add Prometheus library

Prometheus/src/Histogram.cpp

@@ -0,0 +1,151 @@
+//
+// Histogram.cpp
+//
+// Library: Prometheus
+// Package: Core
+// Module:  Histogram
+//
+// Copyright (c) 2022, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#include "Poco/Prometheus/Histogram.h"
+#include "Poco/Prometheus/Gauge.h"
+#include "Poco/Prometheus/Exporter.h"
+#include "Poco/NumberFormatter.h"
+
+using namespace std::string_literals;
+
+
+namespace Poco {
+namespace Prometheus {
+
+
+HistogramSample::HistogramSample(const std::vector<double>& bucketBounds):
+	_bucketBounds(bucketBounds),
+	_bucketCounts(bucketBounds.size(), 0)
+{
+}
+
+
+void HistogramSample::observe(double value)
+{
+	Poco::FastMutex::ScopedLock lock(_mutex);
+
+	const std::size_t n = _bucketBounds.size();
+	for (std::size_t i = 0; i < n; i++)
+	{
+		if (value <= _bucketBounds[i])
+		{
+			_bucketCounts[i]++;
+		}
+	}
+	_sum += value;
+	_count++;
+}
+
+
+void HistogramSample::observe(Poco::Clock::ClockVal v)
+{
+	observe(double(v)/Poco::Clock::resolution());
+}
+
+
+Histogram::Histogram(const std::string& name):
+	LabeledMetricImpl(Metric::Type::HISTOGRAM, name)
+{
+}
+
+
+Histogram::Histogram(const std::string& name, const Params& params):
+	LabeledMetricImpl(Metric::Type::HISTOGRAM, name),
+	_bucketBounds(params.buckets)
+{
+	setHelp(params.help);
+	setLabelNames(params.labelNames);
+}
+
+
+Histogram::Histogram(const std::string& name, Registry* pRegistry):
+	LabeledMetricImpl(Metric::Type::HISTOGRAM, name, pRegistry)
+{
+}
+
+
+Histogram::Histogram(const std::string& name, const Params& params, Registry* pRegistry):
+	LabeledMetricImpl(Metric::Type::HISTOGRAM, name, pRegistry),
+	_bucketBounds(params.buckets)
+{
+	setHelp(params.help);
+	setLabelNames(params.labelNames);
+}
+
+
+Histogram& Histogram::buckets(const std::vector<double>& bucketBounds)
+{
+	_bucketBounds = bucketBounds;
+	return *this;
+}
+
+
+void Histogram::observe(double value)
+{
+	labels(EMPTY_LABEL).observe(value);
+}
+
+
+void Histogram::observe(Poco::Clock::ClockVal v)
+{
+	labels(EMPTY_LABEL).observe(double(v)/Poco::Clock::resolution());
+}
+
+
+HistogramData Histogram::data() const
+{
+	return labels(EMPTY_LABEL).data();
+}
+
+
+std::unique_ptr<HistogramSample> Histogram::createSample() const
+{
+	return std::make_unique<HistogramSample>(_bucketBounds);
+}
+
+
+void Histogram::exportTo(Exporter& exporter) const
+{
+	Poco::FastMutex::ScopedLock lock(_mutex);
+
+	Gauge bucket(name() + "_bucket"s, nullptr);
+	Gauge sum(name() + "_sum"s, nullptr);
+	Gauge count(name() + "_count"s, nullptr);
+
+	exporter.writeHeader(*this);
+	std::vector<std::string> bucketLabels = labelNames();
+	bucketLabels.push_back("le"s);
+	const std::size_t n = _bucketBounds.size();
+	forEach<HistogramSample>(
+		[&](const std::vector<std::string>& labelValues, const HistogramSample& sample)
+		{
+			std::vector<std::string> bucketLabelValues = labelValues;
+			bucketLabelValues.push_back(""s);
+			const HistogramData data = sample.data();
+			for (std::size_t i = 0; i < n; i++)
+			{
+				bucketLabelValues.back() = Poco::NumberFormatter::format(_bucketBounds[i]);
+
+				exporter.writeSample(bucket, bucketLabels, bucketLabelValues, data.bucketCounts[i]);
+			}
+			bucketLabelValues.back() = "+Inf"s;
+			exporter.writeSample(bucket, bucketLabels, bucketLabelValues, data.count);
+			exporter.writeSample(sum, labelNames(), labelValues, data.sum);
+			exporter.writeSample(count, labelNames(), labelValues, data.count);
+		}
+	);
+}
+
+
+} } // namespace Poco::Prometheus