Add more Prometheus metrics (#12274)

10 files changed, 224 insertions, 119 deletions

diff --git a/src/emerge.cpp b/src/emerge.cpp
index 3760b24e6..5c1569f04 100644
--- a/src/emerge.cpp
+++ b/src/emerge.cpp
@@ -61,7 +61,9 @@ public:
 
 	void cancelPendingItems();
 
-	static void runCompletionCallbacks(
+protected:
+
+	void runCompletionCallbacks(
 		const v3s16 &pos, EmergeAction action,
 		const EmergeCallbackList &callbacks);
 
@@ -138,7 +140,7 @@ EmergeParams::EmergeParams(EmergeManager *parent, const BiomeGen *biomegen,
 //// EmergeManager
 ////
 
-EmergeManager::EmergeManager(Server *server)
+EmergeManager::EmergeManager(Server *server, MetricsBackend *mb)
 {
 	this->ndef      = server->getNodeDefManager();
 	this->biomemgr  = new BiomeManager(server);
@@ -156,6 +158,17 @@ EmergeManager::EmergeManager(Server *server)
 
 	enable_mapgen_debug_info = g_settings->getBool("enable_mapgen_debug_info");
 
+	STATIC_ASSERT(ARRLEN(emergeActionStrs) == ARRLEN(m_completed_emerge_counter),
+		enum_size_mismatches);
+	for (u32 i = 0; i < ARRLEN(m_completed_emerge_counter); i++) {
+		std::string help_str("Number of completed emerges with status ");
+		help_str.append(emergeActionStrs[i]);
+		m_completed_emerge_counter[i] = mb->addCounter(
+			"minetest_emerge_completed", help_str,
+			{{"status", emergeActionStrs[i]}}
+		);
+	}
+
 	s16 nthreads = 1;
 	g_settings->getS16NoEx("num_emerge_threads", nthreads);
 	// If automatic, leave a proc for the main thread and one for
@@ -489,6 +502,12 @@ EmergeThread *EmergeManager::getOptimalThread()
 	return m_threads[index];
 }
 
+void EmergeManager::reportCompletedEmerge(EmergeAction action)
+{
+	assert((int)action < ARRLEN(m_completed_emerge_counter));
+	m_completed_emerge_counter[(int)action]->increment();
+}
+
 
 ////
 //// EmergeThread
@@ -540,6 +559,8 @@ void EmergeThread::cancelPendingItems()
 void EmergeThread::runCompletionCallbacks(const v3s16 &pos, EmergeAction action,
 	const EmergeCallbackList &callbacks)
 {
+	m_emerge->reportCompletedEmerge(action);
+
 	for (size_t i = 0; i != callbacks.size(); i++) {
 		EmergeCompletionCallback callback;
 		void *param;
diff --git a/src/emerge.h b/src/emerge.h
index 61e7bda63..1bac4b708 100644
--- a/src/emerge.h
+++ b/src/emerge.h
@@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "network/networkprotocol.h"
 #include "irr_v3d.h"
 #include "util/container.h"
+#include "util/metricsbackend.h"
 #include "mapgen/mapgen.h" // for MapgenParams
 #include "map.h"
 
@@ -69,6 +70,14 @@ enum EmergeAction {
 	EMERGE_GENERATED,
 };
 
+const static std::string emergeActionStrs[] = {
+	"cancelled",
+	"errored",
+	"from_memory",
+	"from_disk",
+	"generated",
+};
+
 // Callback
 typedef void (*EmergeCompletionCallback)(
 	v3s16 blockpos, EmergeAction action, void *param);
@@ -138,7 +147,7 @@ public:
 	MapSettingsManager *map_settings_mgr;
 
 	// Methods
-	EmergeManager(Server *server);
+	EmergeManager(Server *server, MetricsBackend *mb);
 	~EmergeManager();
 	DISABLE_CLASS_COPY(EmergeManager);
 
@@ -197,6 +206,9 @@ private:
 	u32 m_qlimit_diskonly;
 	u32 m_qlimit_generate;
 
+	// Emerge metrics
+	MetricCounterPtr m_completed_emerge_counter[5];
+
 	// Managers of various map generation-related components
 	// Note that each Mapgen gets a copy(!) of these to work with
 	BiomeGen *biomegen;
@@ -218,5 +230,7 @@ private:
 
 	bool popBlockEmergeData(v3s16 pos, BlockEmergeData *bedata);
 
+	void reportCompletedEmerge(EmergeAction action);
+
 	friend class EmergeThread;
 };
diff --git a/src/map.cpp b/src/map.cpp
index 5153dcaa9..ce69accb5 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -336,6 +336,7 @@ void Map::timerUpdate(float dtime, float unload_timeout, u32 max_loaded_blocks,
 	u32 saved_blocks_count = 0;
 	u32 block_count_all = 0;
 
+	const auto start_time = porting::getTimeUs();
 	beginSave();
 
 	// If there is no practical limit, we spare creation of mapblock_queue
@@ -377,6 +378,7 @@ void Map::timerUpdate(float dtime, float unload_timeout, u32 max_loaded_blocks,
 				}
 			}
 
+			// Delete sector if we emptied it
 			if (all_blocks_deleted) {
 				sector_deletion_queue.push_back(sector_it.first);
 			}
@@ -395,6 +397,7 @@ void Map::timerUpdate(float dtime, float unload_timeout, u32 max_loaded_blocks,
 			}
 		}
 		block_count_all = mapblock_queue.size();
+
 		// Delete old blocks, and blocks over the limit from the memory
 		while (!mapblock_queue.empty() && (mapblock_queue.size() > max_loaded_blocks
 				|| mapblock_queue.top().block->getUsageTimer() > unload_timeout)) {
@@ -425,6 +428,7 @@ void Map::timerUpdate(float dtime, float unload_timeout, u32 max_loaded_blocks,
 			deleted_blocks_count++;
 			block_count_all--;
 		}
+
 		// Delete empty sectors
 		for (auto &sector_it : m_sectors) {
 			if (sector_it.second->empty()) {
@@ -432,7 +436,11 @@ void Map::timerUpdate(float dtime, float unload_timeout, u32 max_loaded_blocks,
 			}
 		}
 	}
+
 	endSave();
+	const auto end_time = porting::getTimeUs();
+
+	reportMetrics(end_time - start_time, saved_blocks_count, block_count_all);
 
 	// Finally delete the empty sectors
 	deleteSectors(sector_deletion_queue);
@@ -1218,7 +1226,12 @@ ServerMap::ServerMap(const std::string &savedir, IGameDef *gamedef,
 	m_savedir = savedir;
 	m_map_saving_enabled = false;
 
-	m_save_time_counter = mb->addCounter("minetest_core_map_save_time", "Map save time (in nanoseconds)");
+	m_save_time_counter = mb->addCounter(
+		"minetest_map_save_time", "Time spent saving blocks (in microseconds)");
+	m_save_count_counter = mb->addCounter(
+		"minetest_map_saved_blocks", "Number of blocks saved");
+	m_loaded_blocks_gauge = mb->addGauge(
+		"minetest_map_loaded_blocks", "Number of loaded blocks");
 
 	m_map_compression_level = rangelim(g_settings->getS16("map_compression_level_disk"), -1, 9);
 
@@ -1594,6 +1607,13 @@ void ServerMap::updateVManip(v3s16 pos)
 	vm->m_is_dirty = true;
 }
 
+void ServerMap::reportMetrics(u64 save_time_us, u32 saved_blocks, u32 all_blocks)
+{
+	m_loaded_blocks_gauge->set(all_blocks);
+	m_save_time_counter->increment(save_time_us);
+	m_save_count_counter->increment(saved_blocks);
+}
+
 void ServerMap::save(ModifiedState save_level)
 {
 	if (!m_map_saving_enabled) {
@@ -1601,7 +1621,7 @@ void ServerMap::save(ModifiedState save_level)
 		return;
 	}
 
-	u64 start_time = porting::getTimeNs();
+	const auto start_time = porting::getTimeUs();
 
 	if(save_level == MOD_STATE_CLEAN)
 		infostream<<"ServerMap: Saving whole map, this can take time."
@@ -1662,8 +1682,8 @@ void ServerMap::save(ModifiedState save_level)
 		modprofiler.print(infostream);
 	}
 
-	auto end_time = porting::getTimeNs();
-	m_save_time_counter->increment(end_time - start_time);
+	const auto end_time = porting::getTimeUs();
+	reportMetrics(end_time - start_time, block_count, block_count_all);
 }
 
 void ServerMap::listAllLoadableBlocks(std::vector<v3s16> &dst)
diff --git a/src/map.h b/src/map.h
index 21e3dbd6c..1e5499586 100644
--- a/src/map.h
+++ b/src/map.h
@@ -275,6 +275,9 @@ protected:
 	// This stores the properties of the nodes on the map.
 	const NodeDefManager *m_nodedef;
 
+	// Can be implemented by child class
+	virtual void reportMetrics(u64 save_time_us, u32 saved_blocks, u32 all_blocks) {}
+
 	bool determineAdditionalOcclusionCheck(const v3s16 &pos_camera,
 		const core::aabbox3d<s16> &block_bounds, v3s16 &check);
 	bool isOccluded(const v3s16 &pos_camera, const v3s16 &pos_target,
@@ -392,6 +395,10 @@ public:
 
 	MapSettingsManager settings_mgr;
 
+protected:
+
+	void reportMetrics(u64 save_time_us, u32 saved_blocks, u32 all_blocks) override;
+
 private:
 	friend class LuaVoxelManip;
 
@@ -420,7 +427,10 @@ private:
 	MapDatabase *dbase = nullptr;
 	MapDatabase *dbase_ro = nullptr;
 
+	// Map metrics
+	MetricGaugePtr m_loaded_blocks_gauge;
 	MetricCounterPtr m_save_time_counter;
+	MetricCounterPtr m_save_count_counter;
 };
 
 
diff --git a/src/server.cpp b/src/server.cpp
index d85a2e95a..ebe1d1f6b 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -269,9 +269,15 @@ Server::Server(
 			"minetest_core_latency",
 			"Latency value (in seconds)");
 
-	m_aom_buffer_counter = m_metrics_backend->addCounter(
-			"minetest_core_aom_generated_count",
-			"Number of active object messages generated");
+
+	const std::string aom_types[] = {"reliable", "unreliable"};
+	for (u32 i = 0; i < ARRLEN(aom_types); i++) {
+		std::string help_str("Number of active object messages generated (");
+		help_str.append(aom_types[i]).append(")");
+		m_aom_buffer_counter[i] = m_metrics_backend->addCounter(
+				"minetest_core_aom_generated_count", help_str,
+				{{"type", aom_types[i]}});
+	}
 
 	m_packet_recv_counter = m_metrics_backend->addCounter(
 			"minetest_core_server_packet_recv",
@@ -281,6 +287,10 @@ Server::Server(
 			"minetest_core_server_packet_recv_processed",
 			"Valid received packets processed");
 
+	m_map_edit_event_counter = m_metrics_backend->addCounter(
+			"minetest_core_map_edit_events",
+			"Number of map edit events");
+
 	m_lag_gauge->set(g_settings->getFloat("dedicated_server_step"));
 }
 
@@ -397,7 +407,7 @@ void Server::init()
 	}
 
 	// Create emerge manager
-	m_emerge = new EmergeManager(this);
+	m_emerge = new EmergeManager(this, m_metrics_backend.get());
 
 	// Create ban manager
 	std::string ban_path = m_path_world + DIR_DELIM "ipban.txt";
@@ -462,7 +472,8 @@ void Server::init()
 
 	// Initialize Environment
 	m_startup_server_map = nullptr; // Ownership moved to ServerEnvironment
-	m_env = new ServerEnvironment(servermap, m_script, this, m_path_world);
+	m_env = new ServerEnvironment(servermap, m_script, this,
+		m_path_world, m_metrics_backend.get());
 
 	m_inventory_mgr->setEnv(m_env);
 	m_clients.setEnv(m_env);
@@ -623,6 +634,7 @@ void Server::AsyncRunStep(bool initial_step)
 			max_lag = dtime;
 		}
 		m_env->reportMaxLagEstimate(max_lag);
+
 		// Step environment
 		m_env->step(dtime);
 	}
@@ -773,10 +785,14 @@ void Server::AsyncRunStep(bool initial_step)
 
 		// Get active object messages from environment
 		ActiveObjectMessage aom(0);
-		u32 aom_count = 0;
+		u32 count_reliable = 0, count_unreliable = 0;
 		for(;;) {
 			if (!m_env->getActiveObjectMessage(&aom))
 				break;
+			if (aom.reliable)
+				count_reliable++;
+			else
+				count_unreliable++;
 
 			std::vector<ActiveObjectMessage>* message_list = nullptr;
 			auto n = buffered_messages.find(aom.id);
@@ -787,10 +803,10 @@ void Server::AsyncRunStep(bool initial_step)
 				message_list = n->second;
 			}
 			message_list->push_back(std::move(aom));
-			aom_count++;
 		}
 
-		m_aom_buffer_counter->increment(aom_count);
+		m_aom_buffer_counter[0]->increment(count_reliable);
+		m_aom_buffer_counter[1]->increment(count_unreliable);
 
 		{
 			ClientInterface::AutoLock clientlock(m_clients);
@@ -864,15 +880,13 @@ void Server::AsyncRunStep(bool initial_step)
 		// We will be accessing the environment
 		MutexAutoLock lock(m_env_mutex);
 
-		// Don't send too many at a time
-		//u32 count = 0;
-
-		// Single change sending is disabled if queue size is not small
+		// Single change sending is disabled if queue size is big
 		bool disable_single_change_sending = false;
 		if(m_unsent_map_edit_queue.size() >= 4)
 			disable_single_change_sending = true;
 
-		int event_count = m_unsent_map_edit_queue.size();
+		const auto event_count = m_unsent_map_edit_queue.size();
+		m_map_edit_event_counter->increment(event_count);
 
 		// We'll log the amount of each
 		Profiler prof;
diff --git a/src/server.h b/src/server.h
index b1b9675d9..ecba30b95 100644
--- a/src/server.h
+++ b/src/server.h
@@ -724,11 +724,11 @@ private:
 	MetricCounterPtr m_uptime_counter;
 	MetricGaugePtr m_player_gauge;
 	MetricGaugePtr m_timeofday_gauge;
-	// current server step lag
 	MetricGaugePtr m_lag_gauge;
-	MetricCounterPtr m_aom_buffer_counter;
+	MetricCounterPtr m_aom_buffer_counter[2]; // [0] = rel, [1] = unrel
 	MetricCounterPtr m_packet_recv_counter;
 	MetricCounterPtr m_packet_recv_processed_counter;
+	MetricCounterPtr m_map_edit_event_counter;
 };
 
 /*
diff --git a/src/serverenvironment.cpp b/src/serverenvironment.cpp
index 493210744..630c111c5 100644
--- a/src/serverenvironment.cpp
+++ b/src/serverenvironment.cpp
@@ -393,7 +393,7 @@ static std::random_device seed;
 
 ServerEnvironment::ServerEnvironment(ServerMap *map,
 	ServerScripting *scriptIface, Server *server,
-	const std::string &path_world):
+	const std::string &path_world, MetricsBackend *mb):
 	Environment(server),
 	m_map(map),
 	m_script(scriptIface),
@@ -460,6 +460,15 @@ ServerEnvironment::ServerEnvironment(ServerMap *map,
 
 	m_player_database = openPlayerDatabase(player_backend_name, path_world, conf);
 	m_auth_database = openAuthDatabase(auth_backend_name, path_world, conf);
+
+	m_step_time_counter = mb->addCounter(
+		"minetest_env_step_time", "Time spent in environment step (in microseconds)");
+
+	m_active_block_gauge = mb->addGauge(
+		"minetest_env_active_blocks", "Number of active blocks");
+
+	m_active_object_gauge = mb->addGauge(
+		"minetest_env_active_objects", "Number of active objects");
 }
 
 ServerEnvironment::~ServerEnvironment()
@@ -1283,6 +1292,8 @@ void ServerEnvironment::clearObjects(ClearObjectsMode mode)
 void ServerEnvironment::step(float dtime)
 {
 	ScopeProfiler sp2(g_profiler, "ServerEnv::step()", SPT_AVG);
+	const auto start_time = porting::getTimeUs();
+
 	/* Step time of day */
 	stepTimeOfDay(dtime);
 
@@ -1352,6 +1363,8 @@ void ServerEnvironment::step(float dtime)
 		m_active_blocks.update(players, active_block_range, active_object_range,
 			blocks_removed, blocks_added);
 
+		m_active_block_gauge->set(m_active_blocks.size());
+
 		/*
 			Handle removed blocks
 		*/
@@ -1497,9 +1510,12 @@ void ServerEnvironment::step(float dtime)
 			send_recommended = true;
 		}
 
-		auto cb_state = [this, dtime, send_recommended] (ServerActiveObject *obj) {
+		u32 object_count = 0;
+
+		auto cb_state = [&] (ServerActiveObject *obj) {
 			if (obj->isGone())
 				return;
+			object_count++;
 
 			// Step object
 			obj->step(dtime, send_recommended);
@@ -1507,6 +1523,8 @@ void ServerEnvironment::step(float dtime)
 			obj->dumpAOMessagesToQueue(m_active_object_messages);
 		};
 		m_ao_manager.step(dtime, cb_state);
+
+		m_active_object_gauge->set(object_count);
 	}
 
 	/*
@@ -1548,6 +1566,9 @@ void ServerEnvironment::step(float dtime)
 
 	// Send outdated detached inventories
 	m_server->sendDetachedInventories(PEER_ID_INEXISTENT, true);
+
+	const auto end_time = porting::getTimeUs();
+	m_step_time_counter->increment(end_time - start_time);
 }
 
 ServerEnvironment::BlockStatus ServerEnvironment::getBlockStatus(v3s16 blockpos)
diff --git a/src/serverenvironment.h b/src/serverenvironment.h
index 8733c2dd2..5dc329a60 100644
--- a/src/serverenvironment.h
+++ b/src/serverenvironment.h
@@ -25,6 +25,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "settings.h"
 #include "server/activeobjectmgr.h"
 #include "util/numeric.h"
+#include "util/metricsbackend.h"
 #include <set>
 #include <random>
 
@@ -167,19 +168,21 @@ public:
 		std::set<v3s16> &blocks_removed,
 		std::set<v3s16> &blocks_added);
 
-	bool contains(v3s16 p){
+	bool contains(v3s16 p) const {
 		return (m_list.find(p) != m_list.end());
 	}
 
-	void clear(){
+	auto size() const {
+		return m_list.size();
+	}
+
+	void clear() {
 		m_list.clear();
 	}
 
 	std::set<v3s16> m_list;
 	std::set<v3s16> m_abm_list;
 	std::set<v3s16> m_forceloaded_list;
-
-private:
 };
 
 /*
@@ -198,7 +201,7 @@ class ServerEnvironment : public Environment
 {
 public:
 	ServerEnvironment(ServerMap *map, ServerScripting *scriptIface,
-		Server *server, const std::string &path_world);
+		Server *server, const std::string &path_world, MetricsBackend *mb);
 	~ServerEnvironment();
 
 	Map & getMap();
@@ -487,5 +490,10 @@ private:
 	std::unordered_map<u32, float> m_particle_spawners;
 	std::unordered_map<u32, u16> m_particle_spawner_attachments;
 
+	// Environment metrics
+	MetricCounterPtr m_step_time_counter;
+	MetricGaugePtr m_active_block_gauge;
+	MetricGaugePtr m_active_object_gauge;
+
 	ServerActiveObject* createSAO(ActiveObjectType type, v3f pos, const std::string &data);
 };
diff --git a/src/util/metricsbackend.cpp b/src/util/metricsbackend.cpp
index c3b7def62..63b49ac0a 100644
--- a/src/util/metricsbackend.cpp
+++ b/src/util/metricsbackend.cpp
@@ -18,6 +18,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 */
 
 #include "metricsbackend.h"
+#include "util/thread.h"
 #if USE_PROMETHEUS
 #include <prometheus/exposer.h>
 #include <prometheus/registry.h>
@@ -27,18 +28,78 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "settings.h"
 #endif
 
+/* Plain implementation */
+
+class SimpleMetricCounter : public MetricCounter
+{
+public:
+	SimpleMetricCounter() : MetricCounter(), m_counter(0.0) {}
+
+	virtual ~SimpleMetricCounter() {}
+
+	void increment(double number) override
+	{
+		MutexAutoLock lock(m_mutex);
+		m_counter += number;
+	}
+	double get() const override
+	{
+		MutexAutoLock lock(m_mutex);
+		return m_counter;
+	}
+
+private:
+	mutable std::mutex m_mutex;
+	double m_counter;
+};
+
+class SimpleMetricGauge : public MetricGauge
+{
+public:
+	SimpleMetricGauge() : MetricGauge(), m_gauge(0.0) {}
+
+	virtual ~SimpleMetricGauge() {}
+
+	void increment(double number) override
+	{
+		MutexAutoLock lock(m_mutex);
+		m_gauge += number;
+	}
+	void decrement(double number) override
+	{
+		MutexAutoLock lock(m_mutex);
+		m_gauge -= number;
+	}
+	void set(double number) override
+	{
+		MutexAutoLock lock(m_mutex);
+		m_gauge = number;
+	}
+	double get() const override
+	{
+		MutexAutoLock lock(m_mutex);
+		return m_gauge;
+	}
+
+private:
+	mutable std::mutex m_mutex;
+	double m_gauge;
+};
+
 MetricCounterPtr MetricsBackend::addCounter(
-		const std::string &name, const std::string &help_str)
+		const std::string &name, const std::string &help_str, Labels labels)
 {
-	return std::make_shared<SimpleMetricCounter>(name, help_str);
+	return std::make_shared<SimpleMetricCounter>();
 }
 
 MetricGaugePtr MetricsBackend::addGauge(
-		const std::string &name, const std::string &help_str)
+		const std::string &name, const std::string &help_str, Labels labels)
 {
-	return std::make_shared<SimpleMetricGauge>(name, help_str);
+	return std::make_shared<SimpleMetricGauge>();
 }
 
+/* Prometheus backend */
+
 #if USE_PROMETHEUS
 
 class PrometheusMetricCounter : public MetricCounter
@@ -47,13 +108,14 @@ public:
 	PrometheusMetricCounter() = delete;
 
 	PrometheusMetricCounter(const std::string &name, const std::string &help_str,
+			MetricsBackend::Labels labels,
 			std::shared_ptr<prometheus::Registry> registry) :
 			MetricCounter(),
 			m_family(prometheus::BuildCounter()
 							.Name(name)
 							.Help(help_str)
 							.Register(*registry)),
-			m_counter(m_family.Add({}))
+			m_counter(m_family.Add(labels))
 	{
 	}
 
@@ -73,13 +135,14 @@ public:
 	PrometheusMetricGauge() = delete;
 
 	PrometheusMetricGauge(const std::string &name, const std::string &help_str,
+			MetricsBackend::Labels labels,
 			std::shared_ptr<prometheus::Registry> registry) :
 			MetricGauge(),
 			m_family(prometheus::BuildGauge()
 							.Name(name)
 							.Help(help_str)
 							.Register(*registry)),
-			m_gauge(m_family.Add({}))
+			m_gauge(m_family.Add(labels))
 	{
 	}
 
@@ -107,10 +170,12 @@ public:
 
 	virtual ~PrometheusMetricsBackend() {}
 
-	virtual MetricCounterPtr addCounter(
-			const std::string &name, const std::string &help_str);
-	virtual MetricGaugePtr addGauge(
-			const std::string &name, const std::string &help_str);
+	MetricCounterPtr addCounter(
+			const std::string &name, const std::string &help_str,
+			Labels labels = {}) override;
+	MetricGaugePtr addGauge(
+			const std::string &name, const std::string &help_str,
+			Labels labels = {}) override;
 
 private:
 	std::unique_ptr<prometheus::Exposer> m_exposer;
@@ -118,15 +183,15 @@ private:
 };
 
 MetricCounterPtr PrometheusMetricsBackend::addCounter(
-		const std::string &name, const std::string &help_str)
+		const std::string &name, const std::string &help_str, Labels labels)
 {
-	return std::make_shared<PrometheusMetricCounter>(name, help_str, m_registry);
+	return std::make_shared<PrometheusMetricCounter>(name, help_str, labels, m_registry);
 }
 
 MetricGaugePtr PrometheusMetricsBackend::addGauge(
-		const std::string &name, const std::string &help_str)
+		const std::string &name, const std::string &help_str, Labels labels)
 {
-	return std::make_shared<PrometheusMetricGauge>(name, help_str, m_registry);
+	return std::make_shared<PrometheusMetricGauge>(name, help_str, labels, m_registry);
 }
 
 MetricsBackend *createPrometheusMetricsBackend()
diff --git a/src/util/metricsbackend.h b/src/util/metricsbackend.h
index c37306392..644c73325 100644
--- a/src/util/metricsbackend.h
+++ b/src/util/metricsbackend.h
@@ -19,8 +19,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #pragma once
 #include <memory>
+#include <string>
+#include <utility>
 #include "config.h"
-#include "util/thread.h"
 
 class MetricCounter
 {
@@ -35,38 +36,6 @@ public:
 
 typedef std::shared_ptr<MetricCounter> MetricCounterPtr;
 
-class SimpleMetricCounter : public MetricCounter
-{
-public:
-	SimpleMetricCounter() = delete;
-
-	virtual ~SimpleMetricCounter() {}
-
-	SimpleMetricCounter(const std::string &name, const std::string &help_str) :
-			MetricCounter(), m_name(name), m_help_str(help_str),
-			m_counter(0.0)
-	{
-	}
-
-	virtual void increment(double number)
-	{
-		MutexAutoLock lock(m_mutex);
-		m_counter += number;
-	}
-	virtual double get() const
-	{
-		MutexAutoLock lock(m_mutex);
-		return m_counter;
-	}
-
-private:
-	std::string m_name;
-	std::string m_help_str;
-
-	mutable std::mutex m_mutex;
-	double m_counter;
-};
-
 class MetricGauge
 {
 public:
@@ -81,47 +50,6 @@ public:
 
 typedef std::shared_ptr<MetricGauge> MetricGaugePtr;
 
-class SimpleMetricGauge : public MetricGauge
-{
-public:
-	SimpleMetricGauge() = delete;
-
-	SimpleMetricGauge(const std::string &name, const std::string &help_str) :
-			MetricGauge(), m_name(name), m_help_str(help_str), m_gauge(0.0)
-	{
-	}
-
-	virtual ~SimpleMetricGauge() {}
-
-	virtual void increment(double number)
-	{
-		MutexAutoLock lock(m_mutex);
-		m_gauge += number;
-	}
-	virtual void decrement(double number)
-	{
-		MutexAutoLock lock(m_mutex);
-		m_gauge -= number;
-	}
-	virtual void set(double number)
-	{
-		MutexAutoLock lock(m_mutex);
-		m_gauge = number;
-	}
-	virtual double get() const
-	{
-		MutexAutoLock lock(m_mutex);
-		return m_gauge;
-	}
-
-private:
-	std::string m_name;
-	std::string m_help_str;
-
-	mutable std::mutex m_mutex;
-	double m_gauge;
-};
-
 class MetricsBackend
 {
 public:
@@ -129,10 +57,14 @@ public:
 
 	virtual ~MetricsBackend() {}
 
+	typedef std::initializer_list<std::pair<const std::string, std::string>> Labels;
+
 	virtual MetricCounterPtr addCounter(
-			const std::string &name, const std::string &help_str);
+			const std::string &name, const std::string &help_str,
+			Labels labels = {});
 	virtual MetricGaugePtr addGauge(
-			const std::string &name, const std::string &help_str);
+			const std::string &name, const std::string &help_str,
+			Labels labels = {});
 };
 
 #if USE_PROMETHEUS