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osu-lazer/osu.Game/Screens/OnlinePlay/OngoingOperationTracker.cs
Bartłomiej Dach 8c3955d341 Improve safety of ongoing operation tracker
Finishing an operation started via
`OngoingOperationTracker.BeginOperation()` was risky in cases where the
operation ended at a callback on another thread (which, in the case of
multiplayer, is *most* cases). In particular, if any consumer registered
a callback that mutates transforms when the operation ends, it would
result in crashes after the framework-side safety checks.

Rework `OngoingOperationTracker` into an always-present component
residing in the drawable hierarchy, and ensure that the
`operationInProgress` bindable is always updated on the update thread.
This way consumers don't have to add local schedules in multiple places.
2021-01-09 22:45:24 +01:00

60 lines
2.0 KiB
C#

// 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.
using System;
using osu.Framework.Allocation;
using osu.Framework.Bindables;
using osu.Framework.Graphics;
namespace osu.Game.Screens.OnlinePlay
{
/// <summary>
/// Utility class to track ongoing online operations' progress.
/// Can be used to disable interactivity while waiting for a response from online sources.
/// </summary>
public class OngoingOperationTracker : Component
{
/// <summary>
/// Whether there is an online operation in progress.
/// </summary>
public IBindable<bool> InProgress => inProgress;
private readonly Bindable<bool> inProgress = new BindableBool();
private LeasedBindable<bool> leasedInProgress;
public OngoingOperationTracker()
{
AlwaysPresent = true;
}
/// <summary>
/// Begins tracking a new online operation.
/// </summary>
/// <returns>
/// An <see cref="IDisposable"/> that will automatically mark the operation as ended on disposal.
/// </returns>
/// <exception cref="InvalidOperationException">An operation has already been started.</exception>
public IDisposable BeginOperation()
{
if (leasedInProgress != null)
throw new InvalidOperationException("Cannot begin operation while another is in progress.");
leasedInProgress = inProgress.BeginLease(true);
leasedInProgress.Value = true;
// for extra safety, marshal the end of operation back to the update thread if necessary.
return new InvokeOnDisposal(() => Scheduler.Add(endOperation, false));
}
private void endOperation()
{
if (leasedInProgress == null)
throw new InvalidOperationException("Cannot end operation multiple times.");
leasedInProgress.Return();
leasedInProgress = null;
}
}
}