libdar::compressor Class Reference

compression class for gzip and bzip2 algorithms More...

#include <compressor.hpp>

Inherits libdar::proto_compressor.

Collaboration diagram for libdar::compressor:

Public Member Functions
	compressor (compression x_algo, generic_file &compressed_side, U_I compression_level=9)
	compressor (const compressor &ref)=delete
	compressor (compressor &&ref) noexcept=delete
compressor &	operator= (const compressor &ref)=delete
compressor &	operator= (compressor &&ref) noexcept=delete
virtual compression	get_algo () const override
virtual void	suspend_compression () override
virtual void	resume_compression () override
virtual bool	is_compression_suspended () const override
virtual bool	skippable (skippability direction, const infinint &amount) override
	whether the implementation is able to skip More...
virtual bool	skip (const infinint &pos) override
	skip at the absolute position More...
virtual bool	skip_to_eof () override
	skip to the end of file
virtual bool	skip_relative (S_I x) override
	skip relatively to the current position
virtual bool	truncatable (const infinint &pos) const override
	whether the implementation is able to truncate to the given position
virtual infinint	get_position () const override
	get the current read/write position

Protected Member Functions
virtual void	inherited_read_ahead (const infinint &amount) override
	tells the object that several calls to read() will follow to probably obtain at least the given amount of data More...
virtual U_I	inherited_read (char *a, U_I size) override
	implementation of read() operation More...
virtual void	inherited_write (const char *a, U_I size) override
	implementation of the write() operation More...
virtual void	inherited_truncate (const infinint &pos) override
	truncate file at the give offset More...
virtual void	inherited_sync_write () override
	write down any pending data More...
virtual void	inherited_flush_read () override
	reset internal engine, flush caches in order to read the data at current position More...
virtual void	inherited_terminate () override
	destructor-like call, except that it is allowed to throw exceptions More...

Private Member Functions
void	flush_write ()
	drop all pending write and reset compression engine

Private Attributes
xfer *	compr
	datastructure for bzip2, gzip and zx compression (not use with compression::none
bool	read_mode
	read-only mode or write-only mode, read-write is write-only mode
generic_file *	compressed
	where to read from/write to compressed data
compression	algo
	compression algorithm used
bool	suspended
	whether compression is temporary suspended

Detailed Description

compression class for gzip and bzip2 algorithms

Definition at line 44 of file compressor.hpp.

Constructor & Destructor Documentation

compressor() [1/2]

libdar::compressor::compressor	(	compression	x_algo,
		generic_file &	compressed_side,
		U_I	compression_level = 9
	)

Parameters

x_algo	only gzip, bzip2, xz and none are supported by this class
compressed_side	where to read from/write to compressed data
compression_level	compression level 1..9

compressor() [2/2]

libdar::compressor::compressor ( const compressor &  ref )

delete

Note

compressed_side is not owned by the object and will remains (and must survive) upt to this compressor objet destruction

Member Function Documentation

inherited_flush_read()

virtual void libdar::compressor::inherited_flush_read ( )

overrideprotectedvirtual

reset internal engine, flush caches in order to read the data at current position

Note

when the object relies on external object or system object to fetch the data from for reading, when a call to (inherited_)flush_read() occurs, the current object must not assume that any previously read data is still valid if it has internal buffers or the like and it should flush them asap. This call must not propagate the flush_read to any other gneric_file object it could rely on

Implements libdar::generic_file.

Referenced by skip(), skip_relative(), and skip_to_eof().

inherited_read()

virtual U_I libdar::compressor::inherited_read ( char *  a, U_I  size  )

overrideprotectedvirtual

implementation of read() operation

Parameters

[in,out]	a	where to put the data to read
[in]	size	says how much data to read

Returns

the exact amount of data read and put into 'a'

Note

read as much byte as requested, up to end of file stays blocked if not enough data is available and EOF not yet met. May return less data than requested only if EOF as been reached. in other worlds, EOF is reached when returned data is stricly less than the requested data Any problem shall be reported by throwing an exception.

Implements libdar::generic_file.

inherited_read_ahead()

virtual void libdar::compressor::inherited_read_ahead ( const infinint &  amount )

inlineoverrideprotectedvirtual

tells the object that several calls to read() will follow to probably obtain at least the given amount of data

Parameters

[in]

amount

is the maximum expected amount of data that is known to be read

Note

this call may be implemented as a do-nothing call, its presence is only to allow optimization when possible, like in multi-threaded environment

Implements libdar::generic_file.

Definition at line 79 of file compressor.hpp.

References compressed, and libdar::generic_file::read_ahead().

inherited_sync_write()

virtual void libdar::compressor::inherited_sync_write ( )

overrideprotectedvirtual

write down any pending data

Note

called after sanity checks from generic_file::sync_write() this method's role is to write down any data pending for writing in the current object it has not to be propagated to other gneric_file object this object could rely on

Implements libdar::generic_file.

Referenced by skip(), skip_relative(), and skip_to_eof().

inherited_terminate()

virtual void libdar::compressor::inherited_terminate ( )

overrideprotectedvirtual

destructor-like call, except that it is allowed to throw exceptions

Note

this method must never be called directly but using terminate() instead, generic_file class manages it to never be called more than once

Implements libdar::generic_file.

inherited_truncate()

virtual void libdar::compressor::inherited_truncate ( const infinint &  pos )

overrideprotectedvirtual

truncate file at the give offset

Note

if pos is greater than the current file size, this call may do nothing (not even enlarging the file)

this call should always fail on a read-only generic_file

implementation must throw exception if truncate is not possible for other reason than read/write access mode

Implements libdar::generic_file.

inherited_write()

virtual void libdar::compressor::inherited_write ( const char *  a, U_I  size  )

overrideprotectedvirtual

implementation of the write() operation

Parameters

[in]	a	what data to write
[in]	size	amount of data to write

Note

must either write all data or report an error by throwing an exception

Implements libdar::generic_file.

skip()

virtual bool libdar::compressor::skip ( const infinint &  pos )

inlineoverridevirtual

skip at the absolute position

Parameters

[in]

pos

the offset in byte where next read/write operation must start

Returns

true if operation was successfull and false if the requested position is not valid (after end of file)

Note

if requested position is not valid the reading/writing cursor must be set to the closest valid position

Implements libdar::generic_file.

Definition at line 72 of file compressor.hpp.

References compressed, inherited_flush_read(), inherited_sync_write(), and libdar::generic_file::skip().

skippable()

virtual bool libdar::compressor::skippable ( skippability  direction, const infinint &  amount  )

inlineoverridevirtual

whether the implementation is able to skip

Note

the capability to skip does not mean that skip_relative() or skip() will succeed, but rather that the inherited class implementation does not by construction forbid the requested skip (like inherited class providing a generic_file interface of an anonymous pipe for example)

Implements libdar::generic_file.

Definition at line 71 of file compressor.hpp.

References compressed, and libdar::generic_file::skippable().

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

• compressor.hpp