server/container/guice/queue/rabbitmq/src/main/java/org/apache/james/modules/queue/rabbitmq/RabbitMQModule.java

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package org.apache.james.modules.queue.rabbitmq;

import java.io.FileNotFoundException;
import java.util.Set;

import jakarta.inject.Named;
import jakarta.inject.Provider;
import jakarta.inject.Singleton;

import org.apache.commons.configuration2.ex.ConfigurationException;
import org.apache.james.backends.rabbitmq.RabbitMQConfiguration;
import org.apache.james.backends.rabbitmq.RabbitMQHealthCheck;
import org.apache.james.backends.rabbitmq.ReactorRabbitMQChannelPool;
import org.apache.james.backends.rabbitmq.ReceiverProvider;
import org.apache.james.backends.rabbitmq.SimpleConnectionPool;
import org.apache.james.core.healthcheck.HealthCheck;
import org.apache.james.metrics.api.GaugeRegistry;
import org.apache.james.metrics.api.MetricFactory;
import org.apache.james.utils.InitializationOperation;
import org.apache.james.utils.InitilizationOperationBuilder;
import org.apache.james.utils.PropertiesProvider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.inject.AbstractModule;
import com.google.inject.Provides;
import com.google.inject.Scopes;
import com.google.inject.multibindings.Multibinder;
import com.google.inject.multibindings.ProvidesIntoSet;

import reactor.rabbitmq.RabbitFlux;
import reactor.rabbitmq.ReceiverOptions;
import reactor.rabbitmq.Sender;

public class RabbitMQModule extends AbstractModule {

    public static final String RABBITMQ_CONFIGURATION_NAME = "rabbitmq";

    private static final Logger LOGGER = LoggerFactory.getLogger(RabbitMQModule.class);

    @Override
    protected void configure() {
        bind(SimpleConnectionPool.class).in(Scopes.SINGLETON);

        Multibinder<HealthCheck> healthCheckMultiBinder = Multibinder.newSetBinder(binder(), HealthCheck.class);
        healthCheckMultiBinder.addBinding().to(RabbitMQHealthCheck.class);

        Multibinder<SimpleConnectionPool.ReconnectionHandler> reconnectionHandlerMultibinder = Multibinder.newSetBinder(binder(), SimpleConnectionPool.ReconnectionHandler.class);
    }

    @ProvidesIntoSet
    InitializationOperation configureUsersRepository(SimpleConnectionPool pool, Set<SimpleConnectionPool.ReconnectionHandler> reconnectionHandlers) {
        return InitilizationOperationBuilder
            .forClass(SimpleConnectionPool.class)
            .init(() -> pool.init(reconnectionHandlers));
    }

    @Provides
    @Named(RABBITMQ_CONFIGURATION_NAME)
    @Singleton
    private org.apache.commons.configuration2.Configuration getConfiguration(PropertiesProvider propertiesProvider) throws ConfigurationException {
        try {
            return propertiesProvider.getConfiguration(RABBITMQ_CONFIGURATION_NAME);
        } catch (FileNotFoundException e) {
            LOGGER.error("Could not find " + RABBITMQ_CONFIGURATION_NAME + " configuration file.");
            throw new RuntimeException(e);
        }
    }

    @Provides
    @Singleton
    private RabbitMQConfiguration getMailQueueConfiguration(@Named(RABBITMQ_CONFIGURATION_NAME) org.apache.commons.configuration2.Configuration configuration) {
        return RabbitMQConfiguration.from(configuration);
    }

    @Provides
    @Singleton
    ReactorRabbitMQChannelPool provideReactorRabbitMQChannelPool(SimpleConnectionPool simpleConnectionPool,
                                                                 ReactorRabbitMQChannelPool.Configuration configuration,
                                                                 MetricFactory metricFactory, GaugeRegistry gaugeRegistry) {
        ReactorRabbitMQChannelPool channelPool = new ReactorRabbitMQChannelPool(
            simpleConnectionPool.getResilientConnection(),
            configuration,
            metricFactory,
            gaugeRegistry);
        channelPool.start();
        return channelPool;
    }

    @Provides
    @Singleton
    public Sender provideRabbitMQSender(ReactorRabbitMQChannelPool channelPool) {
        return channelPool.getSender();
    }

    @Provides
    @Singleton
    public ReceiverProvider provideRabbitMQReceiver(SimpleConnectionPool simpleConnectionPool) {
        return () -> RabbitFlux.createReceiver(new ReceiverOptions().connectionMono(simpleConnectionPool.getResilientConnection()));
    }

    @Provides
    @Singleton
    public SimpleConnectionPool.Configuration provideConnectionPoolConfiguration(@Named(RABBITMQ_CONFIGURATION_NAME) Provider<org.apache.commons.configuration2.Configuration> configuration) {
        try {
            return SimpleConnectionPool.Configuration.from(configuration.get());
        } catch (Exception e) {
            LOGGER.info("Error while retrieving SimpleConnectionPool.Configuration, falling back to defaults.", e);
            return SimpleConnectionPool.Configuration.DEFAULT;
        }
    }

    @Provides
    @Singleton
    public ReactorRabbitMQChannelPool.Configuration provideChannelPoolConfiguration(@Named(RABBITMQ_CONFIGURATION_NAME) Provider<org.apache.commons.configuration2.Configuration> configuration) {
        try {
            return ReactorRabbitMQChannelPool.Configuration.from(configuration.get());
        } catch (Exception e) {
            LOGGER.info("Error while retrieving ReactorRabbitMQChannelPool.Configuration, falling back to defaults.", e);
            return ReactorRabbitMQChannelPool.Configuration.DEFAULT;
        }
    }
}