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Dynamic::Var SOO

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Dynamic::Var  small object optimization and some refactoring
This commit is contained in:
aleks-f
2013-02-05 22:12:21 -06:00
parent 54a92c59e5
commit 21da0129b6
16 changed files with 401 additions and 208 deletions
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175
Foundation/include/Poco/Any.h
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@@ -48,6 +48,68 @@
namespace Poco {
namespace Dynamic {
class Var;
class VarHolder;
template <class> class VarHolderImpl;
}
template <typename PlaceholderT, unsigned int SizeV = POCO_SMALL_OBJECT_SIZE>
union Placeholder
/// ValueHolder union (used by Poco::Any and Poco::Dynamic::Var for small
/// object optimization).
///
/// If Holder<Type> fits into POCO_SMALL_OBJECT_SIZE bytes of storage,
/// it will be placement-new-allocated into the local buffer
/// (i.e. there will be no heap-allocation). The local buffer size is one byte
/// larger - [POCO_SMALL_OBJECT_SIZE + 1], additional byte value indicating
/// where the object was allocated (0 => heap, 1 => local).
{
public:
static const unsigned int SIZE = SizeV;
Placeholder ()
{
erase();
}
void erase()
{
std::memset(holder, 0, sizeof(Placeholder));
}
bool isLocal() const
{
return holder[SIZE] != 0;
}
void setLocal(bool local) const
{
holder[SIZE] = local ? 1 : 0;
}
PlaceholderT* content() const
{
if(isLocal())
return reinterpret_cast<PlaceholderT*>(holder);
else
return pHolder;
}
private:
PlaceholderT* pHolder;
mutable unsigned char holder[SIZE + 1];
friend class Any;
friend class Dynamic::Var;
friend class Dynamic::VarHolder;
template <class> friend class VarHolderImpl;
};
class Any
/// An Any class represents a general type and is capable of storing any type, supporting type-safe extraction
/// of the internally stored data.
@@ -58,13 +120,10 @@ class Any
/// Modified for small object optimization support (optionally supported through conditional compilation)
/// by Alex Fabijanic.
{
public:
#ifndef POCO_NO_SOO
union PH;
public:
Any()
/// Creates an empty any type.
{
@@ -75,8 +134,8 @@ public:
/// Creates an any which stores the init parameter inside.
///
/// Example:
/// Any a(13);
/// Any a(string("12345"));
/// Any a(13);
/// Any a(string("12345"));
{
construct(value);
}
@@ -89,13 +148,13 @@ public:
}
~Any()
/// Destructor. If Any is locally held, calls Placeholder destructor;
/// Destructor. If Any is locally held, calls ValueHolder destructor;
/// otherwise, deletes the placeholder from the heap.
{
if(!empty())
{
if(_placeholder.isLocal())
content()->~Placeholder();
if(_valueHolder.isLocal())
content()->~ValueHolder();
else
delete content();
}
@@ -110,14 +169,14 @@ public:
{
if (this == &other) return *this;
if (!_placeholder.isLocal() && !other._placeholder.isLocal())
if (!_valueHolder.isLocal() && !other._valueHolder.isLocal())
{
std::swap(_placeholder.pHolder, other._placeholder.pHolder);
std::swap(_valueHolder.pHolder, other._valueHolder.pHolder);
}
else
{
Any tmp(*this);
if (_placeholder.isLocal()) this->~Any();
if (_valueHolder.isLocal()) this->~Any();
construct(other);
other = tmp;
}
@@ -143,7 +202,7 @@ public:
if ((this != &rhs) && !rhs.empty())
construct(rhs);
else if ((this != &rhs) && rhs.empty())
_placeholder.erase();
_valueHolder.erase();
return *this;
}
@@ -152,7 +211,7 @@ public:
/// Returns true if the Any is empty.
{
char buf[POCO_SMALL_OBJECT_SIZE] = { 0 };
return 0 == std::memcmp(_placeholder.holder, buf, POCO_SMALL_OBJECT_SIZE);
return 0 == std::memcmp(_valueHolder.holder, buf, _valueHolder.SIZE);
}
const std::type_info & type() const
@@ -166,20 +225,20 @@ public:
private:
class Placeholder
class ValueHolder
{
public:
virtual ~Placeholder()
virtual ~ValueHolder()
{
}
virtual const std::type_info & type() const = 0;
virtual void clone(Any::PH*) const = 0;
virtual void clone(Placeholder<ValueHolder>*) const = 0;
};
template<typename ValueType>
class Holder : public Placeholder
class Holder : public ValueHolder
{
public:
Holder(const ValueType & value) : _held(value)
@@ -191,11 +250,11 @@ private:
return typeid(ValueType);
}
virtual void clone(Any::PH* pPlaceholder) const
virtual void clone(Placeholder<ValueHolder>* pPlaceholder) const
{
if ((sizeof(Holder<ValueType>) <= POCO_SMALL_OBJECT_SIZE))
if ((sizeof(Holder<ValueType>) <= pPlaceholder->SIZE))
{
new ((Placeholder*) pPlaceholder->holder) Holder(_held);
new ((ValueHolder*) pPlaceholder->holder) Holder(_held);
pPlaceholder->setLocal(true);
}
else
@@ -211,78 +270,40 @@ private:
Holder & operator = (const Holder &);
};
Placeholder* content() const
ValueHolder* content() const
{
return _placeholder.content();
return _valueHolder.content();
}
template<typename ValueType>
void construct(const ValueType& value)
{
if (sizeof(Holder<ValueType>) <= POCO_SMALL_OBJECT_SIZE)
if (sizeof(Holder<ValueType>) <= _valueHolder.SIZE)
{
new (reinterpret_cast<Placeholder*>(_placeholder.holder)) Holder<ValueType>(value);
_placeholder.setLocal(true);
new (reinterpret_cast<ValueHolder*>(_valueHolder.holder)) Holder<ValueType>(value);
_valueHolder.setLocal(true);
}
else
{
_placeholder.pHolder = new Holder<ValueType>(value);
_placeholder.setLocal(false);
_valueHolder.pHolder = new Holder<ValueType>(value);
_valueHolder.setLocal(false);
}
}
void construct(const Any& other)
{
if(!other.empty())
other.content()->clone(&_placeholder);
other.content()->clone(&_valueHolder);
else
_placeholder.erase();
_valueHolder.erase();
}
union PH
/// Placeholder union. If Holder<Type> fits into POCO_SMALL_OBJECT_SIZE
/// bytes of storage, it will be placement-new-allocated into the local buffer
/// (i.e. there will be no heap-allocation. The local buffer size is one byte
/// larger - [POCO_SMALL_OBJECT_SIZE + 1], additional byte value indicating
/// where the object was allocated (0 => heap, 1 => local).
{
PH ()
{
erase();
}
void erase()
{
std::memset(holder, 0, sizeof(PH));
}
bool isLocal() const
{
return holder[POCO_SMALL_OBJECT_SIZE] != 0;
}
void setLocal(bool local) const
{
holder[POCO_SMALL_OBJECT_SIZE] = local ? 1 : 0;
}
Placeholder* content() const
{
if(isLocal())
return reinterpret_cast<Placeholder*>(holder);
else
return pHolder;
}
Placeholder* pHolder;
mutable unsigned char holder[POCO_SMALL_OBJECT_SIZE + 1];
} _placeholder;
Placeholder<ValueHolder> _valueHolder;
#else // if POCO_NO_SOO
public:
Any(): _pHolder(0)
/// Creates an empty any type.
{
@@ -352,19 +373,19 @@ public:
}
private:
class Placeholder
class ValueHolder
{
public:
virtual ~Placeholder()
virtual ~ValueHolder()
{
}
virtual const std::type_info& type() const = 0;
virtual Placeholder* clone() const = 0;
virtual ValueHolder* clone() const = 0;
};
template <typename ValueType>
class Holder: public Placeholder
class Holder: public ValueHolder
{
public:
Holder(const ValueType& value):
@@ -377,7 +398,7 @@ private:
return typeid(ValueType);
}
virtual Placeholder* clone() const
virtual ValueHolder* clone() const
{
return new Holder(_held);
}
@@ -388,13 +409,13 @@ private:
Holder & operator=(const Holder &);
};
Placeholder* content() const
ValueHolder* content() const
{
return _pHolder;
}
private:
Placeholder* _pHolder;
ValueHolder* _pHolder;
#endif // POCO_NO_SOO