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Improve performance of editdist3() by keeping the costs in sorted order.

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Also add a new regression test to editdist3().

FossilOrigin-Name: dc734c5b61464dfd6bfa7963f2ecce32e405a0c2ba1ef6f453ec9389da080256
This commit is contained in:
drh
2018-02-15 03:56:33 +00:00
parent 46e835a2c4
commit f4bc6c43d7
4 changed files with 108 additions and 21 deletions
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82
ext/misc/spellfix.c
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@ -658,6 +658,79 @@ static void editDist3ConfigDelete(void *pIn){
sqlite3_free(p);
}
/* Compare the FROM values of two EditDist3Cost objects, for sorting.
** Return negative, zero, or positive if the A is less than, equal to,
** or greater than B.
*/
static int editDist3CostCompare(EditDist3Cost *pA, EditDist3Cost *pB){
int n = pA->nFrom;
int rc;
if( n>pB->nFrom ) n = pB->nFrom;
rc = strncmp(pA->a, pB->a, n);
if( rc==0 ) rc = pA->nFrom - pB->nFrom;
return rc;
}
/*
** Merge together two sorted lists of EditDist3Cost objects, in order
** of increasing FROM.
*/
static EditDist3Cost *editDist3CostMerge(
EditDist3Cost *pA,
EditDist3Cost *pB
){
EditDist3Cost *pHead = 0;
EditDist3Cost **ppTail = &pHead;
EditDist3Cost *p;
while( pA && pB ){
if( editDist3CostCompare(pA,pB)<=0 ){
p = pA;
pA = pA->pNext;
}else{
p = pB;
pB = pB->pNext;
}
*ppTail = p;
ppTail = &p->pNext;
}
if( pA ){
*ppTail = pA;
}else{
*ppTail = pB;
}
return pHead;
}
/*
** Sort a list of EditDist3Cost objects into order of increasing FROM
*/
static EditDist3Cost *editDist3CostSort(EditDist3Cost *pList){
EditDist3Cost *ap[60], *p;
int i;
int mx = 0;
ap[0] = 0;
ap[1] = 0;
while( pList ){
p = pList;
pList = p->pNext;
p->pNext = 0;
for(i=0; ap[i]; i++){
p = editDist3CostMerge(ap[i],p);
ap[i] = 0;
}
ap[i] = p;
if( i>mx ){
mx = i;
ap[i+1] = 0;
}
}
p = 0;
for(i=0; i<=mx; i++){
if( ap[i] ) p = editDist3CostMerge(p,ap[i]);
}
return p;
}
/*
** Load all edit-distance weights from a table.
*/
@ -729,6 +802,12 @@ static int editDist3ConfigLoad(
}
rc2 = sqlite3_finalize(pStmt);
if( rc==SQLITE_OK ) rc = rc2;
if( rc==SQLITE_OK ){
int iLang;
for(iLang=0; iLang<p->nLang; iLang++){
p->a[iLang].pCost = editDist3CostSort(p->a[iLang].pCost);
}
}
return rc;
}
@ -943,8 +1022,9 @@ static int editDist3Core(
a2[i2].nByte = utf8Len((unsigned char)z2[i2], n2-i2);
for(p=pLang->pCost; p; p=p->pNext){
EditDist3Cost **apNew;
if( p->nFrom>0 ) continue;
if( p->nFrom>0 ) break;
if( i2+p->nTo>n2 ) continue;
if( p->a[0]>z2[i2] ) break;
if( matchTo(p, z2+i2, n2-i2)==0 ) continue;
a2[i2].nIns++;
apNew = sqlite3_realloc64(a2[i2].apIns, sizeof(*apNew)*a2[i2].nIns);