IW4M-Admin/Data/Helpers/LookupCache.cs

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3.3 KiB
C#
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using Data.Abstractions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using ILogger = Microsoft.Extensions.Logging.ILogger;
namespace Data.Helpers
{
public class LookupCache<T> : ILookupCache<T> where T : class, IUniqueId
{
private readonly ILogger _logger;
private readonly IDatabaseContextFactory _contextFactory;
private Dictionary<long, T> _cachedItems;
private readonly SemaphoreSlim _onOperation = new SemaphoreSlim(1, 1);
public LookupCache(ILogger<LookupCache<T>> logger, IDatabaseContextFactory contextFactory)
{
_logger = logger;
_contextFactory = contextFactory;
}
public async Task<T> AddAsync(T item)
{
await _onOperation.WaitAsync();
T existingItem = null;
if (_cachedItems.ContainsKey(item.Id))
{
existingItem = _cachedItems[item.Id];
}
if (existingItem != null)
{
_logger.LogDebug("Cached item already added for {type} {id} {value}", typeof(T).Name, item.Id,
item.Value);
_onOperation.Release();
return existingItem;
}
try
{
_logger.LogDebug("Adding new {type} with {id} {value}", typeof(T).Name, item.Id, item.Value);
await using var context = _contextFactory.CreateContext();
context.Set<T>().Add(item);
await context.SaveChangesAsync();
_cachedItems.Add(item.Id, item);
return item;
}
catch (Exception ex)
{
_logger.LogError(ex, "Could not add item to cache for {type}", typeof(T).Name);
throw new Exception("Could not add item to cache");
}
finally
{
if (_onOperation.CurrentCount == 0)
{
_onOperation.Release();
}
}
}
public async Task<T> FirstAsync(Func<T, bool> query)
{
await _onOperation.WaitAsync();
try
{
var cachedResult = _cachedItems.Values.Where(query);
if (cachedResult.Any())
{
return cachedResult.FirstOrDefault();
}
}
catch
{
}
finally
{
if (_onOperation.CurrentCount == 0)
{
_onOperation.Release(1);
}
}
return null;
}
public IEnumerable<T> GetAll()
{
return _cachedItems.Values;
}
public async Task InitializeAsync()
{
try
{
await using var context = _contextFactory.CreateContext();
_cachedItems = await context.Set<T>().ToDictionaryAsync(item => item.Id);
}
catch (Exception ex)
{
_logger.LogError(ex, "Could not initialize caching for {cacheType}", typeof(T).Name);
}
}
}
}