public ParseResult visitMetricInstant()

in oap-server/server-query-plugin/promql-plugin/src/main/java/org/apache/skywalking/oap/query/promql/rt/PromQLExprQueryVisitor.java [238:308]
70 lines of code
13 McCabe index (conditional complexity)

    public ParseResult visitMetricInstant(PromQLParser.MetricInstantContext ctx) {
        ParseResult result = new ParseResult();
        try {
            String metricName = ctx.metricName().getText();
            Optional<ValueColumnMetadata.ValueColumn> valueColumn = getValueColumn(metricName);
            if (valueColumn.isEmpty()) {
                result.setErrorType(ErrorType.BAD_DATA);
                result.setErrorInfo("Metric: [" + metricName + "] does not exist.");
                return result;
            }
            if (ctx.labelList() == null) {
                result.setErrorType(ErrorType.BAD_DATA);
                result.setErrorInfo("No labels found in the expression.");
                return result;
            }
            Map<LabelName, String> generalLabelMap = new HashMap<>();
            Map<String, String> queryLabel = new HashMap<>();
            for (PromQLParser.LabelContext labelCtx : ctx.labelList().label()) {
                String labelName = labelCtx.labelName().getText();
                String labelValue = labelCtx.labelValue().getText();
                String labelValueTrim = labelValue.substring(1, labelValue.length() - 1);
                try {
                    if (LabelName.isLabelName(labelName)) {
                        generalLabelMap.put(LabelName.labelOf(labelName), labelValueTrim);
                    } else {
                        queryLabel.put(labelName, labelValueTrim);
                    }
                } catch (IllegalArgumentException e) {
                    throw new IllegalExpressionException("Label:[" + labelName + "] is illegal.");
                }
            }
            final Layer layer;
            checkLabels(generalLabelMap, LabelName.LAYER);
            try {
                layer = Layer.valueOf(generalLabelMap.get(LabelName.LAYER));
            } catch (IllegalArgumentException e) {
                throw new IllegalExpressionException(
                    "Layer:[" + generalLabelMap.get(LabelName.LAYER) + "] is missing or illegal.");
            }
            ValueColumnMetadata.ValueColumn metaData = valueColumn.get();
            Scope scope = Scope.Finder.valueOf(metaData.getScopeId());
            Column.ValueDataType dataType = metaData.getDataType();
            MetricsRangeResult matrixResult = new MetricsRangeResult();
            matrixResult.setResultType(ParseResultType.METRICS_RANGE);
            if (StringUtil.isNotBlank(generalLabelMap.get(LabelName.TOP_N))) {
                if (Column.ValueDataType.SAMPLED_RECORD == dataType) {
                    queryRecords(metricName, layer, scope, generalLabelMap, matrixResult);
                } else {
                    queryTopN(metricName, layer, scope, generalLabelMap, matrixResult);
                }
            } else {
                if (Column.ValueDataType.COMMON_VALUE == dataType) {
                    metricsValuesQuery(metricName, layer, scope, generalLabelMap, matrixResult);
                } else if (Column.ValueDataType.LABELED_VALUE == dataType) {
                    //compatible with old version query, if true support use `labels` as the query label.
                    boolean isMultiIntValues = valueColumn.get().isMultiIntValues();
                    labeledMetricsValuesQuery(metricName, layer, scope, generalLabelMap, queryLabel, matrixResult, isMultiIntValues);
                }
            }
            return matrixResult;
        } catch (IllegalExpressionException e) {
            result.setErrorType(ErrorType.BAD_DATA);
            result.setErrorInfo(e.getMessage());
            return result;
        } catch (IOException e) {
            result.setErrorType(ErrorType.INTERNAL);
            result.setErrorInfo("Internal IO exception.");
            log.error("Query metrics error.", e);
            return result;
        }
    }