/*
 * Copyright 2017-2020 original 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
 *
 * https://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 io.micronaut.health;

import io.micronaut.context.event.ApplicationEventListener;
import io.micronaut.context.event.ApplicationEventPublisher;
import io.micronaut.discovery.ServiceInstance;
import io.micronaut.discovery.event.ServiceReadyEvent;
import io.micronaut.scheduling.annotation.Scheduled;

import javax.inject.Singleton;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

A scheduled task that sends a periodic heartbeat whilst the server is active.
Author:
graemerocher
Since:
1.0/**
 * A scheduled task that sends a periodic heartbeat whilst the server is active.
 *
 * @author graemerocher
 * @since 1.0
 */
@Singleton
@HeartbeatEnabled
public class HeartbeatTask implements ApplicationEventListener<ServiceReadyEvent> {

    private final Set<ServiceInstance> eventsReference = ConcurrentHashMap.newKeySet();

    private final ApplicationEventPublisher eventPublisher;
    private final CurrentHealthStatus currentHealthStatus;

    
Params:
eventPublisher –      To publish the events related to heartbeat
configuration –       The configurations for heartbeat
currentHealthStatus – The current status of health indicator/**
     * @param eventPublisher      To publish the events related to heartbeat
     * @param configuration       The configurations for heartbeat
     * @param currentHealthStatus The current status of health indicator
     */
    public HeartbeatTask(ApplicationEventPublisher eventPublisher, HeartbeatConfiguration configuration, CurrentHealthStatus currentHealthStatus) {
        this.eventPublisher = eventPublisher;
        this.currentHealthStatus = currentHealthStatus;
    }

    
Publish the heartbeat event with current health status.
/**
     * Publish the heartbeat event with current health status.
     */
    @Scheduled(fixedDelay = "${micronaut.heartbeat.interval:15s}",
               initialDelay = "${micronaut.heartbeat.initial-delay:5s}")
    public void pulsate() {
        for (ServiceInstance instance : eventsReference) {
            eventPublisher.publishEvent(new HeartbeatEvent(instance, currentHealthStatus.current()));
        }
    }

    @Override
    public void onApplicationEvent(ServiceReadyEvent event) {
        eventsReference.add(event.getSource());
    }
}