274 lines
8.3 KiB
C++
274 lines
8.3 KiB
C++
/*
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* Copyright (C) 2005 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_STRONG_POINTER_H
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#define ANDROID_STRONG_POINTER_H
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#include <functional>
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#include <type_traits> // for common_type.
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// ---------------------------------------------------------------------------
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namespace android {
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template<typename T> class wp;
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// ---------------------------------------------------------------------------
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// TODO: Maybe remove sp<> ? wp<> comparison? These are dangerous: If the wp<>
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// was created before the sp<>, and they point to different objects, they may
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// compare equal even if they are entirely unrelated. E.g. CameraService
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// currently performa such comparisons.
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#define COMPARE_STRONG(_op_) \
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template<typename U> \
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inline bool operator _op_ (const sp<U>& o) const { \
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return m_ptr _op_ o.m_ptr; \
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} \
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template<typename U> \
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inline bool operator _op_ (const U* o) const { \
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return m_ptr _op_ o; \
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} \
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/* Needed to handle type inference for nullptr: */ \
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inline bool operator _op_ (const T* o) const { \
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return m_ptr _op_ o; \
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}
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template<template<typename C> class comparator, typename T, typename U>
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static inline bool _sp_compare_(T* a, U* b) {
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return comparator<typename std::common_type<T*, U*>::type>()(a, b);
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}
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// Use std::less and friends to avoid undefined behavior when ordering pointers
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// to different objects.
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#define COMPARE_STRONG_FUNCTIONAL(_op_, _compare_) \
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template<typename U> \
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inline bool operator _op_ (const sp<U>& o) const { \
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return _sp_compare_<_compare_>(m_ptr, o.m_ptr); \
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} \
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template<typename U> \
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inline bool operator _op_ (const U* o) const { \
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return _sp_compare_<_compare_>(m_ptr, o); \
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}
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// ---------------------------------------------------------------------------
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template<typename T>
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class sp {
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public:
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inline sp() : m_ptr(nullptr) { }
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sp(T* other); // NOLINT(implicit)
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sp(const sp<T>& other);
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sp(sp<T>&& other) noexcept;
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template<typename U> sp(U* other); // NOLINT(implicit)
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template<typename U> sp(const sp<U>& other); // NOLINT(implicit)
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template<typename U> sp(sp<U>&& other); // NOLINT(implicit)
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~sp();
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// Assignment
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sp& operator = (T* other);
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sp& operator = (const sp<T>& other);
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sp& operator=(sp<T>&& other) noexcept;
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template<typename U> sp& operator = (const sp<U>& other);
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template<typename U> sp& operator = (sp<U>&& other);
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template<typename U> sp& operator = (U* other);
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//! Special optimization for use by ProcessState (and nobody else).
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void force_set(T* other);
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// Reset
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void clear();
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// Accessors
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inline T& operator* () const { return *m_ptr; }
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inline T* operator-> () const { return m_ptr; }
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inline T* get() const { return m_ptr; }
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inline explicit operator bool () const { return m_ptr != nullptr; }
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// Operators
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COMPARE_STRONG(==)
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COMPARE_STRONG(!=)
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COMPARE_STRONG_FUNCTIONAL(>, std::greater)
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COMPARE_STRONG_FUNCTIONAL(<, std::less)
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COMPARE_STRONG_FUNCTIONAL(<=, std::less_equal)
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COMPARE_STRONG_FUNCTIONAL(>=, std::greater_equal)
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// Punt these to the wp<> implementation.
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template<typename U>
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inline bool operator == (const wp<U>& o) const {
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return o == *this;
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}
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template<typename U>
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inline bool operator != (const wp<U>& o) const {
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return o != *this;
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}
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private:
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template<typename Y> friend class sp;
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template<typename Y> friend class wp;
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void set_pointer(T* ptr);
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T* m_ptr;
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};
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// For code size reasons, we do not want this inlined or templated.
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void sp_report_race();
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#undef COMPARE
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// ---------------------------------------------------------------------------
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// No user serviceable parts below here.
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template<typename T>
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sp<T>::sp(T* other)
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: m_ptr(other) {
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if (other)
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other->incStrong(this);
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}
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template<typename T>
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sp<T>::sp(const sp<T>& other)
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: m_ptr(other.m_ptr) {
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if (m_ptr)
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m_ptr->incStrong(this);
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}
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template <typename T>
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sp<T>::sp(sp<T>&& other) noexcept : m_ptr(other.m_ptr) {
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other.m_ptr = nullptr;
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}
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template<typename T> template<typename U>
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sp<T>::sp(U* other)
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: m_ptr(other) {
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if (other)
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(static_cast<T*>(other))->incStrong(this);
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}
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template<typename T> template<typename U>
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sp<T>::sp(const sp<U>& other)
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: m_ptr(other.m_ptr) {
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if (m_ptr)
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m_ptr->incStrong(this);
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}
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template<typename T> template<typename U>
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sp<T>::sp(sp<U>&& other)
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: m_ptr(other.m_ptr) {
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other.m_ptr = nullptr;
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}
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template<typename T>
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sp<T>::~sp() {
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if (m_ptr)
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m_ptr->decStrong(this);
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}
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template<typename T>
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sp<T>& sp<T>::operator =(const sp<T>& other) {
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// Force m_ptr to be read twice, to heuristically check for data races.
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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T* otherPtr(other.m_ptr);
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if (otherPtr) otherPtr->incStrong(this);
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if (oldPtr) oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = otherPtr;
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return *this;
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}
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template <typename T>
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sp<T>& sp<T>::operator=(sp<T>&& other) noexcept {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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if (oldPtr) oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = other.m_ptr;
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other.m_ptr = nullptr;
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return *this;
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}
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template<typename T>
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sp<T>& sp<T>::operator =(T* other) {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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if (other) other->incStrong(this);
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if (oldPtr) oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = other;
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return *this;
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}
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template<typename T> template<typename U>
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sp<T>& sp<T>::operator =(const sp<U>& other) {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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T* otherPtr(other.m_ptr);
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if (otherPtr) otherPtr->incStrong(this);
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if (oldPtr) oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = otherPtr;
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return *this;
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}
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template<typename T> template<typename U>
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sp<T>& sp<T>::operator =(sp<U>&& other) {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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if (m_ptr) m_ptr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = other.m_ptr;
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other.m_ptr = nullptr;
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return *this;
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}
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template<typename T> template<typename U>
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sp<T>& sp<T>::operator =(U* other) {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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if (other) (static_cast<T*>(other))->incStrong(this);
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if (oldPtr) oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = other;
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return *this;
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}
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template<typename T>
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void sp<T>::force_set(T* other) {
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other->forceIncStrong(this);
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m_ptr = other;
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}
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template<typename T>
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void sp<T>::clear() {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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if (oldPtr) {
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oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = nullptr;
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}
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}
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template<typename T>
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void sp<T>::set_pointer(T* ptr) {
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m_ptr = ptr;
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}
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} // namespace android
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// ---------------------------------------------------------------------------
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#endif // ANDROID_STRONG_POINTER_H
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