Program Listing for File span_id.h¶
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// Copyright 2019, OpenTelemetry Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#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_assert(kSize == 8, "update is needed if kSize is not 8");
return *reinterpret_cast<const uint64_t *>(&rep_) != 0ull;
}
// 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