span_id.h - mozsearch

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// Copyright The OpenTelemetry Authors

// SPDX-License-Identifier: Apache-2.0

#pragma once

#include <cstdint>

#include <cstring>

#include "opentelemetry/nostd/span.h"

#include "opentelemetry/version.h"

OPENTELEMETRY_BEGIN_NAMESPACE

namespace trace

class SpanId final

public:

  // The size in bytes of the SpanId.

  static constexpr int kSize = 8;

  // An invalid SpanId (all zeros).

  SpanId() noexcept : rep_{0} {}

  // Creates a SpanId with the given ID.

  explicit SpanId(nostd::span<const uint8_t, kSize> id) noexcept { memcpy(rep_, id.data(), kSize); }

  // Populates the buffer with the lowercase base16 representation of the ID.

  void ToLowerBase16(nostd::span<char, 2 * kSize> buffer) const noexcept

    constexpr char kHex[] = "0123456789abcdef";

    for (int i = 0; i < kSize; ++i)

      buffer[i * 2 + 0] = kHex[(rep_[i] >> 4) & 0xF];

      buffer[i * 2 + 1] = kHex[(rep_[i] >> 0) & 0xF];

  // Returns a nostd::span of the ID.

  nostd::span<const uint8_t, kSize> Id() const noexcept

    return nostd::span<const uint8_t, kSize>(rep_);

  bool operator==(const SpanId &that) const noexcept { return memcmp(rep_, that.rep_, kSize) == 0; }

  bool operator!=(const SpanId &that) const noexcept { return !(*this == that); }

  // Returns false if the SpanId is all zeros.

  bool IsValid() const noexcept

    static constexpr uint8_t kEmptyRep[kSize] = {0};

    return memcmp(rep_, kEmptyRep, kSize) != 0;

  // Copies the opaque SpanId data to dest.

  void CopyBytesTo(nostd::span<uint8_t, kSize> dest) const noexcept

    memcpy(dest.data(), rep_, kSize);

private:

  uint8_t rep_[kSize];

};

}  // namespace trace

OPENTELEMETRY_END_NAMESPACE