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rpm  4.15.0
Files | Functions
String Pool API.

How to store strings in pools. More...

Collaboration diagram for String Pool API.:

Files

file  rpmstrpool.h
 String pools manipulation helper functions.
 

Functions

rpmstrPool rpmstrPoolCreate (void)
 Create a new, empty string pool. More...
 
rpmstrPool rpmstrPoolFree (rpmstrPool pool)
 Free a string pool and its contents. More...
 
rpmstrPool rpmstrPoolLink (rpmstrPool pool)
 Reference a string pool. More...
 
void rpmstrPoolFreeze (rpmstrPool pool, int keephash)
 Freeze a string pool: new strings cannot be added to a frozen pool. More...
 
void rpmstrPoolUnfreeze (rpmstrPool pool)
 Unfreeze a string pool to allow new additions again. More...
 
rpmsid rpmstrPoolId (rpmstrPool pool, const char *s, int create)
 Look up the id of a string. More...
 
rpmsid rpmstrPoolIdn (rpmstrPool pool, const char *s, size_t slen, int create)
 Look up the id of a string with predetermined length. More...
 
const char * rpmstrPoolStr (rpmstrPool pool, rpmsid sid)
 Look up a string by its pool id. More...
 
size_t rpmstrPoolStrlen (rpmstrPool pool, rpmsid sid)
 Return length of a string by its pool id. More...
 
int rpmstrPoolStreq (rpmstrPool poolA, rpmsid sidA, rpmstrPool poolB, rpmsid sidB)
 Compare two strings for equality by their ids. More...
 
rpmsid rpmstrPoolNumStr (rpmstrPool pool)
 Return the number of strings stored in the pool. More...
 

Detailed Description

How to store strings in pools.

Function Documentation

◆ rpmstrPoolCreate()

rpmstrPool rpmstrPoolCreate ( void  )

Create a new, empty string pool.

Returns
new string pool

◆ rpmstrPoolFree()

rpmstrPool rpmstrPoolFree ( rpmstrPool  pool)

Free a string pool and its contents.

While other references exist, this only decrements the reference count.

Parameters
poolstring pool
Returns
NULL always

◆ rpmstrPoolFreeze()

void rpmstrPoolFreeze ( rpmstrPool  pool,
int  keephash 
)

Freeze a string pool: new strings cannot be added to a frozen pool.

If keephash is 0, memory usage is minimized but string -> id lookups are no longer possible and unfreezing is an expensive operation. Id -> string lookups are always possible on a frozen pool too.

Parameters
poolstring pool
keephashshould string -> id hash be kept around?

◆ rpmstrPoolId()

rpmsid rpmstrPoolId ( rpmstrPool  pool,
const char *  s,
int  create 
)

Look up the id of a string.

If create is specified the string is added to the pool if it does not already exist. Creation can only fail if the pool is in frozen state.

Parameters
poolstring pool
s\0-terminated string to look up
createshould an id be created if not already present?
Returns
id of the string or 0 for not found

◆ rpmstrPoolIdn()

rpmsid rpmstrPoolIdn ( rpmstrPool  pool,
const char *  s,
size_t  slen,
int  create 
)

Look up the id of a string with predetermined length.

The string does not have to be \0-terminated. If create is specified the string is added to the pool if it does not already exist. Creation can only fail if the pool is in frozen state.

Parameters
poolstring pool
sstring to look up
slennumber of characters from s to consider
createshould an id be created if not already present?
Returns
id of the string or 0 for not found

◆ rpmstrPoolLink()

rpmstrPool rpmstrPoolLink ( rpmstrPool  pool)

Reference a string pool.

Parameters
poolstring pool
Returns
new string pool reference

◆ rpmstrPoolNumStr()

rpmsid rpmstrPoolNumStr ( rpmstrPool  pool)

Return the number of strings stored in the pool.

This number is also the highest legal id for the pool.

Parameters
poolstring pool
Returns
number of strings in the pool

◆ rpmstrPoolStr()

const char* rpmstrPoolStr ( rpmstrPool  pool,
rpmsid  sid 
)

Look up a string by its pool id.

Parameters
poolstring pool
sidpool id of a string
Returns
pointer to the string or NULL for invalid id

◆ rpmstrPoolStreq()

int rpmstrPoolStreq ( rpmstrPool  poolA,
rpmsid  sidA,
rpmstrPool  poolB,
rpmsid  sidB 
)

Compare two strings for equality by their ids.

The result is equal to calling rstreq() on two strings retrieved through rpmstrPoolStr() but when the id's are within the same pool, this runs in constant time.

Parameters
poolAstring pool of the first string
sidApool id of the first string
poolBstring pool of the second string
sidBpool id of the second string
Returns
1 if strings are equal, 0 otherwise

◆ rpmstrPoolStrlen()

size_t rpmstrPoolStrlen ( rpmstrPool  pool,
rpmsid  sid 
)

Return length of a string by its pool id.

The result is equal to calling strlen() on a string retrieved through rpmstrPoolStr(), but the pool might be able to optimize the calculation.

Parameters
poolstring pool
sidpool id of a string
Returns
length of the string, 0 for invalid pool or id

◆ rpmstrPoolUnfreeze()

void rpmstrPoolUnfreeze ( rpmstrPool  pool)

Unfreeze a string pool to allow new additions again.

If keephash was not specified on freezing, this requires rehashing the entire pool contents.

Parameters
poolstring pool