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Add a few comments to help detail some of these functions.
This commit is contained in:
Kurt Zeilenga
parent
3e48937ac8
commit
433e8ad645
@ -11,6 +11,8 @@
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#include "slap.h"
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#include "back-ldbm.h"
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/* Allocate an ID_BLOCK with room for nids ids */
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ID_BLOCK *
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idl_alloc( int nids )
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{
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@ -24,6 +26,8 @@ idl_alloc( int nids )
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return( new );
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}
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/* Allocate an empty ALLIDS ID_BLOCK */
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ID_BLOCK *
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idl_allids( Backend *be )
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{
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@ -36,16 +40,23 @@ idl_allids( Backend *be )
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return( idl );
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}
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/* Free an ID_BLOCK */
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void
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idl_free( ID_BLOCK *idl )
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{
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if ( idl == NULL ) {
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Debug( LDAP_DEBUG_TRACE,
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"idl_free: called with NULL pointer\n",
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0, 0, 0 );
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return;
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}
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free( (char *) idl );
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}
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/* Fetch an single ID_BLOCK from the cache */
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static ID_BLOCK *
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idl_fetch_one(
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Backend *be,
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@ -67,6 +78,16 @@ idl_fetch_one(
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return( idl );
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}
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/* Fetch a set of ID_BLOCKs from the cache
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* if not INDIRECT
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* if block return is an ALLIDS block,
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* return an new ALLIDS block
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* otherwise
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* return block
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* construct super block from all blocks referenced by INDIRECT block
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* return super block
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*/
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ID_BLOCK *
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idl_fetch(
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Backend *be,
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@ -162,6 +183,8 @@ idl_fetch(
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return( idl );
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}
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/* store a single block */
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static int
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idl_store(
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Backend *be,
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@ -194,54 +217,60 @@ idl_store(
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return( rc );
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}
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/* split the block at id
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* locate ID greater than or equal to id.
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*/
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static void
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idl_split_block(
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ID_BLOCK *b,
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ID id,
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ID_BLOCK **n1,
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ID_BLOCK **n2
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ID_BLOCK **right,
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ID_BLOCK **left
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)
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{
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unsigned int i;
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unsigned int nr, nl;
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/* find where to split the block */
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for ( i = 0; i < ID_BLOCK_NIDS(b) && id > ID_BLOCK_ID(b, i); i++ )
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/* find where to split the block *//* XXX linear search XXX */
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for ( nr = 0; nr < ID_BLOCK_NIDS(b) && id > ID_BLOCK_ID(b, nr); nr++ )
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; /* NULL */
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*n1 = idl_alloc( i == 0 ? 1 : i );
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*n2 = idl_alloc( ID_BLOCK_NIDS(b) - i + (i == 0 ? 0 : 1));
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nl = ID_BLOCK_NIDS(b) - nr;
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*right = idl_alloc( nr == 0 ? 1 : nr );
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*left = idl_alloc( nl + (nr == 0 ? 0 : 1));
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/*
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* everything before the id being inserted in the first block
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* unless there is nothing, in which case the id being inserted
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* goes there.
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*/
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SAFEMEMCPY(
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(char *) &ID_BLOCK_ID(*n1, 0),
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(char *) &ID_BLOCK_ID(b, 0),
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i * sizeof(ID) );
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ID_BLOCK_NIDS(*n1) = (i == 0 ? 1 : i);
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if ( i == 0 ) {
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ID_BLOCK_ID(*n1, 0) = id;
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if ( nr == 0 ) {
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ID_BLOCK_NIDS(*right) = 1;
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ID_BLOCK_ID(*right, 0) = id;
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} else {
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ID_BLOCK_ID(*n2, 0) = id;
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SAFEMEMCPY(
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(char *) &ID_BLOCK_ID(*right, 0),
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(char *) &ID_BLOCK_ID(b, 0),
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nr * sizeof(ID) );
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ID_BLOCK_NIDS(*right) = nr;
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ID_BLOCK_ID(*left, 0) = id;
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}
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/* the id being inserted & everything after in the second block */
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SAFEMEMCPY(
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(char *) &ID_BLOCK_ID(*n2, (i == 0 ? 0 : 1)),
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(char *) &ID_BLOCK_ID(b, i),
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(ID_BLOCK_NIDS(b) - i) * sizeof(ID) );
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ID_BLOCK_NIDS(*n2) = ID_BLOCK_NIDS(b) - i + (i == 0 ? 0 : 1);
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(char *) &ID_BLOCK_ID(*left, (nr == 0 ? 0 : 1)),
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(char *) &ID_BLOCK_ID(b, nr),
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nl * sizeof(ID) );
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ID_BLOCK_NIDS(*left) = nl + (nr == 0 ? 0 : 1);
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}
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/*
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* idl_change_first - called when an indirect block's first key has
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* changed, meaning it needs to be stored under a new key, and the
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* header block pointing to it needs updating.
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*/
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static int
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idl_change_first(
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Backend *be,
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@ -285,6 +314,7 @@ idl_change_first(
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return( 0 );
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}
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int
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idl_insert_key(
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Backend *be,
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@ -384,7 +414,7 @@ idl_insert_key(
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* need to write a new "header" block.
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*/
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/* select the block to try inserting into */
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/* select the block to try inserting into *//* XXX linear search XXX */
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for ( i = 0; !ID_BLOCK_NOID(idl, i) && id > ID_BLOCK_ID(idl, i); i++ )
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; /* NULL */
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if ( i != 0 ) {
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@ -481,7 +511,7 @@ idl_insert_key(
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* and write the indirect header block.
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*/
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/* count how many indirect blocks */
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/* count how many indirect blocks *//* XXX linear count XXX */
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for ( j = 0; !ID_BLOCK_NOID(idl, j); j++ )
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; /* NULL */
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@ -564,14 +594,16 @@ idl_insert_key(
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return( rc );
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}
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/*
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* idl_insert - insert an id into an id list.
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* returns 0 id inserted
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*
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* returns
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* 0 id inserted
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* 1 id inserted, first id in block has changed
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* 2 id not inserted, already there
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* 3 id not inserted, block must be split
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*/
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int
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idl_insert( ID_BLOCK **idl, ID id, int maxids )
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{
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@ -581,7 +613,7 @@ idl_insert( ID_BLOCK **idl, ID id, int maxids )
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return( 2 ); /* already there */
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}
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/* is it already there? XXX bin search XXX */
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/* is it already there? *//* XXX linear search XXX */
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for ( i = 0; i < ID_BLOCK_NIDS(*idl) && id > ID_BLOCK_ID(*idl, i); i++ ) {
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; /* NULL */
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}
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@ -604,7 +636,7 @@ idl_insert( ID_BLOCK **idl, ID id, int maxids )
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(ID_BLOCK_NMAX(*idl) + ID_BLOCK_IDS_OFFSET) * sizeof(ID) );
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}
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/* make a slot for the new id */
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/* make a slot for the new id *//* XXX bubble move XXX */
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for ( j = ID_BLOCK_NIDS(*idl); j != i; j-- ) {
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ID_BLOCK_ID(*idl, j) = ID_BLOCK_ID(*idl, j-1);
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}
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@ -618,6 +650,7 @@ idl_insert( ID_BLOCK **idl, ID id, int maxids )
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return( i == 0 ? 1 : 0 ); /* inserted - first id changed or not */
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}
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int
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idl_delete_key (
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Backend *be,
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@ -718,6 +751,8 @@ idl_delete_key (
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return -1;
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}
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/* return a duplicate of a single ID_BLOCK */
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static ID_BLOCK *
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idl_dup( ID_BLOCK *idl )
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{
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@ -737,16 +772,18 @@ idl_dup( ID_BLOCK *idl )
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return( new );
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}
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/* return the smaller ID_BLOCK */
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static ID_BLOCK *
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idl_min( ID_BLOCK *a, ID_BLOCK *b )
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{
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return( ID_BLOCK_NIDS(a) > ID_BLOCK_NIDS(b) ? b : a );
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}
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/*
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* idl_intersection - return a intersection b
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*/
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ID_BLOCK *
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idl_intersection(
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Backend *be,
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@ -770,8 +807,12 @@ idl_intersection(
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n = idl_dup( idl_min( a, b ) );
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for ( ni = 0, ai = 0, bi = 0; ai < ID_BLOCK_NIDS(a); ai++ ) {
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for ( ; bi < ID_BLOCK_NIDS(b) && ID_BLOCK_ID(b, bi) < ID_BLOCK_ID(a, ai); bi++ )
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for ( ;
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bi < ID_BLOCK_NIDS(b) && ID_BLOCK_ID(b, bi) < ID_BLOCK_ID(a, ai);
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bi++ )
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{
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; /* NULL */
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}
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if ( bi == ID_BLOCK_NIDS(b) ) {
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break;
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@ -791,10 +832,10 @@ idl_intersection(
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return( n );
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}
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/*
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* idl_union - return a union b
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*/
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ID_BLOCK *
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idl_union(
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Backend *be,
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@ -823,7 +864,10 @@ idl_union(
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n = idl_alloc( ID_BLOCK_NIDS(a) + ID_BLOCK_NIDS(b) );
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for ( ni = 0, ai = 0, bi = 0; ai < ID_BLOCK_NIDS(a) && bi < ID_BLOCK_NIDS(b); ) {
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for ( ni = 0, ai = 0, bi = 0;
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ai < ID_BLOCK_NIDS(a) && bi < ID_BLOCK_NIDS(b);
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)
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{
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if ( ID_BLOCK_ID(a, ai) < ID_BLOCK_ID(b, bi) ) {
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ID_BLOCK_ID(n, ni++) = ID_BLOCK_ID(a, ai++);
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@ -847,10 +891,10 @@ idl_union(
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return( n );
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}
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/*
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* idl_notin - return a intersection ~b (or a minus b)
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*/
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ID_BLOCK *
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idl_notin(
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Backend *be,
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@ -924,6 +968,12 @@ idl_notin(
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return( n );
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}
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/* return the first ID in the block
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* if ALLIDS block
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* NIDS > 1 return 1
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* otherwise return NOID
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* otherwise return first ID
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*/
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ID
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idl_firstid( ID_BLOCK *idl )
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{
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@ -938,6 +988,12 @@ idl_firstid( ID_BLOCK *idl )
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return( ID_BLOCK_ID(idl, 0) );
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}
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/* return next ID after id
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* if ALLIDS block, increment id.
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* if id < NIDS return id
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* otherwise NOID.
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* otherwise SEARCH for next id (ugh!)
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*/
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ID
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idl_nextid( ID_BLOCK *idl, ID id )
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{
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