tlbmc/trace/tracer.h

#ifndef THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_TRACE_TRACER_H_
#define THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_TRACE_TRACER_H_

#include <cstddef>
#include <string>
#include <vector>

#include "absl/container/btree_map.h"
#include "absl/container/flat_hash_map.h"
#include "absl/log/log.h"
#include "absl/time/clock.h"
#include "absl/time/time.h"
#include "trace.pb.h"

namespace milotic_tlbmc {

struct CheckPoint {
  std::size_t order;
  std::string keyword;
  bool repeated;
  bool operator<(const CheckPoint& other) const { return order < other.order; }
};

// A simple tracer to profile tlBMC performance.
// The class is thread-safe when it is disabled but thread-unsafe when enabled.
// Currently only support profiling single thread: useful to profile code blocks
// with a single client. Typical use case:
/*

Tracer::Initialize(true);

// init started
Tracer::GetInstance().AddOneOffDatapoint("init_started");
// init finished
Tracer::GetInstance().AddOneOffDatapoint("init_finished");

void HandleRequest() {
  // repeated work A started
  Tracer::GetInstance().AddDatapoint("work_A_started");
  // repeated work A finished
  Tracer::GetInstance().AddDatapoint("work_A_finished");
  // repeated work B started
  Tracer::GetInstance().AddDatapoint("work_B_started");
  // repeated work B finished
  Tracer::GetInstance().AddDatapoint("work_B_finished");
}

// tear down started
Tracer::GetInstance().AddOneOffDatapoint("tear_down_started");
// tear down finished
Tracer::GetInstance().AddOneOffDatapoint("tear_down_finished");

// Done
LOG(INFO) << absl::StrCat(Tracer::GetInstance().Dump());
*/
class Tracer {
 public:
  static Tracer& Initialize(bool enable);
  static Tracer& GetInstance();

  explicit Tracer(bool enable) : enabled_(enable) {
    LOG(INFO) << "Tracer is " << (enabled_ ? "enabled" : "disabled");
  }

  // Add a datapoint (with `timestamp`) to the corresponding checkpoint
  // specified by the `keyword`.
  void AddRepeatedDatapoint(const std::string& keyword,
                            absl::Time timestamp = absl::Now());
  void AddOneOffDatapoint(const std::string& keyword,
                          absl::Time timestamp = absl::Now());
  void Clear();
  Traces Dump() const;
  void EnableTracer(bool enable);

 protected:
  void AddDatapoint(const std::string& keyword, absl::Time timestamp,
                    bool repeated);

 private:
  bool enabled_;
  absl::btree_map<CheckPoint, std::vector<absl::Time>> datapoints_;
  absl::flat_hash_map<std::string, size_t> keyword_to_order_;
};

}  // namespace milotic_tlbmc

#endif  // THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_TRACE_TRACER_H_