public async Task DoRefresh()

in src/Microsoft.IIS.Administration.WebServer.Monitoring/Core/CounterMonitor.cs [121:189]
53 lines of code
20 McCabe index (conditional complexity)

        public async Task DoRefresh()
        {
            if (!NeedsRefresh) {
                return;
            }

            PDH_FMT_COUNTERVALUE value = default(PDH_FMT_COUNTERVALUE);

            uint result = Pdh.PdhCollectQueryData(_query);
            if (result == Pdh.PDH_NO_DATA) {
                throw new MissingCountersException(_counters.Keys);
            }
            if (result != 0) {
                throw new Win32Exception((int)result);
            }

            bool multiSample = false;
            List<IPerfCounter> missingCounters = new List<IPerfCounter>();
            foreach (KeyValuePair<IPerfCounter, PdhCounterHandle> counterInstance in _counters) {

                IPerfCounter counter = counterInstance.Key;
                PdhCounterHandle handle = counterInstance.Value;

                result = Pdh.PdhGetFormattedCounterValue(handle, PdhFormat.PDH_FMT_LARGE, IntPtr.Zero, out value);

                if (result == Pdh.PDH_INVALID_DATA && value.CStatus == Pdh.PDH_CSTATUS_INVALID_DATA && !multiSample) {

                    multiSample = true;

                    result = Pdh.PdhCollectQueryData(_query);
                    if (result != 0) {
                        throw new Win32Exception((int)result);
                    }

                    result = Pdh.PdhGetFormattedCounterValue(handle, PdhFormat.PDH_FMT_LARGE, IntPtr.Zero, out value);
                }

                if ((result != 0 && value.CStatus == Pdh.PDH_CSTATUS_NO_INSTANCE) ||
                        result == Pdh.PDH_INVALID_HANDLE ||
                        result == Pdh.PDH_CALC_NEGATIVE_VALUE ||
                        result == Pdh.PDH_CALC_NEGATIVE_DENOMINATOR ||
                        (result == Pdh.PDH_INVALID_DATA && value.CStatus == Pdh.PDH_INVALID_DATA)) {

                    missingCounters.Add(counter);
                    continue;
                }
                else if (result != 0) {

                    if (!_counterFinder.CounterExists(counter)) {
                        missingCounters.Add(counter);
                        continue;
                    }

                    throw new Win32Exception((int)result);
                }
                else if (value.CStatus != 0) {
                    throw new Win32Exception((int)value.CStatus);
                }

                counter.Value = value.longLongValue;
            }

            if (missingCounters.Count > 0) {
                throw new MissingCountersException(missingCounters);
            }

            TimeSpan calculationDelta = DateTime.UtcNow - _lastCalculatedTime;
            _lastCalculatedTime = DateTime.UtcNow;
        }