Fennel: ByteInputStream Class Reference (original) (raw)

ByteInputStream defines an interface for reading from a stream of bytes. More...

#include <[ByteInputStream.h](ByteInputStream%5F8h-source.html)>

Inheritance diagram for ByteInputStream:

Public Member Functions
uint	readBytes (void *pData, uint cbRequested)
	Reads bytes from the stream.
template
uint	readValue (T &value)
	Reads a fixed-size value from the stream.
PConstBuffer	getReadPointer (uint cbRequested, uint *pcbActual=NULL)
	Copyless alternative for reading bytes from the stream.
void	consumeReadPointer (uint cbUsed)
	Advances stream position after a call to getReadPointer.
void	seekForward (uint cb)
	Skips forward in stream.
void	seekBackward (uint cb)
	Skips backward in stream.
virtual SharedByteStreamMarker	newMarker ()
	Creates a new uninitialized marker for this stream.
virtual void	mark (ByteStreamMarker &marker)
	Marks the current stream position in preparation for a future call to reset().
virtual void	reset (ByteStreamMarker const &marker)
	Resets stream to a previously marked position.
FileSize	getOffset () const
	Returns:current offset from beginning of stream
bool	isClosed () const
	Returns:whether the object has been closed
void	close ()
	Closes this object, releasing any unallocated resources.
Protected Member Functions
	ByteInputStream ()
virtual void	readNextBuffer ()=0
	Must be implemented by derived class by calling either setBuffer or nullifyBuffer.
virtual void	readPrevBuffer ()
	Must be implemented by derived class if seekBackward is to be supported.
void	setBuffer (PConstBuffer pBuffer, uint cbBuffer)
	Sets the current buffer to be read.
void	nullifyBuffer ()
	Nullifies the current buffer, indicating no more data is available.
uint	getBytesAvailable () const
	Returns:number of bytes remaining in current buffer
uint	getBytesConsumed () const
	Returns:number of bytes already consumed from current buffer
virtual void	closeImpl ()=0
	Must be implemented by derived class to release any resources.
Protected Attributes
FileSize	cbOffset
	Byte position in stream.
bool	needsClose
Private Attributes
PConstBuffer	pFirstByte
	First buffered byte of data.
PConstBuffer	pNextByte
	Next buffered byte of data.
PConstBuffer	pEndByte
	End of buffer (one past last byte of data in buffer).

Detailed Description

ByteInputStream defines an interface for reading from a stream of bytes.

Definition at line 34 of file ByteInputStream.h.

Constructor & Destructor Documentation

| ByteInputStream::ByteInputStream | ( | | ) | [explicit, protected] | | -------------------------------- | - | | - | ----------------------- |

Member Function Documentation

| virtual void ByteInputStream::readNextBuffer | ( | | ) | [protected, pure virtual] | | -------------------------------------------- | - | | - | --------------------------- |

| void ByteInputStream::readPrevBuffer | ( | | ) | [protected, virtual] | | ------------------------------------ | - | | - | ---------------------- |

void ByteInputStream::setBuffer	(	PConstBuffer	pBuffer,
uint	cbBuffer
)	[inline, protected]

| void ByteInputStream::nullifyBuffer | ( | | ) | [inline, protected] | | ----------------------------------- | - | | - | --------------------- |

| uint ByteInputStream::getBytesAvailable | ( | | ) | const [inline, protected] | | ---------------------------------------------------------------------------------------------------- | - | | - | --------------------------- |

| uint ByteInputStream::getBytesConsumed | ( | | ) | const [inline, protected] | | --------------------------------------------------------------------------------------------------- | - | | - | --------------------------- |

uint ByteInputStream::readBytes	(	void *	pData,
uint	cbRequested
)

template

uint ByteInputStream::readValue	(	T &	value	)	[inline]

Reads a fixed-size value from the stream.

Parameters:

value	value to write; type must be memcpy-safe

Returns:

number of bytes actually read

Definition at line 112 of file ByteInputStream.h.

Referenced by FtrsTableWriterFactory::loadIndex(), LogicalTxnTest::loadParticipant(), FtrsTableWriterFactory::loadParticipant(), BTreeRecoveryFactory::loadParticipant(), TupleProjection::readPersistent(), TupleDescriptor::readPersistent(), LogicalTxnTest::redoLogicalAction(), DatabaseTest::redoLogicalAction(), LogicalTxnTest::undoLogicalAction(), and DatabaseTest::undoLogicalAction().

00113 { 00114 return readBytes(&value,sizeof(value)); 00115 }

Copyless alternative for reading bytes from the stream.

Provides direct access to the stream's internal buffer, but doesn't move the stream position (see consumeReadPointer).

Note that it is in general dangerous to assume that getReadPointer will be able to access desired data items contiguously. For example, a stream created by calling ByteOutputStream::write is likely to have data items split across buffers. The assumption MAY be valid for streams created by calling ByteOutputStream::getWritePointer with matching values for cbRequested; it depends on the stream implementation.

Parameters:

cbRequested	number of contiguous bytes to access; if a non-zero number of bytes are currently available in the buffer, cbRequested must be no greater than the number of available bytes (otherwise an assertion violation will result)
pcbActual	if non-NULL, receives actual number of contiguous bytes available, which will always be greater than or equal to cbRequested except 0 for end-of-stream

Returns:

pointer to cbActual bytes of available data, or NULL for end-of-stream

Definition at line 209 of file ByteInputStream.h.

References getBytesAvailable(), pEndByte, pNextByte, and readNextBuffer().

Referenced by BTreeWriter::deleteLogged(), BTreeWriter::insertLogged(), and BTreeBuildLevel::processInput().

void ByteInputStream::consumeReadPointer	(	uint	cbUsed	)	[inline]

void ByteInputStream::seekForward	(	uint	cb	)	[inline]

void ByteInputStream::seekBackward	(	uint	cb	)

Creates a new uninitialized marker for this stream.

The returned marker must be passed to mark() in order to initialize it.

Returns:

shared pointer to new marker

Reimplemented in SegInputStream.

Definition at line 92 of file ByteInputStream.cpp.

| FileSize ByteStream::getOffset | ( | | ) | const [inline, inherited] | | ---------------------------------------------------------------------------------- | - | | - | --------------------------- |

| virtual void ClosableObject::closeImpl | ( | | ) | [protected, pure virtual, inherited] | | -------------------------------------- | - | | - | -------------------------------------- |

Must be implemented by derived class to release any resources.

Implemented in CacheImpl< PageT, VictimPolicyT >, ByteArrayInputStream, ByteArrayOutputStream, ByteOutputStream, CheckpointThread, Database, BarrierExecStream, DoubleBufferExecStream, ExecStream, ExecStreamGraphImpl, MockResourceExecStream, ReshapeExecStream, ScratchBufferExecStream, SegBufferExecStream, SegBufferReader, SegBufferReaderExecStream, SegBufferWriter, SegBufferWriterExecStream, JavaSinkExecStream, JavaTransformExecStream, FlatFileBuffer, FlatFileExecStreamImpl, BTreeExecStream, BTreeInsertExecStream, BTreePrefetchSearchExecStream, BTreeReadExecStream, BTreeSearchExecStream, FtrsTableWriterExecStream, LhxAggExecStream, LhxJoinExecStream, LbmBitOpExecStream, LbmChopperExecStream, LbmGeneratorExecStream, LbmIntersectExecStream, LbmMinusExecStream, LbmSplicerExecStream, LbmUnionExecStream, LcsClusterAppendExecStream, LcsRowScanBaseExecStream, LcsRowScanExecStream, DelegatingSegment, DynamicDelegatingSegment, ScratchSegment, SegInputStream, Segment, SegOutputStream, SegPageBackupRestoreDevice, SegStream, SegStreamAllocation, SpillOutputStream, and ExternalSortExecStreamImpl.