Key string class which can represent a few special values. More...

#include <w_key.h>

Public Member Functions
	w_keystr_t ()

	w_keystr_t (const w_keystr_t &r)

w_keystr_t &	operator= (const w_keystr_t &r)

	~w_keystr_t ()

bool	construct_regularkey (const void *nonkeystr, w_keystr_len_t length)

bool	construct_neginfkey ()

bool	construct_posinfkey ()

bool	construct_from_keystr (const void *keystr, w_keystr_len_t length)

bool	construct_from_keystr (const void keystr_prefix, w_keystr_len_t prefix_length, const void keystr_suffix, w_keystr_len_t suffix_length)

bool	construct_from_keystr_poormkey_16 (const void keystr_prefix, w_keystr_len_t prefix_length, w_keystr_len_t total_suffix_length, uint16_t poormkey, const void keystr_suffix)

bool	construct_from_vec (const cvec_t &vect)

bool	copy_from_vec (const cvec_t &vect)

bool	is_constructed () const

bool	is_neginf () const

bool	is_posinf () const

bool	is_regular () const

w_keystr_len_t	common_leading_bytes (const w_keystr_t &r) const

w_keystr_len_t	common_leading_bytes (const unsigned char *str, w_keystr_len_t len) const

int	compare (const w_keystr_t &r) const

int	compare_keystr (const void *keystr, w_keystr_len_t length) const

int	compare_nonkeystr (const void *nonkeystr, w_keystr_len_t length) const

bool	operator== (const w_keystr_t &r) const

bool	operator!= (const w_keystr_t &r) const

bool	operator< (const w_keystr_t &r) const

bool	operator> (const w_keystr_t &r) const

bool	operator<= (const w_keystr_t &r) const

bool	operator>= (const w_keystr_t &r) const

void	serialize_as_nonkeystr (void *buffer) const

std::basic_string< unsigned char >	serialize_as_nonkeystr () const

w_keystr_len_t	get_length_as_nonkeystr () const

void	serialize_as_keystr (void *buffer) const

const void *	buffer_as_keystr () const

w_keystr_len_t	get_length_as_keystr () const

void	clear ()

Static Public Member Functions
static w_keystr_len_t	common_leading_bytes (const unsigned char str1, w_keystr_len_t len1, const unsigned char str2, w_keystr_len_t len2)

static int	compare_bin_str (const void str1, int len1, const void str2, int len2)

Private Member Functions
void	_assure (w_keystr_len_t required_len)

Private Attributes
unsigned char *	_data

uint32_t	_strlen

uint32_t	_memlen

Friends
class	w_keystr_t_test

std::ostream &	operator<< (std::ostream &, const w_keystr_t &v)

Detailed Description

Key string class which can represent a few special values.

This class differs from vec_t/cvec_t mainly for two points.

First, w_keystr_t keeps its copy of string data like std::string. vec_t/cvec_t just keeps pointers to original data, which is efficient but cannot be used for some cases. For example, when the original data is being changed.

Second, w_keystr_t represents a few special values, NULL, Infimum and Supremum both as on-memory data and on-disk data. vec_t/cvec_t loses neg_inf/pos_inf information when it's written out to disk. As we need to store infimum/supremum in B+Tree fence keys, we need a new class to store key data.

In sum, when you just want on-memory data representation, use vec_t/cvec_t. When you need to represent a key to be stored on disk, or to be compared with other keys on disk, use this class.

This is a tiny header-only class. All functions are defined here.

Constructor & Destructor Documentation

§ w_keystr_t() [1/2]

w_keystr_t::w_keystr_t ( )

inline

This class provides only this empty constructor and copy constructor from another w_keystr_t. This is by design to prohibit incorrect use. Explicitly use construct_regularkey()/construct_from_keystr() to make sure if the input already has sign bytes.

§ w_keystr_t() [2/2]

w_keystr_t::w_keystr_t ( const w_keystr_t & r )

inline

§ ~w_keystr_t()

w_keystr_t::~w_keystr_t ( )

inline

Member Function Documentation

§ _assure()

void w_keystr_t::_assure ( w_keystr_len_t required_len )

inlineprivate

re-allocate _data for required length if needed.

§ buffer_as_keystr()

const void * w_keystr_t::buffer_as_keystr ( ) const

inline

Returns the internal content WITH sign byte of this key string.

§ clear()

void w_keystr_t::clear ( )

inline

discards all data and releases all resources.

§ common_leading_bytes() [1/3]

w_keystr_len_t w_keystr_t::common_leading_bytes ( const w_keystr_t & r ) const

inline

Returns the count of common leading bytes with the given key string.

§ common_leading_bytes() [2/3]

w_keystr_len_t w_keystr_t::common_leading_bytes	(	const unsigned char *	str,
		w_keystr_len_t	len
	)		const

inline

Returns the count of common leading bytes with the given key string.

§ common_leading_bytes() [3/3]

w_keystr_len_t w_keystr_t::common_leading_bytes	(	const unsigned char *	str1,
		w_keystr_len_t	len1,
		const unsigned char *	str2,
		w_keystr_len_t	len2
	)

inlinestatic

Returns the count of common leading bytes in the two given strings.

§ compare()

int w_keystr_t::compare ( const w_keystr_t & r ) const

inline

Compares this string with another w_keystr_t object.

Parameters

[in] r another string to compare with

Returns: 0 if equal. <0 if this<r, >0 if this>r

§ compare_bin_str()

int w_keystr_t::compare_bin_str	(	const void *	str1,
		int	len1,
		const void *	str2,
		int	len2
	)

inlinestatic

Compares two strings.

Returns: 0 if equal in string and length. <0 if str1<str2 OR str1=str2 and len1<len2, >0 therwise.

§ compare_keystr()

int w_keystr_t::compare_keystr	(	const void *	keystr,
		w_keystr_len_t	length
	)		const

inline

Compares this string with a string data WITH sign byte which should be a serialized w_keystr_t.

Parameters

[in]	keystr	another string data WITH sign byte to compare with
[in]	length	length of the `keystr`

Returns: 0 if equal. <0 if this<r, >0 if this>r

§ compare_nonkeystr()

int w_keystr_t::compare_nonkeystr	(	const void *	nonkeystr,
		w_keystr_len_t	length
	)		const

inline

Compares this string with a string data WITH sign byte which should be a serialized w_keystr_t. Note that non-key string can't represent infinity.

Parameters

[in]	nonkeystr	another non-key string data WITH sign byte to compare with
[in]	length	length of the `nonkeystr`

Returns: 0 if equal. <0 if this<r, >0 if this>r

§ construct_from_keystr() [1/2]

bool w_keystr_t::construct_from_keystr	(	const void *	keystr,
		w_keystr_len_t	length
	)

inline

Constructs from a key string WITH sign byte.

Parameters

keystr	The string WITH sign byte.
length	The length WITH sign byte.

See also: construct_regularkey (const void *, w_keystr_len_t)

§ construct_from_keystr() [2/2]

bool w_keystr_t::construct_from_keystr	(	const void *	keystr_prefix,
		w_keystr_len_t	prefix_length,
		const void *	keystr_suffix,
		w_keystr_len_t	suffix_length
	)

inline

Used when the key string consists of prefix and suffix.

§ construct_from_keystr_poormkey_16()

bool w_keystr_t::construct_from_keystr_poormkey_16	(	const void *	keystr_prefix,
		w_keystr_len_t	prefix_length,
		w_keystr_len_t	total_suffix_length,
		uint16_t	poormkey,
		const void *	keystr_suffix
	)

inline

Used when the key string consists of prefix, poor-man's key and suffix.

Parameters

total_suffix_length key length including poorman's key and suffix. Note that this might be smaller than sizeof(poormkey)! E.g., total_suffix_length=1: returns prefix and only the first byte of poormkey.

§ construct_from_vec()

bool w_keystr_t::construct_from_vec ( const cvec_t & vect )

Construct from cvec_t. This is implemented in vec_t.cpp. So, link to libcommon if you want to use this method.

§ construct_neginfkey()

bool w_keystr_t::construct_neginfkey ( )

inline

Creates an object that represents negative infinity.

§ construct_posinfkey()

bool w_keystr_t::construct_posinfkey ( )

inline

Creates an object that represents positive infinity.

§ construct_regularkey()

bool w_keystr_t::construct_regularkey	(	const void *	nonkeystr,
		w_keystr_len_t	length
	)

inline

Constructs from a general string without sign byte. Use this method to convert user inputs to a keystr object. Do NOT use this method to copy from other keystr object. You will duplicate the sign byte and mess up all comparisons! To copy from existing keystr object, just use copy constructor or assignment operator.

Usage Example:

w_keystr_t str1;
str1.construct_regularkey ("your_key", 8);

Parameters

nonkeystr	The string WITHOUT sign byte.
length	The length WITHOUT sign byte.

Returns: whether this object is constructed. false if out-of-memory.

See also: construct_from_keystr (const void *, w_keystr_len_t)

§ copy_from_vec()

bool w_keystr_t::copy_from_vec ( const cvec_t & vect )

Copy data from cvec_t without inserting the type byte. This is implemented in vec_t.cpp. So, link to libcommon if you want to use this method.

§ get_length_as_keystr()

w_keystr_len_t w_keystr_t::get_length_as_keystr ( ) const

inline

length of this string WITH sign byte.

§ get_length_as_nonkeystr()

w_keystr_len_t w_keystr_t::get_length_as_nonkeystr ( ) const

inline

length of this string WITHOUT sign byte.

§ is_constructed()

bool w_keystr_t::is_constructed ( ) const

inline

This class does NOT throw exceptions on out-of-memory. Use this function to check if it's constructed.

Returns: whether this object is constructed. false if out-of-memory.

§ is_neginf()

bool w_keystr_t::is_neginf ( ) const

inline

Returns if this object represents negative infinity.

§ is_posinf()

bool w_keystr_t::is_posinf ( ) const

inline

Returns if this object represents positive infinity.

§ is_regular()

bool w_keystr_t::is_regular ( ) const

inline

Returns if this object represents non-inifinity value.

§ operator!=()

bool w_keystr_t::operator!= ( const w_keystr_t & r ) const

inline

§ operator<()

bool w_keystr_t::operator< ( const w_keystr_t & r ) const

inline

§ operator<=()

bool w_keystr_t::operator<= ( const w_keystr_t & r ) const

inline

§ operator=()

w_keystr_t & w_keystr_t::operator= ( const w_keystr_t & r )

inline

§ operator==()

bool w_keystr_t::operator== ( const w_keystr_t & r ) const

inline

operator overloads.

§ operator>()

bool w_keystr_t::operator> ( const w_keystr_t & r ) const

inline

§ operator>=()

bool w_keystr_t::operator>= ( const w_keystr_t & r ) const

inline

§ serialize_as_keystr()

void w_keystr_t::serialize_as_keystr ( void * buffer ) const

inline

Copy the string data of this object to the given buffer WITH sign byte.

§ serialize_as_nonkeystr() [1/2]

void w_keystr_t::serialize_as_nonkeystr ( void * buffer ) const

inline

Copy the string data of this object to the given buffer WITHOUT sign byte.

§ serialize_as_nonkeystr() [2/2]

std::basic_string< unsigned char > w_keystr_t::serialize_as_nonkeystr ( ) const

inline

For convenience. Returns std::string object.

Friends And Related Function Documentation

§ operator<<

std::ostream& operator<<	(	std::ostream &	o,
		const w_keystr_t &	v
	)

friend

§ w_keystr_t_test

friend class w_keystr_t_test

friend

Member Data Documentation

§ _data

unsigned char* w_keystr_t::_data

private

raw data. this internal data starts with a sign byte.

§ _memlen

uint32_t w_keystr_t::_memlen

private

allocated length of _data, which could be larger than _strlen.

§ _strlen

uint32_t w_keystr_t::_strlen

private

length of _data, which is 1 byte longer than the actual data.

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

src/common/w_key.h

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

§ w_keystr_t() [1/2]

§ w_keystr_t() [2/2]

§ ~w_keystr_t()

Member Function Documentation

§ _assure()

§ buffer_as_keystr()

§ clear()

§ common_leading_bytes() [1/3]

§ common_leading_bytes() [2/3]

§ common_leading_bytes() [3/3]

§ compare()

§ compare_bin_str()

§ compare_keystr()

§ compare_nonkeystr()

§ construct_from_keystr() [1/2]

§ construct_from_keystr() [2/2]

§ construct_from_keystr_poormkey_16()

§ construct_from_vec()

§ construct_neginfkey()

§ construct_posinfkey()

§ construct_regularkey()

§ copy_from_vec()

§ get_length_as_keystr()

§ get_length_as_nonkeystr()

§ is_constructed()

§ is_neginf()

§ is_posinf()

§ is_regular()

§ operator!=()

§ operator<()

§ operator<=()

§ operator=()

§ operator==()

§ operator>()

§ operator>=()

§ serialize_as_keystr()

§ serialize_as_nonkeystr() [1/2]

§ serialize_as_nonkeystr() [2/2]

Friends And Related Function Documentation

§ operator<<

§ w_keystr_t_test

Member Data Documentation

§ _data

§ _memlen

§ _strlen