Move merge functions to merge.c

In so doing, promote commit_list to git_commit_list,
with its own internal API header.

src/commit_list.c

+/*
+ * Copyright (C) 2009-2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "commit_list.h"
+#include "common.h"
+#include "revwalk.h"
+#include "pool.h"
+#include "odb.h"
+
+int git_commit_list_time_cmp(void *a, void *b)
+{
+	git_commit_list_node *commit_a = (git_commit_list_node *)a;
+	git_commit_list_node *commit_b = (git_commit_list_node *)b;
+
+	return (commit_a->time < commit_b->time);
+}
+
+git_commit_list *git_commit_list_insert(git_commit_list_node *item, git_commit_list **list_p)
+{
+	git_commit_list *new_list = git__malloc(sizeof(git_commit_list));
+	if (new_list != NULL) {
+		new_list->item = item;
+		new_list->next = *list_p;
+	}
+	*list_p = new_list;
+	return new_list;
+}
+
+git_commit_list *git_commit_list_insert_by_date(git_commit_list_node *item, git_commit_list **list_p)
+{
+	git_commit_list **pp = list_p;
+	git_commit_list *p;
+
+	while ((p = *pp) != NULL) {
+		if (git_commit_list_time_cmp(p->item, item) < 0)
+			break;
+
+		pp = &p->next;
+	}
+
+	return git_commit_list_insert(item, pp);
+}
+
+git_commit_list_node *git_commit_list_alloc_node(git_revwalk *walk)
+{
+	return (git_commit_list_node *)git_pool_malloc(&walk->commit_pool, COMMIT_ALLOC);
+}
+
+static int commit_error(git_commit_list_node *commit, const char *msg)
+{
+	char commit_oid[GIT_OID_HEXSZ + 1];
+	git_oid_fmt(commit_oid, &commit->oid);
+	commit_oid[GIT_OID_HEXSZ] = '\0';
+
+	giterr_set(GITERR_ODB, "Failed to parse commit %s - %s", commit_oid, msg);
+
+	return -1;
+}
+
+static git_commit_list_node **alloc_parents(
+	git_revwalk *walk, git_commit_list_node *commit, size_t n_parents)
+{
+	if (n_parents <= PARENTS_PER_COMMIT)
+		return (git_commit_list_node **)((char *)commit + sizeof(git_commit_list_node));
+
+	return (git_commit_list_node **)git_pool_malloc(
+		&walk->commit_pool, (uint32_t)(n_parents * sizeof(git_commit_list_node *)));
+}
+
+
+void git_commit_list_free(git_commit_list **list_p)
+{
+	git_commit_list *list = *list_p;
+
+	if (list == NULL)
+		return;
+
+	while (list) {
+		git_commit_list *temp = list;
+		list = temp->next;
+		git__free(temp);
+	}
+
+	*list_p = NULL;
+}
+
+git_commit_list_node *git_commit_list_pop(git_commit_list **stack)
+{
+	git_commit_list *top = *stack;
+	git_commit_list_node *item = top ? top->item : NULL;
+
+	if (top) {
+		*stack = top->next;
+		git__free(top);
+	}
+	return item;
+}
+
+static int commit_quick_parse(git_revwalk *walk, git_commit_list_node *commit, git_rawobj *raw)
+{
+	const size_t parent_len = strlen("parent ") + GIT_OID_HEXSZ + 1;
+	unsigned char *buffer = raw->data;
+	unsigned char *buffer_end = buffer + raw->len;
+	unsigned char *parents_start, *committer_start;
+	int i, parents = 0;
+	int commit_time;
+
+	buffer += strlen("tree ") + GIT_OID_HEXSZ + 1;
+
+	parents_start = buffer;
+	while (buffer + parent_len < buffer_end && memcmp(buffer, "parent ", strlen("parent ")) == 0) {
+		parents++;
+		buffer += parent_len;
+	}
+
+	commit->parents = alloc_parents(walk, commit, parents);
+	GITERR_CHECK_ALLOC(commit->parents);
+
+	buffer = parents_start;
+	for (i = 0; i < parents; ++i) {
+		git_oid oid;
+
+		if (git_oid_fromstr(&oid, (char *)buffer + strlen("parent ")) < 0)
+			return -1;
+
+		commit->parents[i] = commit_lookup(walk, &oid);
+		if (commit->parents[i] == NULL)
+			return -1;
+
+		buffer += parent_len;
+	}
+
+	commit->out_degree = (unsigned short)parents;
+
+	if ((committer_start = buffer = memchr(buffer, '\n', buffer_end - buffer)) == NULL)
+		return commit_error(commit, "object is corrupted");
+
+	buffer++;
+
+	if ((buffer = memchr(buffer, '\n', buffer_end - buffer)) == NULL)
+		return commit_error(commit, "object is corrupted");
+
+	/* Skip trailing spaces */
+	while (buffer > committer_start && git__isspace(*buffer))
+		buffer--;
+
+	/* Seek for the begining of the pack of digits */
+	while (buffer > committer_start && git__isdigit(*buffer))
+		buffer--;
+
+	/* Skip potential timezone offset */
+	if ((buffer > committer_start) && (*buffer == '+' || *buffer == '-')) {
+		buffer--;
+
+		while (buffer > committer_start && git__isspace(*buffer))
+			buffer--;
+
+		while (buffer > committer_start && git__isdigit(*buffer))
+			buffer--;
+	}
+
+	if ((buffer == committer_start) || (git__strtol32(&commit_time, (char *)(buffer + 1), NULL, 10) < 0))
+		return commit_error(commit, "cannot parse commit time");
+
+	commit->time = (time_t)commit_time;
+	commit->parsed = 1;
+	return 0;
+}
+
+int git_commit_list_parse(git_revwalk *walk, git_commit_list_node *commit)
+{
+	git_odb_object *obj;
+	int error;
+
+	if (commit->parsed)
+		return 0;
+
+	if ((error = git_odb_read(&obj, walk->odb, &commit->oid)) < 0)
+		return error;
+	assert(obj->raw.type == GIT_OBJ_COMMIT);
+
+	error = commit_quick_parse(walk, commit, &obj->raw);
+	git_odb_object_free(obj);
+	return error;
+}
+

src/commit_list.h

+/*
+ * Copyright (C) 2009-2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_commit_list_h__
+#define INCLUDE_commit_list_h__
+
+#include "git2/oid.h"
+
+#define PARENT1  (1 << 0)
+#define PARENT2  (1 << 1)
+#define RESULT   (1 << 2)
+#define STALE    (1 << 3)
+
+#define PARENTS_PER_COMMIT	2
+#define COMMIT_ALLOC \
+	(sizeof(git_commit_list_node) + PARENTS_PER_COMMIT * sizeof(git_commit_list_node *))
+
+typedef struct git_commit_list_node {
+	git_oid oid;
+	uint32_t time;
+	unsigned int seen:1,
+			 uninteresting:1,
+			 topo_delay:1,
+			 parsed:1,
+			 flags : 4;
+
+	unsigned short in_degree;
+	unsigned short out_degree;
+
+	struct git_commit_list_node **parents;
+} git_commit_list_node;
+
+typedef struct git_commit_list {
+	git_commit_list_node *item;
+	struct git_commit_list *next;
+} git_commit_list;
+
+git_commit_list_node *git_commit_list_alloc_node(git_revwalk *walk);
+int git_commit_list_time_cmp(void *a, void *b);
+void git_commit_list_free(git_commit_list **list_p);
+git_commit_list *git_commit_list_insert(git_commit_list_node *item, git_commit_list **list_p);
+git_commit_list *git_commit_list_insert_by_date(git_commit_list_node *item, git_commit_list **list_p);
+int git_commit_list_parse(git_revwalk *walk, git_commit_list_node *commit);
+git_commit_list_node *git_commit_list_pop(git_commit_list **stack);
+
+#endif

src/merge.c

@@ -6,12 +6,14 @@
  */
 
 #include "repository.h"
+#include "revwalk.h"
 #include "buffer.h"
 #include "merge.h"
 #include "refs.h"
 #include "git2/repository.h"
 #include "git2/merge.h"
 #include "git2/reset.h"
+#include "commit_list.h"
 
 int git_merge__cleanup(git_repository *repo)
 {
@@ -46,3 +48,197 @@ cleanup:
 	return error;
 }
 
+int git_merge_base_many(git_oid *out, git_repository *repo, const git_oid input_array[], size_t length)
+{
+	git_revwalk *walk;
+	git_vector list;
+	git_commit_list *result = NULL;
+	int error = -1;
+	unsigned int i;
+	git_commit_list_node *commit;
+
+	assert(out && repo && input_array);
+
+	if (length < 2) {
+		giterr_set(GITERR_INVALID, "At least two commits are required to find an ancestor. Provided 'length' was %u.", length);
+		return -1;
+	}
+
+	if (git_vector_init(&list, length - 1, NULL) < 0)
+		return -1;
+
+	if (git_revwalk_new(&walk, repo) < 0)
+		goto cleanup;
+
+	for (i = 1; i < length; i++) {
+		commit = commit_lookup(walk, &input_array[i]);
+		if (commit == NULL)
+			goto cleanup;
+
+		git_vector_insert(&list, commit);
+	}
+
+	commit = commit_lookup(walk, &input_array[0]);
+	if (commit == NULL)
+		goto cleanup;
+
+	if (git_merge__bases_many(&result, walk, commit, &list) < 0)
+		goto cleanup;
+
+	if (!result) {
+		error = GIT_ENOTFOUND;
+		goto cleanup;
+	}
+
+	git_oid_cpy(out, &result->item->oid);
+
+	error = 0;
+
+cleanup:
+	git_commit_list_free(&result);
+	git_revwalk_free(walk);
+	git_vector_free(&list);
+	return error;
+}
+
+int git_merge_base(git_oid *out, git_repository *repo, const git_oid *one, const git_oid *two)
+{
+	git_revwalk *walk;
+	git_vector list;
+	git_commit_list *result = NULL;
+	git_commit_list_node *commit;
+	void *contents[1];
+
+	if (git_revwalk_new(&walk, repo) < 0)
+		return -1;
+
+	commit = commit_lookup(walk, two);
+	if (commit == NULL)
+		goto on_error;
+
+	/* This is just one value, so we can do it on the stack */
+	memset(&list, 0x0, sizeof(git_vector));
+	contents[0] = commit;
+	list.length = 1;
+	list.contents = contents;
+
+	commit = commit_lookup(walk, one);
+	if (commit == NULL)
+		goto on_error;
+
+	if (git_merge__bases_many(&result, walk, commit, &list) < 0)
+		goto on_error;
+
+	if (!result) {
+		git_revwalk_free(walk);
+		giterr_clear();
+		return GIT_ENOTFOUND;
+	}
+
+	git_oid_cpy(out, &result->item->oid);
+	git_commit_list_free(&result);
+	git_revwalk_free(walk);
+
+	return 0;
+
+on_error:
+	git_revwalk_free(walk);
+	return -1;
+}
+
+static int interesting(git_pqueue *list)
+{
+	unsigned int i;
+	/* element 0 isn't used - we need to start at 1 */
+	for (i = 1; i < list->size; i++) {
+		git_commit_list_node *commit = list->d[i];
+		if ((commit->flags & STALE) == 0)
+			return 1;
+	}
+
+	return 0;
+}
+
+int git_merge__bases_many(git_commit_list **out, git_revwalk *walk, git_commit_list_node *one, git_vector *twos)
+{
+	int error;
+	unsigned int i;
+	git_commit_list_node *two;
+	git_commit_list *result = NULL, *tmp = NULL;
+	git_pqueue list;
+
+	/* if the commit is repeated, we have a our merge base already */
+	git_vector_foreach(twos, i, two) {
+		if (one == two)
+			return git_commit_list_insert(one, out) ? 0 : -1;
+	}
+
+	if (git_pqueue_init(&list, twos->length * 2, git_commit_list_time_cmp) < 0)
+		return -1;
+
+	if (git_commit_list_parse(walk, one) < 0)
+	    return -1;
+
+	one->flags |= PARENT1;
+	if (git_pqueue_insert(&list, one) < 0)
+		return -1;
+
+	git_vector_foreach(twos, i, two) {
+		git_commit_list_parse(walk, two);
+		two->flags |= PARENT2;
+		if (git_pqueue_insert(&list, two) < 0)
+			return -1;
+	}
+
+	/* as long as there are non-STALE commits */
+	while (interesting(&list)) {
+		git_commit_list_node *commit;
+		int flags;
+
+		commit = git_pqueue_pop(&list);
+
+		flags = commit->flags & (PARENT1 | PARENT2 | STALE);
+		if (flags == (PARENT1 | PARENT2)) {
+			if (!(commit->flags & RESULT)) {
+				commit->flags |= RESULT;
+				if (git_commit_list_insert(commit, &result) == NULL)
+					return -1;
+			}
+			/* we mark the parents of a merge stale */
+			flags |= STALE;
+		}
+
+		for (i = 0; i < commit->out_degree; i++) {
+			git_commit_list_node *p = commit->parents[i];
+			if ((p->flags & flags) == flags)
+				continue;
+
+			if ((error = git_commit_list_parse(walk, p)) < 0)
+				return error;
+
+			p->flags |= flags;
+			if (git_pqueue_insert(&list, p) < 0)
+				return -1;
+		}
+	}
+
+	git_pqueue_free(&list);
+
+	/* filter out any stale commits in the results */
+	tmp = result;
+	result = NULL;
+
+	while (tmp) {
+		struct git_commit_list *next = tmp->next;
+		if (!(tmp->item->flags & STALE))
+			if (git_commit_list_insert_by_date(tmp->item, &result) == NULL)
+				return -1;
+
+		git__free(tmp);
+		tmp = next;
+	}
+
+	*out = result;
+	return 0;
+}
+

src/merge.h

@@ -8,6 +8,8 @@
 #define INCLUDE_merge_h__
 
 #include "git2/types.h"
+#include "git2/merge.h"
+#include "commit_list.h"
 
 #define GIT_MERGE_MSG_FILE		"MERGE_MSG"
 #define GIT_MERGE_MODE_FILE		"MERGE_MODE"
@@ -15,5 +17,6 @@
 #define MERGE_CONFIG_FILE_MODE	0666
 
 int git_merge__cleanup(git_repository *repo);
+int git_merge__bases_many(git_commit_list **out, git_revwalk *walk, git_commit_list_node *one, git_vector *twos);
 
 #endif

src/revwalk.h

+/*
+ * Copyright (C) 2009-2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_revwalk_h__
+#define INCLUDE_revwalk_h__
+
+#include "git2/revwalk.h"
+#include "oidmap.h"
+#include "commit_list.h"
+#include "pqueue.h"
+#include "pool.h"
+#include "vector.h"
+
+GIT__USE_OIDMAP;
+
+struct git_revwalk {
+	git_repository *repo;
+	git_odb *odb;
+
+	git_oidmap *commits;
+	git_pool commit_pool;
+
+	git_commit_list *iterator_topo;
+	git_commit_list *iterator_rand;
+	git_commit_list *iterator_reverse;
+	git_pqueue iterator_time;
+
+	int (*get_next)(git_commit_list_node **, git_revwalk *);
+	int (*enqueue)(git_revwalk *, git_commit_list_node *);
+
+	unsigned walking:1;
+	unsigned int sorting;
+
+	/* merge base calculation */
+	git_commit_list_node *one;
+	git_vector twos;
+};
+
+git_commit_list_node *commit_lookup(git_revwalk *walk, const git_oid *oid);
+
+#endif