statsd metrics reporting (#496)

added support for reporting metrics via statsd style UDP messaging, which is supported by many monitoring solution providers

this change adds reporting only of three cache related metrics (hit/miss/put) but this should be extended to include more metrics after additional evaluation

2 files changed, 38 insertions, 11 deletions

diff --git a/src/zenserver/cache/structuredcachestore.cpp b/src/zenserver/cache/structuredcachestore.cpp
index 89123a70f..6fab14eee 100644
--- a/src/zenserver/cache/structuredcachestore.cpp
+++ b/src/zenserver/cache/structuredcachestore.cpp
@@ -16,6 +16,7 @@
 #include <zencore/timer.h>
 #include <zencore/trace.h>
 #include <zencore/workthreadpool.h>
+#include <zennet/statsdclient.h>
 #include <zenstore/scrubcontext.h>
 #include <zenutil/cache/cache.h>
 
@@ -663,7 +664,7 @@ ZenCacheStore::StorageSize() const
 }
 
 ZenCacheStore::CacheStoreStats
-ZenCacheStore::Stats()
+ZenCacheStore::Stats(bool IncludeNamespaceStats)
 {
 	ZenCacheStore::CacheStoreStats Result{.HitCount			  = m_HitCount,
 										  .MissCount		  = m_MissCount,
@@ -672,13 +673,32 @@ ZenCacheStore::Stats()
 										  .RejectedReadCount  = m_RejectedReadCount,
 										  .PutOps			  = m_PutOps.Snapshot(),
 										  .GetOps			  = m_GetOps.Snapshot()};
-	IterateNamespaces([&](std::string_view NamespaceName, ZenCacheNamespace& Store) {
-		Result.NamespaceStats.emplace_back(NamedNamespaceStats{.NamespaceName = std::string(NamespaceName), .Stats = Store.Stats()});
-	});
+
+	if (IncludeNamespaceStats)
+	{
+		IterateNamespaces([&](std::string_view NamespaceName, ZenCacheNamespace& Store) {
+			Result.NamespaceStats.emplace_back(NamedNamespaceStats{.NamespaceName = std::string(NamespaceName), .Stats = Store.Stats()});
+		});
+	}
+
 	return Result;
 }
 
 void
+ZenCacheStore::ReportMetrics(StatsDaemonClient& Statsd)
+{
+	const bool			   IncludeNamespaceStats = false;
+	const CacheStoreStats  Now					 = Stats(IncludeNamespaceStats);
+	const CacheStoreStats& Old					 = m_LastReportedMetrics;
+
+	Statsd.Meter("zen.cache_hits", Now.HitCount - Old.HitCount);
+	Statsd.Meter("zen.cache_misses", Now.MissCount - Old.MissCount);
+	Statsd.Meter("zen.cache_writes", Now.WriteCount - Old.WriteCount);
+
+	m_LastReportedMetrics = Now;
+}
+
+void
 ZenCacheStore::SetLoggingConfig(const Configuration::LogConfig& Loggingconfig)
 {
 	if (!Loggingconfig.EnableAccessLog && !Loggingconfig.EnableWriteLog)
diff --git a/src/zenserver/cache/structuredcachestore.h b/src/zenserver/cache/structuredcachestore.h
index 02d0e31c0..dacf482d8 100644
--- a/src/zenserver/cache/structuredcachestore.h
+++ b/src/zenserver/cache/structuredcachestore.h
@@ -3,6 +3,7 @@
 #pragma once
 
 #include "cachedisklayer.h"
+#include "stats/statsreporter.h"
 
 #include <zencore/compactbinary.h>
 #include <zencore/iohash.h>
@@ -18,6 +19,8 @@
 
 namespace zen {
 
+class StatsDaemonClient;
+
 /******************************************************************************
 
   /$$$$$$$$                        /$$$$$$                   /$$
@@ -126,7 +129,7 @@ private:
 
   */
 
-class ZenCacheStore final : public RefCounted
+class ZenCacheStore final : public RefCounted, public StatsProvider
 {
 public:
 	static constexpr std::string_view DefaultNamespace =
@@ -161,11 +164,11 @@ public:
 
 	struct CacheStoreStats
 	{
-		uint64_t						 HitCount;
-		uint64_t						 MissCount;
-		uint64_t						 WriteCount;
-		uint64_t						 RejectedWriteCount;
-		uint64_t						 RejectedReadCount;
+		uint64_t						 HitCount			= 0;
+		uint64_t						 MissCount			= 0;
+		uint64_t						 WriteCount			= 0;
+		uint64_t						 RejectedWriteCount = 0;
+		uint64_t						 RejectedReadCount	= 0;
 		metrics::RequestStatsSnapshot	 PutOps;
 		metrics::RequestStatsSnapshot	 GetOps;
 		std::vector<NamedNamespaceStats> NamespaceStats;
@@ -199,7 +202,7 @@ public:
 									  const std::string_view ValueFilter) const;
 
 	GcStorageSize	StorageSize() const;
-	CacheStoreStats Stats();
+	CacheStoreStats Stats(bool IncludeNamespaceStats = true);
 
 	Configuration								 GetConfiguration() const { return m_Configuration; }
 	void										 SetLoggingConfig(const Configuration::LogConfig& Loggingconfig);
@@ -212,6 +215,9 @@ public:
 								 std::string_view																		  Bucket,
 								 std::function<void(const IoHash& Key, const CacheValueDetails::ValueDetails& Details)>&& Fn);
 
+	// StatsProvider
+	virtual void ReportMetrics(StatsDaemonClient& Statsd) override;
+
 private:
 	const ZenCacheNamespace* FindNamespace(std::string_view Namespace) const;
 	ZenCacheNamespace*		 GetNamespace(std::string_view Namespace);
@@ -219,6 +225,7 @@ private:
 
 	typedef std::unordered_map<std::string, std::unique_ptr<ZenCacheNamespace>> NamespaceMap;
 
+	CacheStoreStats									m_LastReportedMetrics;
 	const DiskWriteBlocker*							m_DiskWriteBlocker = nullptr;
 	mutable RwLock									m_NamespacesLock;
 	NamespaceMap									m_Namespaces;