bcache::hasher_t Class Reference

A class for hashing data. More...

#include <hasher.hpp>

Classes
class	hash_t
	A helper class for storing the data hash. More...

Public Member Functions
	hasher_t (const hasher_t &other)
	Copy the hash state into a new hasher_t object. More...
hasher_t &	operator= (const hasher_t &other)
	Copy the hash state to an existing hasher_t object. More...
void	update (const void *data, const size_t size)
	Update the hash with more data. More...
void	update (const std::string &text)
	Update the hash with more data. More...
void	update (const string_list_t &data)
	Update the hash with more data. More...
void	update (const std::map< std::string, std::string > &data)
	Update the hash with more data. More...
void	update_from_file (const std::string &path)
	Update the hash with more data. More...
void	update_from_file_deterministic (const std::string &path)
	Update the hash with more data. More...
void	inject_separator ()
	Update the hash with a separator sequence. More...
hash_t	final ()
	Finalize the hash calculation. More...

Private Member Functions
void	update_from_ar_data (const std::string &data)
	Update the hash with data from an AR archive. More...

Private Attributes
void *	m_state = nullptr

Detailed Description

A class for hashing data.

Constructor & Destructor Documentation

hasher_t()

bcache::hasher_t::hasher_t

(

const hasher_t &

other

)

Copy the hash state into a new hasher_t object.

Parameters

other

The source state to be duplicated.

Member Function Documentation

final()

hasher_t::hash_t bcache::hasher_t::final

(

)

Finalize the hash calculation.

Returns

the result of the hash.

Note

This method must only be called once.

inject_separator()

void bcache::hasher_t::inject_separator

(

)

Update the hash with a separator sequence.

Injecting a separator sequence between other data items is useful for avoiding hash collisions due to similarities of adjacent elements (e.g. "hello","world" v.s. "hell","oworld").

operator=()

hasher_t & bcache::hasher_t::operator=

(

const hasher_t &

other

)

Copy the hash state to an existing hasher_t object.

Parameters

other

The source state to be duplicated.

update() [1/4]

void bcache::hasher_t::update

(

const std::map< std::string, std::string > &

data

)

Update the hash with more data.

Parameters

data	The data to hash.

update() [2/4]

void bcache::hasher_t::update ( const std::string &  text )

inline

Update the hash with more data.

Parameters

text	The data to hash.

update() [3/4]

void bcache::hasher_t::update

(

const string_list_t &

data

)

Update the hash with more data.

Parameters

data	The data to hash.

update() [4/4]

void bcache::hasher_t::update	(	const void *	data,
		const size_t	size
	)

Update the hash with more data.

Parameters

data	Pointer to the data to hash.
size	The number of bytes to hash.

update_from_ar_data()

void bcache::hasher_t::update_from_ar_data ( const std::string &  data )

private

Update the hash with data from an AR archive.

Parameters

data	The raw AR data.

update_from_file()

void bcache::hasher_t::update_from_file

(

const std::string &

path

)

Update the hash with more data.

Parameters

path	Path to a file that contains the data to hash.

Exceptions

runtime_error

if the operation could not be completed.

update_from_file_deterministic()

void bcache::hasher_t::update_from_file_deterministic

(

const std::string &

path

)

Update the hash with more data.

This method tries to produce a deterministic hash by employing file format specific heuristics to exclude things like time stamps.

Parameters

path	Path to a file that contains the data to hash.

Exceptions

runtime_error

if the operation could not be completed.

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

• base/hasher.hpp
• base/hasher.cpp