profile_builder.h

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

#ifndef BASE_PROFILER_PROFILE_BUILDER_H_
#define BASE_PROFILER_PROFILE_BUILDER_H_

#include <memory>
#include <vector>

#include "base/base_export.h"
#include "base/profiler/frame.h"
#include "base/profiler/metadata_recorder.h"
#include "base/profiler/module_cache.h"
#include "base/time/time.h"

namespace base {

// The ProfileBuilder interface allows the user to record profile information on
// the fly in whatever format is desired. Functions are invoked by the profiler
// on its own thread so must not block or perform expensive operations.
class BASE_EXPORT ProfileBuilder {
 public:
  ProfileBuilder() = default;

  ProfileBuilder(const ProfileBuilder&) = delete;
  ProfileBuilder& operator=(const ProfileBuilder&) = delete;

  virtual ~ProfileBuilder() = default;

  // Gets the ModuleCache to be used by the StackSamplingProfiler when looking
  // up modules from addresses.
  virtual ModuleCache* GetModuleCache() = 0;

  // Records metadata to be associated with the current sample. To avoid
  // deadlock on locks taken by the suspended profiled thread, implementations
  // of this method must not execute any code that could take a lock, including
  // heap allocation or use of CHECK/DCHECK/LOG statements. Generally
  // implementations should simply atomically copy metadata state to be
  // associated with the sample.
  virtual void RecordMetadata(
      const MetadataRecorder::MetadataProvider& metadata_provider) {}

  // Applies the specified metadata |item| to samples collected in the range
  // [period_start, period_end), iff the profile already captured execution that
  // covers that range entirely. This restriction avoids bias in the results
  // towards samples in the middle of the period, at the expense of excluding
  // periods overlapping the start or end of the profile. |period_end| must be
  // <= TimeTicks::Now().
  virtual void ApplyMetadataRetrospectively(
      TimeTicks period_start,
      TimeTicks period_end,
      const MetadataRecorder::Item& item) {}

  // Adds the specified metadata |item| to |CallstackProfile::profile_metadata|.
  // |CallstackProfile::profile_metadata| stores metadata global to the profile.
  virtual void AddProfileMetadata(const MetadataRecorder::Item& item) {}

  // Records a new set of frames. Invoked when sampling a sample completes.
  virtual void OnSampleCompleted(std::vector<Frame> frames,
                                 TimeTicks sample_timestamp) = 0;

  // Finishes the profile construction with |profile_duration| and
  // |sampling_period|. Invoked when sampling a profile completes.
  virtual void OnProfileCompleted(TimeDelta profile_duration,
                                  TimeDelta sampling_period) = 0;
};

}  // namespace base

#endif  // BASE_PROFILER_PROFILE_BUILDER_H_