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Improved alpm_list_mmerge() performance (fixed coding style)

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Improved alpm_list_mmerge() performance by removing an extra
pass to obtain the tail node.

This was actually suggested by a TODO comment.

Signed-off-by: Diogo Sousa <diogogsousa@gmail.com>
Signed-off-by: Dan McGee <dan@archlinux.org>
This commit is contained in:
Diogo Sousa 2011-08-24 17:01:11 +01:00 committed by Dan McGee
parent 30d978a966
commit 268d0bbcbe
1 changed files with 15 additions and 10 deletions
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25
lib/libalpm/alpm_list.c
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@ -206,12 +206,18 @@ alpm_list_t SYMEXPORT *alpm_list_join(alpm_list_t *first, alpm_list_t *second)
*/ */
alpm_list_t SYMEXPORT *alpm_list_mmerge(alpm_list_t *left, alpm_list_t *right, alpm_list_fn_cmp fn) alpm_list_t SYMEXPORT *alpm_list_mmerge(alpm_list_t *left, alpm_list_t *right, alpm_list_fn_cmp fn)
{ {
alpm_list_t *newlist, *lp; alpm_list_t *newlist, *lp, *tail_ptr, *left_tail_ptr, *right_tail_ptr;
if(left == NULL) if(left == NULL) {
return right; return right;
if(right == NULL) }
if(right == NULL) {
return left; return left;
}
/* Save tail node pointers for future use */
left_tail_ptr = left->prev;
right_tail_ptr = right->prev;
if(fn(left->data, right->data) <= 0) { if(fn(left->data, right->data) <= 0) {
newlist = left; newlist = left;
@ -242,19 +248,18 @@ alpm_list_t SYMEXPORT *alpm_list_mmerge(alpm_list_t *left, alpm_list_t *right, a
if(left != NULL) { if(left != NULL) {
lp->next = left; lp->next = left;
left->prev = lp; left->prev = lp;
tail_ptr = left_tail_ptr;
} }
else if(right != NULL) { else if(right != NULL) {
lp->next = right; lp->next = right;
right->prev = lp; right->prev = lp;
tail_ptr = right_tail_ptr;
}
else {
tail_ptr = lp;
} }
/* Find our tail pointer newlist->prev = tail_ptr;
* TODO maintain this in the algorithm itself */
lp = newlist;
while(lp && lp->next) {
lp = lp->next;
}
newlist->prev = lp;
return newlist; return newlist;
} }