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diff-tree: convert base+baselen to writable strbuf
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In traversing trees, a full path is splitted into two parts: base
directory and entry. They are however quite often concatenated
whenever a full path is needed. Current code allocates a new buffer,
do two memcpy(), use it, then release.

Instead this patch turns "base" to a writable, extendable buffer. When
a concatenation is needed, the callee only needs to append "entry" to
base, use it, then truncate the entry out again. "base" must remain
unchanged before and after entering a function.

This avoids quite a bit of malloc() and memcpy().

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Nguyễn Thái Ngọc Duy authored and Junio C Hamano committed Feb 3, 2011
1 parent 3bd2bcf commit 4893267
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Showing 3 changed files with 56 additions and 71 deletions.
120 changes: 52 additions & 68 deletions tree-diff.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,34 +6,18 @@
#include "diffcore.h"
#include "tree.h"

static char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
{
char *newbase = xmalloc(baselen + pathlen + 2);
memcpy(newbase, base, baselen);
memcpy(newbase + baselen, path, pathlen);
memcpy(newbase + baselen + pathlen, "/", 2);
return newbase;
}
static void show_entry(struct diff_options *opt, const char *prefix,
struct tree_desc *desc, struct strbuf *base);

static char *malloc_fullname(const char *base, int baselen, const char *path, int pathlen)
{
char *fullname = xmalloc(baselen + pathlen + 1);
memcpy(fullname, base, baselen);
memcpy(fullname + baselen, path, pathlen);
fullname[baselen + pathlen] = 0;
return fullname;
}

static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
const char *base, int baselen);

static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2,
struct strbuf *base, struct diff_options *opt)
{
unsigned mode1, mode2;
const char *path1, *path2;
const unsigned char *sha1, *sha2;
int cmp, pathlen1, pathlen2;
char *fullname;
int old_baselen = base->len;
int retval = 0;

sha1 = tree_entry_extract(t1, &path1, &mode1);
sha2 = tree_entry_extract(t2, &path2, &mode2);
Expand All @@ -42,11 +26,11 @@ static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const
pathlen2 = tree_entry_len(path2, sha2);
cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
if (cmp < 0) {
show_entry(opt, "-", t1, base, baselen);
show_entry(opt, "-", t1, base);
return -1;
}
if (cmp > 0) {
show_entry(opt, "+", t2, base, baselen);
show_entry(opt, "+", t2, base);
return 1;
}
if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) && !hashcmp(sha1, sha2) && mode1 == mode2)
Expand All @@ -57,33 +41,29 @@ static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const
* file, we need to consider it a remove and an add.
*/
if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
show_entry(opt, "-", t1, base, baselen);
show_entry(opt, "+", t2, base, baselen);
show_entry(opt, "-", t1, base);
show_entry(opt, "+", t2, base);
return 0;
}

strbuf_add(base, path1, pathlen1);
if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode1)) {
int retval;
char *newbase = malloc_base(base, baselen, path1, pathlen1);
if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
newbase[baselen + pathlen1] = 0;
opt->change(opt, mode1, mode2,
sha1, sha2, newbase, 0, 0);
newbase[baselen + pathlen1] = '/';
sha1, sha2, base->buf, 0, 0);
}
retval = diff_tree_sha1(sha1, sha2, newbase, opt);
free(newbase);
return retval;
strbuf_addch(base, '/');
retval = diff_tree_sha1(sha1, sha2, base->buf, opt);
} else {
opt->change(opt, mode1, mode2, sha1, sha2, base->buf, 0, 0);
}

fullname = malloc_fullname(base, baselen, path1, pathlen1);
opt->change(opt, mode1, mode2, sha1, sha2, fullname, 0, 0);
free(fullname);
strbuf_setlen(base, old_baselen);
return 0;
}

/* A whole sub-tree went away or appeared */
static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
static void show_tree(struct diff_options *opt, const char *prefix,
struct tree_desc *desc, struct strbuf *base)
{
int all_interesting = 0;
while (desc->size) {
Expand All @@ -92,30 +72,32 @@ static void show_tree(struct diff_options *opt, const char *prefix, struct tree_
if (all_interesting)
show = 1;
else {
show = tree_entry_interesting(&desc->entry, base, baselen, &opt->pathspec);
show = tree_entry_interesting(&desc->entry, base,
&opt->pathspec);
if (show == 2)
all_interesting = 1;
}
if (show < 0)
break;
if (show)
show_entry(opt, prefix, desc, base, baselen);
show_entry(opt, prefix, desc, base);
update_tree_entry(desc);
}
}

/* A file entry went away or appeared */
static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
const char *base, int baselen)
static void show_entry(struct diff_options *opt, const char *prefix,
struct tree_desc *desc, struct strbuf *base)
{
unsigned mode;
const char *path;
const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
int pathlen = tree_entry_len(path, sha1);
int old_baselen = base->len;

strbuf_add(base, path, pathlen);
if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
enum object_type type;
char *newbase = malloc_base(base, baselen, path, pathlen);
struct tree_desc inner;
void *tree;
unsigned long size;
Expand All @@ -124,28 +106,25 @@ static void show_entry(struct diff_options *opt, const char *prefix, struct tree
if (!tree || type != OBJ_TREE)
die("corrupt tree sha %s", sha1_to_hex(sha1));

if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
newbase[baselen + pathlen] = 0;
opt->add_remove(opt, *prefix, mode, sha1, newbase, 0);
newbase[baselen + pathlen] = '/';
}
if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE))
opt->add_remove(opt, *prefix, mode, sha1, base->buf, 0);

init_tree_desc(&inner, tree, size);
show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
strbuf_addch(base, '/');

init_tree_desc(&inner, tree, size);
show_tree(opt, prefix, &inner, base);
free(tree);
free(newbase);
} else {
char *fullname = malloc_fullname(base, baselen, path, pathlen);
opt->add_remove(opt, prefix[0], mode, sha1, fullname, 0);
free(fullname);
}
} else
opt->add_remove(opt, prefix[0], mode, sha1, base->buf, 0);

strbuf_setlen(base, old_baselen);
}

static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt, int *all_interesting)
static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
struct diff_options *opt, int *all_interesting)
{
while (t->size) {
int show = tree_entry_interesting(&t->entry, base, baselen, &opt->pathspec);
int show = tree_entry_interesting(&t->entry, base, &opt->pathspec);
if (show == 2)
*all_interesting = 1;
if (!show) {
Expand All @@ -159,37 +138,40 @@ static void skip_uninteresting(struct tree_desc *t, const char *base, int basele
}
}

int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
const char *base_str, struct diff_options *opt)
{
int baselen = strlen(base);
struct strbuf base;
int baselen = strlen(base_str);
int all_t1_interesting = 0;
int all_t2_interesting = 0;

strbuf_init(&base, PATH_MAX);
strbuf_add(&base, base_str, baselen);

for (;;) {
if (DIFF_OPT_TST(opt, QUICK) &&
DIFF_OPT_TST(opt, HAS_CHANGES))
break;
if (opt->pathspec.nr) {
if (!all_t1_interesting)
skip_uninteresting(t1, base, baselen, opt,
&all_t1_interesting);
skip_uninteresting(t1, &base, opt, &all_t1_interesting);
if (!all_t2_interesting)
skip_uninteresting(t2, base, baselen, opt,
&all_t2_interesting);
skip_uninteresting(t2, &base, opt, &all_t2_interesting);
}
if (!t1->size) {
if (!t2->size)
break;
show_entry(opt, "+", t2, base, baselen);
show_entry(opt, "+", t2, &base);
update_tree_entry(t2);
continue;
}
if (!t2->size) {
show_entry(opt, "-", t1, base, baselen);
show_entry(opt, "-", t1, &base);
update_tree_entry(t1);
continue;
}
switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
switch (compare_tree_entry(t1, t2, &base, opt)) {
case -1:
update_tree_entry(t1);
continue;
Expand All @@ -202,6 +184,8 @@ int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, stru
}
die("git diff-tree: internal error");
}

strbuf_release(&base);
return 0;
}

Expand Down
5 changes: 3 additions & 2 deletions tree-walk.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -468,12 +468,13 @@ int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned ch
* - negative for "no, and no subsequent entries will be either"
*/
int tree_entry_interesting(const struct name_entry *entry,
const char *base, int baselen,
const struct strbuf *base_buf,
const struct pathspec *ps)
{
int i;
int pathlen;
int pathlen, baselen = base_buf->len;
int never_interesting = -1;
const char *base = base_buf->buf;

if (!ps || !ps->nr)
return 2;
Expand Down
2 changes: 1 addition & 1 deletion tree-walk.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,6 @@ static inline int traverse_path_len(const struct traverse_info *info, const stru
return info->pathlen + tree_entry_len(n->path, n->sha1);
}

extern int tree_entry_interesting(const struct name_entry *, const char *, int, const struct pathspec *ps);
extern int tree_entry_interesting(const struct name_entry *, const struct strbuf *, const struct pathspec *ps);

#endif

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