ratpack.exec.util.ParallelBatch Maven / Gradle / Ivy
/*
* Copyright 2016 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package ratpack.exec.util;
import ratpack.exec.ExecResult;
import ratpack.exec.Execution;
import ratpack.exec.Operation;
import ratpack.exec.Promise;
import ratpack.exec.util.internal.DefaultParallelBatch;
import ratpack.func.Action;
import ratpack.func.BiAction;
import ratpack.stream.TransformablePublisher;
import java.util.Arrays;
import java.util.List;
/**
* A batch of promises to be processed, in parallel.
*
* Parallel batches can be created via {@link #of(Iterable)}.
*
* Each promise will be executed in a {@link Execution#fork() forked execution}.
* The {@link #execInit(Action)} method allows each forked execution to be customised before executing the work.
*
* @param the type of value produced by each promise in the batch
* @since 1.4
*/
public interface ParallelBatch extends Batch {
/**
* Creates a new parallel batch of the given promises.
*
* @param promises the promises
* @param the type of item produced by each promise
* @return a {@link ParallelBatch}
*/
static ParallelBatch of(Iterable> promises) {
return new DefaultParallelBatch<>(promises, Action.noop());
}
/**
* Creates a new parallel batch of the given promises.
*
* @param promises the promises
* @param the type of item produced by each promise
* @return a {@link ParallelBatch}
*/
@SafeVarargs
@SuppressWarnings("varargs")
static ParallelBatch of(Promise... promises) {
return of(Arrays.asList(promises));
}
/**
* Specifies an initializer for each forked execution.
*
* The given action will be called with each execution before processing the promise.
* This can be used to seed the execution registry.
*
* The given function will be invoked from the execution in question, and will be executed concurrently.
*
* @param execInit the execution initializer
* @return a new batch, configured to use the given initializer
*/
ParallelBatch execInit(Action execInit);
/**
* {@inheritDoc}
*/
@Override
Promise>> yieldAll();
/**
* {@inheritDoc}
*
* Multiple errors may occur due to promises being in-flight when the first error occurs.
* Subsequent errors will be {@link Throwable#addSuppressed(Throwable)} suppressed by the first error.
*/
@Override
Promise> yield();
/**
* {@inheritDoc}
*
* Multiple errors may occur due to promises being in-flight when the first error occurs.
* Subsequent errors will be {@link Throwable#addSuppressed(Throwable)} suppressed by the first error.
*
* Note that the given function will be executed concurrently, as values become available.
*
*
{@code
* import org.junit.Assert;
* import ratpack.exec.Promise;
* import ratpack.exec.util.ParallelBatch;
* import ratpack.func.Pair;
* import ratpack.test.exec.ExecHarness;
*
* import java.util.Arrays;
* import java.util.List;
* import java.util.Map;
* import java.util.concurrent.ConcurrentHashMap;
*
* public class Example {
*
* public static void main(String... args) throws Exception {
* Map map = new ConcurrentHashMap<>();
*
* ExecHarness.runSingle(e -> {
* List>> promises = Arrays.asList(
* Promise.value(Pair.of("a", 1)),
* Promise.value(Pair.of("b", 2)),
* Promise.value(Pair.of("c", 3)),
* Promise.value(Pair.of("d", 4))
* );
*
* ParallelBatch.of(promises)
* .forEach((i, v) -> map.put(v.left, v.right))
* .then();
* });
*
* Assert.assertEquals(Integer.valueOf(1), map.get("a"));
* Assert.assertEquals(Integer.valueOf(2), map.get("b"));
* Assert.assertEquals(Integer.valueOf(3), map.get("c"));
* Assert.assertEquals(Integer.valueOf(4), map.get("d"));
* }
* }
* }
*/
@Override
Operation forEach(BiAction consumer);
/**
* {@inheritDoc}
*
* Any errors that occur after the initial will be ignored.
*/
@Override
TransformablePublisher publisher();
}