public void Log()

in src/WebJobs.Script.WebHost/Diagnostics/SystemLogger.cs [58:182]
105 lines of code
30 McCabe index (conditional complexity)

        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
        {
            if (!IsEnabled(logLevel) || _isUserFunction || FunctionInvoker.CurrentScope == FunctionInvocationScope.User)
            {
                return;
            }

            // Enumerate all the state values once, capturing the values we'll use below - last one wins.
            string stateSourceValue = null;
            string stateFunctionName = null;
            string stateEventName = null;
            string stateActivityId = null;
            string diagnosticEventErrorCode = null;
            bool isDiagnosticEvent = false;
            if (state is IEnumerable<KeyValuePair<string, object>> stateProps)
            {
                foreach (var kvp in stateProps)
                {
                    if (string.Equals(kvp.Key, ScriptConstants.LogPropertySourceKey, StringComparison.OrdinalIgnoreCase))
                    {
                        stateSourceValue = kvp.Value?.ToString();
                    }
                    else if (string.Equals(kvp.Key, ScriptConstants.DiagnosticEventKey, StringComparison.OrdinalIgnoreCase))
                    {
                        isDiagnosticEvent = true;
                    }
                    else if (string.Equals(kvp.Key, ScriptConstants.ErrorCodeKey, StringComparison.OrdinalIgnoreCase))
                    {
                        diagnosticEventErrorCode = kvp.Value?.ToString();
                    }
                    else if (string.Equals(kvp.Key, ScriptConstants.LogPropertyIsUserLogKey, StringComparison.OrdinalIgnoreCase))
                    {
                        if ((bool)kvp.Value)
                        {
                            return;
                        }
                    }
                    else if (Utility.IsFunctionName(kvp))
                    {
                        stateFunctionName = kvp.Value?.ToString();
                    }
                    else if (string.Equals(kvp.Key, ScriptConstants.LogPropertyEventNameKey, StringComparison.OrdinalIgnoreCase))
                    {
                        stateEventName = kvp.Value?.ToString();
                    }
                    else if (string.Equals(kvp.Key, ScriptConstants.LogPropertyActivityIdKey, StringComparison.OrdinalIgnoreCase))
                    {
                        stateActivityId = kvp.Value?.ToString();
                    }
                }
            }

            // Propagate special exceptions through the EventManager.
            string source = _categoryName ?? stateSourceValue;
            if (exception is FunctionIndexingException && _eventManager != null)
            {
                _eventManager.Publish(new FunctionIndexingEvent(nameof(FunctionIndexingException), source, exception));
            }

            // If we don't have a message, there's nothing to log.
            string formattedMessage = formatter?.Invoke(state, exception);
            if (string.IsNullOrEmpty(formattedMessage))
            {
                return;
            }

            var scopeProps = _scopeProvider.GetScopeDictionaryOrNull();
            string functionName = _functionName ?? stateFunctionName ?? string.Empty;
            if (string.IsNullOrEmpty(functionName) && scopeProps?.Count > 0)
            {
                if (Utility.TryGetFunctionName(scopeProps, out string scopeFunctionName))
                {
                    functionName = scopeFunctionName;
                }
            }

            string invocationId = string.Empty;
            object scopeValue = null;
            string scopeActivityId = null;
            if (scopeProps != null)
            {
                if (scopeProps.TryGetValue(ScriptConstants.LogPropertyFunctionInvocationIdKey, out scopeValue) && scopeValue != null)
                {
                    invocationId = scopeValue.ToString();
                }

                // For Http function invocations we want to stamp invocation logs with
                // the request ID for easy correlation with incoming Http request logs.
                if (scopeProps.TryGetValue(ScriptConstants.AzureFunctionsRequestIdKey, out scopeValue))
                {
                    scopeActivityId = scopeValue as string;
                }
            }

            // Apply standard event properties.
            // Note: we must be sure to default any null values to empty string
            // otherwise the ETW event will fail to be persisted (silently).
            string eventName = !string.IsNullOrEmpty(eventId.Name) ? eventId.Name : stateEventName ?? string.Empty;
            eventName = isDiagnosticEvent ? $"DiagnosticEvent-{diagnosticEventErrorCode}" : eventName;

            string activityId = stateActivityId ?? scopeActivityId ?? string.Empty;
            var options = _appServiceOptions;
            string subscriptionId = options.SubscriptionId ?? string.Empty;
            string appName = options.AppName ?? string.Empty;
            string runtimeSiteName = options.RuntimeSiteName ?? string.Empty;
            string slotName = options.SlotName ?? string.Empty;

            string innerExceptionType = string.Empty;
            string innerExceptionMessage = string.Empty;
            string details = string.Empty;
            if (exception != null)
            {
                // Populate details from the exception.
                if (string.IsNullOrEmpty(functionName) && exception is FunctionException fex)
                {
                    functionName = string.IsNullOrEmpty(fex.MethodName) ? string.Empty : fex.MethodName.Replace("Host.Functions.", string.Empty);
                }

                (innerExceptionType, innerExceptionMessage, details) = exception.GetExceptionDetails();
                formattedMessage = Sanitizer.Sanitize(formattedMessage);
                innerExceptionMessage = innerExceptionMessage ?? string.Empty;
            }

            _eventGenerator.LogFunctionTraceEvent(logLevel, subscriptionId, appName, functionName, eventName, source, details, formattedMessage, innerExceptionType, innerExceptionMessage, invocationId, _hostInstanceId, activityId, runtimeSiteName, slotName, DateTime.UtcNow);
        }