private static void ApplicationPreSendRequestHeaders(object sender, EventArgs e)
        {
            if (!FailFastUserCache.FailFastEnabled)
            {
                return;
            }
            Logger.EnterFunction(ExTraceGlobals.FailureThrottlingTracer, "PowerShellFailureThrottlingModule.ApplicationPreSendRequestContent");
            HttpApplication httpApplication = (HttpApplication)sender;
            HttpContext     context         = httpApplication.Context;

            if (context == null || context.Request == null || context.Response == null)
            {
                Logger.TraceDebug(ExTraceGlobals.FailureThrottlingTracer, "context == null || context.Request == null || context.Response == null", new object[0]);
                Logger.ExitFunction(ExTraceGlobals.FailureThrottlingTracer, "PowerShellFailureThrottlingModule.ApplicationPreSendRequestContent");
                return;
            }
            string text = context.Response.Headers[FailFastModule.HeaderKeyToStoreUserToken];

            Logger.TraceDebug(ExTraceGlobals.FailureThrottlingTracer, "Current UserToken is {0}.", new object[]
            {
                text
            });
            context.Response.Headers.Remove(FailFastModule.HeaderKeyToStoreUserToken);
            Logger.TraceDebug(ExTraceGlobals.FailureThrottlingTracer, "Remove {0} from header.", new object[]
            {
                FailFastModule.HeaderKeyToStoreUserToken
            });
            if (!PowerShellFailureThrottlingModule.failureThrottlingEnabled)
            {
                Logger.TraceDebug(ExTraceGlobals.FailureThrottlingTracer, "Failure throttling is disabled.", new object[0]);
                Logger.ExitFunction(ExTraceGlobals.FailureThrottlingTracer, "PowerShellFailureThrottlingModule.ApplicationPreSendRequestContent");
                return;
            }
            if (!context.Request.IsAuthenticated)
            {
                Logger.TraceDebug(ExTraceGlobals.FailureThrottlingTracer, "Un-authenticated request.", new object[0]);
                Logger.ExitFunction(ExTraceGlobals.FailureThrottlingTracer, "PowerShellFailureThrottlingModule.ApplicationPreSendRequestContent");
                return;
            }
            if (!string.IsNullOrEmpty(text) && FailureThrottling.CountBasedOnStatusCode(text, context.Response.StatusCode))
            {
                HttpLogger.SafeAppendColumn(RpsCommonMetadata.ContributeToFailFast, "FailureThrottling", LoggerHelper.GetContributeToFailFastValue("User", text, "NewRequest", -1.0));
                Logger.TraceDebug(ExTraceGlobals.FailureThrottlingTracer, "Add user {0} to fail-fast user cache.", new object[]
                {
                    text
                });
                FailFastUserCache.Instance.AddUserToCache(text, BlockedType.NewRequest, TimeSpan.Zero);
            }
            Logger.ExitFunction(ExTraceGlobals.FailureThrottlingTracer, "PowerShellFailureThrottlingModule.ApplicationPreSendRequestContent");
        }
        internal static bool CountBasedOnStatusCode(string userToken, int statusCode)
        {
            int num;

            if (statusCode != 200)
            {
                if (statusCode != 400 && statusCode != 500)
                {
                    return(false);
                }
                num = 1;
            }
            else
            {
                num = -1;
            }
            FailureThrottling.FailureCounter counter = FailureThrottling.GetCounter(userToken);
            counter.AddDelta(num);
            Logger.TraceDebug(ExTraceGlobals.FailureThrottlingTracer, "User {0} counter changed to be {1}. Current status code is {2}.", new object[]
            {
                userToken,
                counter.Value,
                statusCode
            });
            if (num == 1 && counter.Value > FailureThrottling.failureThrottlingLimit)
            {
                Logger.TraceDebug(ExTraceGlobals.FailureThrottlingTracer, "User {0} is OverBudget. Counter: {1}. FailureThrottlingLimit: {2}", new object[]
                {
                    userToken,
                    counter.Value,
                    FailureThrottling.failureThrottlingLimit
                });
                return(true);
            }
            return(false);
        }