src/DotPulsar/Extensions/ConsumerExtensions.cs

/*
 * 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.
 */

namespace DotPulsar.Extensions;

using DotPulsar.Abstractions;
using DotPulsar.Internal;
using DotPulsar.Internal.Extensions;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;

/// <summary>
/// Extensions for IConsumer.
/// </summary>
public static class ConsumerExtensions
{
    /// <summary>
    /// Acknowledge the consumption of a single message.
    /// </summary>
    public static async ValueTask Acknowledge(this IConsumer consumer, IMessage message, CancellationToken cancellationToken = default)
        => await consumer.Acknowledge(message.MessageId, cancellationToken).ConfigureAwait(false);

    /// <summary>
    /// Acknowledge the consumption of all the messages in the topic up to and including the provided message.
    /// </summary>
    public static async ValueTask AcknowledgeCumulative(this IConsumer consumer, IMessage message, CancellationToken cancellationToken = default)
        => await consumer.AcknowledgeCumulative(message.MessageId, cancellationToken).ConfigureAwait(false);

    /// <summary>
    /// Process and auto-acknowledge a message.
    /// </summary>
    public static async ValueTask Process<TMessage>(
        this IConsumer<TMessage> consumer,
        Func<IMessage<TMessage>, CancellationToken, ValueTask> processor,
        CancellationToken cancellationToken = default)
    {
        const string operation = "process";
        var operationName = $"{consumer.Topic} {operation}";

        var activityTags = new KeyValuePair<string, object?>[]
        {
            new KeyValuePair<string, object?>("messaging.destination", consumer.Topic),
            new KeyValuePair<string, object?>("messaging.destination_kind", "topic"),
            new KeyValuePair<string, object?>("messaging.operation", operation),
            new KeyValuePair<string, object?>("messaging.system", "pulsar"),
            new KeyValuePair<string, object?>("messaging.url", consumer.ServiceUrl),
            new KeyValuePair<string, object?>("messaging.pulsar.subscription", consumer.SubscriptionName)
        };

        var meterTags = new KeyValuePair<string, object?>[]
        {
            new KeyValuePair<string, object?>("topic", consumer.Topic),
            new KeyValuePair<string, object?>("subscription", consumer.SubscriptionName)
        };

        while (!cancellationToken.IsCancellationRequested)
        {
            var message = await consumer.Receive(cancellationToken).ConfigureAwait(false);

            var activity = DotPulsarActivitySource.StartConsumerActivity(message, operationName, activityTags);
            if (activity is not null && activity.IsAllDataRequested)
            {
                activity.SetMessageId(message.MessageId);
                activity.SetPayloadSize(message.Data.Length);
                activity.SetStatus(ActivityStatusCode.Ok);
            }

            var startTimestamp = DotPulsarMeter.MessageProcessedEnabled ? Stopwatch.GetTimestamp() : 0;

            try
            {
                await processor(message, cancellationToken).ConfigureAwait(false);
            }
            catch (Exception exception)
            {
                if (activity is not null && activity.IsAllDataRequested)
                    activity.AddException(exception);
            }

            if (startTimestamp != 0)
                DotPulsarMeter.MessageProcessed(startTimestamp, meterTags);

            activity?.Dispose();

            await consumer.Acknowledge(message.MessageId, cancellationToken).ConfigureAwait(false);
        }
    }

    /// <summary>
    /// Wait for the state to change to a specific state.
    /// </summary>
    /// <returns>
    /// The current state.
    /// </returns>
    /// <remarks>
    /// If the state change to a final state, then all awaiting tasks will complete.
    /// </remarks>
    public static async ValueTask<ConsumerStateChanged> StateChangedTo(this IConsumer consumer, ConsumerState state, CancellationToken cancellationToken = default)
    {
        var newState = await consumer.OnStateChangeTo(state, cancellationToken).ConfigureAwait(false);
        return new ConsumerStateChanged(consumer, newState);
    }

    /// <summary>
    /// Wait for the state to change from a specific state.
    /// </summary>
    /// <returns>
    /// The current state.
    /// </returns>
    /// <remarks>
    /// If the state change to a final state, then all awaiting tasks will complete.
    /// </remarks>
    public static async ValueTask<ConsumerStateChanged> StateChangedFrom(this IConsumer consumer, ConsumerState state, CancellationToken cancellationToken = default)
    {
        var newState = await consumer.OnStateChangeFrom(state, cancellationToken).ConfigureAwait(false);
        return new ConsumerStateChanged(consumer, newState);
    }
}