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Public Member Functions | Protected Member Functions | Private Member Functions | Private Attributes | List of all members
libdar::compressor Class Reference

compression class for gzip and bzip2 algorithms More...

#include <compressor.hpp>

Inherits libdar::generic_file.

Public Member Functions

 compressor (compression algo, generic_file &compressed_side, U_I compression_level=9)
 
 compressor (compression algo, generic_file *compressed_side, U_I compression_level=9)
 
 compressor (const compressor &ref)=delete
 
 compressor (compressor &&ref)=delete
 
compressoroperator= (const compressor &ref)=delete
 
compressoroperator= (compressor &&ref)=delete
 
compression get_algo () const
 
void suspend_compression ()
 
void resume_compression ()
 
bool is_compression_suspended () const
 
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 infinint get_position () const override
 get the current read/write position
 
- Public Member Functions inherited from libdar::generic_file
 generic_file (gf_mode m)
 main constructor
 
 generic_file (const generic_file &ref)
 copy constructor
 
 generic_file (generic_file &&ref) noexcept
 move constructor
 
generic_fileoperator= (const generic_file &ref)
 assignment operator
 
generic_fileoperator= (generic_file &&ref) noexcept
 move operator
 
 ~generic_file () noexcept(false)
 virtual destructor, More...
 
void terminate ()
 destructor-like call, except that it is allowed to throw exceptions
 
bool operator== (generic_file &ref)
 
bool operator!= (generic_file &ref)
 
gf_mode get_mode () const
 retreive the openning mode for this object
 
void read_ahead (const infinint &amount)
 
void ignore_read_ahead (bool mode)
 
virtual U_I read (char *a, U_I size) override
 read data from the generic_file inherited from proto_generic_file
 
virtual void write (const char *a, U_I size) override
 write data to the generic_file inherited from proto_generic_file
 
void write (const std::string &arg)
 write a string to the generic_file More...
 
S_I read_back (char &a)
 skip back one char, read on char and skip back one char
 
S_I read_forward (char &a)
 read one char
 
virtual void copy_to (generic_file &ref)
 copy all data from current position to the object in argument
 
virtual void copy_to (generic_file &ref, const infinint &crc_size, crc *&value)
 copy all data from the current position to the object in argument and computes a CRC value of the transmitted data More...
 
U_32 copy_to (generic_file &ref, U_32 size)
 small copy (up to 4GB) with CRC calculation
 
infinint copy_to (generic_file &ref, infinint size)
 copy the given amount to the object in argument
 
bool diff (generic_file &f, const infinint &me_read_ahead, const infinint &you_read_ahead, const infinint &crc_size, crc *&value)
 compares the contents with the object in argument More...
 
bool diff (generic_file &f, const infinint &me_read_ahead, const infinint &you_read_ahead, const infinint &crc_size, crc *&value, infinint &err_offset)
 
void reset_crc (const infinint &width)
 reset CRC on read or writen data More...
 
bool crc_status () const
 to known whether CRC calculation is activated or not
 
crcget_crc ()
 get CRC of the transfered date since last reset More...
 
void sync_write ()
 write any pending data
 
void flush_read ()
 be ready to read at current position, reseting all pending data for reading, cached and in compression engine for example
 
- Public Member Functions inherited from libdar::proto_generic_file
 proto_generic_file (const proto_generic_file &ref)=default
 copy constructor
 
 proto_generic_file (proto_generic_file &&ref) noexcept=default
 move constructor
 
proto_generic_fileoperator= (const proto_generic_file &ref)=default
 assignment operator
 
proto_generic_fileoperator= (proto_generic_file &&ref) noexcept=default
 move operator
 
virtual ~proto_generic_file () noexcept(false)
 virtual destructor More...
 

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_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...
 
- Protected Member Functions inherited from libdar::generic_file
void set_mode (gf_mode x)
 
bool is_terminated () const
 

Private Member Functions

void init (compression algo, generic_file *compressed_side, U_I compression_level)
 
void local_terminate ()
 
U_I none_read (char *a, U_I size)
 
U_I gzip_read (char *a, U_I size)
 
U_I lzo_read (char *a, U_I size)
 
void none_write (const char *a, U_I size)
 
void gzip_write (const char *a, U_I size)
 
void lzo_write (const char *a, U_I size)
 
void lzo_compress_buffer_and_write ()
 
void lzo_read_and_uncompress_to_buffer ()
 
void change_algo (compression new_algo, U_I new_compression_level)
 changes compression algorithm used by the compressor More...
 
void change_algo (compression new_algo)
 changes the compression algorithm keeping the same compression level
 
void compr_flush_write ()
 
void compr_flush_read ()
 
void clean_read ()
 
void clean_write ()
 

Private Attributes

xfer * compr
 
xfer * decompr
 datastructure for bzip2 an gzip compression
 
char * lzo_read_buffer
 stores clear data (uncompressed) read from the compressed generic_file
 
char * lzo_write_buffer
 stores the clear data to be compressed and written to the compressed generic_file
 
U_I lzo_read_size
 number of available bytes in the read buffer for lzo decompression
 
U_I lzo_write_size
 number of available bytes to compress and next place where to add more data in the wite buffer
 
U_I lzo_read_start
 location of the next byte to read out from the read buffer
 
bool lzo_write_flushed
 whether write flushing has been done
 
bool lzo_read_reached_eof
 whether reading reached end of file and the lzo engine has to be reset to uncompress further data
 
char * lzo_compressed
 compressed data just read or about to be written
 
char * lzo_wrkmem
 work memory for LZO library
 
generic_filecompressed
 
bool compressed_owner
 
compression current_algo
 
bool suspended
 
compression suspended_compr
 
U_I current_level
 
U_I(compressor::* read_ptr )(char *a, U_I size)
 
void(compressor::* write_ptr )(const char *a, U_I size)
 

Additional Inherited Members

- Public Types inherited from libdar::generic_file
enum  skippability { skip_backward, skip_forward }
 

Detailed Description

compression class for gzip and bzip2 algorithms

Definition at line 45 of file compressor.hpp.

Member Function Documentation

◆ change_algo()

void libdar::compressor::change_algo ( compression  new_algo,
U_I  new_compression_level 
)
private

changes compression algorithm used by the compressor

Parameters
[in]new_algodefines the new algorithm to use
[in]new_compression_leveldefines the new compression level to use.
Note
valid value for new_compression_level range from 0 (no compression) to 9 (maximum compression).

Referenced by change_algo().

◆ inherited_flush_read()

virtual void libdar::compressor::inherited_flush_read ( )
inlineoverrideprotectedvirtual

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.

Definition at line 81 of file compressor.hpp.

◆ inherited_read()

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

implementation of read() operation

Parameters
[in,out]awhere to put the data to read
[in]sizesays 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.

Definition at line 78 of file compressor.hpp.

◆ 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]amountis 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 77 of file compressor.hpp.

References libdar::generic_file::read_ahead().

◆ inherited_sync_write()

virtual void libdar::compressor::inherited_sync_write ( )
inlineoverrideprotectedvirtual

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.

Definition at line 80 of file compressor.hpp.

◆ inherited_terminate()

virtual void libdar::compressor::inherited_terminate ( )
inlineoverrideprotectedvirtual

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.

Definition at line 82 of file compressor.hpp.

◆ inherited_write()

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

implementation of the write() operation

Parameters
[in]awhat data to write
[in]sizeamount of data to write
Note
must either write all data or report an error by throwing an exception

Implements libdar::generic_file.

Definition at line 79 of file compressor.hpp.

◆ skip()

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

skip at the absolute position

Parameters
[in]posthe 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 71 of file compressor.hpp.

References 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 70 of file compressor.hpp.

References libdar::generic_file::skippable().


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