third_party/ipcz/src/util/ref_counted.cc

// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "util/ref_counted.h"

#include "third_party/abseil-cpp/absl/base/macros.h"

namespace ipcz::internal {

RefCountedBase::RefCountedBase() = default;

RefCountedBase::~RefCountedBase() = default;

void RefCountedBase::AcquireImpl() {
  ref_count_.fetch_add(1, std::memory_order_relaxed);
}

bool RefCountedBase::ReleaseImpl() {
  // SUBTLE: Technically the load does not need to be an acquire unless we're
  // releasing the last reference and need to delete `this`, but it's not clear
  // whether std::memory_order_acq_rel here will produce more or less efficient
  // code compared to a plain std::memory_order_release followed by an acquire
  // fence in the conditional block below.
  int last_count = ref_count_.fetch_sub(1, std::memory_order_acq_rel);
  ABSL_ASSERT(last_count > 0);
  return last_count == 1;
}

}  // namespace ipcz::internal