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Update the SECURE_DELETE code to track the latest changes in the pager. (CVS 5928)

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FossilOrigin-Name: e058f509374e98e48eafeba2f1dadff9633d1190
This commit is contained in:
drh
2008-11-19 18:30:29 +00:00
parent f3d3c27a0c
commit 1feb7dd391
5 changed files with 113 additions and 64 deletions
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146
src/bitvec.c
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@@ -34,21 +34,42 @@
** start of a transaction, and is thus usually less than a few thousand,
** but can be as large as 2 billion for a really big database.
**
** @(#) $Id: bitvec.c,v 1.8 2008/11/11 15:48:48 drh Exp $
** @(#) $Id: bitvec.c,v 1.9 2008/11/19 18:30:35 shane Exp $
*/
#include "sqliteInt.h"
/* Size of the Bitvec structure in bytes. */
#define BITVEC_SZ 512
/* Round the union size down to the nearest pointer boundary, since that's how
** it will be aligned within the Bitvec struct. */
#define BITVEC_USIZE (((BITVEC_SZ-12)/sizeof(Bitvec*))*sizeof(Bitvec*))
#define BITVEC_NCHAR BITVEC_USIZE
#define BITVEC_NBIT (BITVEC_NCHAR*8)
#define BITVEC_NINT (BITVEC_USIZE/4)
#define BITVEC_USIZE (((BITVEC_SZ-(3*sizeof(u32)))/sizeof(Bitvec*))*sizeof(Bitvec*))
/* Type of the array "element" for the bitmap representation.
** Should be a power of 2, and ideally, evenly divide into BITVEC_USIZE.
** Setting this to the "natural word" size of your CPU may improve
** performance. */
#define BITVEC_TELEM u8
/* Size, in bits, of the bitmap element. */
#define BITVEC_SZELEM 8
/* Number of elements in a bitmap array. */
#define BITVEC_NELEM (BITVEC_USIZE/sizeof(BITVEC_TELEM))
/* Number of bits in the bitmap array. */
#define BITVEC_NBIT (BITVEC_NELEM*BITVEC_SZELEM)
/* Number of u32 values in hash table. */
#define BITVEC_NINT (BITVEC_USIZE/sizeof(u32))
/* Maximum number of entries in hash table before
** sub-dividing and re-hashing. */
#define BITVEC_MXHASH (BITVEC_NINT/2)
/* Hashing function for the aHash representation.
** Empirical testing showed that the *37 multiplier
** (an arbitrary prime)in the hash function provided
** no fewer collisions than the no-op *1. */
#define BITVEC_HASH(X) (((X)*1)%BITVEC_NINT)
#define BITVEC_NPTR (BITVEC_USIZE/sizeof(Bitvec *))
#define BITVEC_HASH(X) (((X)*37)%BITVEC_NINT)
/*
** A bitmap is an instance of the following structure.
@@ -72,11 +93,15 @@
** to hold deal with values between 1 and iDivisor.
*/
struct Bitvec {
u32 iSize; /* Maximum bit index */
u32 nSet; /* Number of bits that are set */
u32 iDivisor; /* Number of bits handled by each apSub[] entry */
u32 iSize; /* Maximum bit index. Max iSize is 4,294,967,296. */
u32 nSet; /* Number of bits that are set - only valid for aHash element */
/* Max nSet is BITVEC_NINT. For BITVEC_SZ of 512, this would be 125. */
u32 iDivisor; /* Number of bits handled by each apSub[] entry. */
/* Should >=0 for apSub element. */
/* Max iDivisor is max(u32) / BITVEC_NPTR + 1. */
/* For a BITVEC_SZ of 512, this would be 34,359,739. */
union {
u8 aBitmap[BITVEC_NCHAR]; /* Bitmap representation */
BITVEC_TELEM aBitmap[BITVEC_NELEM]; /* Bitmap representation */
u32 aHash[BITVEC_NINT]; /* Hash table representation */
Bitvec *apSub[BITVEC_NPTR]; /* Recursive representation */
} u;
@@ -105,16 +130,19 @@ Bitvec *sqlite3BitvecCreate(u32 iSize){
int sqlite3BitvecTest(Bitvec *p, u32 i){
if( p==0 ) return 0;
if( i>p->iSize || i==0 ) return 0;
if( p->iSize<=BITVEC_NBIT ){
i--;
return (p->u.aBitmap[i/8] & (1<<(i&7)))!=0;
i--;
while( p->iDivisor ){
u32 bin = i/p->iDivisor;
i = i%p->iDivisor;
p = p->u.apSub[bin];
if (!p) {
return 0;
}
}
if( p->iDivisor>0 ){
u32 bin = (i-1)/p->iDivisor;
i = (i-1)%p->iDivisor + 1;
return sqlite3BitvecTest(p->u.apSub[bin], i);
}else{
u32 h = BITVEC_HASH(i);
if( p->iSize<=BITVEC_NBIT ){
return (p->u.aBitmap[i/BITVEC_SZELEM] & (1<<(i&(BITVEC_SZELEM-1))))!=0;
} else{
u32 h = BITVEC_HASH(i++);
while( p->u.aHash[h] ){
if( p->u.aHash[h]==i ) return 1;
h++;
@@ -141,35 +169,50 @@ int sqlite3BitvecSet(Bitvec *p, u32 i){
assert( p!=0 );
assert( i>0 );
assert( i<=p->iSize );
if( p->iSize<=BITVEC_NBIT ){
i--;
p->u.aBitmap[i/8] |= 1 << (i&7);
return SQLITE_OK;
}
if( p->iDivisor ){
u32 bin = (i-1)/p->iDivisor;
i = (i-1)%p->iDivisor + 1;
i--;
while((p->iSize > BITVEC_NBIT) && p->iDivisor) {
u32 bin = i/p->iDivisor;
i = i%p->iDivisor;
if( p->u.apSub[bin]==0 ){
sqlite3BeginBenignMalloc();
p->u.apSub[bin] = sqlite3BitvecCreate( p->iDivisor );
sqlite3EndBenignMalloc();
if( p->u.apSub[bin]==0 ) return SQLITE_NOMEM;
}
return sqlite3BitvecSet(p->u.apSub[bin], i);
p = p->u.apSub[bin];
}
h = BITVEC_HASH(i);
while( p->u.aHash[h] ){
if( p->iSize<=BITVEC_NBIT ){
p->u.aBitmap[i/BITVEC_SZELEM] |= 1 << (i&(BITVEC_SZELEM-1));
return SQLITE_OK;
}
h = BITVEC_HASH(i++);
/* if there wasn't a hash collision, and this doesn't */
/* completely fill the hash, then just add it without */
/* worring about sub-dividing and re-hashing. */
if( !p->u.aHash[h] ){
if (p->nSet<(BITVEC_NINT-1)) {
goto bitvec_set_end;
} else {
goto bitvec_set_rehash;
}
}
/* there was a collision, check to see if it's already */
/* in hash, if not, try to find a spot for it */
do {
if( p->u.aHash[h]==i ) return SQLITE_OK;
h++;
if( h==BITVEC_NINT ) h = 0;
}
p->nSet++;
if( h>=BITVEC_NINT ) h = 0;
} while( p->u.aHash[h] );
/* we didn't find it in the hash. h points to the first */
/* available free spot. check to see if this is going to */
/* make our hash too "full". */
bitvec_set_rehash:
if( p->nSet>=BITVEC_MXHASH ){
unsigned int j;
int rc;
u32 aiValues[BITVEC_NINT];
memcpy(aiValues, p->u.aHash, sizeof(aiValues));
memset(p->u.apSub, 0, sizeof(p->u.apSub[0])*BITVEC_NPTR);
memset(p->u.apSub, 0, sizeof(aiValues));
p->iDivisor = (p->iSize + BITVEC_NPTR - 1)/BITVEC_NPTR;
rc = sqlite3BitvecSet(p, i);
for(j=0; j<BITVEC_NINT; j++){
@@ -177,35 +220,44 @@ int sqlite3BitvecSet(Bitvec *p, u32 i){
}
return rc;
}
bitvec_set_end:
p->nSet++;
p->u.aHash[h] = i;
return SQLITE_OK;
}
/*
** Clear the i-th bit. Return 0 on success and an error code if
** anything goes wrong.
** Clear the i-th bit.
*/
void sqlite3BitvecClear(Bitvec *p, u32 i){
assert( p!=0 );
assert( i>0 );
if( p->iSize<=BITVEC_NBIT ){
i--;
p->u.aBitmap[i/8] &= ~(1 << (i&7));
}else if( p->iDivisor ){
u32 bin = (i-1)/p->iDivisor;
i = (i-1)%p->iDivisor + 1;
if( p->u.apSub[bin] ){
sqlite3BitvecClear(p->u.apSub[bin], i);
i--;
while( p->iDivisor ){
u32 bin = i/p->iDivisor;
i = i%p->iDivisor;
p = p->u.apSub[bin];
if (!p) {
return;
}
}
if( p->iSize<=BITVEC_NBIT ){
p->u.aBitmap[i/BITVEC_SZELEM] &= ~(1 << (i&(BITVEC_SZELEM-1)));
}else{
unsigned int j;
u32 aiValues[BITVEC_NINT];
memcpy(aiValues, p->u.aHash, sizeof(aiValues));
memset(p->u.aHash, 0, sizeof(p->u.aHash[0])*BITVEC_NINT);
memset(p->u.aHash, 0, sizeof(aiValues));
p->nSet = 0;
for(j=0; j<BITVEC_NINT; j++){
if( aiValues[j] && aiValues[j]!=i ){
sqlite3BitvecSet(p, aiValues[j]);
if( aiValues[j] && aiValues[j]!=(i+1) ){
u32 h = BITVEC_HASH(aiValues[j]-1);
p->nSet++;
while( p->u.aHash[h] ){
h++;
if( h>=BITVEC_NINT ) h = 0;
}
p->u.aHash[h] = aiValues[j];
}
}
}