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Revision 531942d353758305e29879654b93f4ba3dcbcc63 authored by Elijah Newren on 28 September 2020, 17:37:16 UTC, committed by Elijah Newren on 13 October 2020, 22:37:51 UTC 
t6423: more involved rules for renaming directories into each other
 
Testcases 12b and 12c were both slightly weird; they were marked as
having a weird resolution, but with the note that even straightforward
simple rules can give weird results when the input is bizarre.

However, during optimization work for merge-ort, I discovered a
significant speedup that is possible if we add one more fairly
straightforward rule: we don't bother doing directory rename detection
if there are no new files added to the directory on the other side of
the history to be affected by the directory rename.  This seems like an
obvious and straightforward rule, but there was one funny corner case
where directory rename detection could affect only existing files: the
funny corner case where two directories are renamed into each other on
opposite sides of history.  In other words, it only results in a
different output for testcases 12b and 12c.

Since we already thought testcases 12b and 12c were weird anyway, and
because the optimization often has a significant effect on common cases
(but is entirely prevented if we can't change how 12b and 12c function),
let's add the additional rule and tweak how 12b and 12c work.  Split
both testcases into two (one where we add no new files, and one where
the side that doesn't rename a given directory will add files to it),
and mark them with the new expectation.

Signed-off-by: Elijah Newren <newren@gmail.com>
1 parent 146d6f4
Raw File
cache-tree.h 
#ifndef CACHE_TREE_H
#define CACHE_TREE_H

#include "cache.h"
#include "tree.h"
#include "tree-walk.h"

struct cache_tree;
struct cache_tree_sub {
	struct cache_tree *cache_tree;
	int count;		/* internally used by update_one() */
	int namelen;
	int used;
	char name[FLEX_ARRAY];
};

struct cache_tree {
	int entry_count; /* negative means "invalid" */
	struct object_id oid;
	int subtree_nr;
	int subtree_alloc;
	struct cache_tree_sub **down;
};

struct cache_tree *cache_tree(void);
void cache_tree_free(struct cache_tree **);
void cache_tree_invalidate_path(struct index_state *, const char *);
struct cache_tree_sub *cache_tree_sub(struct cache_tree *, const char *);

void cache_tree_write(struct strbuf *, struct cache_tree *root);
struct cache_tree *cache_tree_read(const char *buffer, unsigned long size);

int cache_tree_fully_valid(struct cache_tree *);
int cache_tree_update(struct index_state *, int);
void cache_tree_verify(struct repository *, struct index_state *);

/* bitmasks to write_index_as_tree flags */
#define WRITE_TREE_MISSING_OK 1
#define WRITE_TREE_IGNORE_CACHE_TREE 2
#define WRITE_TREE_DRY_RUN 4
#define WRITE_TREE_SILENT 8
#define WRITE_TREE_REPAIR 16

/* error return codes */
#define WRITE_TREE_UNREADABLE_INDEX (-1)
#define WRITE_TREE_UNMERGED_INDEX (-2)
#define WRITE_TREE_PREFIX_ERROR (-3)

struct tree* write_in_core_index_as_tree(struct repository *repo);
int write_index_as_tree(struct object_id *oid, struct index_state *index_state, const char *index_path, int flags, const char *prefix);
void prime_cache_tree(struct repository *, struct index_state *, struct tree *);

int cache_tree_matches_traversal(struct cache_tree *, struct name_entry *ent, struct traverse_info *info);

#ifdef USE_THE_INDEX_COMPATIBILITY_MACROS
static inline int write_cache_as_tree(struct object_id *oid, int flags, const char *prefix)
{
	return write_index_as_tree(oid, &the_index, get_index_file(), flags, prefix);
}

static inline int update_main_cache_tree(int flags)
{
	if (!the_index.cache_tree)
		the_index.cache_tree = cache_tree();
	return cache_tree_update(&the_index, flags);
}
#endif

#endif
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