oblak/cloud-services/src/main/java/cloud/commandframework/services/ServicePipeline.java
2020-09-27 23:12:13 +02:00

240 lines
10 KiB
Java

//
// MIT License
//
// Copyright (c) 2020 IntellectualSites
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
package cloud.commandframework.services;
import com.google.common.reflect.TypeToken;
import cloud.commandframework.services.types.Service;
import javax.annotation.Nonnull;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Executor;
import java.util.function.Predicate;
/**
* Service pipeline
*/
public final class ServicePipeline {
private final Object lock = new Object();
private final Map<TypeToken<? extends Service<?, ?>>, ServiceRepository<?, ?>> repositories;
private final Executor executor;
ServicePipeline(@Nonnull final Executor executor) {
this.repositories = new HashMap<>();
this.executor = executor;
}
/**
* Create a new {@link ServicePipelineBuilder}
*
* @return Builder instance
*/
@Nonnull
public static ServicePipelineBuilder builder() {
return new ServicePipelineBuilder();
}
/**
* Register a service type so that it is recognized by the pipeline
*
* @param type Service type
* @param defaultImplementation Default implementation of the service. This must *always* be
* supplied and will be the last service implementation that the
* pipeline attempts to access. This will never be filtered out.
* @param <Context> Service context type
* @param <Result> Service result type
* @return ServicePipeline The service pipeline instance
*/
public <Context, Result> ServicePipeline registerServiceType(
@Nonnull final TypeToken<? extends Service<Context, Result>> type,
@Nonnull final Service<Context, Result> defaultImplementation) {
synchronized (this.lock) {
if (repositories.containsKey(type)) {
throw new IllegalArgumentException(String
.format("Service of type '%s' has already been registered", type.toString()));
}
final ServiceRepository<Context, Result> repository = new ServiceRepository<>(type);
repository.registerImplementation(defaultImplementation, Collections.emptyList());
this.repositories.put(type, repository);
return this;
}
}
/**
* Scan a given class for methods annotated with {@link cloud.commandframework.services.annotations.ServiceImplementation}
* and register them as service implementations.
* <p>
* The methods should be of the form:
* <pre>{@code
* {@literal @}Nullable
* {@literal @}ServiceImplementation(YourService.class)
* public YourResult handle(YourContext) {
* return result;
* }
* }</pre>
*
* @param instance Instance of the class to scan
* @param <T> Type of the instance
* @return Service pipeline instance
* @throws Exception Any exceptions thrown during the registration process
*/
@SuppressWarnings("unchecked")
public <T> ServicePipeline registerMethods(
@Nonnull final T instance) throws Exception {
synchronized (this.lock) {
final Map<? extends Service<?, ?>, TypeToken<? extends Service<?, ?>>> services =
AnnotatedMethodServiceFactory.INSTANCE.lookupServices(instance);
for (final Map.Entry<? extends Service<?, ?>, TypeToken<? extends Service<?, ?>>> serviceEntry : services
.entrySet()) {
final TypeToken<? extends Service<?, ?>> type = serviceEntry.getValue();
final ServiceRepository<?, ?> repository = this.repositories.get(type);
if (repository == null) {
throw new IllegalArgumentException(
String.format("No service registered for type '%s'", type.toString()));
}
repository.<Service>registerImplementation(serviceEntry.getKey(),
Collections.emptyList());
}
}
return this;
}
/**
* Register a service implementation for a type that is recognized by the pipeline. It is
* important that a call to {@link #registerServiceType(TypeToken, Service)} has been made
* beforehand, otherwise a {@link IllegalArgumentException} will be thrown
*
* @param type Service type
* @param implementation Implementation of the service
* @param filters Filters that will be used to determine whether or not the service gets
* used
* @param <Context> Service context type
* @param <Result> Service result type
* @return ServicePipeline The service pipeline instance
*/
public <Context, Result> ServicePipeline registerServiceImplementation(
@Nonnull final TypeToken<? extends Service<Context, Result>> type,
@Nonnull final Service<Context, Result> implementation,
@Nonnull final Collection<Predicate<Context>> filters) {
synchronized (this.lock) {
final ServiceRepository<Context, Result> repository = getRepository(type);
repository.registerImplementation(implementation, filters);
}
return this;
}
/**
* Register a service implementation for a type that is recognized by the pipeline. It is
* important that a call to {@link #registerServiceType(TypeToken, Service)} has been made
* beforehand, otherwise a {@link IllegalArgumentException} will be thrown
*
* @param type Service type
* @param implementation Implementation of the service
* @param filters Filters that will be used to determine whether or not the service gets
* used
* @param <Context> Service context type
* @param <Result> Service result type
* @return ServicePipeline The service pipeline instance
*/
public <Context, Result> ServicePipeline registerServiceImplementation(
@Nonnull final Class<? extends Service<Context, Result>> type,
@Nonnull final Service<Context, Result> implementation,
@Nonnull final Collection<Predicate<Context>> filters) {
return registerServiceImplementation(TypeToken.of(type), implementation, filters);
}
/**
* Start traversing the pipeline by providing the context that will be used to generate the
* results
*
* @param context Context
* @param <Context> Context type
* @return Service pumper instance
*/
@Nonnull
public <Context> ServicePump<Context> pump(@Nonnull final Context context) {
return new ServicePump<>(this, context);
}
@SuppressWarnings("unchecked")
@Nonnull
<Context, Result> ServiceRepository<Context, Result> getRepository(
@Nonnull final TypeToken<? extends Service<Context, Result>> type) {
final ServiceRepository<Context, Result> repository =
(ServiceRepository<Context, Result>) this.repositories.get(type);
if (repository == null) {
throw new IllegalArgumentException(
String.format("No service registered for type '%s'", type.toString()));
}
return repository;
}
/**
* Get a collection of all the recognised service types.
*
* @return Returns an Immutable collection of the service types registered.
*/
@Nonnull
public Collection<TypeToken<? extends Service<?, ?>>> getRecognizedTypes() {
return Collections.unmodifiableCollection(this.repositories.keySet());
}
/**
* Get a collection of all the {@link TypeToken} of all implementations for a given type.
*
* @param type The {@link TypeToken} of the service to get implementations for.
* @param <Context> The context type.
* @param <Result> The result type.
* @param <S> The service type.
* @return Returns an collection of the {@link TypeToken}s of the implementations for a given
* service. Iterator order matches the priority when pumping contexts through the pipeline
*/
@Nonnull
@SuppressWarnings("unchecked")
public <Context, Result, S extends Service<Context, Result>> Collection<TypeToken<? extends S>> getImplementations(
@Nonnull final TypeToken<S> type) {
ServiceRepository<Context, Result> repository = getRepository(type);
List<TypeToken<? extends S>> collection = new LinkedList<>();
final LinkedList<? extends ServiceRepository<Context, Result>.ServiceWrapper<? extends Service<Context, Result>>>
queue = repository.getQueue();
queue.sort(null);
Collections.reverse(queue);
for (ServiceRepository<Context, Result>.ServiceWrapper<? extends Service<Context, Result>> wrapper : queue) {
collection
.add((TypeToken<? extends S>) TypeToken.of(wrapper.getImplementation().getClass()));
}
return Collections.unmodifiableList(collection);
}
@Nonnull
Executor getExecutor() {
return this.executor;
}
}