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merge-recursive: do not use on-file index when not needed.
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This revamps the merge-recursive implementation following the
outline in:

	Message-ID: <7v8xgileza.fsf@assigned-by-dhcp.cox.net>

There is no need to write out the index until the very end just
once from merge-recursive.  Also there is no need to write out
the resulting tree object for the simple case of merging with a
single merge base.

Signed-off-by: Junio C Hamano <junkio@cox.net>
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Junio C Hamano committed Jan 10, 2007
1 parent f518438 commit 8b944b5
Showing 1 changed file with 46 additions and 123 deletions.
169 changes: 46 additions & 123 deletions merge-recursive.c
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Original file line number Diff line number Diff line change
Expand Up @@ -110,35 +110,6 @@ static void output_commit_title(struct commit *commit)
}
}

static const char *current_index_file = NULL;
static const char *original_index_file;
static const char *temporary_index_file;
static int cache_dirty = 0;

static int flush_cache(void)
{
/* flush temporary index */
struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
int fd = hold_lock_file_for_update(lock, current_index_file, 1);
if (write_cache(fd, active_cache, active_nr) ||
close(fd) || commit_lock_file(lock))
die ("unable to write %s", current_index_file);
discard_cache();
cache_dirty = 0;
return 0;
}

static void setup_index(int temp)
{
current_index_file = temp ? temporary_index_file: original_index_file;
if (cache_dirty) {
discard_cache();
cache_dirty = 0;
}
unlink(temporary_index_file);
discard_cache();
}

static struct cache_entry *make_cache_entry(unsigned int mode,
const unsigned char *sha1, const char *path, int stage, int refresh)
{
Expand Down Expand Up @@ -167,9 +138,6 @@ static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
const char *path, int stage, int refresh, int options)
{
struct cache_entry *ce;
if (!cache_dirty)
read_cache_from(current_index_file);
cache_dirty++;
ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
if (!ce)
return error("cache_addinfo failed: %s", strerror(cache_errno));
Expand All @@ -187,26 +155,6 @@ static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
*/
static int index_only = 0;

static int git_read_tree(struct tree *tree)
{
int rc;
struct object_list *trees = NULL;
struct unpack_trees_options opts;

if (cache_dirty)
die("read-tree with dirty cache");

memset(&opts, 0, sizeof(opts));
object_list_append(&tree->object, &trees);
rc = unpack_trees(trees, &opts);
cache_tree_free(&active_cache_tree);

if (rc == 0)
cache_dirty = 1;

return rc;
}

static int git_merge_trees(int index_only,
struct tree *common,
struct tree *head,
Expand All @@ -216,11 +164,6 @@ static int git_merge_trees(int index_only,
struct object_list *trees = NULL;
struct unpack_trees_options opts;

if (!cache_dirty) {
read_cache_from(current_index_file);
cache_dirty = 1;
}

memset(&opts, 0, sizeof(opts));
if (index_only)
opts.index_only = 1;
Expand All @@ -236,39 +179,37 @@ static int git_merge_trees(int index_only,

rc = unpack_trees(trees, &opts);
cache_tree_free(&active_cache_tree);

cache_dirty = 1;

return rc;
}

static int unmerged_index(void)
{
int i;
for (i = 0; i < active_nr; i++) {
struct cache_entry *ce = active_cache[i];
if (ce_stage(ce))
return 1;
}
return 0;
}

static struct tree *git_write_tree(void)
{
struct tree *result = NULL;

if (cache_dirty) {
unsigned i;
for (i = 0; i < active_nr; i++) {
struct cache_entry *ce = active_cache[i];
if (ce_stage(ce))
return NULL;
}
} else
read_cache_from(current_index_file);
if (unmerged_index())
return NULL;

if (!active_cache_tree)
active_cache_tree = cache_tree();

if (!cache_tree_fully_valid(active_cache_tree) &&
cache_tree_update(active_cache_tree,
active_cache, active_nr, 0, 0) < 0)
cache_tree_update(active_cache_tree,
active_cache, active_nr, 0, 0) < 0)
die("error building trees");

result = lookup_tree(active_cache_tree->sha1);

flush_cache();
cache_dirty = 0;

return result;
}

Expand Down Expand Up @@ -331,10 +272,7 @@ static struct path_list *get_unmerged(void)
int i;

unmerged->strdup_paths = 1;
if (!cache_dirty) {
read_cache_from(current_index_file);
cache_dirty++;
}

for (i = 0; i < active_nr; i++) {
struct path_list_item *item;
struct stage_data *e;
Expand Down Expand Up @@ -469,9 +407,6 @@ static int remove_file(int clean, const char *path, int no_wd)
int update_working_directory = !index_only && !no_wd;

if (update_cache) {
if (!cache_dirty)
read_cache_from(current_index_file);
cache_dirty++;
if (remove_file_from_cache(path))
return -1;
}
Expand Down Expand Up @@ -1105,9 +1040,7 @@ static int merge_trees(struct tree *head,
sha1_to_hex(head->object.sha1),
sha1_to_hex(merge->object.sha1));

*result = git_write_tree();

if (!*result) {
if (unmerged_index()) {
struct path_list *entries, *re_head, *re_merge;
int i;
path_list_clear(&current_file_set, 1);
Expand All @@ -1128,24 +1061,20 @@ static int merge_trees(struct tree *head,
if (!process_entry(path, e, branch1, branch2))
clean = 0;
}
if (cache_dirty)
flush_cache();

path_list_clear(re_merge, 0);
path_list_clear(re_head, 0);
path_list_clear(entries, 1);

if (clean || index_only)
*result = git_write_tree();
else
*result = NULL;
} else {
clean = 1;
printf("merging of trees %s and %s resulted in %s\n",
sha1_to_hex(head->object.sha1),
sha1_to_hex(merge->object.sha1),
sha1_to_hex((*result)->object.sha1));
}
if (index_only)
*result = git_write_tree();

return clean;
}
Expand All @@ -1170,10 +1099,10 @@ static int merge(struct commit *h1,
const char *branch1,
const char *branch2,
int call_depth /* =0 */,
struct commit *ancestor /* =None */,
struct commit_list *ca,
struct commit **result)
{
struct commit_list *ca = NULL, *iter;
struct commit_list *iter;
struct commit *merged_common_ancestors;
struct tree *mrtree;
int clean;
Expand All @@ -1182,10 +1111,10 @@ static int merge(struct commit *h1,
output_commit_title(h1);
output_commit_title(h2);

if (ancestor)
commit_list_insert(ancestor, &ca);
else
ca = reverse_commit_list(get_merge_bases(h1, h2, 1));
if (!ca) {
ca = get_merge_bases(h1, h2, 1);
ca = reverse_commit_list(ca);
}

output("found %u common ancestor(s):", commit_list_count(ca));
for (iter = ca; iter; iter = iter->next)
Expand All @@ -1211,6 +1140,7 @@ static int merge(struct commit *h1,
* merge_trees has always overwritten it: the commited
* "conflicts" were already resolved.
*/
discard_cache();
merge(merged_common_ancestors, iter->item,
"Temporary merge branch 1",
"Temporary merge branch 2",
Expand All @@ -1223,25 +1153,21 @@ static int merge(struct commit *h1,
die("merge returned no commit");
}

discard_cache();
if (call_depth == 0) {
setup_index(0 /* $GIT_DIR/index */);
read_cache();
index_only = 0;
} else {
setup_index(1 /* temporary index */);
git_read_tree(h1->tree);
} else
index_only = 1;
}

clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
branch1, branch2, &mrtree);

if (!ancestor && (clean || index_only)) {
if (index_only) {
*result = make_virtual_commit(mrtree, "merged tree");
commit_list_insert(h1, &(*result)->parents);
commit_list_insert(h2, &(*result)->parents->next);
} else
*result = NULL;

}
return clean;
}

Expand Down Expand Up @@ -1277,19 +1203,16 @@ static struct commit *get_ref(const char *ref)

int main(int argc, char *argv[])
{
static const char *bases[2];
static const char *bases[20];
static unsigned bases_count = 0;
int i, clean;
const char *branch1, *branch2;
struct commit *result, *h1, *h2;
struct commit_list *ca = NULL;
struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
int index_fd;

git_config(git_default_config); /* core.filemode */
original_index_file = getenv(INDEX_ENVIRONMENT);

if (!original_index_file)
original_index_file = xstrdup(git_path("index"));

temporary_index_file = xstrdup(git_path("mrg-rcrsv-tmp-idx"));

if (argc < 4)
die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
Expand All @@ -1313,18 +1236,18 @@ int main(int argc, char *argv[])
branch2 = better_branch_name(branch2);
printf("Merging %s with %s\n", branch1, branch2);

if (bases_count == 1) {
struct commit *ancestor = get_ref(bases[0]);
clean = merge(h1, h2, branch1, branch2, 0, ancestor, &result);
} else
clean = merge(h1, h2, branch1, branch2, 0, NULL, &result);
index_fd = hold_lock_file_for_update(lock, get_index_file(), 1);

if (cache_dirty)
flush_cache();
for (i = 0; i < bases_count; i++) {
struct commit *ancestor = get_ref(bases[i]);
ca = commit_list_insert(ancestor, &ca);
}
clean = merge(h1, h2, branch1, branch2, 0, ca, &result);

if (active_cache_changed &&
(write_cache(index_fd, active_cache, active_nr) ||
close(index_fd) || commit_lock_file(lock)))
die ("unable to write %s", get_index_file());

return clean ? 0: 1;
}

/*
vim: sw=8 noet
*/

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