osvr::common::IPCRingBuffer Class Reference

A ring buffer for interprocess communication, with managed occupancy. More...

#include <osvr/Common/IPCRingBuffer.h>

Inheritance diagram for osvr::common::IPCRingBuffer:

Classes
class	BufferReadProxy
	A class providing access to an entry in the ring buffer, holding a sharable mutex lock preventing it from being overwritten while this object is in scope. More...
class	BufferWriteProxy
	A class providing write access to the next available element in the ring buffer, owning the appropriate mutex locks and providing access to the sequence number. More...
class	Options

Public Types
typedef uint8_t	BackendType
typedef uint16_t	alignment_type
typedef uint16_t	entry_count_type
typedef uint32_t	entry_size_type
typedef uint32_t	abi_level_type
typedef uint32_t	sequence_type
	The sequence number is automatically incremented with each "put" into the buffer. Note that, as an unsigned integer, it does have (and uses) well-defined overflow semantics.
typedef uint8_t	value_type
typedef value_type *	pointer_type
typedef value_type const *	pointer_to_const_type
typedef shared_ptr< value_type >	smart_pointer_type

Public Member Functions
BackendType	getBackend () const
	Returns an integer identifying the IPC backend used.
std::string const &	getName () const
	Returns the name string used to create or find this ring buffer.
uint32_t	getEntrySize () const
	Returns the size of each individual buffer entry, in bytes.
uint16_t	getEntries () const
	Returns the total capacity, in number of buffer entries, of this ring buffer.
sequence_type	put (pointer_to_const_type data, size_t len)
	Puts the data in the next element in the buffer (using memcpy). Buffer sizes are not checked! More...
BufferWriteProxy	put ()
	Gets a proxy object for putting data in the next element in the buffer. You're responsible for doing the copying and, once you let the returned object exit scope, the notification (possibly with sequence number)
BufferReadProxy	get (sequence_type num)
	Gets access to an element in the buffer by sequence number: returns a proxy object that behaves mostly like a smart pointer.
BufferReadProxy	getLatest ()
	Gets access to the most recent element in the buffer: returns a proxy object that behaves mostly like a smart pointer, and that also contains the associated sequence number.
	~IPCRingBuffer ()
	Destructor.

Static Public Member Functions
static abi_level_type	getABILevel ()
	Gets an integer representing a unique arrangement of the internal shared memory layout, such that if two processes try to communicate with different ABI levels, they will (likely) not succeed and thus should not try.
static IPCRingBufferPtr	create (Options const &opts)
	Named constructor, for use by server processes: creates a shared memory ring buffer given the options structure. More...
static IPCRingBufferPtr	find (Options const &opts)
	Named constructor, for use by client processes: accesses an IPC ring buffer using the options structure. Only the name field is used from the options. More...

Detailed Description

A ring buffer for interprocess communication, with managed occupancy.

Each element in the ring buffer (that is, the contained buffers) is aligned to the given power of 2 alignment.

Designed to provide large-format data transfer in single-producer, roughly broadcast model, with an outside channel for communicating the segment name and signalling new data, and no guarantee that the data you were notified about won't be overwritten - just that if you're currently accessing data, we won't overwrite that.

Definition at line 65 of file IPCRingBuffer.h.

Member Function Documentation

static IPCRingBufferPtr osvr::common::IPCRingBuffer::create ( Options const &  opts )

static

Named constructor, for use by server processes: creates a shared memory ring buffer given the options structure.

If the returned pointer is not valid, the named segment could not be created for some reason.

static IPCRingBufferPtr osvr::common::IPCRingBuffer::find ( Options const &  opts )

static

Named constructor, for use by client processes: accesses an IPC ring buffer using the options structure. Only the name field is used from the options.

If the returned pointer is not valid, the named buffer could not be found.

sequence_type osvr::common::IPCRingBuffer::put	(	pointer_to_const_type	data,
		size_t	len
	)

Puts the data in the next element in the buffer (using memcpy). Buffer sizes are not checked!

This is a convenience wrapper around the other put() signature.

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

• osvr/Common/IPCRingBuffer.h