internal/ceres/execution_summary.h

// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2023 Google Inc. All rights reserved.
// http://ceres-solver.org/
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// Author: sameeragarwal@google.com (Sameer Agarwal)

#ifndef CERES_INTERNAL_EXECUTION_SUMMARY_H_
#define CERES_INTERNAL_EXECUTION_SUMMARY_H_

#include <map>
#include <mutex>
#include <string>
#include <utility>

#include "ceres/internal/export.h"
#include "ceres/wall_time.h"

namespace ceres::internal {

struct CallStatistics {
  CallStatistics() = default;
  double time{0.};
  int calls{0};
};

// Struct used by various objects to report statistics about their
// execution.
class ExecutionSummary {
 public:
  void IncrementTimeBy(const std::string& name, const double value) {
    std::lock_guard<std::mutex> l(mutex_);
    CallStatistics& call_stats = statistics_[name];
    call_stats.time += value;
    ++call_stats.calls;
  }

  const std::map<std::string, CallStatistics>& statistics() const {
    return statistics_;
  }

 private:
  std::mutex mutex_;
  std::map<std::string, CallStatistics> statistics_;
};

class ScopedExecutionTimer {
 public:
  ScopedExecutionTimer(std::string name, ExecutionSummary* summary)
      : start_time_(WallTimeInSeconds()),
        name_(std::move(name)),
        summary_(summary) {}

  ~ScopedExecutionTimer() {
    summary_->IncrementTimeBy(name_, WallTimeInSeconds() - start_time_);
  }

 private:
  const double start_time_;
  const std::string name_;
  ExecutionSummary* summary_;
};

}  // namespace ceres::internal

#endif  // CERES_INTERNAL_EXECUTION_SUMMARY_H_