IgniteAsyncStreamExtensions-Test1.cs

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Apache.Ignite.Core.Cache;
using Apache.Ignite.Core.Cache.Event;
using Apache.Ignite.Core.Cache.Query.Continuous;

namespace IgniteAsyncStreams
{
    public static class IgniteAsyncStreamExtensions
    {
        public static IAsyncEnumerable<ICacheEntry<TK, TV>> QueryContinuousAsync<TK, TV>(
            this ICache<TK, TV> cache)
        {
            return new AsyncContinuousQueryEnumerable<TK, TV>(cache);
        }

        public static async IAsyncEnumerable<ICacheEntry<TK, TV>> QueryContinuousAsync2<TK, TV>(
            this ICache<TK, TV> cache)
        {
            var queryListener = new AsyncContinuousQueryListener<TK, TV>();
            var continuousQuery = new ContinuousQuery<TK, TV>(queryListener);

            using (cache.QueryContinuous(continuousQuery))
            {
                while (true)
                {
                    while (queryListener.Events.TryDequeue(out var entryEvent))
                    {
                        yield return entryEvent;
                    }

                    await queryListener.HasData.WaitAsync();
                }
            }
        }

        private class AsyncContinuousQueryEnumerable<TK, TV> : IAsyncEnumerable<ICacheEntry<TK, TV>>
        {
            private readonly ICache<TK, TV> _cache;

            public AsyncContinuousQueryEnumerable(ICache<TK, TV> cache)
            {
                _cache = cache;
            }

            public IAsyncEnumerator<ICacheEntry<TK, TV>> GetAsyncEnumerator(
                CancellationToken cancellationToken = new CancellationToken())
            {
                var queryListener = new AsyncContinuousQueryListener<TK, TV>();
                var continuousQuery = new ContinuousQuery<TK, TV>(queryListener);
                var queryHandle = _cache.QueryContinuous(continuousQuery);

                return new AsyncContinuousQueryEnumerator<TK, TV>(queryListener, queryHandle);
            }
        }

        private class AsyncContinuousQueryEnumerator<TK, TV> : IAsyncEnumerator<ICacheEntryEvent<TK, TV>>
        {
            private readonly AsyncContinuousQueryListener<TK, TV> _queryListener;

            private readonly IContinuousQueryHandle _queryHandle;

            public AsyncContinuousQueryEnumerator(AsyncContinuousQueryListener<TK, TV> queryListener,
                IContinuousQueryHandle queryHandle)
            {
                _queryListener = queryListener;
                _queryHandle = queryHandle;
            }

            public ValueTask DisposeAsync()
            {
                _queryHandle.Dispose();
                return default;
            }

            public async ValueTask<bool> MoveNextAsync()
            {
                ICacheEntryEvent<TK, TV>? entryEvent;
                while (!_queryListener.Events.TryDequeue(out entryEvent))
                {
                    await _queryListener.HasData.WaitAsync();
                }

                Current = entryEvent;
                return true;
            }

#nullable disable
            public ICacheEntryEvent<TK, TV> Current { get; private set; }
#nullable restore
        }

        private class AsyncContinuousQueryListener<TK, TV> : ICacheEntryEventListener<TK, TV>
        {
            public readonly SemaphoreSlim HasData = new SemaphoreSlim(0, 1);

            public readonly ConcurrentQueue<ICacheEntryEvent<TK, TV>> Events
                = new ConcurrentQueue<ICacheEntryEvent<TK, TV>>();

            public void OnEvent(IEnumerable<ICacheEntryEvent<TK, TV>> events)
            {
                foreach (var entryEvent in events)
                {
                    Console.WriteLine("Received entry: " + entryEvent.Value);
                    Events.Enqueue(entryEvent);
                }

                HasData.Release();
            }
        }
    }
}