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861c830bb7
SqMod/shared/Base/Buffer.hpp
Sandu Liviu Catalin 861c830bb7 Improve the constructors in shared buffers implementation.
2016-06-15 10:00:28 +03:00

874 lines
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#ifndef _BASE_BUFFER_HPP_
#define _BASE_BUFFER_HPP_
// ------------------------------------------------------------------------------------------------
#include <cassert>
#include <cstdarg>
// ------------------------------------------------------------------------------------------------
#include <utility>
// ------------------------------------------------------------------------------------------------
namespace SqMod {
// ------------------------------------------------------------------------------------------------
class Memory;
class Buffer;
/* ------------------------------------------------------------------------------------------------
* A counted reference to a memory manager instance.
*/
class MemRef
{
private:
// --------------------------------------------------------------------------------------------
static MemRef s_Mem;
// --------------------------------------------------------------------------------------------
typedef unsigned int Counter;
// --------------------------------------------------------------------------------------------
Memory* m_Ptr; // The memory manager instance.
Counter* m_Ref; // Reference count to the managed instance.
/* --------------------------------------------------------------------------------------------
* Grab a strong reference to a memory manager.
*/
void Grab();
/* --------------------------------------------------------------------------------------------
* Drop a strong reference to a memory manager.
*/
void Drop();
public:
/* --------------------------------------------------------------------------------------------
* Get a reference to the global memory manager instance.
*/
static const MemRef & Get();
/* --------------------------------------------------------------------------------------------
* Default constructor (null).
*/
MemRef()
: m_Ptr(s_Mem.m_Ptr)
, m_Ref(s_Mem.m_Ref)
{
Grab();
}
/* --------------------------------------------------------------------------------------------
* Copy constructor.
*/
MemRef(const MemRef & o)
: m_Ptr(o.m_Ptr)
, m_Ref(o.m_Ref)
{
Grab();
}
/* --------------------------------------------------------------------------------------------
* Move constructor.
*/
MemRef(MemRef && o)
: m_Ptr(o.m_Ptr), m_Ref(o.m_Ref)
{
o.m_Ptr = nullptr;
o.m_Ref = nullptr;
}
/* --------------------------------------------------------------------------------------------
* Destructor.
*/
~MemRef()
{
Drop();
}
/* --------------------------------------------------------------------------------------------
* Copy assignment operator.
*/
MemRef & operator = (const MemRef & o)
{
if (m_Ptr != o.m_Ptr)
{
Drop();
m_Ptr = o.m_Ptr;
m_Ref = o.m_Ref;
Grab();
}
return *this;
}
/* --------------------------------------------------------------------------------------------
* Move assignment operator.
*/
MemRef & operator = (MemRef && o)
{
if (m_Ptr != o.m_Ptr)
{
Drop();
m_Ptr = o.m_Ptr;
m_Ref = o.m_Ref;
o.m_Ptr = nullptr;
o.m_Ref = nullptr;
}
return *this;
}
/* --------------------------------------------------------------------------------------------
* Perform an equality comparison between two memory managers.
*/
bool operator == (const MemRef & o) const
{
return (m_Ptr == o.m_Ptr);
}
/* --------------------------------------------------------------------------------------------
* Perform an inequality comparison between two memory managers.
*/
bool operator != (const MemRef & o) const
{
return (m_Ptr != o.m_Ptr);
}
/* --------------------------------------------------------------------------------------------
* Implicit conversion to boolean for use in boolean operations.
*/
operator bool () const
{
return m_Ptr;
}
/* --------------------------------------------------------------------------------------------
* Member operator for dereferencing the managed pointer.
*/
Memory * operator -> () const
{
assert(m_Ptr);
return m_Ptr;
}
/* --------------------------------------------------------------------------------------------
* Indirection operator for obtaining a reference of the managed pointer.
*/
Memory & operator * () const
{
assert(m_Ptr);
return *m_Ptr;
}
/* --------------------------------------------------------------------------------------------
* Release the reference to the managed instance.
*/
void Reset()
{
if (m_Ptr)
{
Drop();
}
}
};
// ------------------------------------------------------------------------------------------------
void ThrowMemExcept(const char * msg, ...);
/* ------------------------------------------------------------------------------------------------
* Reusable and re-scalable buffer memory for quick memory allocations.
*/
class Buffer
{
public:
// --------------------------------------------------------------------------------------------
typedef char Value; // The type of value used to represent a byte.
// --------------------------------------------------------------------------------------------
typedef Value & Reference; // A reference to the stored value type.
typedef const Value & ConstRef; // A const reference to the stored value type.
// --------------------------------------------------------------------------------------------
typedef Value * Pointer; // A pointer to the stored value type.
typedef const Value * ConstPtr; // A const pointer to the stored value type.
// --------------------------------------------------------------------------------------------
typedef unsigned int SzType; // The type used to represent size in general.
private:
/* --------------------------------------------------------------------------------------------
* Construct and take ownership of the specified buffer.
*/
Buffer(Pointer & ptr, SzType & cap, SzType & cur, const MemRef & mem)
: m_Ptr(ptr)
, m_Cap(cap)
, m_Cur(cur)
, m_Mem(mem)
{
ptr = nullptr;
cap = 0;
cur = 0;
}
public:
/* --------------------------------------------------------------------------------------------
* Default constructor. (null)
*/
Buffer()
: m_Ptr(nullptr)
, m_Cap(0)
, m_Cur(0)
, m_Mem(MemRef::Get())
{
/* ... */
}
/* --------------------------------------------------------------------------------------------
* Explicit size constructor.
*/
Buffer(SzType size)
: m_Ptr(nullptr)
, m_Cap(0)
, m_Cur(0)
, m_Mem(MemRef::Get())
{
Request(size < 8 ? 8 : size);
}
/* --------------------------------------------------------------------------------------------
* Explicit size and cursor position constructor.
*/
Buffer(SzType size, SzType pos)
: m_Ptr(nullptr)
, m_Cap(0)
, m_Cur(0)
, m_Mem(MemRef::Get())
{
Request(size < 8 ? 8 : size);
Move(pos);
}
/* --------------------------------------------------------------------------------------------
* Explicit size and buffer constructor.
*/
Buffer(ConstPtr data, SzType size)
: m_Ptr(nullptr)
, m_Cap(0)
, m_Cur(0)
, m_Mem(MemRef::Get())
{
Request(size < 8 ? 8 : size);
m_Cur += Write(m_Cur, data, size);
}
/* --------------------------------------------------------------------------------------------
* Explicit size, data and cursor position constructor.
*/
Buffer(ConstPtr data, SzType size, SzType pos)
: m_Ptr(nullptr)
, m_Cap(0)
, m_Cur(0)
, m_Mem(MemRef::Get())
{
Request(size < 8 ? 8 : size);
m_Cur += Write(m_Cur, data, size);
Move(pos);
}
/* --------------------------------------------------------------------------------------------
* Copy constructor.
*/
Buffer(const Buffer & o);
/* --------------------------------------------------------------------------------------------
* Move constructor.
*/
Buffer(Buffer && o)
: m_Ptr(o.m_Ptr)
, m_Cap(o.m_Cap)
, m_Cur(o.m_Cur)
, m_Mem(o.m_Mem)
{
o.m_Ptr = nullptr;
}
/* --------------------------------------------------------------------------------------------
* Destructor.
*/
~Buffer();
/* --------------------------------------------------------------------------------------------
* Copy assignment operator.
*/
Buffer & operator = (const Buffer & o);
/* --------------------------------------------------------------------------------------------
* Copy assignment operator.
*/
Buffer & operator = (Buffer && o)
{
if (m_Ptr != o.m_Ptr)
{
if (m_Ptr)
{
Release();
}
m_Ptr = o.m_Ptr;
m_Cap = o.m_Cap;
m_Cur = o.m_Cur;
m_Mem = o.m_Mem;
o.m_Ptr = nullptr;
}
return *this;
}
/* --------------------------------------------------------------------------------------------
* Equality comparison operator.
*/
bool operator == (const Buffer & o) const
{
return (m_Cap == o.m_Cap);
}
/* --------------------------------------------------------------------------------------------
* Inequality comparison operator.
*/
bool operator != (const Buffer & o) const
{
return (m_Cap != o.m_Cap);
}
/* --------------------------------------------------------------------------------------------
* Less than comparison operator.
*/
bool operator < (const Buffer & o) const
{
return (m_Cap < o.m_Cap);
}
/* --------------------------------------------------------------------------------------------
* Greater than comparison operator.
*/
bool operator > (const Buffer & o) const
{
return (m_Cap > o.m_Cap);
}
/* --------------------------------------------------------------------------------------------
* Less than or equal comparison operator.
*/
bool operator <= (const Buffer & o) const
{
return (m_Cap <= o.m_Cap);
}
/* --------------------------------------------------------------------------------------------
* Greater than or equal comparison operator.
*/
bool operator >= (const Buffer & o) const
{
return (m_Cap >= o.m_Cap);
}
/* --------------------------------------------------------------------------------------------
* Implicit conversion to boolean.
*/
operator bool () const
{
return m_Ptr;
}
/* --------------------------------------------------------------------------------------------
* Retrieve the internal buffer.
*/
Pointer Data()
{
return m_Ptr;
}
/* --------------------------------------------------------------------------------------------
* Retrieve the internal buffer.
*/
ConstPtr Data() const
{
return m_Ptr;
}
/* --------------------------------------------------------------------------------------------
* Retrieve the internal buffer casted as a different type.
*/
template < typename T = Value > T * Get()
{
return reinterpret_cast< T * >(m_Ptr);
}
/* --------------------------------------------------------------------------------------------
* Retrieve the internal buffer casted as a different type.
*/
template < typename T = Value > const T * Get() const
{
return reinterpret_cast< const T * >(m_Ptr);
}
/* --------------------------------------------------------------------------------------------
* Retrieve a certain element type at the specified position.
*/
template < typename T = Value > T & At(SzType n)
{
assert(n < static_cast< SzType >(m_Cap / sizeof(T)));
return reinterpret_cast< T * >(m_Ptr)[n];
}
/* --------------------------------------------------------------------------------------------
* Retrieve a certain element type at the specified position.
*/
template < typename T = Value > const T & At(SzType n) const
{
assert(n < static_cast< SzType >(m_Cap / sizeof(T)));
return reinterpret_cast< const T * >(m_Ptr)[n];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the internal buffer casted as a different type.
*/
template < typename T = Value > T * Begin()
{
return reinterpret_cast< T * >(m_Ptr);
}
/* --------------------------------------------------------------------------------------------
* Retrieve the internal buffer casted as a different type.
*/
template < typename T = Value > const T * Begin() const
{
return reinterpret_cast< const T * >(m_Ptr);
}
/* --------------------------------------------------------------------------------------------
* Retrieve the internal buffer casted as a different type.
*/
template < typename T = Value > T * End()
{
return reinterpret_cast< T * >(m_Ptr) + (m_Cap / sizeof(T));
}
/* --------------------------------------------------------------------------------------------
* Retrieve the internal buffer casted as a different type.
*/
template < typename T = Value > const T * End() const
{
return reinterpret_cast< const T * >(m_Ptr) + (m_Cap / sizeof(T));
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element at the front of the buffer.
*/
template < typename T = Value > T & Front()
{
assert(m_Cap >= sizeof(T));
return reinterpret_cast< T * >(m_Ptr)[0];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element at the front of the buffer.
*/
template < typename T = Value > const T & Front() const
{
assert(m_Cap >= sizeof(T));
return reinterpret_cast< const T * >(m_Ptr)[0];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element after the first element in the buffer.
*/
template < typename T = Value > T & Next()
{
assert(m_Cap >= (sizeof(T) * 2));
return reinterpret_cast< T * >(m_Ptr)[1];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element after the first element in the buffer.
*/
template < typename T = Value > const T & Next() const
{
assert(m_Cap >= (sizeof(T) * 2));
return reinterpret_cast< const T * >(m_Ptr)[1];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element at the back of the buffer.
*/
template < typename T = Value > T & Back()
{
assert(m_Cap >= sizeof(T));
return reinterpret_cast< T * >(m_Ptr)[(m_Cap / sizeof(T))-1];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element at the back of the buffer.
*/
template < typename T = Value > const T & Back() const
{
assert(m_Cap >= sizeof(T));
return reinterpret_cast< const T * >(m_Ptr)[(m_Cap / sizeof(T))-1];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element before the last element in the buffer.
*/
template < typename T = Value > T & Prev()
{
assert(m_Cap >= (sizeof(T) * 2));
return reinterpret_cast< T * >(m_Ptr)[(m_Cap / sizeof(T))-2];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element before the last element in the buffer.
*/
template < typename T = Value > const T & Prev() const
{
assert(m_Cap >= (sizeof(T) * 2));
return reinterpret_cast< const T * >(m_Ptr)[(m_Cap / sizeof(T))-2];
}
/* --------------------------------------------------------------------------------------------
* Reposition the edit cursor to the specified number of elements ahead.
*/
template < typename T = Value > void Advance(SzType n)
{
// Do we need to scale the buffer?
if ((m_Cur + (n * sizeof(T))) >= m_Cap)
{
Grow(m_Cur + (n * sizeof(T)));
}
// Advance to the specified position
m_Cur += (n * sizeof(T));
}
/* --------------------------------------------------------------------------------------------
* Reposition the edit cursor to the specified number of elements behind.
*/
template < typename T = Value > void Retreat(SzType n)
{
// Can we move that much backward?
if ((n * sizeof(T)) <= m_Cur)
{
m_Cur -= (n * sizeof(T));
}
// Just got to the beginning
else
{
m_Cur = 0;
}
}
/* --------------------------------------------------------------------------------------------
* Reposition the edit cursor to a fixed position within the buffer.
*/
template < typename T = Value > void Move(SzType n)
{
// Do we need to scale the buffer?
if ((n * sizeof(T)) >= m_Cap)
{
Grow(n * sizeof(T));
}
// Move to the specified position
m_Cur = (n * sizeof(T));
}
/* --------------------------------------------------------------------------------------------
* Append a value to the current cursor location and advance the cursor.
*/
template < typename T = Value > void Push(T v)
{
// Do we need to scale the buffer?
if ((m_Cur + sizeof(T)) >= m_Cap)
{
Grow(m_Cap + sizeof(T));
}
// Assign the specified value
reinterpret_cast< T * >(m_Ptr)[m_Cur] = v;
// Move to the next element
m_Cur += sizeof(T);
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element at the cursor position.
*/
template < typename T = Value > T & Cursor()
{
assert((m_Cur / sizeof(T)) < (m_Cap / sizeof(T)));
return reinterpret_cast< T * >(m_Ptr)[m_Cur];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element at the cursor position.
*/
template < typename T = Value > const T & Cursor() const
{
assert((m_Cur / sizeof(T)) < (m_Cap / sizeof(T)));
return reinterpret_cast< const T * >(m_Ptr)[m_Cur];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element before the cursor position.
*/
template < typename T = Value > T & Before()
{
assert(m_Cur >= sizeof(T));
return reinterpret_cast< T * >(m_Ptr)[(m_Cur / sizeof(T))-1];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element before the cursor position.
*/
template < typename T = Value > const T & Before() const
{
assert(m_Cur >= sizeof(T));
return reinterpret_cast< const T * >(m_Ptr)[(m_Cur / sizeof(T))-1];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element after the cursor position.
*/
template < typename T = Value > T & After()
{
assert(m_Cap >= sizeof(T) && (m_Cur + sizeof(T)) <= (m_Cap - sizeof(T)));
return reinterpret_cast< T * >(m_Ptr)[(m_Cur / sizeof(T))+1];
}
/* --------------------------------------------------------------------------------------------
* Retrieve the element after the cursor position.
*/
template < typename T = Value > const T & After() const
{
assert(m_Cap >= sizeof(T) && (m_Cur + sizeof(T)) <= (m_Cap - sizeof(T)));
return reinterpret_cast< const T * >(m_Ptr)[(m_Cur / sizeof(T))+1];
}
/* --------------------------------------------------------------------------------------------
* Retrieve maximum elements it can hold for a certain type.
*/
template < typename T = Value > static SzType Max()
{
return static_cast< SzType >(0xFFFFFFFF / sizeof(T));
}
/* --------------------------------------------------------------------------------------------
* Retrieve the current buffer capacity in element count.
*/
template < typename T = Value > SzType Size() const
{
return static_cast< SzType >(m_Cap / sizeof(T));
}
/* --------------------------------------------------------------------------------------------
* Retrieve the current buffer capacity in byte count.
*/
SzType Capacity() const
{
return m_Cap;
}
/* --------------------------------------------------------------------------------------------
* Retrieve the current position of the cursor in the buffer.
*/
template < typename T = Value > SzType Position() const
{
return static_cast< SzType >(m_Cur / sizeof(T));
}
/* --------------------------------------------------------------------------------------------
* Retrieve the amount of unused buffer after the edit cursor.
*/
template < typename T = Value > SzType Remaining() const
{
return static_cast< SzType >((m_Cap - m_Cur) / sizeof(T));
}
/* --------------------------------------------------------------------------------------------
* Grow the size of the internal buffer by the specified amount of bytes.
*/
void Grow(SzType n);
/* --------------------------------------------------------------------------------------------
* Makes sure there is enough capacity to hold the specified element count.
*/
template < typename T = Value > Buffer Adjust(SzType n)
{
// Do we meet the minimum size?
if (n < 8)
{
n = 8; // Adjust to minimum size
}
// See if the requested capacity doesn't exceed the limit
if (n > Max< T >())
{
ThrowMemExcept("Requested buffer of (%u) elements exceeds the (%u) limit", n, Max< T >());
}
// Is there an existing buffer?
else if (n && !m_Cap)
{
Request(n * sizeof(T)); // Request the memory
}
// Should the size be increased?
else if (n > m_Cap)
{
// Backup the current memory
Buffer bkp(m_Ptr, m_Cap, m_Cur, m_Mem);
// Request the memory
Request(n * sizeof(T));
// Return the backup
return std::move(bkp);
}
// Return an empty buffer
return Buffer();
}
/* --------------------------------------------------------------------------------------------
* Release the managed memory.
*/
void Reset()
{
if (m_Ptr)
{
Release();
}
}
/* --------------------------------------------------------------------------------------------
* Release the managed memory and manager.
*/
void ResetAll()
{
if (m_Ptr)
{
Release();
}
m_Mem.Reset();
}
/* --------------------------------------------------------------------------------------------
* Swap the contents of two buffers.
*/
void Swap(Buffer & o)
{
Pointer p = m_Ptr;
SzType n = m_Cap;
m_Ptr = o.m_Ptr;
m_Cap = o.m_Cap;
o.m_Ptr = p;
o.m_Cap = n;
}
/* --------------------------------------------------------------------------------------------
* Write a portion of a buffer to the internal buffer.
*/
SzType Write(SzType pos, ConstPtr data, SzType size);
/* --------------------------------------------------------------------------------------------
* Write another buffer to the internal buffer.
*/
SzType Write(SzType pos, const Buffer & b)
{
return Write(pos, b.m_Ptr, b.m_Cur);
}
/* --------------------------------------------------------------------------------------------
* Write a formatted string to the internal buffer.
*/
SzType WriteF(SzType pos, const char * fmt, ...);
/* --------------------------------------------------------------------------------------------
* Write a formatted string to the internal buffer.
*/
SzType WriteF(SzType pos, const char * fmt, va_list args);
/* --------------------------------------------------------------------------------------------
* Write a string to the internal buffer.
*/
SzType WriteS(SzType pos, const char * str);
/* --------------------------------------------------------------------------------------------
* Write a portion of a string to the internal buffer.
*/
SzType WriteS(SzType pos, const char * str, SzType size)
{
return Write(pos, str, size);
}
/* --------------------------------------------------------------------------------------------
* Append a portion of a buffer to the internal buffer.
*/
void Append(ConstPtr data, SzType size)
{
m_Cur += Write(m_Cur, data, size);
}
/* --------------------------------------------------------------------------------------------
* Append another buffer to the internal buffer.
*/
void Append(const Buffer & b)
{
m_Cur += Write(m_Cur, b.m_Ptr, b.m_Cur);
}
/* --------------------------------------------------------------------------------------------
* Append a formatted string to the internal buffer.
*/
void AppendF(const char * fmt, ...);
/* --------------------------------------------------------------------------------------------
* Append a formatted string to the internal buffer.
*/
void AppendF(const char * fmt, va_list args)
{
m_Cur += WriteF(m_Cur, fmt, args);
}
/* --------------------------------------------------------------------------------------------
* Append a string to the internal buffer.
*/
void AppendS(const char * str);
/* --------------------------------------------------------------------------------------------
* Append a portion of a string to the internal buffer.
*/
void AppendS(const char * str, SzType size)
{
m_Cur += Write(m_Cur, str, size);
}
protected:
/* --------------------------------------------------------------------------------------------
* Request the memory specified in the capacity.
*/
void Request(SzType n);
/* --------------------------------------------------------------------------------------------
* Release the managed memory buffer.
*/
void Release();
private:
// --------------------------------------------------------------------------------------------
Pointer m_Ptr; /* Pointer to the memory buffer. */
SzType m_Cap; /* The total size of the buffer. */
SzType m_Cur; /* The buffer edit cursor. */
// --------------------------------------------------------------------------------------------
MemRef m_Mem; /* Reference to the associated memory manager. */
};
} // Namespace:: SqMod
#endif // _BASE_BUFFER_HPP_
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