osu/osu.Game/Online/PollingComponent.cs

127 lines
3.7 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 System.Diagnostics;
using System.Threading.Tasks;
using osu.Framework.Bindables;
using osu.Framework.Development;
using osu.Framework.Graphics.Containers;
using osu.Framework.Threading;
namespace osu.Game.Online
{
/// <summary>
/// A component which requires a constant polling process.
/// </summary>
public abstract class PollingComponent : CompositeDrawable // switch away from Component because InternalChildren are used in usages.
{
private double? lastTimePolled;
private ScheduledDelegate scheduledPoll;
private bool pollingActive;
/// <summary>
/// The time in milliseconds to wait between polls.
/// Setting to zero stops all polling.
/// </summary>
public readonly Bindable<double> TimeBetweenPolls = new Bindable<double>();
/// <summary>
///
/// </summary>
/// <param name="timeBetweenPolls">The initial time in milliseconds to wait between polls. Setting to zero stops all polling.</param>
protected PollingComponent(double timeBetweenPolls = 0)
{
TimeBetweenPolls.BindValueChanged(_ =>
{
scheduledPoll?.Cancel();
pollIfNecessary();
});
TimeBetweenPolls.Value = timeBetweenPolls;
}
protected override void LoadComplete()
{
base.LoadComplete();
pollIfNecessary();
}
/// <summary>
/// Immediately performs a <see cref="Poll"/>.
/// </summary>
public void PollImmediately()
{
lastTimePolled = Time.Current - TimeBetweenPolls.Value;
scheduleNextPoll();
}
/// <summary>
/// Performs a poll. Implement but do not call this.
/// </summary>
protected virtual Task Poll()
{
return Task.CompletedTask;
}
private void doPoll()
{
Debug.Assert(ThreadSafety.IsUpdateThread);
scheduledPoll = null;
pollingActive = true;
Poll().ContinueWith(_ => pollComplete());
}
/// <summary>
/// Call when a poll operation has completed.
/// </summary>
private void pollComplete()
{
lastTimePolled = Time.Current;
pollingActive = false;
if (scheduledPoll == null)
pollIfNecessary();
}
private void pollIfNecessary()
{
// we must be loaded so we have access to clock.
if (!IsLoaded) return;
// there's already a poll process running.
if (pollingActive) return;
// don't try polling if the time between polls hasn't been set.
if (TimeBetweenPolls.Value == 0) return;
if (!lastTimePolled.HasValue)
{
Scheduler.AddOnce(doPoll);
return;
}
if (Time.Current - lastTimePolled.Value > TimeBetweenPolls.Value)
{
Scheduler.AddOnce(doPoll);
return;
}
// not enough time has passed since the last poll. we do want to schedule a poll to happen, though.
scheduleNextPoll();
}
private void scheduleNextPoll()
{
scheduledPoll?.Cancel();
double lastPollDuration = lastTimePolled.HasValue ? Time.Current - lastTimePolled.Value : 0;
scheduledPoll = Scheduler.AddDelayed(doPoll, Math.Max(0, TimeBetweenPolls.Value - lastPollDuration));
}
}
}