osu/osu.Game/Database/DatabaseBackedStore.cs

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// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.
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using System.Linq;
using Microsoft.EntityFrameworkCore;
using osu.Framework.Platform;
namespace osu.Game.Database
{
public abstract class DatabaseBackedStore
{
protected readonly Storage Storage;
protected readonly IDatabaseContextFactory ContextFactory;
/// <summary>
/// Refresh an instance potentially from a different thread with a local context-tracked instance.
/// </summary>
/// <param name="obj">The object to use as a reference when negotiating a local instance.</param>
/// <param name="lookupSource">An optional lookup source which will be used to query and populate a freshly retrieved replacement. If not provided, the refreshed object will still be returned but will not have any includes.</param>
/// <typeparam name="T">A valid EF-stored type.</typeparam>
protected void Refresh<T>(ref T obj, IQueryable<T> lookupSource = null) where T : class, IHasPrimaryKey
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{
using (var usage = ContextFactory.GetForWrite())
{
var context = usage.Context;
if (context.Entry(obj).State != EntityState.Detached) return;
int id = obj.ID;
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var foundObject = lookupSource?.SingleOrDefault(t => t.ID == id) ?? context.Find<T>(id);
if (foundObject != null)
obj = foundObject;
else
context.Add(obj);
}
}
protected DatabaseBackedStore(IDatabaseContextFactory contextFactory, Storage storage = null)
{
ContextFactory = contextFactory;
Storage = storage;
}
/// <summary>
/// Perform any common clean-up tasks. Should be run when idle, or whenever necessary.
/// </summary>
public virtual void Cleanup()
{
}
}
}