Classes
class	boost::afio::utils::secded_ecc< blocksize >
	Calculates the single error correcting double error detecting (SECDED) Hamming Error Correcting Code for a blocksize block of bytes. For example, a secdec_ecc<8> would be the very common 72,64 Hamming code used in ECC RAM, or secdec_ecc<4096> would be for a 32784,32768 Hamming code. More...
class	boost::afio::utils::page_allocator< T >
	An STL allocator which allocates large TLB page memory.If the operating system is configured to allow it, this type of memory is particularly efficient for doing large scale file i/o. This is because the kernel must normally convert the scatter gather buffers you pass into extended scatter gather buffers as the memory you see as contiguous may not, and probably isn't, actually be contiguous in physical memory. Regions returned by this allocator may be allocated contiguously in physical memory and therefore the kernel can pass through your scatter gather buffers unmodified. More...
Functions
BOOST_AFIO_DECL std::vector < size_t >	boost::afio::utils::page_sizes (bool only_actually_available=true) noexcept
	Returns the page sizes of this architecture which is useful for calculating direct i/o multiples.
size_t	boost::afio::utils::file_buffer_default_size () noexcept
	Returns a reasonable default size for page_allocator, typically the closest page size from page_sizes() to 1Mb.
BOOST_AFIO_DECL void	boost::afio::utils::random_fill (char *buffer, size_t bytes)
	Fills the buffer supplied with cryptographically strong randomness. Uses the OS kernel API.
size_t	boost::afio::utils::to_hex_string (char out, size_t outlen, const char _in, size_t inlen)
	Converts a number to a hex string. Out buffer can be same as in buffer.
size_t	boost::afio::utils::from_hex_string (char out, size_t outlen, const char in, size_t inlen)
	Converts a hex string to a number. Out buffer can be same as in buffer.
std::string	boost::afio::utils::random_string (size_t randomlen)
	Returns a cryptographically random string capable of being used as a filename. Essentially random_fill() + to_hex_string().

Function Documentation

BOOST_AFIO_DECL std::vector<size_t> boost::afio::utils::page_sizes ( bool only_actually_available = true )

Returns the page sizes of this architecture which is useful for calculating direct i/o multiples.

Parameters:

only_actually_available Only return page sizes actually available to the user running this process

Returns:: The page sizes of this architecture.

{Whatever the system API takes (one would hope constant time).} {Any error from the operating system or std::bad_alloc.}

size_t boost::afio::utils::file_buffer_default_size ( )

Returns a reasonable default size for page_allocator, typically the closest page size from page_sizes() to 1Mb.

Returns:: A value of a TLB large page size close to 1Mb.

{Whatever the system API takes (one would hope constant time).} {Any error from the operating system or std::bad_alloc.}

Definition at line 5764 of file afio.hpp.

BOOST_AFIO_DECL void boost::afio::utils::random_fill	(	char *	buffer,
		size_t	bytes
	)

Fills the buffer supplied with cryptographically strong randomness. Uses the OS kernel API.

Parameters:

buffer	A buffer to fill
bytes	How many bytes to fill

{Whatever the system API takes.} {Any error from the operating system.}

size_t boost::afio::utils::to_hex_string	(	char *	out,
		size_t	outlen,
		const char *	_in,
		size_t	inlen
	)

Converts a number to a hex string. Out buffer can be same as in buffer.

Note that the character range used is a 16 item table of:

0123456789abcdef

This lets one pack one byte of input into two bytes of output.

{O(N) where N is the length of the number.} {Throws exception if output buffer is too small for input.}

Definition at line 5808 of file afio.hpp.

size_t boost::afio::utils::from_hex_string	(	char *	out,
		size_t	outlen,
		const char *	in,
		size_t	inlen
	)

Converts a hex string to a number. Out buffer can be same as in buffer.

Note that this routine is about 43% slower than to_hex_string(), half of which is due to input validation.

{O(N) where N is the length of the string.} {Throws exception if output buffer is too small for input or input size is not multiple of two.}

Definition at line 5847 of file afio.hpp.

std::string boost::afio::utils::random_string ( size_t randomlen )

Returns a cryptographically random string capable of being used as a filename. Essentially random_fill() + to_hex_string().

Parameters:

randomlen The number of bytes of randomness to use for the string.

Returns:: A string representing the randomness at a 2x ratio, so if 32 bytes were requested, this string would be 64 bytes long.

{Whatever the system API takes.} {Any error from the operating system.}

Definition at line 5915 of file afio.hpp.

Classes

Functions

Function Documentation