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Commit 433e8ad6 authored by Kurt Zeilenga's avatar Kurt Zeilenga
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Add a few comments to help detail some of these functions.

parent 3e48937a
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servers/slapd/back-ldbm/idl.c
View file @ 433e8ad6
......@@ -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 )
{
......
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