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Implemented a patch contributed by Igor Nazarenko reimplementing the list_sort() function to use a C qsort() function instead of a hand-crafted merge-sort algorithm. Makes some list sortings (e.g. 1,2,1,2,1,2,1,2,...) extremely faster, in turn significantly speeding up some project builds.

Browse Source 
[SVN r44195]
This commit is contained in:
Jurko Gospodnetić
2008-04-11 21:03:06 +00:00
parent 116f956f3c
commit 1b601354c0
1 changed files with 39 additions and 79 deletions
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118
src/engine/lists.c
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@@ -13,12 +13,12 @@
*
* This implementation essentially uses a singly linked list, but
* guarantees that the head element of every list has a valid pointer
* to the tail of the list, so the new elements can efficiently and
* to the tail of the list, so the new elements can efficiently and
* properly be appended to the end of a list.
*
* To avoid massive allocation, list_free() just tacks the whole freed
* chain onto freelist and list_new() looks on freelist first for an
* available list struct. list_free() does not free the strings in the
* available list struct. list_free() does not free the strings in the
* chain: it lazily lets list_new() do so.
*
* 08/23/94 (seiwald) - new list_append()
@@ -32,7 +32,7 @@ static LIST *freelist = 0; /* junkpile for list_free() */
*/
LIST *
list_append(
list_append(
LIST *l,
LIST *nl )
{
@@ -59,7 +59,7 @@ list_append(
*/
LIST *
list_new(
list_new(
LIST *head,
char *string )
{
@@ -102,7 +102,7 @@ list_new(
*/
LIST *
list_copy(
list_copy(
LIST *l,
LIST *nl )
{
@@ -117,7 +117,7 @@ list_copy(
*/
LIST *
list_sublist(
list_sublist(
LIST *l,
int start,
int count )
@@ -133,82 +133,42 @@ list_sublist(
return nl;
}
static int str_ptr_compare(const void *va, const void *vb)
{
char* a = *( (char**)va );
char* b = *( (char**)vb );
return strcmp(a, b);
}
LIST *
list_sort(
LIST *l)
{
LIST* first = 0;
LIST* second = 0;
LIST* merged = l;
LIST* result;
int len, ii;
char** strings;
LIST* listp;
LIST* result = 0;
if (!l)
return L0;
for(;;) {
/* Split the list in two */
LIST** dst = &first;
LIST* src = merged;
for(;;) {
*dst = list_append(*dst, list_new(0, src->string));
if (!src->next)
break;
len = list_length(l);
strings = (char**)BJAM_MALLOC( len * sizeof(char*) );
if (strcmp(src->string, src->next->string) > 0)
{
if (dst == &first)
dst = &second;
else
dst = &first;
}
src = src->next;
}
if (merged != l)
list_free( merged );
merged = 0;
if (second == 0) {
result = first;
break;
}
/* Merge lists 'first' and 'second' into 'merged' and free
'first'/'second'. */
{
LIST* f = first;
LIST* s = second;
while(f && s)
{
if (strcmp(f->string, s->string) < 0)
{
merged = list_append( merged, list_new(0, f->string ));
f = f->next;
}
else
{
merged = list_append( merged, list_new(0, s->string ));
s = s->next;
}
}
merged = list_copy( merged, f );
merged = list_copy( merged, s );
list_free( first );
list_free( second );
first = 0;
second = 0;
}
listp = l;
for (ii = 0; ii < len; ++ii) {
strings[ii] = listp->string;
listp = listp->next;
}
qsort(strings, len, sizeof(char*), str_ptr_compare);
for (ii = 0; ii < len; ++ii) {
result = list_append( result, list_new(0, strings[ii]) );
}
BJAM_FREE(strings);
return result;
}
@@ -251,12 +211,12 @@ LIST * list_pop_front( LIST *l )
void
list_print( LIST *l )
{
LIST *p = 0;
LIST *p = 0;
for( ; l; p = l, l = list_next( l ) )
if ( p )
if ( p )
printf( "%s ", p->string );
if ( p )
printf( "%s", p->string );
printf( "%s", p->string );
}
/*
@@ -274,7 +234,7 @@ list_length( LIST *l )
return n;
}
int
int
list_in(LIST* l, char* value)
{
for(; l; l = l->next)
@@ -283,7 +243,7 @@ list_in(LIST* l, char* value)
return 0;
}
LIST *
LIST *
list_unique( LIST *sorted_list)
{
LIST* result = 0;
@@ -297,7 +257,7 @@ list_unique( LIST *sorted_list)
last_added = sorted_list;
}
}
return result;
return result;
}
@@ -316,7 +276,7 @@ lol_init( LOL *lol )
*/
void
lol_add(
lol_add(
LOL *lol,
LIST *l )
{
@@ -344,7 +304,7 @@ lol_free( LOL *lol )
*/
LIST *
lol_get(
lol_get(
LOL *lol,
int i )
{