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sort-in-topological-order: use prio-queue

Use the prio-queue data structure to implement a priority queue of
commits sorted by committer date, when handling --date-order.  The
structure can also be used as a simple LIFO stack, which is a good
match for --topo-order processing.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
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1 parent b4b594a commit da24b1044f7dc85cda52d6423f5a794a7074fbf8 @gitster gitster committed Jun 7, 2013
Showing with 60 additions and 31 deletions.
  1. +44 −31 commit.c
  2. +13 −0 prio-queue.c
  3. +3 −0 prio-queue.h
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@@ -9,6 +9,7 @@
#include "gpg-interface.h"
#include "mergesort.h"
#include "commit-slab.h"
+#include "prio-queue.h"
static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
@@ -509,21 +510,42 @@ struct commit *pop_commit(struct commit_list **stack)
/* count number of children that have not been emitted */
define_commit_slab(indegree_slab, int);
+static int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
+{
+ const struct commit *a = a_, *b = b_;
+ /* newer commits with larger date first */
+ if (a->date < b->date)
+ return 1;
+ else if (a->date > b->date)
+ return -1;
+ return 0;
+}
+
/*
* Performs an in-place topological sort on the list supplied.
*/
-void sort_in_topological_order(struct commit_list ** list, enum rev_sort_order sort_order)
+void sort_in_topological_order(struct commit_list **list, enum rev_sort_order sort_order)
{
struct commit_list *next, *orig = *list;
- struct commit_list *work, **insert;
struct commit_list **pptr;
struct indegree_slab indegree;
+ struct prio_queue queue;
+ struct commit *commit;
if (!orig)
return;
*list = NULL;
init_indegree_slab(&indegree);
+ memset(&queue, '\0', sizeof(queue));
+ switch (sort_order) {
+ default: /* REV_SORT_IN_GRAPH_ORDER */
+ queue.compare = NULL;
+ break;
+ case REV_SORT_BY_COMMIT_DATE:
+ queue.compare = compare_commits_by_commit_date;
+ break;
+ }
/* Mark them and clear the indegree */
for (next = orig; next; next = next->next) {
@@ -533,7 +555,7 @@ void sort_in_topological_order(struct commit_list ** list, enum rev_sort_order s
/* update the indegree */
for (next = orig; next; next = next->next) {
- struct commit_list * parents = next->item->parents;
+ struct commit_list *parents = next->item->parents;
while (parents) {
struct commit *parent = parents->item;
int *pi = indegree_slab_at(&indegree, parent);
@@ -551,30 +573,28 @@ void sort_in_topological_order(struct commit_list ** list, enum rev_sort_order s
*
* the tips serve as a starting set for the work queue.
*/
- work = NULL;
- insert = &work;
for (next = orig; next; next = next->next) {
struct commit *commit = next->item;
if (*(indegree_slab_at(&indegree, commit)) == 1)
- insert = &commit_list_insert(commit, insert)->next;
+ prio_queue_put(&queue, commit);
}
- /* process the list in topological order */
- if (sort_order != REV_SORT_IN_GRAPH_ORDER)
- commit_list_sort_by_date(&work);
+ /*
+ * This is unfortunate; the initial tips need to be shown
+ * in the order given from the revision traversal machinery.
+ */
+ if (sort_order == REV_SORT_IN_GRAPH_ORDER)
+ prio_queue_reverse(&queue);
+
+ /* We no longer need the commit list */
+ free_commit_list(orig);
pptr = list;
*list = NULL;
- while (work) {
- struct commit *commit;
- struct commit_list *parents, *work_item;
-
- work_item = work;
- work = work_item->next;
- work_item->next = NULL;
+ while ((commit = prio_queue_get(&queue)) != NULL) {
+ struct commit_list *parents;
- commit = work_item->item;
for (parents = commit->parents; parents ; parents = parents->next) {
struct commit *parent = parents->item;
int *pi = indegree_slab_at(&indegree, parent);
@@ -587,27 +607,20 @@ void sort_in_topological_order(struct commit_list ** list, enum rev_sort_order s
* when all their children have been emitted thereby
* guaranteeing topological order.
*/
- if (--(*pi) == 1) {
- switch (sort_order) {
- case REV_SORT_BY_COMMIT_DATE:
- commit_list_insert_by_date(parent, &work);
- break;
- default: /* REV_SORT_IN_GRAPH_ORDER */
- commit_list_insert(parent, &work);
- break;
- }
- }
+ if (--(*pi) == 1)
+ prio_queue_put(&queue, parent);
}
/*
- * work_item is a commit all of whose children
- * have already been emitted. we can emit it now.
+ * all children of commit have already been
+ * emitted. we can emit it now.
*/
*(indegree_slab_at(&indegree, commit)) = 0;
- *pptr = work_item;
- pptr = &work_item->next;
+
+ pptr = &commit_list_insert(commit, pptr)->next;
}
clear_indegree_slab(&indegree);
+ clear_prio_queue(&queue);
}
/* merge-base stuff */
View
@@ -2,6 +2,19 @@
#include "commit.h"
#include "prio-queue.h"
+void prio_queue_reverse(struct prio_queue *queue)
+{
+ int i, j;
+
+ if (queue->compare != NULL)
+ die("BUG: prio_queue_reverse() on non-LIFO queue");
+ for (i = 0; i <= (j = (queue->nr - 1) - i); i++) {
+ struct commit *swap = queue->array[i];
+ queue->array[i] = queue->array[j];
+ queue->array[j] = swap;
+ }
+}
+
void clear_prio_queue(struct prio_queue *queue)
{
free(queue->array);
View
@@ -42,4 +42,7 @@ extern void *prio_queue_get(struct prio_queue *);
extern void clear_prio_queue(struct prio_queue *);
+/* Reverse the LIFO elements */
+extern void prio_queue_reverse(struct prio_queue *);
+
#endif /* PRIO_QUEUE_H */

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