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Add SpanId class. (open-telemetry#10)
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g-easy authored Jan 16, 2020
1 parent b3645fc commit 5241561
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14 changes: 14 additions & 0 deletions api/BUILD
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@@ -1,3 +1,17 @@
# 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.

package(default_visibility = ["//visibility:public"])

cc_library(
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74 changes: 74 additions & 0 deletions api/include/opentelemetry/trace/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"

namespace opentelemetry
{
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 { return *this != SpanId(); }

// 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
} // namespace opentelemetry
11 changes: 11 additions & 0 deletions api/test/trace/BUILD
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Expand Up @@ -8,3 +8,14 @@ cc_test(
"@com_google_googletest//:gtest_main",
],
)

cc_test(
name = "span_id_test",
srcs = [
"span_id_test.cc",
],
deps = [
"//api",
"@com_google_googletest//:gtest_main",
],
)
5 changes: 5 additions & 0 deletions api/test/trace/CMakeLists.txt
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Expand Up @@ -4,3 +4,8 @@ add_executable(noop_test noop_test.cc)
target_link_libraries(noop_test ${GTEST_BOTH_LIBRARIES}
${CMAKE_THREAD_LIBS_INIT} opentelemetry_api)
gtest_add_tests(TARGET noop_test TEST_PREFIX trace. TEST_LIST noop_test)

add_executable(span_id_test span_id_test.cc)
target_link_libraries(span_id_test ${GTEST_BOTH_LIBRARIES}
${CMAKE_THREAD_LIBS_INIT} opentelemetry_api)
gtest_add_tests(TARGET span_id_test TEST_PREFIX trace. TEST_LIST span_id_test)
45 changes: 45 additions & 0 deletions api/test/trace/span_id_test.cc
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#include "opentelemetry/trace/span_id.h"

#include <cstring>
#include <string>

#include <gtest/gtest.h>

namespace
{

using opentelemetry::trace::SpanId;

std::string Hex(const opentelemetry::trace::SpanId &span)
{
char buf[16];
span.ToLowerBase16(buf);
return std::string(buf, sizeof(buf));
}

TEST(SpanIdTest, DefaultConstruction)
{
SpanId id;
EXPECT_FALSE(id.IsValid());
EXPECT_EQ("0000000000000000", Hex(id));
}

TEST(SpanIdTest, ValidId)
{
constexpr uint8_t buf[] = {1, 2, 3, 4, 5, 6, 7, 8};
SpanId id(buf);
EXPECT_TRUE(id.IsValid());
EXPECT_EQ("0102030405060708", Hex(id));
EXPECT_NE(SpanId(), id);
EXPECT_EQ(SpanId(buf), id);
}

TEST(SpanIdTest, CopyBytesTo)
{
constexpr uint8_t src[] = {1, 2, 3, 4, 5, 6, 7, 8};
SpanId id(src);
uint8_t buf[8];
id.CopyBytesTo(buf);
EXPECT_TRUE(memcmp(src, buf, 8) == 0);
}
} // namespace

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