Revision b018ff60857ee7d79e3c4a8772bac08656a2a3c6 authored by Jeff King on 29 December 2012, 20:51:54 UTC, committed by Junio C Hamano on 04 November 2013, 18:13:27 UTC
When we call "read-tree --reset -u HEAD ORIG_HEAD", the first thing we do with the index is to call read_cache_unmerged. Originally that would read the index, leaving aside any unmerged entries. However, as of d1a43f2 (reset --hard/read-tree --reset -u: remove unmerged new paths, 2008-10-15), it actually creates a new cache entry to serve as a placeholder, so that we later know to update the working tree. However, we later noticed that the sha1 of that unmerged entry was just copied from some higher stage, leaving you with random content in the index. That was fixed by e11d7b5 ("reset --merge": fix unmerged case, 2009-12-31), which instead puts the null sha1 into the newly created entry, and sets a CE_CONFLICTED flag. At the same time, it teaches the unpack-trees machinery to pay attention to this flag, so that oneway_merge throws away the current value. However, it did not update the code paths for twoway_merge, which is where we end up in the two-way read-tree with --reset. We notice that the HEAD and ORIG_HEAD versions are the same, and say "oh, we can just reuse the current version". But that's not true. The current version is bogus. Notice this case and make sure we do not keep the bogus entry; either we do not have that path in the tree we are moving to (i.e. remove it), or we want to have the cache entry we created for the tree we are moving to (i.e. resolve by explicitly saying the "newtree" version is what we want). [jc: this is from the almost year-old $gmane/212316] Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent c479d14
xpatience.c
/*
* LibXDiff by Davide Libenzi ( File Differential Library )
* Copyright (C) 2003-2009 Davide Libenzi, Johannes E. Schindelin
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Davide Libenzi <davidel@xmailserver.org>
*
*/
#include "xinclude.h"
#include "xtypes.h"
#include "xdiff.h"
/*
* The basic idea of patience diff is to find lines that are unique in
* both files. These are intuitively the ones that we want to see as
* common lines.
*
* The maximal ordered sequence of such line pairs (where ordered means
* that the order in the sequence agrees with the order of the lines in
* both files) naturally defines an initial set of common lines.
*
* Now, the algorithm tries to extend the set of common lines by growing
* the line ranges where the files have identical lines.
*
* Between those common lines, the patience diff algorithm is applied
* recursively, until no unique line pairs can be found; these line ranges
* are handled by the well-known Myers algorithm.
*/
#define NON_UNIQUE ULONG_MAX
/*
* This is a hash mapping from line hash to line numbers in the first and
* second file.
*/
struct hashmap {
int nr, alloc;
struct entry {
unsigned long hash;
/*
* 0 = unused entry, 1 = first line, 2 = second, etc.
* line2 is NON_UNIQUE if the line is not unique
* in either the first or the second file.
*/
unsigned long line1, line2;
/*
* "next" & "previous" are used for the longest common
* sequence;
* initially, "next" reflects only the order in file1.
*/
struct entry *next, *previous;
} *entries, *first, *last;
/* were common records found? */
unsigned long has_matches;
mmfile_t *file1, *file2;
xdfenv_t *env;
xpparam_t const *xpp;
};
/* The argument "pass" is 1 for the first file, 2 for the second. */
static void insert_record(int line, struct hashmap *map, int pass)
{
xrecord_t **records = pass == 1 ?
map->env->xdf1.recs : map->env->xdf2.recs;
xrecord_t *record = records[line - 1], *other;
/*
* After xdl_prepare_env() (or more precisely, due to
* xdl_classify_record()), the "ha" member of the records (AKA lines)
* is _not_ the hash anymore, but a linearized version of it. In
* other words, the "ha" member is guaranteed to start with 0 and
* the second record's ha can only be 0 or 1, etc.
*
* So we multiply ha by 2 in the hope that the hashing was
* "unique enough".
*/
int index = (int)((record->ha << 1) % map->alloc);
while (map->entries[index].line1) {
other = map->env->xdf1.recs[map->entries[index].line1 - 1];
if (map->entries[index].hash != record->ha ||
!xdl_recmatch(record->ptr, record->size,
other->ptr, other->size,
map->xpp->flags)) {
if (++index >= map->alloc)
index = 0;
continue;
}
if (pass == 2)
map->has_matches = 1;
if (pass == 1 || map->entries[index].line2)
map->entries[index].line2 = NON_UNIQUE;
else
map->entries[index].line2 = line;
return;
}
if (pass == 2)
return;
map->entries[index].line1 = line;
map->entries[index].hash = record->ha;
if (!map->first)
map->first = map->entries + index;
if (map->last) {
map->last->next = map->entries + index;
map->entries[index].previous = map->last;
}
map->last = map->entries + index;
map->nr++;
}
/*
* This function has to be called for each recursion into the inter-hunk
* parts, as previously non-unique lines can become unique when being
* restricted to a smaller part of the files.
*
* It is assumed that env has been prepared using xdl_prepare().
*/
static int fill_hashmap(mmfile_t *file1, mmfile_t *file2,
xpparam_t const *xpp, xdfenv_t *env,
struct hashmap *result,
int line1, int count1, int line2, int count2)
{
result->file1 = file1;
result->file2 = file2;
result->xpp = xpp;
result->env = env;
/* We know exactly how large we want the hash map */
result->alloc = count1 * 2;
result->entries = (struct entry *)
xdl_malloc(result->alloc * sizeof(struct entry));
if (!result->entries)
return -1;
memset(result->entries, 0, result->alloc * sizeof(struct entry));
/* First, fill with entries from the first file */
while (count1--)
insert_record(line1++, result, 1);
/* Then search for matches in the second file */
while (count2--)
insert_record(line2++, result, 2);
return 0;
}
/*
* Find the longest sequence with a smaller last element (meaning a smaller
* line2, as we construct the sequence with entries ordered by line1).
*/
static int binary_search(struct entry **sequence, int longest,
struct entry *entry)
{
int left = -1, right = longest;
while (left + 1 < right) {
int middle = (left + right) / 2;
/* by construction, no two entries can be equal */
if (sequence[middle]->line2 > entry->line2)
right = middle;
else
left = middle;
}
/* return the index in "sequence", _not_ the sequence length */
return left;
}
/*
* The idea is to start with the list of common unique lines sorted by
* the order in file1. For each of these pairs, the longest (partial)
* sequence whose last element's line2 is smaller is determined.
*
* For efficiency, the sequences are kept in a list containing exactly one
* item per sequence length: the sequence with the smallest last
* element (in terms of line2).
*/
static struct entry *find_longest_common_sequence(struct hashmap *map)
{
struct entry **sequence = xdl_malloc(map->nr * sizeof(struct entry *));
int longest = 0, i;
struct entry *entry;
for (entry = map->first; entry; entry = entry->next) {
if (!entry->line2 || entry->line2 == NON_UNIQUE)
continue;
i = binary_search(sequence, longest, entry);
entry->previous = i < 0 ? NULL : sequence[i];
sequence[++i] = entry;
if (i == longest)
longest++;
}
/* No common unique lines were found */
if (!longest) {
xdl_free(sequence);
return NULL;
}
/* Iterate starting at the last element, adjusting the "next" members */
entry = sequence[longest - 1];
entry->next = NULL;
while (entry->previous) {
entry->previous->next = entry;
entry = entry->previous;
}
xdl_free(sequence);
return entry;
}
static int match(struct hashmap *map, int line1, int line2)
{
xrecord_t *record1 = map->env->xdf1.recs[line1 - 1];
xrecord_t *record2 = map->env->xdf2.recs[line2 - 1];
return xdl_recmatch(record1->ptr, record1->size,
record2->ptr, record2->size, map->xpp->flags);
}
static int patience_diff(mmfile_t *file1, mmfile_t *file2,
xpparam_t const *xpp, xdfenv_t *env,
int line1, int count1, int line2, int count2);
static int walk_common_sequence(struct hashmap *map, struct entry *first,
int line1, int count1, int line2, int count2)
{
int end1 = line1 + count1, end2 = line2 + count2;
int next1, next2;
for (;;) {
/* Try to grow the line ranges of common lines */
if (first) {
next1 = first->line1;
next2 = first->line2;
while (next1 > line1 && next2 > line2 &&
match(map, next1 - 1, next2 - 1)) {
next1--;
next2--;
}
} else {
next1 = end1;
next2 = end2;
}
while (line1 < next1 && line2 < next2 &&
match(map, line1, line2)) {
line1++;
line2++;
}
/* Recurse */
if (next1 > line1 || next2 > line2) {
struct hashmap submap;
memset(&submap, 0, sizeof(submap));
if (patience_diff(map->file1, map->file2,
map->xpp, map->env,
line1, next1 - line1,
line2, next2 - line2))
return -1;
}
if (!first)
return 0;
while (first->next &&
first->next->line1 == first->line1 + 1 &&
first->next->line2 == first->line2 + 1)
first = first->next;
line1 = first->line1 + 1;
line2 = first->line2 + 1;
first = first->next;
}
}
static int fall_back_to_classic_diff(struct hashmap *map,
int line1, int count1, int line2, int count2)
{
xpparam_t xpp;
xpp.flags = map->xpp->flags & ~XDF_PATIENCE_DIFF;
return xdl_fall_back_diff(map->env, &xpp,
line1, count1, line2, count2);
}
/*
* Recursively find the longest common sequence of unique lines,
* and if none was found, ask xdl_do_diff() to do the job.
*
* This function assumes that env was prepared with xdl_prepare_env().
*/
static int patience_diff(mmfile_t *file1, mmfile_t *file2,
xpparam_t const *xpp, xdfenv_t *env,
int line1, int count1, int line2, int count2)
{
struct hashmap map;
struct entry *first;
int result = 0;
/* trivial case: one side is empty */
if (!count1) {
while(count2--)
env->xdf2.rchg[line2++ - 1] = 1;
return 0;
} else if (!count2) {
while(count1--)
env->xdf1.rchg[line1++ - 1] = 1;
return 0;
}
memset(&map, 0, sizeof(map));
if (fill_hashmap(file1, file2, xpp, env, &map,
line1, count1, line2, count2))
return -1;
/* are there any matching lines at all? */
if (!map.has_matches) {
while(count1--)
env->xdf1.rchg[line1++ - 1] = 1;
while(count2--)
env->xdf2.rchg[line2++ - 1] = 1;
xdl_free(map.entries);
return 0;
}
first = find_longest_common_sequence(&map);
if (first)
result = walk_common_sequence(&map, first,
line1, count1, line2, count2);
else
result = fall_back_to_classic_diff(&map,
line1, count1, line2, count2);
xdl_free(map.entries);
return result;
}
int xdl_do_patience_diff(mmfile_t *file1, mmfile_t *file2,
xpparam_t const *xpp, xdfenv_t *env)
{
if (xdl_prepare_env(file1, file2, xpp, env) < 0)
return -1;
/* environment is cleaned up in xdl_diff() */
return patience_diff(file1, file2, xpp, env,
1, env->xdf1.nrec, 1, env->xdf2.nrec);
}
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