com.github.robozonky.internal.tenant.LazyEvent Maven / Gradle / Ivy
/*
* Copyright 2020 The RoboZonky Project
*
* 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 com.github.robozonky.internal.tenant;
import java.util.function.Supplier;
import com.github.robozonky.api.notifications.Event;
import com.github.robozonky.api.notifications.EventListenerSupplier;
/**
* Encapsulates the creation of {@link Event}. This is useful in cases where the creation of events is expensive,
* such as when additional remote information needs to be retrieved or calculations performed. We can first determine
* whether someone is actually listening for the event first, and only then perform these heavy operations.
*
* @param Type of the event being fired.
*/
public interface LazyEvent extends Supplier {
/**
* Type of the event so that we can pre-scan all the {@link EventListenerSupplier}s.
*
* @return never null
*/
Class getEventType();
/**
* Instantiate the event. This may result in expensive calls and should therefore only be performed when we are
* sure we need the {@link Event} instance. The instantiation process only happens once, every subsequent
* invocation must return the same object.
*
* @return Instantiated instance.
*/
@Override
T get();
}