sharp-chat/SharpChatCommon/RateLimiter.cs

37 lines
1.5 KiB
C#

using System;
namespace SharpChat {
public class RateLimiter {
private readonly int Size;
private readonly int MinimumDelay;
private readonly int RiskyOffset;
private readonly long[] TimePoints;
public RateLimiter(int size, int minDelay, int riskyOffset = 0) {
if(size < 2)
throw new ArgumentException("Size is too small.", nameof(size));
if(minDelay < 1000)
throw new ArgumentException("Minimum delay is inhuman.", nameof(minDelay));
if(riskyOffset != 0) {
if(riskyOffset >= size)
throw new ArgumentException("Risky offset may not be greater or equal to the size.", nameof(riskyOffset));
else if(riskyOffset < 0)
throw new ArgumentException("Risky offset may not be negative.", nameof(riskyOffset));
}
Size = size;
MinimumDelay = minDelay;
RiskyOffset = riskyOffset;
TimePoints = new long[Size];
}
public bool IsRisky => TimePoints[RiskyOffset] != 0 && TimePoints[RiskyOffset + 1] != 0 && TimePoints[RiskyOffset] + MinimumDelay >= TimePoints[Size - 1];
public bool IsExceeded => TimePoints[0] != 0 && TimePoints[1] != 0 && TimePoints[0] + MinimumDelay >= TimePoints[Size - 1];
public void Update() {
for(int i = 1; i < Size; ++i)
TimePoints[i - 1] = TimePoints[i];
TimePoints[Size - 1] = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
}
}
}