/// <inheritdoc />
protected override async Task <HttpResponseMessage> ImplementationAsync
(
Func <Context, CancellationToken, Task <HttpResponseMessage> > action,
Context context,
CancellationToken cancellationToken,
bool continueOnCapturedContext
)
{
if (!context.TryGetValue("endpoint", out var rawEndpoint) || !(rawEndpoint is string endpoint))
{
throw new InvalidOperationException("No endpoint set.");
}
if (!_rateLimitBuckets.TryGetValue(endpoint, out var rateLimitBucket))
{
rateLimitBucket = _globalRateLimitBucket;
}
var now = DateTime.UtcNow;
if (!await rateLimitBucket.TryTakeAsync())
{
var rateLimitedResponse = new HttpResponseMessage(HttpStatusCode.TooManyRequests);
var delay = rateLimitBucket.ResetsAt - now;
rateLimitedResponse.Headers.RetryAfter = new RetryConditionHeaderValue(delay);
return(rateLimitedResponse);
}
// The request can proceed without hitting rate limits, and we've taken a token
var requestAction = action(context, cancellationToken).ConfigureAwait(continueOnCapturedContext);
var response = await requestAction;
if (!RateLimitBucket.TryParse(response.Headers, out var newLimits))
{
return(response);
}
if (newLimits.IsGlobal)
{
if (_globalRateLimitBucket.ResetsAt < newLimits.ResetsAt)
{
_globalRateLimitBucket = newLimits;
}
return(response);
}
_rateLimitBuckets.AddOrUpdate
(
endpoint,
newLimits,
(_, old) => old.ResetsAt < newLimits.ResetsAt ? newLimits : old
);
return(response);
}
/// <summary>
/// Initializes a new instance of the <see cref="DiscordRateLimitPolicy"/> class.
/// </summary>
private DiscordRateLimitPolicy()
{
_globalRateLimitBucket = new RateLimitBucket
(
10000,
10000,
DateTime.Today + TimeSpan.FromDays(1),
"global",
true
);
_rateLimitBuckets = new ConcurrentDictionary <string, RateLimitBucket>();
}
