blob: 9c64c18bb30729543f7d0913c7a69539a3f659df [file] [log] [blame]
// Copyright 2022 The Chromium Authors. All rights reserved.
// 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 {
RefCounted::RefCounted() = default;
RefCounted::~RefCounted() = default;
void RefCounted::AcquireRef() {
ref_count_.fetch_add(1, std::memory_order_relaxed);
}
void RefCounted::ReleaseRef() {
// 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);
if (last_count == 1) {
delete this;
}
}
GenericRef::GenericRef(decltype(RefCounted::kAdoptExistingRef), RefCounted* ptr)
: ptr_(ptr) {}
GenericRef::GenericRef(RefCounted* ptr) : ptr_(ptr) {
if (ptr_) {
ptr_->AcquireRef();
}
}
GenericRef::GenericRef(GenericRef&& other)
: ptr_(std::exchange(other.ptr_, nullptr)) {}
GenericRef& GenericRef::operator=(GenericRef&& other) {
reset();
ptr_ = std::exchange(other.ptr_, nullptr);
return *this;
}
GenericRef::GenericRef(const GenericRef& other) : ptr_(other.ptr_) {
if (ptr_) {
ptr_->AcquireRef();
}
}
GenericRef& GenericRef::operator=(const GenericRef& other) {
reset();
ptr_ = other.ptr_;
if (ptr_) {
ptr_->AcquireRef();
}
return *this;
}
GenericRef::~GenericRef() {
reset();
}
void GenericRef::reset() {
if (ptr_) {
std::exchange(ptr_, nullptr)->ReleaseRef();
}
}
void* GenericRef::ReleaseImpl() {
return std::exchange(ptr_, nullptr);
}
} // namespace ipcz