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5f320cd426
Theoretically safer due to avoiding a potential data race (change in `leasedInProgress` between the time of the check and start of schedule execution).
83 lines
3.0 KiB
C#
83 lines
3.0 KiB
C#
// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
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// See the LICENCE file in the repository root for full licence text.
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using System;
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using osu.Framework.Bindables;
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using osu.Framework.Graphics;
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namespace osu.Game.Screens.OnlinePlay
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{
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/// <summary>
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/// Utility class to track ongoing online operations' progress.
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/// Can be used to disable interactivity while waiting for a response from online sources.
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/// </summary>
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public class OngoingOperationTracker : Component
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{
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/// <summary>
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/// Whether there is an online operation in progress.
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/// </summary>
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public IBindable<bool> InProgress => inProgress;
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private readonly Bindable<bool> inProgress = new BindableBool();
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private LeasedBindable<bool> leasedInProgress;
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public OngoingOperationTracker()
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{
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AlwaysPresent = true;
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}
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/// <summary>
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/// Begins tracking a new online operation.
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/// </summary>
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/// <returns>
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/// An <see cref="IDisposable"/> that will automatically mark the operation as ended on disposal.
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/// </returns>
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/// <exception cref="InvalidOperationException">An operation has already been started.</exception>
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public IDisposable BeginOperation()
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{
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if (leasedInProgress != null)
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throw new InvalidOperationException("Cannot begin operation while another is in progress.");
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leasedInProgress = inProgress.BeginLease(true);
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leasedInProgress.Value = true;
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return new OngoingOperation(this, leasedInProgress);
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}
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private void endOperationWithKnownLease(LeasedBindable<bool> lease)
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{
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// for extra safety, marshal the end of operation back to the update thread if necessary.
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Scheduler.Add(() =>
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{
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if (lease != leasedInProgress)
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return;
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// UnbindAll() is purposefully used instead of Return() - the two do roughly the same thing, with one difference:
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// the former won't throw if the lease has already been returned before.
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// this matters because framework can unbind the lease via the internal UnbindAllBindables(), which is not always detectable
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// (it is in the case of disposal, but not in the case of screen exit - at least not cleanly).
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leasedInProgress?.UnbindAll();
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leasedInProgress = null;
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}, false);
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}
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private class OngoingOperation : IDisposable
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{
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private readonly OngoingOperationTracker tracker;
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private readonly LeasedBindable<bool> lease;
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public OngoingOperation(OngoingOperationTracker tracker, LeasedBindable<bool> lease)
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{
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this.tracker = tracker;
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this.lease = lease;
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}
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public void Dispose()
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{
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tracker.endOperationWithKnownLease(lease);
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}
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}
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}
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}
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