зеркало из https://github.com/microsoft/git.git
git-merge-tree: generalize the "traverse <n> trees in sync" functionality
It's actually very useful for other things too. Notably, we could do the combined diff a lot more efficiently with this. Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Linus Torvalds
Junio C Hamano
Родитель
01df529722
Коммит
164dcb97f0
132
merge-tree.c
132
merge-tree.c
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@ -125,44 +125,19 @@ static void unresolved(const char *base, struct name_entry n[3])
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printf("3 %06o %s %s%s\n", n[2].mode, sha1_to_hex(n[2].sha1), base, n[2].path);
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}
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/*
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* Merge two trees together (t[1] and t[2]), using a common base (t[0])
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* as the origin.
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*
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* This walks the (sorted) trees in lock-step, checking every possible
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* name. Note that directories automatically sort differently from other
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* files (see "base_name_compare"), so you'll never see file/directory
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* conflicts, because they won't ever compare the same.
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*
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* IOW, if a directory changes to a filename, it will automatically be
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* seen as the directory going away, and the filename being created.
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*
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* Think of this as a three-way diff.
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*
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* The output will be either:
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* - successful merge
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* "0 mode sha1 filename"
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* NOTE NOTE NOTE! FIXME! We really really need to walk the index
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* in parallel with this too!
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*
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* - conflict:
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* "1 mode sha1 filename"
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* "2 mode sha1 filename"
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* "3 mode sha1 filename"
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* where not all of the 1/2/3 lines may exist, of course.
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*
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* The successful merge rules are the same as for the three-way merge
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* in git-read-tree.
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*/
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static void merge_trees(struct tree_desc t[3], const char *base)
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typedef void (*traverse_callback_t)(int n, unsigned long mask, struct name_entry *entry, const char *base);
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static void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callback_t callback)
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{
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struct name_entry *entry = xmalloc(n*sizeof(*entry));
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for (;;) {
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struct name_entry entry[3];
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unsigned int mask = 0;
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unsigned long mask = 0;
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int i, last;
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last = -1;
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for (i = 0; i < 3; i++) {
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for (i = 0; i < n; i++) {
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if (!t[i].size)
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continue;
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entry_extract(t+i, entry+i);
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@ -182,7 +157,7 @@ static void merge_trees(struct tree_desc t[3], const char *base)
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if (cmp < 0)
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mask = 0;
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}
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mask |= 1u << i;
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mask |= 1ul << i;
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last = i;
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}
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if (!mask)
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@ -192,38 +167,77 @@ static void merge_trees(struct tree_desc t[3], const char *base)
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* Update the tree entries we've walked, and clear
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* all the unused name-entries.
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*/
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for (i = 0; i < 3; i++) {
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if (mask & (1u << i)) {
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for (i = 0; i < n; i++) {
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if (mask & (1ul << i)) {
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update_tree_entry(t+i);
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continue;
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}
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entry_clear(entry + i);
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}
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/* Same in both? */
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if (same_entry(entry+1, entry+2)) {
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if (entry[0].sha1) {
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resolve(base, NULL, entry+1);
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continue;
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}
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}
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if (same_entry(entry+0, entry+1)) {
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if (entry[2].sha1 && !S_ISDIR(entry[2].mode)) {
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resolve(base, entry+1, entry+2);
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continue;
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}
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}
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if (same_entry(entry+0, entry+2)) {
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if (entry[1].sha1 && !S_ISDIR(entry[1].mode)) {
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resolve(base, NULL, entry+1);
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continue;
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}
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}
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unresolved(base, entry);
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callback(n, mask, entry, base);
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}
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free(entry);
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}
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/*
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* Merge two trees together (t[1] and t[2]), using a common base (t[0])
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* as the origin.
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*
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* This walks the (sorted) trees in lock-step, checking every possible
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* name. Note that directories automatically sort differently from other
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* files (see "base_name_compare"), so you'll never see file/directory
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* conflicts, because they won't ever compare the same.
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*
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* IOW, if a directory changes to a filename, it will automatically be
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* seen as the directory going away, and the filename being created.
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*
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* Think of this as a three-way diff.
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*
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* The output will be either:
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* - successful merge
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* "0 mode sha1 filename"
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* NOTE NOTE NOTE! FIXME! We really really need to walk the index
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* in parallel with this too!
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*
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* - conflict:
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* "1 mode sha1 filename"
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* "2 mode sha1 filename"
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* "3 mode sha1 filename"
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* where not all of the 1/2/3 lines may exist, of course.
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*
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* The successful merge rules are the same as for the three-way merge
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* in git-read-tree.
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*/
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static void threeway_callback(int n, unsigned long mask, struct name_entry *entry, const char *base)
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{
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/* Same in both? */
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if (same_entry(entry+1, entry+2)) {
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if (entry[0].sha1) {
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resolve(base, NULL, entry+1);
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return;
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}
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}
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if (same_entry(entry+0, entry+1)) {
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if (entry[2].sha1 && !S_ISDIR(entry[2].mode)) {
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resolve(base, entry+1, entry+2);
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return;
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}
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}
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if (same_entry(entry+0, entry+2)) {
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if (entry[1].sha1 && !S_ISDIR(entry[1].mode)) {
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resolve(base, NULL, entry+1);
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return;
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}
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}
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unresolved(base, entry);
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}
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static void merge_trees(struct tree_desc t[3], const char *base)
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{
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traverse_trees(3, t, base, threeway_callback);
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}
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static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
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