Refactor metrics implementation to follow the API described in the

metrics refactor RFC: pytorch#1492

cpp/src/utils/CMakeLists.txt

@@ -5,8 +5,7 @@ list(APPEND TS_UTILS_SOURCE_FILES ${TS_UTILS_SRC_DIR}/file_system.cc)
 list(APPEND TS_UTILS_SOURCE_FILES ${TS_UTILS_SRC_DIR}/model_archive.cc)
 list(APPEND TS_UTILS_SOURCE_FILES ${TS_UTILS_SRC_DIR}/logging.cc)
 list(APPEND TS_UTILS_SOURCE_FILES ${TS_UTILS_SRC_DIR}/metrics/units.cc)
-list(APPEND TS_UTILS_SOURCE_FILES ${TS_UTILS_SRC_DIR}/metrics/dimension.cc)
-list(APPEND TS_UTILS_SOURCE_FILES ${TS_UTILS_SRC_DIR}/metrics/metric.cc)
+list(APPEND TS_UTILS_SOURCE_FILES ${TS_UTILS_SRC_DIR}/metrics/log_metric.cc)
 add_library(ts_utils SHARED ${TS_UTILS_SOURCE_FILES})
 target_include_directories(ts_utils PUBLIC ${TS_UTILS_SRC_DIR})
 target_include_directories(ts_utils PRIVATE ${Boost_INCLUDE_DIRS})

cpp/src/utils/metrics/emitter.hh

@@ -0,0 +1,11 @@
+#ifndef TS_CPP_UTILS_METRICS_EMITTER_HH_
+#define TS_CPP_UTILS_METRICS_EMITTER_HH_
+
+namespace torchserve {
+    class Emitter {
+        public:
+        virtual void Emit() = 0;
+    };
+} // namespace torchserve
+
+#endif // TS_CPP_UTILS_METRICS_EMITTER_HH_

cpp/src/utils/metrics/log_metric.cc

@@ -0,0 +1,53 @@
+#include <chrono>
+#include <boost/asio.hpp>
+
+#include "src/utils/metrics/units.hh"
+#include "src/utils/logging.hh"
+#include "src/utils/metrics/log_metric.hh"
+
+namespace torchserve {
+    LogMetric::LogMetric(const std::string& name, const std::string& unit,
+                         const std::map<std::string, std::string>& dimensions, const MetricType& type) :
+                         name{name}, unit{Units::GetUnitMapping(unit)}, dimensions{dimensions}, type{type} {}
+
+    void LogMetric::Update(const double& value, const std::string& request_id) {
+        if(type == MetricType::COUNTER && value < 0.0) {
+            return;
+        }
+
+        uint64_t time_since_epoch_in_seconds = std::chrono::duration_cast<std::chrono::seconds>(
+                std::chrono::system_clock::now().time_since_epoch()).count();
+        values.push_back(std::make_tuple(value, time_since_epoch_in_seconds, request_id));
+    }
+
+    void LogMetric::Reset() {
+        values.clear();
+    }
+
+    void LogMetric::Emit() {
+        std::string dimensions_string = "";
+        for(auto iter = dimensions.begin(); iter != dimensions.end(); iter++) {
+            dimensions_string += iter->first + ":" + iter->second;
+            if (std::next(iter) != dimensions.end()) {
+                dimensions_string += ",";
+            }
+        }
+        std::string hostname = ::boost::asio::ip::host_name();
+
+        for(const auto& value_entry : values) {
+            double value;
+            std::uint64_t timestamp;
+            std::string request_id;
+            std::tie(value, timestamp, request_id) = value_entry;
+
+            if (request_id.empty()) {
+                TS_LOGF(INFO, "[METRICS]{}.{}:{}|#{}|#hostname:{},{}",
+                        name, unit, value, dimensions_string, hostname, timestamp);
+            }
+            else {
+                TS_LOGF(INFO, "[METRICS]{}.{}:{}|#{}|#hostname:{},{},{}",
+                        name, unit, value, dimensions_string, hostname, timestamp, request_id);
+            }
+        }
+    }
+} // namespace torchserve

cpp/src/utils/metrics/log_metric.hh

@@ -0,0 +1,33 @@
+#ifndef TS_CPP_UTILS_METRICS_LOG_METRIC_HH_
+#define TS_CPP_UTILS_METRICS_LOG_METRIC_HH_
+
+#include <string>
+#include <tuple>
+#include <vector>
+#include <map>
+
+#include "src/utils/metrics/metric.hh"
+#include "src/utils/metrics/emitter.hh"
+
+namespace torchserve {
+    // Value entry for log metric consisting of <metric_value, timestamp, request_id>
+    typedef std::tuple<double, std::uint64_t, std::string> LogMetricValue;
+
+    class LogMetric : public Metric, public Emitter {
+        public:
+        LogMetric(const std::string& name, const std::string& unit,
+                  const std::map<std::string, std::string>& dimensions, const MetricType& type);
+        void Update(const double& value, const std::string& request_id = "");
+        void Reset();
+        void Emit();
+
+        private:
+        const std::string name;
+        const std::string unit;
+        const std::map<std::string, std::string> dimensions;
+        const MetricType type;
+        std::vector<LogMetricValue> values;
+    };
+} // namespace torchserve
+
+#endif // TS_CPP_UTILS_METRICS_LOG_METRIC_HH_

cpp/src/utils/metrics/metric.hh

@@ -2,9 +2,6 @@
 #define TS_CPP_UTILS_METRICS_METRIC_HH_
 
 #include <string>
-#include <vector>
-
-#include "src/utils/metrics/dimension.hh"
 
 namespace torchserve {
     enum MetricType {
@@ -13,37 +10,10 @@ namespace torchserve {
         HISTOGRAM
     };
 
-    class MetricValue {
-        public:
-        MetricValue(const double& value, const uint64_t& timestamp, const std::string& request_id);
-        double GetValue() const;
-        uint64_t GetTimestamp() const;
-        const std::string GetRequestId() const;
-
-        private:
-        const double value;
-        const uint64_t timestamp;
-        const std::string request_id;
-    };
-
     class Metric {
         public:
-        Metric(const std::string& name, const std::string& unit,
-               const MetricType& type, const std::vector<Dimension>& dimensions);
-        const std::string GetName() const;
-        const std::string GetUnit() const;
-        MetricType GetType() const;
-        const std::vector<Dimension> GetDimensions() const;
-        const std::vector<MetricValue> GetValues() const;
-        void Update(const double& value, const std::string& request_id = "");
-        void Reset();
-
-        private:
-        const std::string name;
-        const std::string unit;
-        const MetricType type;
-        const std::vector<Dimension> dimensions;
-        std::vector<MetricValue> values;
+        virtual void Update(const double& value, const std::string& request_id = "") = 0;
+        virtual void Reset() = 0;
     };
 } // namespace torchserve
 

cpp/src/utils/metrics/metric_cache.hh

@@ -0,0 +1,19 @@
+#ifndef TS_CPP_UTILS_METRICS_METRIC_CACHE_HH_
+#define TS_CPP_UTILS_METRICS_METRIC_CACHE_HH_
+
+#include <string>
+#include <map>
+
+#include "src/utils/metrics/metric.hh"
+
+namespace torchserve {
+    class MetricCache {
+        public:
+        virtual Metric AddMetric(const std::string& name, const std::string& unit,
+                                 const std::map<std::string, std::string>& dimensions, const MetricType& type) = 0;
+        virtual Metric GetMetric(const std::string& name, const std::map<std::string, std::string>& dimensions) = 0;
+        virtual void Flush() = 0;
+    };
+} // namespace torchserve
+
+#endif // TS_CPP_UTILS_METRICS_METRIC_CACHE_HH_