A base class for buffering data. More...

#include <IOStream.h>

Public Member Functions
	IOStream (IOChannel &input, size_t buflen=8192)
	Create IOStream.

virtual	~IOStream ()

size_t	available () const
	Number of bytes available to be copied from the buffer of IOStream.

bool	isNewInput () const
	Did last read(), or read(buf,len) call result in a new file being opened?

size_t	read ()
	Do an IOChannel::read into the internal buffer of IOStream.

size_t	readBuf (void *buf, size_t len) throw ()
	Copy available bytes from the internal buffer to buf, returning the number of bytes copied, which may be less then len.

size_t	read (void *buf, size_t len)
	Read len bytes of data into buf.

size_t	skip (size_t len)
	If the internal buffer is empty, do an IOChannel::read into the buffer.

size_t	backup (size_t len) throw ()
	Move the read buffer pointer backwards by len number of bytes, so that the next readBuf will return data that was previously read.

size_t	backup () throw ()
	Move the read buffer pointer backwards to the beginning of the buffer.

size_t	readUntil (void *buf, size_t len, char term)
	Read into the user buffer until a terminating character is found or len-1 bytes have been read.

size_t	write (const struct iovec *iov, int nbufs, bool flush)
	Write data.

size_t	write (const void *buf, size_t len, bool flush)

void	flush ()
	Flush buffer to physical device.

dsm_time_t	createFile (dsm_time_t t, bool exact)
	Request that IOChannel object open a new file, with a name based on a time.

const std::string &	getName () const

long long	getNumInputBytes () const
	Number of bytes read with this IOStream.

void	addNumInputBytes (int val)

long long	getNumOutputBytes () const
	Total number of bytes written with this IOStream.

void	addNumOutputBytes (int val)

Protected Member Functions
void	reallocateBuffer (size_t len)

Protected Attributes
IOChannel &	_iochannel

Private Member Functions
	IOStream (const IOStream &)
	No copying.

IOStream &	operator= (const IOStream &)
	No assignment.

Private Attributes
char *	_buffer
	data buffer

char *	_head
	where we insert bytes into the buffer

char *	_tail
	where we remove bytes from the buffer

size_t	_buflen
	The actual buffer size.

size_t	_halflen

char *	_eob
	One past end of buffer.

bool	_newInput
	Was the previous read performed on a newly opened file?

long long	_nbytesIn

long long	_nbytesOut

size_t	_nEAGAIN

Detailed Description

A base class for buffering data.

Constructor & Destructor Documentation

◆ IOStream() [1/2]

IOStream::IOStream	(	IOChannel &	input,
		size_t	buflen = 8192 )

Create IOStream.

Parameters

input	reference to an Input object providing the physical IO
buflen	length of buffer, in bytes.

References reallocateBuffer().

◆ ~IOStream()

IOStream::~IOStream ( )

virtual

References _buffer.

◆ IOStream() [2/2]

nidas::core::IOStream::IOStream ( const IOStream & )

private

No copying.

Member Function Documentation

◆ addNumInputBytes()

void nidas::core::IOStream::addNumInputBytes ( int val )

inline

References _nbytesIn, and nidas::core::getSample().

Referenced by readBuf().

◆ addNumOutputBytes()

void nidas::core::IOStream::addNumOutputBytes ( int val )

inline

References _nbytesOut, and nidas::core::getSample().

Referenced by flush(), and write().

◆ available()

size_t nidas::core::IOStream::available ( ) const

inline

Number of bytes available to be copied from the buffer of IOStream.

References _head, and _tail.

Referenced by read(), nidas::dynld::SampleInputStream::read(), read(), readBuf(), nidas::dynld::SampleInputStream::readSamples(), readUntil(), and skip().

◆ backup() [1/2]

size_t IOStream::backup	(		)
throw	(	)

Move the read buffer pointer backwards to the beginning of the buffer.

References _buffer, _tail, and backup().

Referenced by backup().

◆ backup() [2/2]

size_t IOStream::backup	(	size_t	len	)
throw	(	)

Move the read buffer pointer backwards by len number of bytes, so that the next readBuf will return data that was previously read.

This just backs over bytes in the current buffer, and does not reposition the physical device.

Returns: The number of bytes backed over, which may be less than the number requested if there are fewer than len number of bytes in the buffer.

References nidas::util::addBackslashSequences(), DLOG, nidas::core::getSample(), len, and WLOG.

Referenced by nidas::dynld::SampleInputStream::handleNewInput(), and nidas::dynld::SampleInputStream::parseInputHeader().

◆ createFile()

dsm_time_t nidas::core::IOStream::createFile	(	dsm_time_t	t,
		bool	exact )

inline

Request that IOChannel object open a new file, with a name based on a time.

Parameters

t	Time to use when creating file name.
exact	Use exact time when creating file name, else the time is truncated down to an even time interval.

Returns: Start time of next file.

Exceptions

nidas::util::IOException

References _iochannel, nidas::core::IOChannel::createFile(), and flush().

◆ flush()

void IOStream::flush ( )

Flush buffer to physical device.

This is not done automatically by the destructor - the user must call flush before destroying this IOStream.

Exceptions

nidas::util::IOException

References _buffer, _head, _iochannel, _tail, addNumOutputBytes(), nidas::core::IOChannel::flush(), nidas::core::getSample(), and nidas::core::IOChannel::write().

Referenced by createFile(), nidas::dynld::SampleOutputStream::flush(), write(), and write().

◆ getName()

const std::string & nidas::core::IOStream::getName ( ) const

inline

References _iochannel, and nidas::core::IOChannel::getName().

Referenced by reallocateBuffer(), and write().

◆ getNumInputBytes()

long long nidas::core::IOStream::getNumInputBytes ( ) const

inline

Number of bytes read with this IOStream.

References _nbytesIn.

Referenced by nidas::dynld::SampleInputStream::handleNewInput(), nidas::dynld::SampleInputStream::parseInputHeader(), nidas::dynld::SampleInputStream::readInputHeader(), and nidas::dynld::SampleInputStream::sampleFromHeader().

◆ getNumOutputBytes()

long long nidas::core::IOStream::getNumOutputBytes ( ) const

inline

Total number of bytes written with this IOStream.

References _nbytesOut.

◆ isNewInput()

bool nidas::core::IOStream::isNewInput ( ) const

inline

Did last read(), or read(buf,len) call result in a new file being opened?

References _newInput.

Referenced by nidas::dynld::SampleInputStream::read().

◆ operator=()

IOStream & nidas::core::IOStream::operator= ( const IOStream & )

private

No assignment.

◆ read() [1/2]

size_t IOStream::read ( )

Do an IOChannel::read into the internal buffer of IOStream.

Returns: number of bytes read. If there is still data in the IOStream buffer, then no physical read will be done, and a length of 0 is returned.

Exceptions

nidas::util::IOException

References _buffer, _eob, _head, _iochannel, _nbytesIn, _newInput, _tail, available(), nidas::core::getSample(), nidas::core::IOChannel::isNewInput(), nidas::core::IOChannel::read(), and VLOG.

Referenced by nidas::dynld::SampleInputStream::read(), read(), nidas::dynld::SampleInputStream::readInputHeader(), readUntil(), and skip().

◆ read() [2/2]

size_t IOStream::read	(	void *	buf,
		size_t	len )

Read len bytes of data into buf.

Returns: Number of bytes read. This will be less than len if an end of file is encountered, or if the IOChannel is configured for non-blocking reads and no data is available. This method may perform 0 or more physical reads of the IOChannel.

Exceptions

nidas::util::IOException

References _iochannel, _newInput, available(), nidas::core::getSample(), nidas::core::IOChannel::isNewInput(), len, read(), and readBuf().

◆ readBuf()

size_t nidas::core::IOStream::readBuf	(	void *	buf,
		size_t	len )
throw	(	)

inline

Copy available bytes from the internal buffer to buf, returning the number of bytes copied, which may be less then len.

An IOChannel::read() is not done, even if the internal buffer is empty.

References _tail, addNumInputBytes(), available(), nidas::core::getSample(), and len.

Referenced by nidas::dynld::SampleInputStream::read(), and read().

◆ readUntil()

size_t IOStream::readUntil	(	void *	buf,
		size_t	len,
		char	term )

Read into the user buffer until a terminating character is found or len-1 bytes have been read.

The buffer is NULL terminated.

Returns: number of bytes read, not including the NULL character. Therefore the return value will not be more than len-1. This method will do an IOChannel::read() until the termination character is found of the buffer is full. Using this method on a non-blocking device may cause a system lockup. If an IOChannel::isNewInput is encountered before the readUntil() is satisfied, then any previous contents of the buffer are discarded and the reading proceeds with the new input.

Todo: throw an exception if used with a non-blocking physical device.

Exceptions

nidas::util::IOException

References _head, _iochannel, _nbytesIn, _newInput, _tail, available(), nidas::core::getSample(), nidas::core::IOChannel::isNewInput(), len, and read().

◆ reallocateBuffer()

void IOStream::reallocateBuffer ( size_t len )

protected

References _buffer, _buflen, _eob, _halflen, _head, _tail, DLOG, getName(), nidas::core::getSample(), len, and VLOG.

Referenced by IOStream(), and write().

◆ skip()

size_t IOStream::skip ( size_t len )

If the internal buffer is empty, do an IOChannel::read into the buffer.

Then skip over len bytes in the user buffer.

Returns: number of bytes skipped. May be less than the user asked for.

Exceptions

nidas::util::IOException

References _nbytesIn, _newInput, _tail, available(), nidas::core::getSample(), len, and read().

◆ write() [1/2]

size_t IOStream::write	(	const struct iovec *	iov,
		int	nbufs,
		bool	flush )

Write data.

This supports an atomic write of data from multiple buffers into an output buffer. The write either completely succeeds (all buffers written), or completely fails (no buffers written). This prevents partial data samples from being written, and also reduces the need for copying to a temporary buffer.

Parameters

iov	Array of pointers to buffers of data to be written.
nbufs	Number of buffers, the length of iov.
flush	force a write to the physical device.

Returns: true: all data in bufs was copied to output buffer; false: no data copied because the buffer was full and the physical device is bogged down. Typically one must chuck the data and proceed.

Exceptions

nidas::util::IOException

References _buffer, _buflen, _eob, _halflen, _head, _iochannel, _nEAGAIN, _tail, addNumOutputBytes(), flush(), getName(), nidas::core::getSample(), reallocateBuffer(), WLOG, and nidas::core::IOChannel::write().

Referenced by nidas::dynld::SampleOutputStream::write(), write(), nidas::dynld::SampleOutputStream::write(), and nidas::core::SampleInputHeader::write().

◆ write() [2/2]

size_t IOStream::write	(	const void *	buf,
		size_t	len,
		bool	flush )

Exceptions

nidas::util::IOException

References flush(), nidas::core::getSample(), len, and write().

Member Data Documentation

◆ _buffer

char* nidas::core::IOStream::_buffer

private

data buffer

Referenced by backup(), flush(), read(), reallocateBuffer(), write(), and ~IOStream().

◆ _buflen

size_t nidas::core::IOStream::_buflen

private

The actual buffer size.

Referenced by reallocateBuffer(), and write().

◆ _eob

char* nidas::core::IOStream::_eob

private

One past end of buffer.

Referenced by read(), reallocateBuffer(), and write().

◆ _halflen

size_t nidas::core::IOStream::_halflen

private

Referenced by reallocateBuffer(), and write().

◆ _head

char* nidas::core::IOStream::_head

private

where we insert bytes into the buffer

Referenced by available(), flush(), read(), readUntil(), reallocateBuffer(), and write().

◆ _iochannel

IOChannel& nidas::core::IOStream::_iochannel

protected

Referenced by createFile(), flush(), getName(), read(), read(), readUntil(), and write().

◆ _nbytesIn

long long nidas::core::IOStream::_nbytesIn

private

Referenced by addNumInputBytes(), getNumInputBytes(), read(), readUntil(), and skip().

◆ _nbytesOut

long long nidas::core::IOStream::_nbytesOut

private

Referenced by addNumOutputBytes(), and getNumOutputBytes().

◆ _nEAGAIN

size_t nidas::core::IOStream::_nEAGAIN

private

Referenced by write().

◆ _newInput

bool nidas::core::IOStream::_newInput

private

Was the previous read performed on a newly opened file?

Referenced by isNewInput(), read(), read(), readUntil(), and skip().

◆ _tail

char* nidas::core::IOStream::_tail

private

where we remove bytes from the buffer

Referenced by available(), backup(), flush(), read(), readBuf(), readUntil(), reallocateBuffer(), skip(), and write().

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

nidas/core/IOStream.h
nidas/core/IOStream.cc

Public Member Functions

Protected Member Functions

Protected Attributes

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ IOStream() [1/2]

◆ ~IOStream()

◆ IOStream() [2/2]

Member Function Documentation

◆ addNumInputBytes()

◆ addNumOutputBytes()

◆ available()

◆ backup() [1/2]

◆ backup() [2/2]

◆ createFile()

◆ flush()

◆ getName()

◆ getNumInputBytes()

◆ getNumOutputBytes()

◆ isNewInput()

◆ operator=()

◆ read() [1/2]

◆ read() [2/2]

◆ readBuf()

◆ readUntil()

◆ reallocateBuffer()

◆ skip()

◆ write() [1/2]

◆ write() [2/2]

Member Data Documentation

◆ _buffer

◆ _buflen

◆ _eob

◆ _halflen

◆ _head

◆ _iochannel

◆ _nbytesIn

◆ _nbytesOut

◆ _nEAGAIN

◆ _newInput

◆ _tail