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Public Types | Public Member Functions | Protected Member Functions | Private Member Functions | Private Attributes | List of all members
libdar::generic_file Class Referenceabstract

this is the interface class from which all other data transfer classes inherit More...

#include <generic_file.hpp>

+ Inheritance diagram for libdar::generic_file:
+ Collaboration diagram for libdar::generic_file:

Public Types

enum  skippability { skip_backward , skip_forward }
 

Public Member Functions

 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 bool skippable (skippability direction, const infinint &amount)=0
 whether the implementation is able to skip More...
 
virtual bool skip (const infinint &pos)=0
 skip at the absolute position More...
 
virtual bool skip_to_eof ()=0
 skip to the end of file
 
virtual bool skip_relative (S_I x)=0
 skip relatively to the current position
 
virtual bool truncatable (const infinint &pos) const =0
 whether the implementation is able to truncate to the given position
 
virtual void truncate (const infinint &pos)
 truncate file at the given offset More...
 
virtual infinint get_position () const =0
 get the current read/write position
 
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

void set_mode (gf_mode x)
 
virtual void inherited_read_ahead (const infinint &amount)=0
 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)=0
 implementation of read() operation More...
 
virtual void inherited_write (const char *a, U_I size)=0
 implementation of the write() operation More...
 
virtual void inherited_truncate (const infinint &pos)=0
 truncate file at the give offset More...
 
virtual void inherited_sync_write ()=0
 write down any pending data More...
 
virtual void inherited_flush_read ()=0
 reset internal engine, flush caches in order to read the data at current position More...
 
virtual void inherited_terminate ()=0
 destructor-like call, except that it is allowed to throw exceptions More...
 
bool is_terminated () const
 

Private Member Functions

void enable_crc (bool mode)
 
U_I read_crc (char *a, U_I size)
 
void write_crc (const char *a, U_I size)
 
void destroy ()
 
void nullifyptr () noexcept
 
void copy_from (const generic_file &ref)
 
void move_from (generic_file &&ref) noexcept
 

Private Attributes

gf_mode rw
 
crcchecksum
 
bool terminated
 
bool no_read_ahead
 
U_I(generic_file::* active_read )(char *a, U_I size)
 
void(generic_file::* active_write )(const char *a, U_I size)
 

Detailed Description

this is the interface class from which all other data transfer classes inherit

it provides mainly read and write operations, skip operations and few other functions.

Note
the read and write method are similar to the read and write system calls except that they never return negative values, but throw exception instead. returning zero means end of generic_file. The call is blocked if no data is available for reading. write returns the number of bytes written, and never make partial writtings. Thus, it is blocked until all bytes are written or occures an exception inconsequences the returned value is always the value of the argument "size".

Definition at line 76 of file generic_file.hpp.

Constructor & Destructor Documentation

◆ ~generic_file()

libdar::generic_file::~generic_file ( )
inlinenoexcept

virtual destructor,

Note
this let inherited destructor to be called even from a generic_file pointer to an inherited class

Definition at line 97 of file generic_file.hpp.

Member Function Documentation

◆ copy_to()

virtual void libdar::generic_file::copy_to ( generic_file ref,
const infinint crc_size,
crc *&  value 
)
virtual

copy all data from the current position to the object in argument and computes a CRC value of the transmitted data

Parameters
[in]refdefines where to copy the data to
[in]crc_sizetell the width of the crc to compute on the copied data
[out]valuepoints to a newly allocated crc object containing the crc value
Note
value has to be deleted by the caller when no more needed

Reimplemented in libdar::pile.

◆ diff() [1/2]

bool libdar::generic_file::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

Parameters
[in]fis the file to compare the current object with
[in]me_read_aheadis the amount of data to read ahead from "*this" (0 for no limit, up to end of eof)
[in]you_read_aheadis the amount of data to read ahead from f (0 for no limit, up to end of file
[in]crc_sizeis the width of the CRC to use for calculation
[out]valueis the computed checksum, its value can be used for additional testing if this method returns false (no difference between files). The given checksum has to be set to the expected width by the caller.
Returns
true if arg differ from "this"
Note
value has to be deleted by the caller when no more needed
the more simple operator == method may be prefered to diff() when no crc calculation is required

◆ diff() [2/2]

bool libdar::generic_file::diff ( generic_file f,
const infinint me_read_ahead,
const infinint you_read_ahead,
const infinint crc_size,
crc *&  value,
infinint err_offset 
)

compare the contents with the object in argument, also providing the offset of the first difference met

Parameters
[in]fis the file to compare the current object with
[in]me_read_aheadis the amount of data to read ahead from "*this" (0 for no limit, up to end of eof)
[in]you_read_aheadis the amount of data to read ahead from f (0 for no limit, up to end of file
[in]crc_sizeis the width of the CRC to use for calculation
[out]valueis the computed checksum, its value can be used for additional
[out]err_offsetin case of difference, holds the offset of the first difference met testing if this method returns false (no difference between files). The given checksum has to be set to the expected width by the caller.
Returns
true if arg differ from "this", else false is returned and err_offset is set
Note
value has to be deleted by the caller when no more needed
the more simple operator == method may be prefered to diff() when no crc calculation is required

◆ get_crc()

crc* libdar::generic_file::get_crc ( )

get CRC of the transfered date since last reset

Returns
a newly allocated crc object, that the caller has the responsibility to delete
Note
does also ends checksum calculation, which if needed again have to be re-enabled calling reset_crc() method

◆ ignore_read_ahead()

void libdar::generic_file::ignore_read_ahead ( bool  mode)
inline

ignore read ahead requests

Parameters
[in]modeif set to true read_ahead requests are ignored: inherited_read_ahead() of the inherited class is not called
Note
read_ahead is useful in multi-thread environement when a slave thread can work in advanced and asynchronously to provide read content to reader thread. However, read_ahead is a waste of CPU cycle for in a single threading model

Definition at line 123 of file generic_file.hpp.

◆ inherited_flush_read()

virtual void libdar::generic_file::inherited_flush_read ( )
protectedpure virtual

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

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

◆ inherited_read()

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

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.

Implemented in libdar::zapette, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::generic_rsync, libdar::fichier_global, libdar::compressor_zstd, libdar::compressor, and libdar::cache.

◆ inherited_read_ahead()

virtual void libdar::generic_file::inherited_read_ahead ( const infinint amount)
protectedpure virtual

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

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

◆ inherited_sync_write()

virtual void libdar::generic_file::inherited_sync_write ( )
protectedpure virtual

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

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

◆ inherited_terminate()

virtual void libdar::generic_file::inherited_terminate ( )
protectedpure virtual

◆ inherited_truncate()

virtual void libdar::generic_file::inherited_truncate ( const infinint pos)
protectedpure virtual

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

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

◆ inherited_write()

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

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

Implemented in libdar::zapette, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::memory_file, libdar::generic_rsync, libdar::fichier_global, libdar::compressor_zstd, libdar::compressor, libdar::cache, and libdar::null_file.

◆ is_terminated()

bool libdar::generic_file::is_terminated ( ) const
inlineprotected

◆ operator==()

bool libdar::generic_file::operator== ( generic_file ref)

compaire the object content (implies skipping and reading)

Note
this is a more simple method than diff()

◆ read_ahead()

void libdar::generic_file::read_ahead ( const infinint amount)

read ahead information

Parameters
[in]amountis the expected amount of data the caller will read, if zero is given the object shall prepare as much as possible data for reading until a skip request, write request or a new read_ahead request
Note
after sanity checks, the protected inherited_read_ahead() method is called

Referenced by libdar::cache_global::inherited_read_ahead(), libdar::compressor::inherited_read_ahead(), libdar::compressor_zstd::inherited_read_ahead(), libdar::hash_fichier::inherited_read_ahead(), libdar::trivial_sar::inherited_read_ahead(), and libdar::tuyau_global::inherited_read_ahead().

◆ reset_crc()

void libdar::generic_file::reset_crc ( const infinint width)

reset CRC on read or writen data

Parameters
[in]widthis the width to use for the CRC

◆ skip()

virtual bool libdar::generic_file::skip ( const infinint pos)
pure virtual

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

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

Referenced by libdar::compressor::skip(), libdar::compressor_zstd::skip(), and libdar::generic_to_global_file::skip().

◆ skippable()

virtual bool libdar::generic_file::skippable ( skippability  direction,
const infinint amount 
)
pure virtual

◆ truncate()

virtual void libdar::generic_file::truncate ( const infinint pos)
virtual

truncate file at the given offset

Parameters
[in]posis the offset of the where to cut the file, in other word the pos - 1 will be the last byte of the file (if its size is greater than 1). If pos is greater than EOF the implementation should not enlarge the file and may even no skip the file to its current eof. Though this request is not considered an error implementation can thus do nothing when asked to truncate after EOF.
Note
running this call on a read-only object will always yeld an exception
if current file position is after the point to truncate, implementation has to skip back the current writing offset to the new end of file.
implementation of backward skippability and truncate operation should be coherent: If its not possible to skip backward it should not be possible to truncate the file to this position. If truncate a file to requested position is not possible, it should not be possible to skip backward to that position. This truncatable() with the skip_backward direction should indicate whether the truncate() action will succeed or generate an exception

Referenced by libdar::cache_global::inherited_truncate(), libdar::generic_to_global_file::inherited_truncate(), libdar::trivial_sar::inherited_truncate(), and libdar::tuyau_global::inherited_truncate().

◆ write()

void libdar::generic_file::write ( const std::string &  arg)

write a string to the generic_file

Note
throws a exception if not all data could be written as expected

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