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>
Junio C Hamano committed
Jun 6, 2013 at 21:58 UTC
da24b1044f7dc85cda52d6423f5a794a7074fbf8
3 files changed
+60
-31
commit.c
+44
-31
@@ -9,6 +9,7 @@
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#include "gpg-interface.h"
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#include "mergesort.h"
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#include "commit-slab.h"
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+#include "prio-queue.h"
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static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
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@@ -509,21 +510,42 @@ struct commit *pop_commit(struct commit_list **stack)
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/* count number of children that have not been emitted */
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define_commit_slab(indegree_slab, int);
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+static int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
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+{
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+ const struct commit *a = a_, *b = b_;
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+ /* newer commits with larger date first */
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+ if (a->date < b->date)
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+ return 1;
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+ else if (a->date > b->date)
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+ return -1;
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+ return 0;
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+}
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+
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/*
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* Performs an in-place topological sort on the list supplied.
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*/
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-void sort_in_topological_order(struct commit_list ** list, enum rev_sort_order sort_order)
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+void sort_in_topological_order(struct commit_list **list, enum rev_sort_order sort_order)
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{
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struct commit_list *next, *orig = *list;
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- struct commit_list *work, **insert;
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struct commit_list **pptr;
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struct indegree_slab indegree;
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+ struct prio_queue queue;
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+ struct commit *commit;
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if (!orig)
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return;
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*list = NULL;
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init_indegree_slab(&indegree);
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+ memset(&queue, '\0', sizeof(queue));
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+ switch (sort_order) {
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+ default: /* REV_SORT_IN_GRAPH_ORDER */
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+ queue.compare = NULL;
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+ break;
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+ case REV_SORT_BY_COMMIT_DATE:
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+ queue.compare = compare_commits_by_commit_date;
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+ break;
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+ }
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/* Mark them and clear the indegree */
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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
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/* update the indegree */
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for (next = orig; next; next = next->next) {
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- struct commit_list * parents = next->item->parents;
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+ struct commit_list *parents = next->item->parents;
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while (parents) {
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struct commit *parent = parents->item;
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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
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*
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* the tips serve as a starting set for the work queue.
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*/
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- work = NULL;
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- insert = &work;
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for (next = orig; next; next = next->next) {
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struct commit *commit = next->item;
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if (*(indegree_slab_at(&indegree, commit)) == 1)
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- insert = &commit_list_insert(commit, insert)->next;
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+ prio_queue_put(&queue, commit);
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}
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- /* process the list in topological order */
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- if (sort_order != REV_SORT_IN_GRAPH_ORDER)
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- commit_list_sort_by_date(&work);
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+ /*
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+ * This is unfortunate; the initial tips need to be shown
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+ * in the order given from the revision traversal machinery.
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+ */
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+ if (sort_order == REV_SORT_IN_GRAPH_ORDER)
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+ prio_queue_reverse(&queue);
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+
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+ /* We no longer need the commit list */
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+ free_commit_list(orig);
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pptr = list;
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*list = NULL;
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- while (work) {
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- struct commit *commit;
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- struct commit_list *parents, *work_item;
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-
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- work_item = work;
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- work = work_item->next;
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- work_item->next = NULL;
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+ while ((commit = prio_queue_get(&queue)) != NULL) {
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+ struct commit_list *parents;
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- commit = work_item->item;
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for (parents = commit->parents; parents ; parents = parents->next) {
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struct commit *parent = parents->item;
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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
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* when all their children have been emitted thereby
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* guaranteeing topological order.
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*/
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- if (--(*pi) == 1) {
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- switch (sort_order) {
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- case REV_SORT_BY_COMMIT_DATE:
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- commit_list_insert_by_date(parent, &work);
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- break;
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- default: /* REV_SORT_IN_GRAPH_ORDER */
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- commit_list_insert(parent, &work);
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- break;
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- }
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- }
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+ if (--(*pi) == 1)
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+ prio_queue_put(&queue, parent);
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}
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/*
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- * work_item is a commit all of whose children
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- * have already been emitted. we can emit it now.
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+ * all children of commit have already been
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+ * emitted. we can emit it now.
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*/
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*(indegree_slab_at(&indegree, commit)) = 0;
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- *pptr = work_item;
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- pptr = &work_item->next;
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+
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+ pptr = &commit_list_insert(commit, pptr)->next;
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}
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clear_indegree_slab(&indegree);
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+ clear_prio_queue(&queue);
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}
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/* merge-base stuff */
prio-queue.c
+13
@@ -2,6 +2,19 @@
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#include "commit.h"
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#include "prio-queue.h"
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+void prio_queue_reverse(struct prio_queue *queue)
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+{
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+ int i, j;
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+
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+ if (queue->compare != NULL)
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+ die("BUG: prio_queue_reverse() on non-LIFO queue");
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+ for (i = 0; i <= (j = (queue->nr - 1) - i); i++) {
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+ struct commit *swap = queue->array[i];
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+ queue->array[i] = queue->array[j];
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+ queue->array[j] = swap;
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+ }
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+}
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+
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void clear_prio_queue(struct prio_queue *queue)
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{
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free(queue->array);
prio-queue.h
+3
@@ -42,4 +42,7 @@ extern void *prio_queue_get(struct prio_queue *);
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extern void clear_prio_queue(struct prio_queue *);
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+/* Reverse the LIFO elements */
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+extern void prio_queue_reverse(struct prio_queue *);
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+
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#endif /* PRIO_QUEUE_H */