// Copyright 2019 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ml/request_metrics.h"

#include <errno.h>

#include <base/check.h>
#include <base/logging.h>

#include "ml/mojom/machine_learning_service.mojom.h"
#include "ml/process.h"

namespace ml {

namespace {

using chromeos::machine_learning::mojom::LoadModelResult;

// Renumbering the errno of waiptid to make it suitable for UMA recording.
// Also added an "unknown" error.
enum class WaitPidError {
  kUnknown = 0,  // errno equals values other than below.
  kECHILD = 1,   // errno == ECHILD.
  kEINTR = 2,    // errno == EINTR.
  kEINVAL = 3,   // errno == kEINVAL.
  kMaxValue = kEINVAL,
};

}  // namespace

RequestMetrics::RequestMetrics(const std::string& model_name,
                               const std::string& request_name)
    : name_base_(std::string(kGlobalMetricsPrefix) + model_name + "." +
                 request_name),
      initial_cpu_clock_(0),
      initial_memory_(0),
      status_(Status::kNotStarted) {}

void RequestMetrics::StartRecordingPerformanceMetrics() {
  DCHECK(status_ == Status::kNotStarted);
  // Get initial CPU clock in order to set the "zero" point of the CPU usage
  // counter.
  initial_cpu_clock_ = std::clock();
  DCHECK(initial_cpu_clock_ != static_cast<std::clock_t>(-1));
  // Query memory usage.
  size_t usage = 0;
  if (!GetTotalProcessMemoryUsage(&usage)) {
    LOG(DFATAL) << "Getting process memory usage failed.";
    return;
  }
  initial_memory_ = static_cast<int64_t>(usage);

  status_ = Status::kRecording;
}

void RequestMetrics::FinishRecordingPerformanceMetrics() {
  DCHECK(status_ == Status::kRecording);
  status_ = Status::kFinished;
  // Get CPU time by `clock()`.
  const int64_t cpu_time_microsec = static_cast<int64_t>(
      (std::clock() - initial_cpu_clock_) * 1000000.0 / CLOCKS_PER_SEC);

  // Memory usage
  size_t usage = 0;
  if (!GetTotalProcessMemoryUsage(&usage)) {
    LOG(DFATAL) << "Getting process memory usage failed.";
    return;
  }
  const int64_t memory_usage_kb = static_cast<int64_t>(usage) - initial_memory_;

  metrics_library_.SendToUMA(name_base_ + kTotalMemoryDeltaSuffix,
                             memory_usage_kb, kMemoryDeltaMinKb,
                             kMemoryDeltaMaxKb, kMemoryDeltaBuckets);
  metrics_library_.SendToUMA(name_base_ + kCpuTimeSuffix, cpu_time_microsec,
                             kCpuTimeMinMicrosec, kCpuTimeMaxMicrosec,
                             kCpuTimeBuckets);
}

// Records in MachineLearningService.LoadModelResult rather than a
// model-specific enum histogram because the model name is unknown.
void RecordModelSpecificationErrorEvent() {
  MetricsLibrary().SendEnumToUMA("MachineLearningService.LoadModelResult",
                                 LoadModelResult::MODEL_SPEC_ERROR);
}

void RecordProcessErrorEvent(ProcessError error) {
  MetricsLibrary().SendEnumToUMA("MachineLearningService.ProcessError", error);
}

void RecordWorkerProcessExitStatus(int status) {
  MetricsLibrary().SendSparseToUMA(
      "MachineLearningService.WorkerProcessExitStatus", status);
}

void RecordReapWorkerProcessErrno(int error_number) {
  WaitPidError waitpid_error = WaitPidError::kUnknown;
  if (error_number == ECHILD) {
    waitpid_error = WaitPidError::kECHILD;
  } else if (error_number == EINTR) {
    waitpid_error = WaitPidError::kEINTR;
  } else if (error_number == EINVAL) {
    waitpid_error = WaitPidError::kEINVAL;
  }
  MetricsLibrary().SendEnumToUMA(
      "MachineLearningService.ReapWorkerProcessErrno", waitpid_error);
}

}  // namespace ml