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Use quicksort instead of heapsort for hdb_idl_sort

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This commit is contained in:
Howard Chu 2005-09-12 03:54:52 +00:00
parent 52cf1f5f0a
commit 2dd87ed9e6
2 changed files with 60 additions and 31 deletions
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86
servers/slapd/back-bdb/idl.c
View file

@ -1297,43 +1297,71 @@ int bdb_idl_append( ID *a, ID *b )
}
/* Sort an IDL using HeapSort */
static void
siftDown(ID *ids, int root, int bottom)
{
int child;
ID temp;
/* Quicksort + Insertion sort for small arrays */
temp = ids[root];
while ((child=root*2) <= bottom) {
if (child < bottom && ids[child] < ids[child + 1])
child++;
if (temp >= ids[child])
break;
ids[root] = ids[child];
root = child;
}
ids[root] = temp;
}
#define SMALL 8
#define SWAP(a,b) a^=b;b^=a;a^=b /* Swap integers without temp var */
void
bdb_idl_sort( ID *ids )
{
int i;
ID temp;
int istack[BDB_IDL_LOGN*4];
int i,j,k,l,ir,jstack;
ID a;
if ( BDB_IDL_IS_RANGE( ids ))
return;
for (i = ids[0] / 2; i >= 1; i--)
siftDown(ids, i, ids[0]);
for (i = ids[0]; i > 1; i--)
{
temp = ids[i];
ids[i] = ids[1];
ids[1] = temp;
siftDown(ids, 1, i-1);
ir = ids[0];
l = 1;
jstack = 0;
for(;;) {
if (ir - l < SMALL) { /* Insertion sort */
for (j=l+1;j<=ir;j++) {
a = ids[j];
for (i=j-1;i>=1;i--) {
if (ids[i] <= a) break;
ids[i+1] = ids[i];
}
ids[i+1] = a;
}
if (jstack == 0) break;
ir = istack[jstack--];
l = istack[jstack--];
} else {
k = (l + ir) >> 1; /* Choose median of left, center, right */
SWAP(ids[k], ids[l+1]);
if (ids[l] > ids[ir]) {
SWAP(ids[l], ids[ir]);
}
if (ids[l+1] > ids[ir]) {
SWAP(ids[l+1], ids[ir]);
}
if (ids[l] > ids[l+1]) {
SWAP(ids[l], ids[l+1]);
}
i = l+1;
j = ir;
a = ids[l+1];
for(;;) {
do i++; while(ids[i] < a);
do j--; while(ids[j] > a);
if (j < i) break;
SWAP(ids[i],ids[j]);
}
ids[l+1] = ids[j];
ids[j] = a;
jstack += 2;
assert(jstack <= BDB_IDL_LOGN*4);
if (ir-i+1 >= j-1) {
istack[jstack] = ir;
istack[jstack-1] = i;
ir = j-1;
} else {
istack[jstack] = j-1;
istack[jstack-1] = l;
l = i;
}
}
}
}

5
servers/slapd/back-bdb/idl.h
View file

@ -20,8 +20,9 @@
/* IDL sizes - likely should be even bigger
* limiting factors: sizeof(ID), thread stack size
*/
#define BDB_IDL_DB_SIZE (1<<16) /* 64K IDL on disk */
#define BDB_IDL_UM_SIZE (1<<17) /* 128K IDL in memory */
#define BDB_IDL_LOGN 16 /* DB_SIZE is 2^16, UM_SIZE is 2^17 */
#define BDB_IDL_DB_SIZE (1<<BDB_IDL_LOGN)
#define BDB_IDL_UM_SIZE (1<<(BDB_IDL_LOGN+1))
#define BDB_IDL_UM_SIZEOF (BDB_IDL_UM_SIZE * sizeof(ID))
#define BDB_IDL_DB_MAX (BDB_IDL_DB_SIZE-1)