Add SpanId class. (open-telemetry#10)

api/BUILD

@@ -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(

api/include/opentelemetry/trace/span_id.h

@@ -0,0 +1,74 @@
+// 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

api/test/trace/BUILD

@@ -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",
+ ],
+)

api/test/trace/CMakeLists.txt

@@ -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)

api/test/trace/span_id_test.cc

@@ -0,0 +1,45 @@
+#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