From 433e8ad64544c9abacdc5727a39a1fbc5d826f55 Mon Sep 17 00:00:00 2001 From: Kurt Zeilenga Date: Tue, 2 Feb 1999 03:40:19 +0000 Subject: [PATCH] Add a few comments to help detail some of these functions. --- servers/slapd/back-ldbm/idl.c | 120 +++++++++++++++++++++++++--------- 1 file changed, 88 insertions(+), 32 deletions(-) diff --git a/servers/slapd/back-ldbm/idl.c b/servers/slapd/back-ldbm/idl.c index 10a03ddc14..b6c9b7b995 100644 --- a/servers/slapd/back-ldbm/idl.c +++ b/servers/slapd/back-ldbm/idl.c @@ -11,6 +11,8 @@ #include "slap.h" #include "back-ldbm.h" + +/* Allocate an ID_BLOCK with room for nids ids */ ID_BLOCK * idl_alloc( int nids ) { @@ -24,6 +26,8 @@ idl_alloc( int nids ) return( new ); } + +/* Allocate an empty ALLIDS ID_BLOCK */ ID_BLOCK * idl_allids( Backend *be ) { @@ -36,16 +40,23 @@ idl_allids( Backend *be ) return( idl ); } + +/* Free an ID_BLOCK */ void idl_free( ID_BLOCK *idl ) { if ( idl == NULL ) { + Debug( LDAP_DEBUG_TRACE, + "idl_free: called with NULL pointer\n", + 0, 0, 0 ); return; } free( (char *) idl ); } + +/* Fetch an single ID_BLOCK from the cache */ static ID_BLOCK * idl_fetch_one( Backend *be, @@ -67,6 +78,16 @@ idl_fetch_one( return( idl ); } + +/* Fetch a set of ID_BLOCKs from the cache + * if not INDIRECT + * if block return is an ALLIDS block, + * return an new ALLIDS block + * otherwise + * return block + * construct super block from all blocks referenced by INDIRECT block + * return super block + */ ID_BLOCK * idl_fetch( Backend *be, @@ -162,6 +183,8 @@ idl_fetch( return( idl ); } + +/* store a single block */ static int idl_store( Backend *be, @@ -194,54 +217,60 @@ idl_store( return( rc ); } + +/* split the block at id + * locate ID greater than or equal to id. + */ static void idl_split_block( ID_BLOCK *b, ID id, - ID_BLOCK **n1, - ID_BLOCK **n2 + ID_BLOCK **right, + ID_BLOCK **left ) { - unsigned int i; + unsigned int nr, nl; - /* find where to split the block */ - for ( i = 0; i < ID_BLOCK_NIDS(b) && id > ID_BLOCK_ID(b, i); i++ ) + /* find where to split the block *//* XXX linear search XXX */ + for ( nr = 0; nr < ID_BLOCK_NIDS(b) && id > ID_BLOCK_ID(b, nr); nr++ ) ; /* NULL */ - *n1 = idl_alloc( i == 0 ? 1 : i ); - *n2 = idl_alloc( ID_BLOCK_NIDS(b) - i + (i == 0 ? 0 : 1)); + nl = ID_BLOCK_NIDS(b) - nr; + + *right = idl_alloc( nr == 0 ? 1 : nr ); + *left = idl_alloc( nl + (nr == 0 ? 0 : 1)); /* * everything before the id being inserted in the first block * unless there is nothing, in which case the id being inserted * goes there. */ - SAFEMEMCPY( - (char *) &ID_BLOCK_ID(*n1, 0), - (char *) &ID_BLOCK_ID(b, 0), - i * sizeof(ID) ); - ID_BLOCK_NIDS(*n1) = (i == 0 ? 1 : i); - - if ( i == 0 ) { - ID_BLOCK_ID(*n1, 0) = id; + if ( nr == 0 ) { + ID_BLOCK_NIDS(*right) = 1; + ID_BLOCK_ID(*right, 0) = id; } else { - ID_BLOCK_ID(*n2, 0) = id; + SAFEMEMCPY( + (char *) &ID_BLOCK_ID(*right, 0), + (char *) &ID_BLOCK_ID(b, 0), + nr * sizeof(ID) ); + ID_BLOCK_NIDS(*right) = nr; + ID_BLOCK_ID(*left, 0) = id; } /* the id being inserted & everything after in the second block */ SAFEMEMCPY( - (char *) &ID_BLOCK_ID(*n2, (i == 0 ? 0 : 1)), - (char *) &ID_BLOCK_ID(b, i), - (ID_BLOCK_NIDS(b) - i) * sizeof(ID) ); - ID_BLOCK_NIDS(*n2) = ID_BLOCK_NIDS(b) - i + (i == 0 ? 0 : 1); + (char *) &ID_BLOCK_ID(*left, (nr == 0 ? 0 : 1)), + (char *) &ID_BLOCK_ID(b, nr), + nl * sizeof(ID) ); + ID_BLOCK_NIDS(*left) = nl + (nr == 0 ? 0 : 1); } + /* * idl_change_first - called when an indirect block's first key has * changed, meaning it needs to be stored under a new key, and the * header block pointing to it needs updating. */ - static int idl_change_first( Backend *be, @@ -285,6 +314,7 @@ idl_change_first( return( 0 ); } + int idl_insert_key( Backend *be, @@ -384,7 +414,7 @@ idl_insert_key( * need to write a new "header" block. */ - /* select the block to try inserting into */ + /* select the block to try inserting into *//* XXX linear search XXX */ for ( i = 0; !ID_BLOCK_NOID(idl, i) && id > ID_BLOCK_ID(idl, i); i++ ) ; /* NULL */ if ( i != 0 ) { @@ -481,7 +511,7 @@ idl_insert_key( * and write the indirect header block. */ - /* count how many indirect blocks */ + /* count how many indirect blocks *//* XXX linear count XXX */ for ( j = 0; !ID_BLOCK_NOID(idl, j); j++ ) ; /* NULL */ @@ -564,14 +594,16 @@ idl_insert_key( return( rc ); } + /* * idl_insert - insert an id into an id list. - * returns 0 id inserted + * + * returns + * 0 id inserted * 1 id inserted, first id in block has changed * 2 id not inserted, already there * 3 id not inserted, block must be split */ - int idl_insert( ID_BLOCK **idl, ID id, int maxids ) { @@ -581,7 +613,7 @@ idl_insert( ID_BLOCK **idl, ID id, int maxids ) return( 2 ); /* already there */ } - /* is it already there? XXX bin search XXX */ + /* is it already there? *//* XXX linear search XXX */ for ( i = 0; i < ID_BLOCK_NIDS(*idl) && id > ID_BLOCK_ID(*idl, i); i++ ) { ; /* NULL */ } @@ -604,7 +636,7 @@ idl_insert( ID_BLOCK **idl, ID id, int maxids ) (ID_BLOCK_NMAX(*idl) + ID_BLOCK_IDS_OFFSET) * sizeof(ID) ); } - /* make a slot for the new id */ + /* make a slot for the new id *//* XXX bubble move XXX */ for ( j = ID_BLOCK_NIDS(*idl); j != i; j-- ) { ID_BLOCK_ID(*idl, j) = ID_BLOCK_ID(*idl, j-1); } @@ -618,6 +650,7 @@ idl_insert( ID_BLOCK **idl, ID id, int maxids ) return( i == 0 ? 1 : 0 ); /* inserted - first id changed or not */ } + int idl_delete_key ( Backend *be, @@ -718,6 +751,8 @@ idl_delete_key ( return -1; } + +/* return a duplicate of a single ID_BLOCK */ static ID_BLOCK * idl_dup( ID_BLOCK *idl ) { @@ -737,16 +772,18 @@ idl_dup( ID_BLOCK *idl ) return( new ); } + +/* return the smaller ID_BLOCK */ static ID_BLOCK * idl_min( ID_BLOCK *a, ID_BLOCK *b ) { return( ID_BLOCK_NIDS(a) > ID_BLOCK_NIDS(b) ? b : a ); } + /* * idl_intersection - return a intersection b */ - ID_BLOCK * idl_intersection( Backend *be, @@ -770,8 +807,12 @@ idl_intersection( n = idl_dup( idl_min( a, b ) ); for ( ni = 0, ai = 0, bi = 0; ai < ID_BLOCK_NIDS(a); ai++ ) { - for ( ; bi < ID_BLOCK_NIDS(b) && ID_BLOCK_ID(b, bi) < ID_BLOCK_ID(a, ai); bi++ ) + for ( ; + bi < ID_BLOCK_NIDS(b) && ID_BLOCK_ID(b, bi) < ID_BLOCK_ID(a, ai); + bi++ ) + { ; /* NULL */ + } if ( bi == ID_BLOCK_NIDS(b) ) { break; @@ -791,10 +832,10 @@ idl_intersection( return( n ); } + /* * idl_union - return a union b */ - ID_BLOCK * idl_union( Backend *be, @@ -823,7 +864,10 @@ idl_union( n = idl_alloc( ID_BLOCK_NIDS(a) + ID_BLOCK_NIDS(b) ); - for ( ni = 0, ai = 0, bi = 0; ai < ID_BLOCK_NIDS(a) && bi < ID_BLOCK_NIDS(b); ) { + for ( ni = 0, ai = 0, bi = 0; + ai < ID_BLOCK_NIDS(a) && bi < ID_BLOCK_NIDS(b); + ) + { if ( ID_BLOCK_ID(a, ai) < ID_BLOCK_ID(b, bi) ) { ID_BLOCK_ID(n, ni++) = ID_BLOCK_ID(a, ai++); @@ -847,10 +891,10 @@ idl_union( return( n ); } + /* * idl_notin - return a intersection ~b (or a minus b) */ - ID_BLOCK * idl_notin( Backend *be, @@ -924,6 +968,12 @@ idl_notin( return( n ); } +/* return the first ID in the block + * if ALLIDS block + * NIDS > 1 return 1 + * otherwise return NOID + * otherwise return first ID + */ ID idl_firstid( ID_BLOCK *idl ) { @@ -938,6 +988,12 @@ idl_firstid( ID_BLOCK *idl ) return( ID_BLOCK_ID(idl, 0) ); } +/* return next ID after id + * if ALLIDS block, increment id. + * if id < NIDS return id + * otherwise NOID. + * otherwise SEARCH for next id (ugh!) + */ ID idl_nextid( ID_BLOCK *idl, ID id ) { -- 2.39.5