A base class for buffering data. More...

#include <IOStream.h>

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

virtual	~IOStream ()

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

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

size_t	read () throw (nidas::util::IOException)
	Do an IOChannel::read into the internal buffer of IOStream. More...

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. More...

size_t	read (void *buf, size_t len) throw (nidas::util::IOException)
	Read len bytes of data into buf. More...

size_t	skip (size_t len) throw (nidas::util::IOException)
	If the internal buffer is empty, do an IOChannel::read into the buffer. More...

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. More...

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

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

size_t	write (const struct iovec *iov, int nbufs, bool flush) throw (nidas::util::IOException)
	Write data. More...

size_t	write (const void *buf, size_t len, bool flush) throw (nidas::util::IOException)

void	flush () throw (nidas::util::IOException)
	Flush buffer to physical device. More...

dsm_time_t	createFile (dsm_time_t t, bool exact) throw (nidas::util::IOException)
	Request that IOChannel object open a new file, with a name based on a time. More...

const std::string &	getName () const

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

void	addNumInputBytes (int val)

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

void	addNumOutputBytes (int val)

Protected Member Functions
void	reallocateBuffer (size_t len)

Protected Attributes
IOChannel &	_iochannel

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

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

Private Attributes
char *	_buffer
	data buffer More...

char *	_head
	where we insert bytes into the buffer More...

char *	_tail
	where we remove bytes from the buffer More...

size_t	_buflen
	The actual buffer size. More...

size_t	_halflen

char *	_eob
	One past end of buffer. More...

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

long long	_nbytesIn

long long	_nbytesOut

size_t	_nEAGAIN

Detailed Description

A base class for buffering data.

Constructor & Destructor Documentation

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 ( )

virtual

References _buffer.

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

private

No copying.

Member Function Documentation

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

inline

References _nbytesIn.

Referenced by readBuf().

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

inline

References _nbytesOut.

Referenced by flush().

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(), readBuf(), nidas::dynld::SampleInputStream::readSamples(), and HeaderUtil::run().

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, len, and WLOG.

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

size_t IOStream::backup	(	)
throw	(
	)

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

References _buffer, and _tail.

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

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.

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

void IOStream::flush	(		)
throw	(	nidas::util::IOException
	)

Flush buffer to physical device.

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

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

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

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

inline

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

Referenced by reallocateBuffer().

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().

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

inline

Total number of bytes written with this IOStream.

References _nbytesOut.

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().

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

private

No assignment.

size_t IOStream::read	(		)
throw	(	nidas::util::IOException
	)

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.

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

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

size_t IOStream::read	(	void *	buf,
		size_t	len
	)
throw	(	nidas::util::IOException
	)

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.

References len.

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(), and len.

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

size_t IOStream::readUntil	(	void *	buf,
		size_t	len,
		char	term
	)
throw	(	nidas::util::IOException
	)

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.

References len.

void IOStream::reallocateBuffer ( size_t len )

protected

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

Referenced by IOStream().

size_t IOStream::skip	(	size_t	len	)
throw	(	nidas::util::IOException
	)

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.

References len.

Referenced by HeaderUtil::run().

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

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.

References nidas::util::Exception::getErrno(), and WLOG.

Referenced by WriterThread::run().