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/** |
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* This file is part of the CernVM File System. |
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*/ |
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#ifndef CVMFS_UTIL_SHARED_PTR_H_ |
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#define CVMFS_UTIL_SHARED_PTR_H_ |
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#include <cstdlib> |
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#include "atomic.h" |
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#ifdef CVMFS_NAMESPACE_GUARD |
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namespace CVMFS_NAMESPACE_GUARD { |
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#endif // CVMFS_NAMESPACE_GUARD |
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template <typename T> |
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class SharedPtr { |
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public: |
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typedef T element_type; |
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SharedPtr() { // never throws |
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value_ = NULL; |
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count_ = NULL; |
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} |
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template <class Y> |
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explicit SharedPtr(Y* p) { |
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value_ = static_cast<element_type*>(p); |
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count_ = new atomic_int64; |
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atomic_write64(count_, 1); |
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} |
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~SharedPtr() { // never throws |
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if (count_) { |
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atomic_dec64(count_); |
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if (atomic_read64(count_) == 0) { |
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delete value_; |
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delete count_; |
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} |
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} |
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} |
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SharedPtr(SharedPtr const& r) |
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: value_(r.value_), count_(r.count_) { // never throws |
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if (count_) { |
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atomic_inc64(count_); |
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} |
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} |
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template <class Y> |
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SharedPtr(SharedPtr<Y> const& r) |
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: value_(r.value_), count_(r.count_) { // never throws |
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if (count_) { |
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atomic_inc64(count_); |
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} |
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} |
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SharedPtr& operator=(SharedPtr const& r) { // never throws |
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Reset(); |
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value_ = r.value_; |
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count_ = r.count_; |
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if (count_) { |
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atomic_inc64(count_); |
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} |
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return *this; |
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} |
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template <class Y> |
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SharedPtr& operator=(SharedPtr<Y> const& r) { // never throws |
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Reset(); |
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value_ = r.value_; |
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count_ = r.count_; |
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if (count_) { |
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atomic_inc64(count_); |
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} |
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return *this; |
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} |
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void Reset() { // never throws |
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if (count_) { |
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atomic_dec64(count_); |
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if (atomic_read64(count_) == 0) { |
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delete value_; |
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delete count_; |
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} |
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value_ = NULL; |
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count_ = NULL; |
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} |
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} |
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template <class Y> |
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void Reset(Y* p) { |
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Reset(); |
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value_ = static_cast<element_type*>(p); |
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count_ = new atomic_int64; |
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atomic_write64(count_, 1); |
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} |
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T& operator*() const { // never throws |
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return *value_; |
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} |
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T* operator->() const { // never throws |
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return value_; |
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} |
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element_type* Get() const { // never throws |
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return value_; |
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} |
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bool Unique() const { // never throws |
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return count_ && (atomic_read64(count_) == 1); |
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} |
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int64_t UseCount() const { // never throws |
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return count_ ? atomic_read64(count_) : -1; |
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} |
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operator void*() const { // never throws |
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return static_cast<void*>(value_); |
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} |
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private: |
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element_type* value_; |
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atomic_int64* count_; |
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}; |
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template <class T, class U> |
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bool operator==(SharedPtr<T> const& a, |
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SharedPtr<U> const& b) { // never throws |
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return a.value_ == b.value_; |
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} |
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template <class T, class U> |
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bool operator!=(SharedPtr<T> const& a, |
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SharedPtr<U> const& b) { // never throws |
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return a.value_ != b.value_; |
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} |
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template <class T, class U> |
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bool operator<(SharedPtr<T> const& a, SharedPtr<U> const& b) { // never throws |
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return a.value_ < b.value_; |
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} |
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template <class T> |
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typename SharedPtr<T>::element_type* GetPointer( |
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SharedPtr<T> const& p) { // never throws |
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return p.value_; |
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} |
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template <class T, class U> |
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SharedPtr<T> StaticPointerCast(SharedPtr<U> const& r) { // never throws |
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return SharedPtr<T>(static_cast<T*>(r.value_)); |
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} |
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template <class T, class U> |
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SharedPtr<T> ConstPointerCast(SharedPtr<U> const& r) { // never throws |
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return SharedPtr<T>(const_cast<T*>(r.value_)); |
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} |
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template <class T, class U> |
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SharedPtr<T> DynamicPointerCast(SharedPtr<U> const& r) { // never throws |
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return SharedPtr<T>(dynamic_cast<T*>(r.value_)); |
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} |
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template <class T, class U> |
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SharedPtr<T> ReinterpretPointerCast(SharedPtr<U> const& r) { // never throws |
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return SharedPtr<T>(reinterpret_cast<T*>(r.value_)); |
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} |
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#ifdef CVMFS_NAMESPACE_GUARD |
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} // namespace CVMFS_NAMESPACE_GUARD |
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#endif |
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#endif // CVMFS_UTIL_SHARED_PTR_H_ |