wfio_iobuf_t Struct Reference

A generic I/O buffer. More...

#include <iobuf.h>

Public Attributes
const int	flags
	Flags associated with this buffer.
const size_t	capacity
	The maximum capacity of this buffer.
const size_t	facet
	The capacity of this facet of the buffer. More...
const size_t	avail
	The number of available characters for consumption in this buffer.
const size_t	start
	The starting index of this buffer.
const size_t	end
	The end index of this buffer.
void *const	base
	The base address of this buffer's data.

Detailed Description

A generic I/O buffer.

An wfio_iobuf_t represents a generic circular buffer that can be used to implement buffering operations on devices or other objects which do not immediately provide it.

An wfio_iobuf_t may be allocated in two ways: as an exclusive buffer which allocates the entire memory to a single buffer, or as a shared double-buffer. To allocate an exclusive buffer, use the wfio_iobuf_alloc() function.

A shared buffer divides its memory into two facets which are respectively called facet 0 and facet 1. Facet 0 occupies the lower portion of memory, whereas facet 1 occupies the upper portion. Which facet is in use may be interrogated by the WFIO_IOBUF_FLIPPED bit; if it is set, then facet 1 is in use; otherwise, facet 0 is in use.

Shared buffers are extremely useful for implementing read-write devices so that the contents of the read or write buffer are not lost whenever performing the opposing operation.

Member Data Documentation

facet

const size_t wfio_iobuf_t::facet

The capacity of this facet of the buffer.

If this IOBuf is shared, this refers to the maximum writable size of this facet.

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The documentation for this struct was generated from the following file:

• include/wfio/iobuf.h