add c++ wrapper for prometheus & common metrics

src/core/core.pri

@@ -96,6 +96,7 @@ HEADERS += \
 	$$PWD/inspectdata.h \
 	$$PWD/cors.h \
 	$$PWD/simplehttpserver.h \
+	$$PWD/prometheus.h \
 	$$PWD/stats.h \
 	$$PWD/statsmanager.h \
 	$$PWD/settings.h
@@ -128,6 +129,7 @@ SOURCES += \
 	$$PWD/statusreasons.cpp \
 	$$PWD/cors.cpp \
 	$$PWD/simplehttpserver.cpp \
+	$$PWD/prometheus.cpp \
 	$$PWD/stats.cpp \
 	$$PWD/statsmanager.cpp \
 	$$PWD/settings.cpp

src/core/prometheus.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2026 Fastly, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "prometheus.h"
+
+PrometheusServer::PrometheusServer(ffi::PrometheusServer *handle) : inner_(handle) {}
+
+PrometheusServer::~PrometheusServer() { ffi::prometheus_server_destroy(inner_); }
+
+// static
+std::unique_ptr<PrometheusServer> PrometheusServer::create(const QString &addr,
+                                                           const ffi::PrometheusRegistry *registry,
+                                                           QString *error) {
+    const char *errStr = nullptr;
+    ffi::PrometheusServer *handle =
+        ffi::prometheus_server_create(addr.toUtf8().data(), registry, &errStr);
+    if (!handle) {
+        if (error && errStr)
+            *error = QString::fromUtf8(errStr);
+        ffi::prometheus_server_error_destroy(errStr);
+        return nullptr;
+    }
+    return std::unique_ptr<PrometheusServer>(new PrometheusServer(handle));
+}

src/core/prometheus.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2026 Fastly, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef PROMETHEUS_H
+#define PROMETHEUS_H
+
+#include "rust/bindings.h"
+#include <QString>
+#include <memory>
+
+/// RAII wrapper around the Rust-backed prometheus HTTP server. Destroying this object blocks
+/// until the server thread stops.
+class PrometheusServer {
+public:
+    ~PrometheusServer();
+
+    PrometheusServer(const PrometheusServer &) = delete;
+    PrometheusServer &operator=(const PrometheusServer &) = delete;
+
+    /// Create and start a prometheus HTTP server listening on `addr`. The registry is cloned
+    /// internally so the server is independent of the registry's lifetime. On failure returns
+    /// nullptr and writes a description to `*error` if `error` is non-null.
+    static std::unique_ptr<PrometheusServer>
+    create(const QString &addr, const ffi::PrometheusRegistry *registry, QString *error = nullptr);
+
+private:
+    explicit PrometheusServer(ffi::PrometheusServer *handle);
+    ffi::PrometheusServer *inner_;
+};
+
+#endif

src/core/statsmanager.cpp

@@ -1322,6 +1322,30 @@ class StatsManager::Private {
     }
 };
 
+StatsManager::CommonMetrics::CommonMetrics(ffi::CommonMetrics *handle) : inner_(handle) {}
+
+StatsManager::CommonMetrics::~CommonMetrics() { ffi::statsmanager_commonmetrics_destroy(inner_); }
+
+// static
+std::unique_ptr<StatsManager::CommonMetrics>
+StatsManager::CommonMetrics::create(const QString &prefix) {
+    ffi::CommonMetrics *handle = ffi::statsmanager_commonmetrics_create(prefix.toUtf8().data());
+    if (!handle)
+        return nullptr;
+    return std::unique_ptr<StatsManager::CommonMetrics>(new StatsManager::CommonMetrics(handle));
+}
+
+const ffi::PrometheusRegistry *StatsManager::CommonMetrics::registry() const {
+    return ffi::statsmanager_commonmetrics_registry(inner_);
+}
+
+void StatsManager::CommonMetrics::update(uint32_t requestReceived, uint32_t connectionConnected,
+                                         uint32_t connectionMinute, uint32_t messageReceived,
+                                         uint32_t messageSent) {
+    ffi::statsmanager_commonmetrics_update(inner_, requestReceived, connectionConnected,
+                                           connectionMinute, messageReceived, messageSent);
+}
+
 StatsManager::StatsManager(int connectionsMax, int subscriptionsMax) {
     d = new Private(this, connectionsMax, subscriptionsMax);
 }

src/core/statsmanager.h

@@ -25,6 +25,7 @@
 #define STATSMANAGER_H
 
 #include "packet/statspacket.h"
+#include "rust/bindings.h"
 #include "stats.h"
 #include <boost/signals2.hpp>
 
@@ -40,6 +41,26 @@ class StatsManager {
 
     enum Format { TnetStringFormat, JsonFormat };
 
+    /// RAII wrapper around the Rust-backed CommonMetrics object, which holds the prometheus
+    /// registry and all metric handles.
+    class CommonMetrics {
+    public:
+        ~CommonMetrics();
+
+        CommonMetrics(const CommonMetrics &) = delete;
+        CommonMetrics &operator=(const CommonMetrics &) = delete;
+
+        static std::unique_ptr<CommonMetrics> create(const QString &prefix);
+
+        const ffi::PrometheusRegistry *registry() const;
+        void update(uint32_t requestReceived, uint32_t connectionConnected,
+                    uint32_t connectionMinute, uint32_t messageReceived, uint32_t messageSent);
+
+    private:
+        explicit CommonMetrics(ffi::CommonMetrics *handle);
+        ffi::CommonMetrics *inner_;
+    };
+
     StatsManager(int connectionsMax, int subscriptionsMax);
     ~StatsManager();