squidex/src/Squidex.Infrastructure/Log/LockingLogStore.cs

// ==========================================================================
//  Squidex Headless CMS
// ==========================================================================
//  Copyright (c) Squidex UG (haftungsbeschraenkt)
//  All rights reserved. Licensed under the MIT license.
// ==========================================================================

using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Orleans;
using Squidex.Infrastructure.Orleans;

namespace Squidex.Infrastructure.Log
{
    public sealed class LockingLogStore : ILogStore
    {
        private static readonly TimeSpan LockWaitingTime = TimeSpan.FromMinutes(10);
        private readonly ILogStore inner;
        private readonly ILockGrain lockGrain;

        public LockingLogStore(ILogStore inner, IGrainFactory grainFactory)
        {
            Guard.NotNull(inner, nameof(inner));
            Guard.NotNull(grainFactory, nameof(grainFactory));

            this.inner = inner;

            lockGrain = grainFactory.GetGrain<ILockGrain>(SingleGrain.Id);
        }

        public async Task ReadLockAsync(string key, DateTime from, DateTime to, Stream stream)
        {
            string releaseToken = null;

            using (var cts = new CancellationTokenSource(LockWaitingTime))
            {
                while (!cts.IsCancellationRequested)
                {
                    releaseToken = await lockGrain.AcquireLockAsync(key);

                    if (releaseToken != null)
                    {
                        break;
                    }

                    await Task.Delay(2000);
                }
            }

            try
            {
                await inner.ReadLockAsync(key, from, to, stream);
            }
            finally
            {
                await lockGrain.ReleaseLockAsync(releaseToken);
            }
        }
    }
}