event-bus/api/src/main/java/org/apache/james/events/EventDeadLettersHealthCheck.java

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package org.apache.james.events;

import javax.inject.Inject;

import org.apache.james.core.healthcheck.ComponentName;
import org.apache.james.core.healthcheck.HealthCheck;
import org.apache.james.core.healthcheck.Result;

import reactor.core.publisher.Mono;

public class EventDeadLettersHealthCheck implements HealthCheck {
    private static final ComponentName COMPONENT_NAME = new ComponentName("EventDeadLettersHealthCheck");

    private final EventDeadLetters eventDeadLetters;

    @Inject
    public EventDeadLettersHealthCheck(EventDeadLetters eventDeadLetters) {
        this.eventDeadLetters = eventDeadLetters;
    }

    @Override
    public ComponentName componentName() {
        return COMPONENT_NAME;
    }

    @Override
    public Mono<Result> check() {
        return eventDeadLetters.containEvents()
            .map(containEvents -> {
                if (containEvents) {
                    return Result.degraded(COMPONENT_NAME, "EventDeadLetters contain events. This might indicate transient failure on event processing.");
                }

                return Result.healthy(COMPONENT_NAME);
            })
            .onErrorResume(e -> Mono.just(Result.unhealthy(COMPONENT_NAME, "Error checking EventDeadLettersHealthCheck", e)));
    }
}