/// <summary>
/// Limits the number of concurrent requests that can be handled used by the subsequent stages in the owin pipeline.
/// </summary>
/// <param name="builder">The OWIN builder instance.</param>
/// <param name="options">The max concurrent request options.</param>
/// <returns>The OWIN builder instance.</returns>
/// <exception cref="System.ArgumentNullException">builder</exception>
/// <exception cref="System.ArgumentNullException">options</exception>
public static BuildFunc MaxConcurrentRequests(this BuildFunc builder, MaxConcurrentRequestOptions options)
{
builder.MustNotNull("builder");
options.MustNotNull("options");
builder(_ => MaxConcurrentRequests(options));
return builder;
}
/// <summary>
/// Limits the number of concurrent requests that can be handled used by the subsequent stages in the owin pipeline.
/// </summary>
/// <param name="builder">The IAppBuilder instance.</param>
/// <param name="options">The max concurrent request options.</param>
/// <returns>The IAppBuilder instance.</returns>
/// <exception cref="System.ArgumentNullException">builder</exception>
public static IAppBuilder MaxConcurrentRequests(this IAppBuilder builder, MaxConcurrentRequestOptions options)
{
builder.MustNotNull("builder");
options.MustNotNull("options");
builder
.UseOwin()
.MaxConcurrentRequests(options);
return builder;
}
/// <summary>
/// Limits the number of concurrent requests that can be handled used by the subsequent stages in the owin pipeline.
/// </summary>
/// <param name="options">The max concurrent request options.</param>
/// <returns>An OWIN middleware delegate.</returns>
/// <exception cref="System.ArgumentNullException">options</exception>
public static MidFunc MaxConcurrentRequests(MaxConcurrentRequestOptions options)
{
options.MustNotNull("options");
int concurrentRequestCounter = 0;
return
next =>
async env =>
{
int maxConcurrentRequests = options.MaxConcurrentRequests;
if (maxConcurrentRequests <= 0)
{
maxConcurrentRequests = int.MaxValue;
}
try
{
int concurrentRequests = Interlocked.Increment(ref concurrentRequestCounter);
options.Tracer.AsVerbose("Concurrent counter incremented.");
options.Tracer.AsVerbose("Checking concurrent request #{0}.", concurrentRequests);
if (concurrentRequests > maxConcurrentRequests)
{
options.Tracer.AsInfo("Limit of {0} exceeded with #{1}. Request rejected.", maxConcurrentRequests, concurrentRequests);
IOwinResponse response = new OwinContext(env).Response;
response.StatusCode = 503;
response.ReasonPhrase = options.LimitReachedReasonPhrase(response.StatusCode);
return;
}
options.Tracer.AsVerbose("Request forwarded.");
await next(env);
}
finally
{
Interlocked.Decrement(ref concurrentRequestCounter);
options.Tracer.AsVerbose("Concurrent counter decremented.");
}
};
}