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//
//
// Copyright 2017 gRPC 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.
//
//
#ifndef GRPC_SRC_CORE_LIB_GPRPP_ATOMIC_UTILS_H
#define GRPC_SRC_CORE_LIB_GPRPP_ATOMIC_UTILS_H
#include <grpc/support/port_platform.h>
#include <atomic>
namespace grpc_core {
// Atomically increment a counter only if the counter value is not zero.
// Returns true if increment took place; false if counter is zero.
template <typename T>
inline bool IncrementIfNonzero(std::atomic<T>* p) {
T count = p->load(std::memory_order_acquire);
do {
// If zero, we are done (without an increment). If not, we must do a CAS
// to maintain the contract: do not increment the counter if it is already
// zero
if (count == 0) {
return false;
}
} while (!p->compare_exchange_weak(
count, count + 1, std::memory_order_acq_rel, std::memory_order_acquire));
return true;
}
} // namespace grpc_core
#endif // GRPC_SRC_CORE_LIB_GPRPP_ATOMIC_UTILS_H
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