An implementation of a ring buffer with a BDataIO interface. More...

Inherits BDataIO.

Public Member Functions
	BMemoryRingIO (size_t size)
	Creates a new BMemoryRingIO object with the given buffer size.

virtual	~BMemoryRingIO ()
	Free up resources held by the object.

size_t	BufferSize ()
	Get the total capacity of the object.

size_t	BytesAvailable ()
	Get the amount of data stored in the object.

void	Clear ()
	Discard all data in the object.

status_t	InitCheck () const
	Whether the object has been initialized correctly.

virtual ssize_t	Read (void *buffer, size_t size)
	Reads data from the object into a buffer.

status_t	SetSize (size_t size)
	Change the ring buffer capacity.

void	SetWriteDisabled (bool disabled)
	Set whether writes to the ring buffer is disabled.

size_t	SpaceAvailable ()
	Get the amount of space left in the object.

status_t	WaitForRead (bigtime_t timeout=B_INFINITE_TIMEOUT)
	Wait for data to be available for reading.

status_t	WaitForWrite (bigtime_t timeout=B_INFINITE_TIMEOUT)
	Wait for space to be available for writing.

virtual ssize_t	Write (const void *buffer, size_t size)
	Writes data from a buffer to the object.

bool	WriteDisabled ()
	Indicates whether writes to the ring buffer is disabled.

Public Member Functions inherited from BDataIO
	BDataIO ()
	This constructor does nothing.

virtual	~BDataIO ()
	This destructor does nothing.

virtual status_t	Flush ()
	Writes pending data to underlying storage.

virtual ssize_t	Read (void *buffer, size_t size)
	Reads data from the object into a buffer.

status_t	ReadExactly (void buffer, size_t size, size_t _bytesRead=NULL)
	Reads an exact amount of data from the object into a buffer.

virtual ssize_t	Write (const void *buffer, size_t size)
	Writes data from a buffer to the object.

status_t	WriteExactly (const void buffer, size_t size, size_t _bytesWritten=NULL)
	Writes an exact amount of data from a buffer to the object.

Detailed Description

An implementation of a ring buffer with a BDataIO interface.

Since: Haiku R1

Constructor & Destructor Documentation

◆ BMemoryRingIO()

BMemoryRingIO::BMemoryRingIO ( size_t size )

Creates a new BMemoryRingIO object with the given buffer size.

Call InitCheck() to verify that the buffer has been successfully created.

Parameters

size	The initial size of the buffer.

Since: Haiku R1

See also: SetSize()

◆ ~BMemoryRingIO()

BMemoryRingIO::~BMemoryRingIO ( )

virtual

Free up resources held by the object.

Since: Haiku R1

Member Function Documentation

◆ BufferSize()

size_t BMemoryRingIO::BufferSize ( )

Get the total capacity of the object.

Returns: The total capacity of the object in bytes.

Since: Haiku R1

See also: SpaceAvailable() for the amount of space left for writing in the object.; BytesAvailable() for the amount of data ready to be read.

◆ BytesAvailable()

size_t BMemoryRingIO::BytesAvailable ( )

Get the amount of data stored in the object.

Returns: The amount of bytes ready to be read from the object.

Since: Haiku R1

See also: BufferSize() for the total buffer size.; SpaceAvailable() for the amount of space left for writing in the object.

◆ Clear()

void BMemoryRingIO::Clear ( )

Discard all data in the object.

This method will discard all data within the buffer. However it does not free the memory held by the buffer. If this is desired, use in combination with SetSize() with 0 as the new capacity.

Since: Haiku R1

See also: SetSize() for freeing memory held by the buffer, or for growing the buffer's size.

◆ InitCheck()

status_t BMemoryRingIO::InitCheck ( ) const

Whether the object has been initialized correctly.

Return values

B_OK	Everything is initialized.
B_NO_INIT	The internal buffer couldn't be created or the buffer capacity is `0`.

Since: Haiku R1

◆ Read()

ssize_t BMemoryRingIO::Read	(	void *	buffer,
		size_t	size
	)

virtual

Reads data from the object into a buffer.

If the ring buffer is empty, this method blocks until some data is made available. 0 is returned if size is 0 or the buffer is empty and was set to have write disabled.

Returns: The amount of bytes read.

Return values

B_BAD_VALUE buffer is NULL

Since: Haiku R1

See also: SetWriteDisabled()

Reimplemented from BDataIO.

◆ SetSize()

status_t BMemoryRingIO::SetSize ( size_t size )

Change the ring buffer capacity.

Parameters

size	The new capacity for the ring buffer. This value will be rounded up to the nearest power of two. The new capacity must be larger or equal to BytesAvailable(). If set to `0` when there are no the bytes available to be read, the buffer will be freed.

Return values

B_OK	The operation was successful.
B_BAD_VALUE	The new capacity is smaller than BytesAvailable().
B_NO_MEMORY	Memory couldn't be allocated to grow/create the buffer. The buffer remains unchanged.

Since: Haiku R1

See also: BytesAvailable() for the amount of data to be read.

◆ SetWriteDisabled()

void BMemoryRingIO::SetWriteDisabled ( bool disabled )

Set whether writes to the ring buffer is disabled.

This method controls whether further writes to the ring buffer is allowed. If writing is disabled, any further writes will error with B_READ_ONLY_DEVICE, and read will no longer block on an empty buffer and instead return 0. In addition, WaitForRead() and WaitForWrite() will return B_READ_ONLY_DEVICE.

This method is usually used to notify the writer/reader of the pipe to not write more and/or to wait for more data.

Parameters

disabled Whether writes should be disabled.

See also: WriteDisabled() to see whether writes to the ring buffer is currently disabled.

◆ SpaceAvailable()

size_t BMemoryRingIO::SpaceAvailable ( )

Get the amount of space left in the object.

Returns: The remaining storage capacity of the object in bytes.

Since: Haiku R1

See also: BufferSize() for the total buffer size.; BytesAvailable() for the amount of data ready to be read.

◆ WaitForRead()

status_t BMemoryRingIO::WaitForRead ( bigtime_t timeout = B_INFINITE_TIMEOUT )

Wait for data to be available for reading.

This method will block the current thread until there's data ready to be Read() from the object or until timeout has been reached.

Parameters

timeout The minimum amount of time to wait in microseconds. If the value is B_INFINITE_TIMEOUT, this method will not return until data can be read from the object.

Return values

B_OK	There's data ready to be read.
B_TIMED_OUT	Timeout reached but no data has been made available.
B_READ_ONLY_DEVICE	The buffer has write disabled.

See also: Read(); SetWriteDisabled()

◆ WaitForWrite()

status_t BMemoryRingIO::WaitForWrite ( bigtime_t timeout = B_INFINITE_TIMEOUT )

Wait for space to be available for writing.

This method will block the current thread until there are storage space available for a Write() operation or until timeout has been reached.

Parameters

timeout The minimum amount of time to wait in microseconds. If the value is B_INFINITE_TIMEOUT, this method will not return until data can be written into the object.

Return values

B_OK	There's storage space to write to.
B_TIMED_OUT	Timeout reached but no additional storage space has been made available.
B_READ_ONLY_DEVICE	The buffer has write disabled.

See also: Write(); SetWriteDisabled()

◆ Write()

ssize_t BMemoryRingIO::Write	(	const void *	buffer,
		size_t	size
	)

virtual

Writes data from a buffer to the object.

If the ring buffer is full, this method blocks until some space is made available.

Returns: The amount of bytes written. If the ring buffer is filled or size is 0, 0 will be returned.

Return values

B_BAD_VALUE	`buffer` is `NULL`
B_READ_ONLY_DEVICE	Writes to the buffer has been disabled.

Since: Haiku R1

See also: SetWriteDisabled()

Reimplemented from BDataIO.

◆ WriteDisabled()

bool BMemoryRingIO::WriteDisabled ( )

Indicates whether writes to the ring buffer is disabled.

This method indicates whether further writes to the ring buffer is allowed. See SetWriteDisabled() for more information.

See also: SetWriteDisabled() to control whether writes to the ring buffer is disabled.

Returns: true if writes to the ring buffer is disabled, false if not.

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ BMemoryRingIO()

◆ ~BMemoryRingIO()

Member Function Documentation

◆ BufferSize()

◆ BytesAvailable()

◆ Clear()

◆ InitCheck()

◆ Read()

◆ SetSize()

◆ SetWriteDisabled()

◆ SpaceAvailable()

◆ WaitForRead()

◆ WaitForWrite()

◆ Write()

◆ WriteDisabled()