chromium/components/segmentation_platform/internal/database/signal_key.h

// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_SEGMENTATION_PLATFORM_INTERNAL_DATABASE_SIGNAL_KEY_H_
#define COMPONENTS_SEGMENTATION_PLATFORM_INTERNAL_DATABASE_SIGNAL_KEY_H_

#include <cstdint>
#include <ostream>
#include <string>

#include "base/time/time.h"

namespace segmentation_platform {

// The SignalKey is used for identifying a particular record in the
// SignalDatabase. The format is defined in go/chrome-segmentation-storage-mvp.
//
// It provides functionality to convert to and from a binary format. The format
// for this binary key must never change on a single device, so an internal
// representation for this, SignalKeyInternal, is used.
//
// The SignalKey is not meant to be used by external clients in any way,
// and should be considered as an internal implementation detail of the
// SignalDatabase.
//
// The binary representation of the key does not store any resolution smaller
// than seconds, so any constructed SignalKey is immediately stripped of
// resolutions smaller than 1 second to ensure a SignalKey which has been
// converted to a binary key and back again matches the original SignalKey.
//
// Since the binary representation is not human readable, the struct also
// supports being streamed or by calling ToDebugString(), which will make it be
// presented using this format:
// {kind=..., name_hash=..., range_start=..., range_start=...} which is useful
// for debugging.
//
// The binary representation of a key can be lexicographically compared. The
// fields are in the following order: kind, name_hash, range_start, range_end.
class SignalKey { … };

std::ostream& operator<<(std::ostream& os, const SignalKey& key);

}  // namespace segmentation_platform

#endif  // COMPONENTS_SEGMENTATION_PLATFORM_INTERNAL_DATABASE_SIGNAL_KEY_H_