From 84fccb72fcfbbdaf21aa7d6e556cec85b873a2b6 Mon Sep 17 00:00:00 2001
From: Jan Travnicek <Jan.Travnicek@fit.cvut.cz>
Date: Sun, 4 Nov 2018 09:38:27 +0100
Subject: [PATCH] simplify cow_shared_ptr implementation
---
alib2common/src/object/AnyObjectBase.h | 2 +-
alib2common/src/object/Object.h | 2 +-
alib2std/src/extensions/memory.hpp | 407 +------------------
alib2std/test-src/extensions/SharedPtrTest.h | 2 +-
4 files changed, 22 insertions(+), 391 deletions(-)
diff --git a/alib2common/src/object/AnyObjectBase.h b/alib2common/src/object/AnyObjectBase.h
index 0bc59e4d6e..46ba0cbf6e 100644
--- a/alib2common/src/object/AnyObjectBase.h
+++ b/alib2common/src/object/AnyObjectBase.h
@@ -31,7 +31,7 @@
namespace object {
-class AnyObjectBase : public ext::cow_shared_ptr_base {
+class AnyObjectBase {
public:
/**
* \brief
diff --git a/alib2common/src/object/Object.h b/alib2common/src/object/Object.h
index 14b53b5de1..d1f7dcdbf0 100644
--- a/alib2common/src/object/Object.h
+++ b/alib2common/src/object/Object.h
@@ -28,7 +28,7 @@ class Object {
* Unifies the shared pointers. For internal use when two pointer eval equal.
*/
void unify ( Object & other ) {
- if ( this->m_data.getUseCount ( ) > other.m_data.getUseCount ( ) )
+ if ( this->m_data.use_count ( ) > other.m_data.use_count ( ) )
other.m_data = this->m_data;
else
this->m_data = other.m_data;
diff --git a/alib2std/src/extensions/memory.hpp b/alib2std/src/extensions/memory.hpp
index 0fa5458ee7..4d9e2a64c6 100644
--- a/alib2std/src/extensions/memory.hpp
+++ b/alib2std/src/extensions/memory.hpp
@@ -33,37 +33,6 @@
namespace ext {
-/**
- * \brief
- * Predeclaration of copy on write shared ptr class.
- */
-template < typename T, typename Enable = void >
-class cow_shared_ptr;
-
-/**
- * \brief
- * Base class of classes used inside copy on write pointers.
- */
-class cow_shared_ptr_base {
-public:
- /**
- * Constructor of the copy on write shared ptr base class. The use count is initialized to zero.
- */
- cow_shared_ptr_base ( ) : m_UseCount ( 0 ) { }
-
-private:
- /**
- * Caries the number of uses of this instance as a managed pointer inside copy on write pointer.
- */
- unsigned m_UseCount;
-
- /**
- * To make m_UseCount accessible from copy on write pointer class.
- */
- template < typename T, typename Enable >
- friend class cow_shared_ptr;
-};
-
/**
* \brief
* Specialisation of copy on write pointer for classes based with copy on write pointer base.
@@ -75,24 +44,20 @@ private:
* \tparam T the type of managed objects
*/
template < class T >
-class cow_shared_ptr < T, typename std::enable_if < std::is_base_of < cow_shared_ptr_base, T >::value >::type > {
+class cow_shared_ptr : std::shared_ptr < T > {
public:
/**
* \brief
* Default initialization to null.
*/
- explicit cow_shared_ptr ( ) {
- attach ( NULL );
+ explicit cow_shared_ptr ( ) : std::shared_ptr < T > ( nullptr ) {
}
/**
* \brief
* Constructor which takes ownership of the provided pointer.
*/
- explicit cow_shared_ptr ( T * data ) {
- if ( data ) data->m_UseCount = 0;
-
- attach ( data );
+ explicit cow_shared_ptr ( T * data ) : std::shared_ptr < T > ( data ) {
}
/**
@@ -101,8 +66,7 @@ public:
*
* \param other the source instance
*/
- cow_shared_ptr ( const cow_shared_ptr & other ) {
- attach ( other.m_Data );
+ cow_shared_ptr ( const cow_shared_ptr & other ) : std::shared_ptr < T > ( other ) {
}
/**
@@ -111,9 +75,7 @@ public:
*
* \param other the source instance
*/
- cow_shared_ptr ( cow_shared_ptr && other ) noexcept {
- m_Data = other.m_Data;
- other.m_Data = NULL;
+ cow_shared_ptr ( cow_shared_ptr && other ) noexcept : std::shared_ptr < T > ( std::move ( other ) ) {
}
/**
@@ -121,7 +83,6 @@ public:
* The destructor of the shared pointer.
*/
~cow_shared_ptr ( ) noexcept {
- detach ( );
}
/**
@@ -131,11 +92,7 @@ public:
* \param other the source instance
*/
cow_shared_ptr & operator =( const cow_shared_ptr & other ) {
- if ( this == & other ) return * this;
-
- detach ( );
- attach ( other.m_Data );
-
+ static_cast < std::shared_ptr < T > & > ( * this ) = static_cast < const std::shared_ptr < T > & > ( other );
return * this;
}
@@ -146,7 +103,7 @@ public:
* \param other the source instance
*/
cow_shared_ptr & operator =( cow_shared_ptr && other ) noexcept {
- swap ( * this, other );
+ static_cast < std::shared_ptr < T > & > ( * this ) = static_cast < std::shared_ptr < T > && > ( other );
return * this;
}
@@ -157,8 +114,7 @@ public:
* \return the managed pointer
*/
T * operator ->( ) {
- make_unique ( );
- return m_Data;
+ return this->get ( );
}
/**
@@ -168,7 +124,7 @@ public:
* \return the managed pointer
*/
T const * operator ->( ) const {
- return m_Data;
+ return this->get ( );
}
/**
@@ -178,8 +134,7 @@ public:
* \return reference to managed data
*/
T & operator *( ) {
- make_unique ( );
- return * m_Data;
+ return * this->get ( );
}
/**
@@ -189,7 +144,7 @@ public:
* \return reference to managed data
*/
T const & operator *( ) const {
- return * m_Data;
+ return * this->get ( );
}
/**
@@ -199,7 +154,7 @@ public:
*/
T * get ( ) {
make_unique ( );
- return m_Data;
+ return std::shared_ptr < T >::get ( );
}
/**
@@ -208,7 +163,7 @@ public:
* \return the managed pointer
*/
T const * get ( ) const {
- return m_Data;
+ return std::shared_ptr < T >::get ( );
}
/**
@@ -218,7 +173,7 @@ public:
* \return bool true if the managed pointer is referenced from one location only, false otherwise
*/
bool unique ( ) const {
- return m_Data == NULL || m_Data->m_UseCount == 1;
+ return std::shared_ptr < T >::unique ( );
}
/**
@@ -227,10 +182,8 @@ public:
*
* \return the use count
*/
- unsigned getUseCount ( ) const {
- if ( m_Data == NULL ) return 0;
-
- return m_Data->m_UseCount;
+ unsigned use_count ( ) const {
+ return std::shared_ptr < T >::use_count ( );
}
/**
@@ -239,31 +192,10 @@ public:
* \return true if the managed pointer is not null and the use count is nonzero, false otherwise
*/
explicit operator bool( ) const {
- return getUseCount ( ) != 0;
+ return use_count ( ) != 0;
}
private:
- /**
- * \brief
- * Changes the managed pointer and increases its use count
- *
- * \param data the new value of managed pointer
- */
- void attach ( T * data ) {
- m_Data = data;
-
- if ( m_Data ) m_Data->m_UseCount++;
- }
-
- /**
- * \brief
- * Decreases the use count of managed pointer, if needed the pointer is freed. Managed pointer stored in this instance is set to null.
- */
- void detach ( ) {
- if ( m_Data && ( --( m_Data->m_UseCount ) <= 0 ) ) delete m_Data;
-
- m_Data = NULL;
- }
/**
* \brief
@@ -272,308 +204,9 @@ private:
void make_unique ( ) {
if ( unique ( ) ) return;
- T * tmp = m_Data;
- detach ( );
- tmp = ext::clone ( * tmp );
- tmp->m_UseCount = 0;
- attach ( tmp );
- }
-
- /**
- * \brief
- * The managed pointer
- */
- T * m_Data;
-
- /**
- * \brief
- * Specialisation of swap method to copy on write shared pointers.
- *
- * \param first the first instance
- * \param second the second instance
- */
- friend void swap ( cow_shared_ptr & first, cow_shared_ptr & second ) {
- T * tmp = first.m_Data;
-
- first.m_Data = second.m_Data;
- second.m_Data = tmp;
- }
-
-};
-
-/**
- * \brief
- * Specialisation of copy on write pointer for classes not based with copy on write pointer base.
- *
- * The class is essentially mimicking the behavior of shared_ptr. Additionaly the use of dereference (either through operator* or operator->) in non-constant context causes the managed pointer to ensure the referenced object is referenced from this class only.
- *
- * The class also uniques the referenced instances when they are equal.
- *
- * \tparam T the type of managed objects
- */
-template < class T >
-class cow_shared_ptr < T, typename std::enable_if < !std::is_base_of < cow_shared_ptr_base, T >::value >::type > {
- /**
- * \brief
- * The inner structure to hold managed pointer and its use count (the number how many times it is referenced).
- */
- struct cow_shared_ptr_data {
- /**
- * \brief
- * The managed pointer.
- */
- T * m_Data;
-
- /**
- * Caries the number of uses of this instance as a managed pointer inside copy on write pointer.
- */
- unsigned m_UseCount;
-
- /**
- * \brief
- * Contructs the inner shared resource based on the managed pointer.
- *
- * The class takes ownership of the provided pointer
- */
- cow_shared_ptr_data ( T * data ) : m_Data ( data ), m_UseCount ( 0 ) { }
-
- /**
- * \brief
- * Destructor to free the managed pointer.
- */
- ~cow_shared_ptr_data ( ) {
- delete m_Data;
- }
-
- /**
- * Disable copy construction.
- */
- cow_shared_ptr_data ( const cow_shared_ptr_data & ) = delete;
-
- /**
- * Disable copy operator of assignment.
- */
- cow_shared_ptr_data & operator = ( const cow_shared_ptr_data & ) = delete;
-
- /**
- * Disable move construction.
- */
- cow_shared_ptr_data ( cow_shared_ptr_data && ) = delete;
-
- /**
- * Disable move operator of assignment.
- */
- cow_shared_ptr_data & operator = ( cow_shared_ptr_data && ) = delete;
- };
-
-public:
- /**
- * \brief
- * Default initialization to null.
- */
- explicit cow_shared_ptr ( ) {
- attach ( NULL );
- }
-
- /**
- * \brief
- * Constructor which takes ownership of the provided pointer.
- */
- explicit cow_shared_ptr ( T * data ) {
- attach ( data ? new cow_shared_ptr_data ( data ) : NULL );
- }
-
- /**
- * \brief
- * Copy constructor to create new instance of shared pointer reffering the same data.
- *
- * \param other the source instance
- */
- cow_shared_ptr ( const cow_shared_ptr & other ) {
- attach ( other.m_Data );
- }
-
- /**
- * \brief
- * Move constructor to create new instance of shared pointer reffering the same data.
- *
- * \param other the source instance
- */
- cow_shared_ptr ( cow_shared_ptr && other ) noexcept {
- m_Data = other.m_Data;
- other.m_Data = NULL;
- }
-
- /**
- * \brief
- * The destructor of the shared pointer.
- */
- ~cow_shared_ptr ( ) noexcept {
- detach ( );
- }
-
- /**
- * \brief
- * Copy assignment operator to change reffered instace to source one.
- *
- * \param other the source instance
- */
- cow_shared_ptr & operator =( const cow_shared_ptr & other ) {
- if ( this == & other ) return * this;
-
- detach ( );
- attach ( other.m_Data );
-
- return * this;
+ static_cast < std::shared_ptr < T > & > ( * this ) = std::shared_ptr < T > ( ext::clone ( * std::shared_ptr < T >::get ( ) ) );
}
- /**
- * \brief
- * Move assignment operator to change reffered instace to source one.
- *
- * \param other the source instance
- */
- cow_shared_ptr & operator =( cow_shared_ptr && other ) noexcept {
- swap ( * this, other );
- return * this;
- }
-
- /**
- * \brief
- * Operator arrow to chain dereferece to inner managed pointer.
- *
- * \return the managed pointer
- */
- T * operator ->( ) {
- make_unique ( );
- return m_Data->m_Data;
- }
-
- /**
- * \brief
- * Operator arrow to chain dereferece to inner managed pointer.
- *
- * \return the managed pointer
- */
- T const * operator ->( ) const {
- return m_Data->m_Data;
- }
-
- /**
- * \brief
- * Operator dereference to access the inner managed pointer.
- *
- * \return reference to managed data
- */
- T & operator *( ) {
- make_unique ( );
- return * ( m_Data->m_Data );
- }
-
- /**
- * \brief
- * Operator dereference to access the inner managed pointer.
- *
- * \return reference to managed data
- */
- T const & operator *( ) const {
- return * ( m_Data->m_Data );
- }
-
- /**
- * \brief
- * Getter of the raw managed pointer.
- *
- * \return the managed pointer
- */
- T * get ( ) {
- make_unique ( );
- return m_Data->m_Data;
- }
-
- /**
- * \brief
- * Getter of the raw managed pointer.
- *
- * \return the managed pointer
- */
- T const * get ( ) const {
- return m_Data->m_Data;
- }
-
- /**
- * \brief
- * Tests whether the managed pointer is referenced from one location only (or the class stores null pointer).
- *
- * \return bool true if the managed pointer is referenced from one location only, false otherwise
- */
- bool unique ( ) const {
- return m_Data == NULL || m_Data->m_UseCount == 1;
- }
-
- /**
- * \brief
- * Getter of the number how many times the managed pointer is referenced.
- *
- * \return the use count
- */
- unsigned getUseCount ( ) const {
- if ( m_Data == NULL ) return 0;
-
- return m_Data->m_UseCount;
- }
-
- /**
- * \brief
- * Tests the instance whether the managed pointer is valid
- *
- * \return true if the managed pointer is not null and the use count is nonzero, false otherwise
- */
- explicit operator bool( ) const {
- return getUseCount ( ) != 0;
- }
-
-private:
- /**
- * \brief
- * Changes the managed pointer and increases its use count
- *
- * \param data the new value of managed pointer
- */
- void attach ( typename cow_shared_ptr < T >::cow_shared_ptr_data * data ) {
- m_Data = data;
-
- if ( m_Data ) m_Data->m_UseCount++;
- }
-
- /**
- * \brief
- * Decreases the use count of managed pointer, if needed the pointer is freed. Managed pointer stored in this instance is set to null.
- */
- void detach ( ) {
- if ( m_Data && ( --( m_Data->m_UseCount ) <= 0 ) ) delete m_Data;
-
- m_Data = NULL;
- }
-
- /**
- * \brief
- * Ensures the managed pointer is unique by copy constructing the managed instance if needed.
- */
- void make_unique ( ) {
- if ( unique ( ) ) return;
-
- typename cow_shared_ptr < T >::cow_shared_ptr_data * tmp = m_Data;
- detach ( );
- attach ( new cow_shared_ptr_data ( ext::clone ( * tmp->m_Data ) ) );
- }
-
- /**
- * \brief
- * The instance of sturucture containing managed pointer and its use count.
- */
- cow_shared_ptr_data * m_Data;
-
/**
* \brief
* Specialisation of swap method to copy on write shared pointers.
@@ -582,9 +215,7 @@ private:
* \param second the second instance
*/
friend void swap ( cow_shared_ptr & first, cow_shared_ptr & second ) {
- typename cow_shared_ptr < T >::cow_shared_ptr_data * tmp = first.m_Data;
- first.m_Data = second.m_Data;
- second.m_Data = tmp;
+ std::swap ( static_cast < std::shared_ptr < T > & > ( first ), static_cast < std::shared_ptr < T > & > ( second ) );
}
};
diff --git a/alib2std/test-src/extensions/SharedPtrTest.h b/alib2std/test-src/extensions/SharedPtrTest.h
index 63ed1d2a3f..2ed9aa6f7f 100644
--- a/alib2std/test-src/extensions/SharedPtrTest.h
+++ b/alib2std/test-src/extensions/SharedPtrTest.h
@@ -36,7 +36,7 @@ public:
}
};
-class Moveable2 : public ext::cow_shared_ptr_base {
+class Moveable2 {
int& m_moves;
int& m_copies;
--
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