Export etl metrics to prometheus (#1256)

Fixes #1248.

src/util/prometheus/Bool.hpp

@@ -0,0 +1,89 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2024, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#pragma once
+
+#include "util/Assert.hpp"
+#include "util/prometheus/Gauge.hpp"
+
+#include <cstdint>
+#include <functional>
+
+namespace util::prometheus {
+
+template <typename T>
+concept SomeBoolImpl = requires(T a) {
+    {
+        a.set(0)
+    } -> std::same_as<void>;
+    {
+        a.value()
+    } -> std::same_as<int64_t>;
+};
+
+/**
+ * @brief A wrapped to provide bool interface for a Prometheus metric
+ * @note Prometheus does not have a native bool type, so we use a counter with a value of 0 or 1
+ */
+template <SomeBoolImpl ImplType>
+class AnyBool {
+    std::reference_wrapper<ImplType> impl_;
+
+public:
+    /**
+     * @brief Construct a bool metric
+     *
+     * @param impl The implementation of the metric
+     */
+    explicit AnyBool(ImplType& impl) : impl_(impl)
+    {
+    }
+
+    /**
+     * @brief Set the value of the bool metric
+     *
+     * @param value The value to set
+     * @return A reference to the metric
+     */
+    AnyBool&
+    operator=(bool value)
+    {
+        impl_.get().set(value ? 1 : 0);
+        return *this;
+    }
+
+    /**
+     * @brief Get the value of the bool metric
+     *
+     * @return The value of the metric
+     */
+    operator bool() const
+    {
+        auto const value = impl_.get().value();
+        ASSERT(value == 0 || value == 1, "Invalid value for bool: {}", value);
+        return value == 1;
+    }
+};
+
+/**
+ * @brief Alias for Prometheus bool metric with GaugeInt implementation
+ */
+using Bool = AnyBool<GaugeInt>;
+
+}  // namespace util::prometheus

src/util/prometheus/Counter.hpp

@@ -83,6 +83,18 @@ struct AnyCounter : MetricBase, impl::AnyCounterBase<NumberType> {
         return *this;
     }
 
+    /**
+     * @brief Set the value of the counter
+     *
+     * @param value The value to set the counter to
+     */
+    void
+    set(ValueType value)
+    {
+        ASSERT(value >= this->value(), "Cannot decrease a counter {}", this->name());
+        this->pimpl_->set(value);
+    }
+
     /**
      * @brief Reset the counter to zero
      */

src/util/prometheus/Prometheus.cpp

@@ -21,6 +21,7 @@
 
 #include "util/Assert.hpp"
 #include "util/config/Config.hpp"
+#include "util/prometheus/Bool.hpp"
 #include "util/prometheus/Counter.hpp"
 #include "util/prometheus/Gauge.hpp"
 #include "util/prometheus/Histogram.hpp"
@@ -52,6 +53,13 @@ convertBaseTo(MetricBase& metricBase)
 
 }  // namespace
 
+Bool
+PrometheusImpl::boolMetric(std::string name, Labels labels, std::optional<std::string> description)
+{
+    auto& metric = gaugeInt(std::move(name), std::move(labels), std::move(description));
+    return Bool{metric};
+}
+
 CounterInt&
 PrometheusImpl::counterInt(std::string name, Labels labels, std::optional<std::string> description)
 {
@@ -175,6 +183,12 @@ PrometheusService::init(util::Config const& config)
     instance_ = std::make_unique<util::prometheus::PrometheusImpl>(enabled, compressReply);
 }
 
+util::prometheus::Bool
+PrometheusService::boolMetric(std::string name, util::prometheus::Labels labels, std::optional<std::string> description)
+{
+    return instance().boolMetric(std::move(name), std::move(labels), std::move(description));
+}
+
 util::prometheus::CounterInt&
 PrometheusService::counterInt(std::string name, util::prometheus::Labels labels, std::optional<std::string> description)
 {

src/util/prometheus/Prometheus.hpp

@@ -20,6 +20,7 @@
 #pragma once
 
 #include "util/config/Config.hpp"
+#include "util/prometheus/Bool.hpp"
 #include "util/prometheus/Counter.hpp"
 #include "util/prometheus/Gauge.hpp"
 #include "util/prometheus/Histogram.hpp"
@@ -54,6 +55,18 @@ public:
 
     virtual ~PrometheusInterface() = default;
 
+    /**
+     * @brief Get a bool based metric. It will be created if it doesn't exist
+     * @note Prometheus does not have a native bool type, so we use a counter with a value of 0 or 1
+     *
+     * @param name The name of the metric
+     * @param labels The labels of the metric
+     * @param description The description of the metric
+     * @return The bool object
+     */
+    virtual Bool
+    boolMetric(std::string name, Labels labels, std::optional<std::string> description = std::nullopt) = 0;
+
     /**
      * @brief Get an integer based counter metric. It will be created if it doesn't exist
      *
@@ -176,6 +189,9 @@ class PrometheusImpl : public PrometheusInterface {
 public:
     using PrometheusInterface::PrometheusInterface;
 
+    Bool
+    boolMetric(std::string name, Labels labels, std::optional<std::string> description = std::nullopt) override;
+
     CounterInt&
     counterInt(std::string name, Labels labels, std::optional<std::string> description) override;
 
@@ -242,6 +258,22 @@ public:
      */
     void static init(util::Config const& config = util::Config{});
 
+    /**
+     * @brief Get a bool based metric. It will be created if it doesn't exist
+     * @note Prometheus does not have a native bool type, so we use a counter with a value of 0 or 1
+     *
+     * @param name The name of the metric
+     * @param labels The labels of the metric
+     * @param description The description of the metric
+     * @return The bool object
+     */
+    static util::prometheus::Bool
+    boolMetric(
+        std::string name,
+        util::prometheus::Labels labels,
+        std::optional<std::string> description = std::nullopt
+    );
+
     /**
      * @brief Get an integer based counter metric. It will be created if it doesn't exist
      *