SboxSuperuser/Core/Prefixes/PrefixRequestGate.cs
A small in-memory rate limiter for prefix snapshot requests. Tracks one timestamp per client Guid, rejects repeats inside a 2 second interval, and evicts entries older than 10 seconds, capping the table at 1024 clients.
namespace SboxSuperuser.Core.Prefixes;
/// <summary>Bounds client snapshot retries so one connection cannot amplify them into repeated large replies.</summary>
internal sealed class PrefixRequestGate
{
private static readonly TimeSpan Interval = TimeSpan.FromSeconds( 2 );
private static readonly TimeSpan Retention = TimeSpan.FromSeconds( 10 );
private const int MaximumClients = 1024;
private readonly Dictionary<Guid, DateTimeOffset> _requests = new();
internal bool TryEnter( Guid connection, DateTimeOffset now )
{
foreach ( var id in _requests.Where( pair => now - pair.Value >= Retention ).Select( pair => pair.Key ).ToArray() )
{
_requests.Remove( id );
}
if ( _requests.TryGetValue( connection, out var previous ) && now - previous < Interval ) return false;
if ( !_requests.ContainsKey( connection ) && _requests.Count >= MaximumClients ) return false;
_requests[ connection ] = now;
return true;
}
}