Abseil Common Libraries (C++) (grcp 依赖) https://abseil.io/
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//
// Copyright 2019 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 <cstring>
namespace absl {
// 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
#define ABSL_FLAGS_ATOMIC_GET(T) \
T GetFlag(const absl::Flag<T>& flag) { \
T result; \
flag.internal.Read(&result, &flags_internal::FlagOps<T>); \
return result; \
}
#else
#define ABSL_FLAGS_ATOMIC_GET(T) \
T GetFlag(const absl::Flag<T>& flag) { \
const int64_t r = flag.internal.atomic.load(std::memory_order_acquire); \
if (r != flags_internal::CommandLineFlag::kAtomicInit) { \
T t; \
memcpy(&t, &r, sizeof(T)); \
return t; \
} \
T result; \
flag.internal.Read(&result, &flags_internal::FlagOps<T>); \
return result; \
}
#endif
ABSL_FLAGS_INTERNAL_FOR_EACH_LOCK_FREE(ABSL_FLAGS_ATOMIC_GET)
#undef ABSL_FLAGS_ATOMIC_GET
} // namespace absl