How to throttle requests in a Web Api?
[Route("api/dothis/{id}")]
[AcceptVerbs("POST")]
[Throttle(Name = "ApiThrottle", Message = "You must wait {n} seconds before accessing this url again.", Seconds = 5)]
[Authorize]
public HttpResponseMessage DoThis(int id)
{
// do something
}
public class ThrottleAttribute : ActionFilterAttribute
{
/// <summary>
/// A unique name for this Throttle.
/// </summary>
/// <remarks>
/// We'll be inserting a Cache record based on this name and client IP, e.g. "Name-192.168.0.1"
/// </remarks>
public string Name { get; set; }
/// <summary>
/// The number of seconds clients must wait before executing this decorated route again.
/// </summary>
public int Seconds { get; set; }
/// <summary>
/// A text message that will be sent to the client upon throttling. You can include the token {n} to
/// show this.Seconds in the message, e.g. "Wait {n} seconds before trying again".
/// </summary>
public string Message { get; set; }
public override void OnActionExecuting(HttpActionContext actionContext)
{
var key = string.Concat(Name, "-", GetClientIp(actionContext.Request));
var allowExecute = false;
if (HttpRuntime.Cache[key] == null)
{
HttpRuntime.Cache.Add(key,
true, // is this the smallest data we can have?
null, // no dependencies
DateTime.Now.AddSeconds(Seconds), // absolute expiration
Cache.NoSlidingExpiration,
CacheItemPriority.Low,
null); // no callback
allowExecute = true;
}
if (!allowExecute)
{
if (string.IsNullOrEmpty(Message))
{
Message = "You may only perform this action every {n} seconds.";
}
actionContext.Response = actionContext.Request.CreateResponse(
HttpStatusCode.Conflict,
Message.Replace("{n}", Seconds.ToString())
);
}
}
}