GeoFeed/AS1024.GeoFeed.Core/GeoFeedPreloader/PreloadGeoFeed.cs

using AS1024.GeoFeed.Core.Interfaces;
using Microsoft.Extensions.Caching.Memory;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace AS1024.GeoFeed.Core.GeoFeedPreloader
{
    public class PreLoadGeoFeed : IHostedService
    {
        private readonly ILogger<PreLoadGeoFeed> logger;
        private readonly IGeoFeedProvider provider;
        private readonly IMemoryCache memoryCache;
        private readonly IHostEnvironment environment;
        private const string GeoFeedCacheKey = "GeoFeedData";

        public PreLoadGeoFeed(ILogger<PreLoadGeoFeed> logger,
            IGeoFeedProvider provider,
            IMemoryCache memoryCache,
            IHostEnvironment environment)
        {
            this.logger = logger;
            this.provider = provider;
            this.memoryCache = memoryCache;
            this.environment = environment;
        }

        async Task IHostedService.StartAsync(CancellationToken cancellationToken)
        {
            try
            {
                if (environment.IsProduction())
                    await StartPreLoad();
            }
            catch (Exception ex)
            {
                logger.LogWarning($"Failed to preload, exception settings below:\n{ex}");
            }
        }

        private async Task StartPreLoad()
        {
            logger.LogInformation("Preloading GeoFeed data in memory...");
            List<Models.IPGeoFeed> feed = await provider.GetGeoFeedData();
            MemoryCacheEntryOptions cacheEntryOptions = new MemoryCacheEntryOptions().SetAbsoluteExpiration(TimeSpan.FromMinutes(45));
            memoryCache.Set(GeoFeedCacheKey, feed, cacheEntryOptions);
        }

        Task IHostedService.StopAsync(CancellationToken cancellationToken)
        {
            return Task.CompletedTask;
        }
    }
}