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Code simplifications and comment improvements in support of structural

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coverage testing. (CVS 6899)

FossilOrigin-Name: 945251798144110787b197f9eb552a2dd4a25cb4
This commit is contained in:
drh
2009-07-16 18:21:17 +00:00
parent b5526ea67f
commit e64ca7ba11
9 changed files with 59 additions and 81 deletions
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28
src/pcache.c
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@@ -11,7 +11,7 @@
*************************************************************************
** This file implements that page cache.
**
** @(#) $Id: pcache.c,v 1.44 2009/03/31 01:32:18 drh Exp $
** @(#) $Id: pcache.c,v 1.45 2009/07/16 18:21:18 drh Exp $
*/
#include "sqliteInt.h"
@@ -470,24 +470,22 @@ static PgHdr *pcacheMergeDirtyList(PgHdr *pA, PgHdr *pB){
** Sort the list of pages in accending order by pgno. Pages are
** connected by pDirty pointers. The pDirtyPrev pointers are
** corrupted by this sort.
**
** Since there cannot be more than 2^31 distinct pages in a database,
** there cannot be more than 31 buckets required by the merge sorter.
** One extra bucket is added to catch overflow in case something
** ever changes to make the previous sentence incorrect.
*/
#define N_SORT_BUCKET_ALLOC 25
#define N_SORT_BUCKET 25
#ifdef SQLITE_TEST
int sqlite3_pager_n_sort_bucket = 0;
#undef N_SORT_BUCKET
#define N_SORT_BUCKET \
(sqlite3_pager_n_sort_bucket?sqlite3_pager_n_sort_bucket:N_SORT_BUCKET_ALLOC)
#endif
#define N_SORT_BUCKET 32
static PgHdr *pcacheSortDirtyList(PgHdr *pIn){
PgHdr *a[N_SORT_BUCKET_ALLOC], *p;
PgHdr *a[N_SORT_BUCKET], *p;
int i;
memset(a, 0, sizeof(a));
while( pIn ){
p = pIn;
pIn = p->pDirty;
p->pDirty = 0;
for(i=0; i<N_SORT_BUCKET-1; i++){
for(i=0; ALWAYS(i<N_SORT_BUCKET-1); i++){
if( a[i]==0 ){
a[i] = p;
break;
@@ -496,11 +494,9 @@ static PgHdr *pcacheSortDirtyList(PgHdr *pIn){
a[i] = 0;
}
}
if( i==N_SORT_BUCKET-1 ){
/* Coverage: To get here, there need to be 2^(N_SORT_BUCKET)
** elements in the input list. This is possible, but impractical.
** Testing this line is the point of global variable
** sqlite3_pager_n_sort_bucket.
if( NEVER(i==N_SORT_BUCKET-1) ){
/* To get here, there need to be 2^(N_SORT_BUCKET) elements in
** the input list. But that is impossible.
*/
a[i] = pcacheMergeDirtyList(a[i], p);
}