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rpm/rpmio/rpmstrpool.h

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First cut of a libsolv-style string <-> id pool API - The pool stores "arbitrary" number of strings in a space-efficient manner, with near constant (hashed) string -> id lookup/store and constant time id -> string and id -> string length lookups. - Credits for the idea go to the Suse developers working on libsolv, the basic concept is directly lifted from there but details differ due to using rpm's own hash table implementation etc. Another minor difference is using size_t for offsets to permit over 4GB total data size on 64bit systems, the total number of id's in the pool is limited to uint32 max however (like in libsolv). - Any (re)implementation bugs by yours truly, this is almost certainly going to need further tuning and tweaking, API and otherwise.
2012-09-07 15:33:22 +08:00
#ifndef _RPMSTRPOOL_H
#define _RPMSTRPOOL_H
Move string pool typedefs to rpmtypes.h - I suspect these will be used widely, to avoid having to include rpmstrpool.h all over in headers...
2012-09-07 19:09:35 +08:00
#include <rpm/rpmtypes.h>
First cut of a libsolv-style string <-> id pool API - The pool stores "arbitrary" number of strings in a space-efficient manner, with near constant (hashed) string -> id lookup/store and constant time id -> string and id -> string length lookups. - Credits for the idea go to the Suse developers working on libsolv, the basic concept is directly lifted from there but details differ due to using rpm's own hash table implementation etc. Another minor difference is using size_t for offsets to permit over 4GB total data size on 64bit systems, the total number of id's in the pool is limited to uint32 max however (like in libsolv). - Any (re)implementation bugs by yours truly, this is almost certainly going to need further tuning and tweaking, API and otherwise.
2012-09-07 15:33:22 +08:00
#ifdef __cplusplus
extern "C" {
#endif
/* XXX TODO: properly document... */
/* create a new string pool */
rpmstrPool rpmstrPoolCreate(void);
/* destroy a string pool (refcounted) */
rpmstrPool rpmstrPoolFree(rpmstrPool sidpool);
/* reference a string pool */
rpmstrPool rpmstrPoolLink(rpmstrPool sidpool);
Allow keeping hash table around on pool freeze, adjust callers - Pool id -> string always works with a frozen pool, but in some cases we'll need to go the other way, allow caller to specify whether string -> id lookups should be possible on frozen pool. - On glibc, realloc() to smaller size doesn't move the data but on other platforms (including valgrind) it can and does move, which would require a full rehash. For now, just leave all the data alone unless we're also freeing the hash, the memory savings isn't much for a global pool (which is where this matters)
2012-09-12 21:47:43 +08:00
/* freeze pool to free memory (keephash required for string -> id lookups) */
void rpmstrPoolFreeze(rpmstrPool sidpool, int keephash);
First cut of a libsolv-style string <-> id pool API - The pool stores "arbitrary" number of strings in a space-efficient manner, with near constant (hashed) string -> id lookup/store and constant time id -> string and id -> string length lookups. - Credits for the idea go to the Suse developers working on libsolv, the basic concept is directly lifted from there but details differ due to using rpm's own hash table implementation etc. Another minor difference is using size_t for offsets to permit over 4GB total data size on 64bit systems, the total number of id's in the pool is limited to uint32 max however (like in libsolv). - Any (re)implementation bugs by yours truly, this is almost certainly going to need further tuning and tweaking, API and otherwise.
2012-09-07 15:33:22 +08:00
/* unfreeze pool (ie recreate hash table) */
void rpmstrPoolUnfreeze(rpmstrPool sidpool);
/* get the id of a string, optionally storing if not already present */
rpmsid rpmstrPoolId(rpmstrPool sidpool, const char *s, int create);
/* get the id of a string + length, optionally storing if not already present */
rpmsid rpmstrPoolIdn(rpmstrPool sidpool, const char *s, size_t slen, int create);
/* get a string by its id */
const char * rpmstrPoolStr(rpmstrPool sidpool, rpmsid sid);
/* get a strings length by its id (in constant time) */
size_t rpmstrPoolStrlen(rpmstrPool pool, rpmsid sid);
#ifdef __cplusplus
}
#endif
#endif /* _RPMSIDPOOL_H */