SharedMemoryBlock Class Reference

An encapsulation of a block of memory that can be mapped by one or more (not necessarily related) processes; when one process changes the data in the block, the changes are immediately visible to the other processes. More...

#include <SharedMemoryBlock.h++>

Inheritance diagram for SharedMemoryBlock:

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Collaboration diagram for SharedMemoryBlock:

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List of all members.

Public Member Functions
	SharedMemoryBlock (const String &name, size_t size, const Permissions &perm=Permissions::USER_READ_WRITE)
	Construct a new SharedMemoryBlock.
	~SharedMemoryBlock () throw ()
	Destructor.
void	attach (bool readOnly=false) throw (SystemException)
	Attach to the memory block, creating it if it does not yet exist.
void	detach () throw ()
	Detach from the memory block, and destroy it if no other process currently has it mapped.
virtual void	setBase (byte_t *base) throw ()
	Overridden to have no effect.
virtual void	setSize (size_t size) throw ()
	Overridden to have no effect.
String	getName () const
	Get the name of the memory block.
void	zero () throw ()
	Zero the memory block.
void	fill (byte_t value) throw ()
	Fill the memory block with the given byte value.
byte_t *	getBase () throw ()
	Get a pointer to the beginning of the memory block.
const byte_t *	getBase () const throw ()
	Get a pointer to the beginning of the memory block.
size_t	getSize () const throw ()
	Get the size of the memory block.
bool	operator== (const MemoryBlock &other) const throw ()
	Equality operator.
bool	operator!= (const MemoryBlock &other) const throw ()
	Inequality operator.
byte_t	operator[] (uint_t index) const throw (OutOfBoundsException)
	Bounds-checked access.
byte_t &	operator[] (uint_t index) throw (OutOfBoundsException)
	Bounds-checked access.
bool	copyFrom (const MemoryBlock &other) throw ()
	Copy data from another memory block to this one.
void	moveFrom (MemoryBlock &other) throw ()
	Copy data from another (possibly overlapping) memory block to this one.
int	indexOf (byte_t val, uint_t startIndex=0) const throw ()
	Find the first occurrence of a given byte value in the memory block, starting at a given index.
bool	operator! () const throw ()
	Test if the base of the block is NULL.
Protected Attributes
byte_t *	_base
	A pointer to the beginning of the memory block.
size_t	_size
	The size of the memory block, in bytes.

Detailed Description

An encapsulation of a block of memory that can be mapped by one or more (not necessarily related) processes; when one process changes the data in the block, the changes are immediately visible to the other processes.

Author:: Mark Lindner

Constructor & Destructor Documentation

SharedMemoryBlock	(	const String &	name,
		size_t	size,
		const Permissions &	perm = `Permissions::USER_READ_WRITE`
	)

Construct a new SharedMemoryBlock.

The actual memory segment is not created and mapped until a call to attach() is made.

Parameters:

	name	The name of the memory block. For maximal portability, the name should consist of at most 14 alphanumeric characters and should not contain slashes.
	size	The size of the memory block, in bytes. This size will be rounded up to the nearest multiple of the system page size.
	perm	The permissions with which to create the memory block, if it does not exist at the time of the attach().

~SharedMemoryBlock ( ) throw ()

Destructor.

Detaches from the memory block.

Member Function Documentation

void attach ( bool readOnly = false ) throw (SystemException)

Attach to the memory block, creating it if it does not yet exist.

Parameters:

readOnly

A flag indicating whether the memory block should be mapped for read-only access or read-write access.

Exceptions:

SystemException

If the operation fails.

bool copyFrom ( const MemoryBlock & other ) throw () [inherited]

Copy data from another memory block to this one.

The number of bytes copied is the minimum of the sizes of the two blocks. The blocks may not overlap.

Parameters:

other

The block to copy from.

Returns:: true if the copy succeeded, false if the blocks overlap.

void detach ( ) throw ()

Detach from the memory block, and destroy it if no other process currently has it mapped.

void fill ( byte_t value ) throw () [inherited]

Fill the memory block with the given byte value.

const byte_t* getBase ( ) const throw () [inline, inherited]

Get a pointer to the beginning of the memory block.

byte_t* getBase ( ) throw () [inline, inherited]

Get a pointer to the beginning of the memory block.

String getName ( ) const [inline]

Get the name of the memory block.

size_t getSize ( ) const throw () [inline, inherited]

Get the size of the memory block.

int indexOf	(	byte_t	val,
		uint_t	startIndex = `0`
	)			const throw () `[inherited]`

Find the first occurrence of a given byte value in the memory block, starting at a given index.

Parameters:

	val	The value to search for.
	startIndex	The index to begin searching at.

Returns:: The index of the first matching value, or -1 if not found.

void moveFrom ( MemoryBlock & other ) throw () [inherited]

Copy data from another (possibly overlapping) memory block to this one.

The number of bytes copied is the minimum of the sizes of the two blocks.

Parameters:

other

The block to copy from. Note that the copy may result in both blocks being modified, if the source area overlaps the target area.

bool operator! ( ) const throw () [inline, inherited]

Test if the base of the block is NULL.

bool operator!= ( const MemoryBlock & other ) const throw () [inline, inherited]

Inequality operator.

bool operator== ( const MemoryBlock & other ) const throw () [inherited]

Equality operator.

byte_t & operator[] ( uint_t index ) throw (OutOfBoundsException) [inherited]

Bounds-checked access.

byte_t operator[] ( uint_t index ) const throw (OutOfBoundsException) [inherited]

Bounds-checked access.

void setBase ( byte_t * base ) throw () [virtual]

Overridden to have no effect.

Reimplemented from MemoryBlock.

void setSize ( size_t size ) throw () [virtual]

Overridden to have no effect.

Reimplemented from MemoryBlock.

void zero ( ) throw () [inline, inherited]

Zero the memory block.

Member Data Documentation

byte_t* _base [protected, inherited]

A pointer to the beginning of the memory block.

size_t _size [protected, inherited]

The size of the memory block, in bytes.

The documentation for this class was generated from the following files:

SharedMemoryBlock Class Reference

Public Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation