exception { List<String> events = Lists.newArrayList(); ExecHarness.runSingle(e -> Operation.of(() -> Blocking.get(() -> events.add("1")) .then(b -> events.add("2")) ) .then(() -> events.add("3")) ); assertEquals(Arrays.asList("1", "2", "3"), events); } }
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Default Methods Modifier and Type Method Description default Operation
blockingNext(Block operation)
Executes the given block as an operation, on a blocking thread.default <T> Promise<T>
flatMap(Promise<T> promise)
default <T> Promise<T>
flatMap(Factory<? extends Promise<T>> factory)
static Operation
flatten(Factory<Operation> factory)
Create an operation that delegates to another operation.default <T> Promise<T>
map(Factory<? extends T> factory)
default Operation
mapError(Action<? super java.lang.Throwable> action)
Convert an error to a success or different error.default Operation
next(Operation operation)
default Operation
next(Block operation)
static Operation
noop()
static Operation
of(Block block)
Operation
onError(Action<? super java.lang.Throwable> onError)
Promise<java.lang.Void>
promise()
default void
then()
void
then(Block block)
default <O> O
to(Function<? super Operation,? extends O> function)
default Operation
wiretap(Action<? super java.util.Optional<? extends java.lang.Throwable>> action)
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Method Detail
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flatten
static Operation flatten(Factory<Operation> factory)
Create an operation that delegates to another operation.- Parameters:
factory
- a factory for the operation- Returns:
- an operation
- Since:
- 1.5
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mapError
default Operation mapError(Action<? super java.lang.Throwable> action)
Convert an error to a success or different error.The given action receives the upstream error and is executed as an operation. If the operation completes without error, the original error is considered handled and the returned operation will propagate success.
If the given action operation throws an exception, the returned operation will propagate that exception.
This method differs to
onError(Action)
in that it does not terminate the operation.- Parameters:
action
- the error handler- Returns:
- an operation
- Since:
- 1.5
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then
@NonBlocking void then(Block block)
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then
@NonBlocking default void then()
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promise
Promise<java.lang.Void> promise()
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blockingNext
default Operation blockingNext(Block operation)
Executes the given block as an operation, on a blocking thread.- Parameters:
operation
- a block of code to be executed, on a blocking thread- Returns:
- an operation
- Since:
- 1.4
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to
default <O> O to(Function<? super Operation,? extends O> function) throws java.lang.Exception
- Throws:
java.lang.Exception
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wiretap
default Operation wiretap(Action<? super java.util.Optional<? extends java.lang.Throwable>> action)
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noop
static Operation noop()
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