metric_family.h

// Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
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#pragma once

#ifdef TRITON_ENABLE_METRICS

#include <mutex>
#include <set>
#include <unordered_map>

#include "infer_parameter.h"
#include "prometheus/registry.h"
#include "tritonserver_apis.h"

namespace triton { namespace core {

//
// Implementation for TRITONSERVER_MetricFamily.
//
class Metric;
class MetricFamily {
 public:
  MetricFamily(
      TRITONSERVER_MetricKind kind, const char* name, const char* description);
  ~MetricFamily();

  void* Family() const { return family_; }
  TRITONSERVER_MetricKind Kind() const { return kind_; }

  void* Add(std::map<std::string, std::string> label_map, Metric* metric);
  void Remove(void* prom_metric, Metric* metric);

  int NumMetrics()
  {
    std::lock_guard<std::mutex> lk(metric_mtx_);
    return child_metrics_.size();
  }

 private:
  // If a MetricFamily is deleted before its dependent Metric, we want to
  // invalidate the reference so we don't access invalid memory.
  void InvalidateReferences();

  void* family_;
  TRITONSERVER_MetricKind kind_;
  // Synchronize access of related metric objects
  std::mutex metric_mtx_;
  // Prometheus returns the existing metric pointer if the metric with the same
  // set of labels are requested, as a result, different Metric objects may
  // refer to the same prometheus metric. So we must track the reference count
  // of the metric and request prometheus to remove it only when all references
  // are released.
  std::unordered_map<void*, size_t> prom_metric_ref_cnt_;
  // Maintain references to metrics created from this metric family to
  // invalidate their references if a family is deleted before its metric
  std::set<Metric*> child_metrics_;
};

//
// Implementation for TRITONSERVER_Metric.
//
class Metric {
 public:
  Metric(
      TRITONSERVER_MetricFamily* family,
      std::vector<const InferenceParameter*> labels);
  ~Metric();

  MetricFamily* Family() const { return family_; }
  TRITONSERVER_MetricKind Kind() const { return kind_; }

  TRITONSERVER_Error* Value(double* value);
  TRITONSERVER_Error* Increment(double value);
  TRITONSERVER_Error* Set(double value);

  // If a MetricFamily is deleted before its dependent Metric, we want to
  // invalidate the references so we don't access invalid memory.
  void Invalidate();

 private:
  void* metric_;
  MetricFamily* family_;
  TRITONSERVER_MetricKind kind_;
};

}}  // namespace triton::core

#endif  // TRITON_ENABLE_METRICS