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-rw-r--r--absl/flags/BUILD.bazel17
-rw-r--r--absl/flags/flag.cc9
-rw-r--r--absl/flags/flag.h24
-rw-r--r--absl/flags/flag_benchmark.cc111
4 files changed, 150 insertions, 11 deletions
diff --git a/absl/flags/BUILD.bazel b/absl/flags/BUILD.bazel
index 6c7b2b6..cbdbae5 100644
--- a/absl/flags/BUILD.bazel
+++ b/absl/flags/BUILD.bazel
@@ -324,6 +324,23 @@ cc_test(
],
)
+cc_binary(
+ name = "flag_benchmark",
+ testonly = 1,
+ srcs = [
+ "flag_benchmark.cc",
+ ],
+ copts = ABSL_TEST_COPTS,
+ tags = ["benchmark"],
+ visibility = ["//visibility:private"],
+ deps = [
+ ":flag",
+ "//absl/time",
+ "//absl/types:optional",
+ "@com_github_google_benchmark//:benchmark_main",
+ ],
+)
+
cc_test(
name = "marshalling_test",
size = "small",
diff --git a/absl/flags/flag.cc b/absl/flags/flag.cc
index 9af8007..e67f730 100644
--- a/absl/flags/flag.cc
+++ b/absl/flags/flag.cc
@@ -22,7 +22,14 @@
namespace absl {
ABSL_NAMESPACE_BEGIN
-// This global nutex protects on-demand construction of flag objects in MSVC
+#ifndef NDEBUG
+#define ABSL_FLAGS_GET(T) \
+ T GetFlag(const absl::Flag<T>& flag) { return flag.Get(); }
+ABSL_FLAGS_INTERNAL_BUILTIN_TYPES(ABSL_FLAGS_GET)
+#undef ABSL_FLAGS_GET
+#endif
+
+// This global mutex protects on-demand construction of flag objects in MSVC
// builds.
#if defined(_MSC_VER) && !defined(__clang__)
diff --git a/absl/flags/flag.h b/absl/flags/flag.h
index cc22cdb..bd61668 100644
--- a/absl/flags/flag.h
+++ b/absl/flags/flag.h
@@ -186,25 +186,29 @@ class Flag {
//
// // FLAGS_firstname is a Flag of type `std::string`
// std::string first_name = absl::GetFlag(FLAGS_firstname);
-template <typename T,
- typename std::enable_if<
- !flags_internal::IsAtomicFlagTypeTrait<T>::value, int>::type = 0>
-ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) {
- return flag.Get();
-}
-
+#ifndef NDEBUG
// We want to validate the type mismatch between type definition and
// declaration. The lock-free implementation does not allow us to do it,
// so in debug builds we always use the slower implementation, which always
// validates the type.
-#ifndef NDEBUG
+template <typename T>
+ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) {
+ return flag.Get();
+}
+// We currently need an external linkage for built-in types because shared
+// libraries have different addresses of flags_internal::FlagOps<T> which
+// might cause log spam when checking the same flag type.
+#define ABSL_FLAGS_INTERNAL_BUILT_IN_EXPORT(T) \
+ ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag);
+ABSL_FLAGS_INTERNAL_BUILTIN_TYPES(ABSL_FLAGS_INTERNAL_BUILT_IN_EXPORT)
+#undef ABSL_FLAGS_INTERNAL_BUILT_IN_EXPORT
+#else
template <typename T,
typename std::enable_if<
- flags_internal::IsAtomicFlagTypeTrait<T>::value, int>::type = 0>
+ !flags_internal::IsAtomicFlagTypeTrait<T>::value, int>::type = 0>
ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) {
return flag.Get();
}
-#else
// Overload for `GetFlag()` for types that support lock-free reads.
template <typename T,
typename std::enable_if<
diff --git a/absl/flags/flag_benchmark.cc b/absl/flags/flag_benchmark.cc
new file mode 100644
index 0000000..87f7317
--- /dev/null
+++ b/absl/flags/flag_benchmark.cc
@@ -0,0 +1,111 @@
+//
+// Copyright 2020 The Abseil 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
+//
+// https://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.
+
+#include "absl/flags/flag.h"
+#include "absl/time/time.h"
+#include "absl/types/optional.h"
+#include "benchmark/benchmark.h"
+
+namespace {
+using String = std::string;
+using VectorOfStrings = std::vector<std::string>;
+using AbslDuration = absl::Duration;
+
+// We do not want to take over marshalling for the types absl::optional<int>,
+// absl::optional<std::string> which we do not own. Instead we introduce unique
+// "aliases" to these types, which we do.
+using AbslOptionalInt = absl::optional<int>;
+struct OptionalInt : AbslOptionalInt {
+ using AbslOptionalInt::AbslOptionalInt;
+};
+// Next two functions represent Abseil Flags marshalling for OptionalInt.
+bool AbslParseFlag(absl::string_view src, OptionalInt* flag,
+ std::string* error) {
+ int val;
+ if (src.empty())
+ flag->reset();
+ else if (!absl::ParseFlag(src, &val, error))
+ return false;
+ *flag = val;
+ return true;
+}
+std::string AbslUnparseFlag(const OptionalInt& flag) {
+ return !flag ? "" : absl::UnparseFlag(*flag);
+}
+
+using AbslOptionalString = absl::optional<std::string>;
+struct OptionalString : AbslOptionalString {
+ using AbslOptionalString::AbslOptionalString;
+};
+// Next two functions represent Abseil Flags marshalling for OptionalString.
+bool AbslParseFlag(absl::string_view src, OptionalString* flag,
+ std::string* error) {
+ std::string val;
+ if (src.empty())
+ flag->reset();
+ else if (!absl::ParseFlag(src, &val, error))
+ return false;
+ *flag = val;
+ return true;
+}
+std::string AbslUnparseFlag(const OptionalString& flag) {
+ return !flag ? "" : absl::UnparseFlag(*flag);
+}
+
+struct UDT {
+ UDT() = default;
+ UDT(const UDT&) {}
+ UDT& operator=(const UDT&) { return *this; }
+};
+// Next two functions represent Abseil Flags marshalling for UDT.
+bool AbslParseFlag(absl::string_view, UDT*, std::string*) { return true; }
+std::string AbslUnparseFlag(const UDT&) { return ""; }
+
+} // namespace
+
+#define BENCHMARKED_TYPES(A) \
+ A(bool) \
+ A(int16_t) \
+ A(uint16_t) \
+ A(int32_t) \
+ A(uint32_t) \
+ A(int64_t) \
+ A(uint64_t) \
+ A(double) \
+ A(float) \
+ A(String) \
+ A(VectorOfStrings) \
+ A(OptionalInt) \
+ A(OptionalString) \
+ A(AbslDuration) \
+ A(UDT)
+
+#define FLAG_DEF(T) ABSL_FLAG(T, T##_flag, {}, "");
+
+BENCHMARKED_TYPES(FLAG_DEF)
+
+namespace {
+
+#define BM_GetFlag(T) \
+ void BM_GetFlag_##T(benchmark::State& state) { \
+ for (auto _ : state) { \
+ benchmark::DoNotOptimize(absl::GetFlag(FLAGS_##T##_flag)); \
+ } \
+ } \
+ BENCHMARK(BM_GetFlag_##T);
+
+BENCHMARKED_TYPES(BM_GetFlag)
+
+} // namespace
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