private void init() {
        this.samples = ctx.getSamples();
        if (ctx.isHistogram()) {
            if (ctx.getPercentiles() != null && ctx.getPercentiles().length > 0) {
                metricType = MetricType.histogramPercentile;
                this.percentiles = ctx.getPercentiles();
            } else {
                metricType = MetricType.histogram;
            }
        } else {
            if (ctx.getLabels().isEmpty()) {
                metricType = MetricType.single;
            } else {
                metricType = MetricType.labeled;
            }
        }
        createMetric(ctx.getScopeType(), metricType.literal, ctx.getDownsampling());
    }
analyse intends to parse expression with input samples to meter-system metrics.

@param sampleFamilies input samples.
oap-server/analyzer/meter-analyzer/src/main/java/org/apache/skywalking/oap/meter/analyzer/Analyzer.java