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read_packed_refs(): use mmap to read the packed-refs file

Browse source 
It's still done in a pretty stupid way, involving more data copying
than necessary. That will improve in future commits.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Michael Haggerty 2017-09-13 19:15:59 +02:00 committed by Junio C Hamano
parent 735267aa10
commit 49a03ef466
1 changed files with 32 additions and 10 deletions
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42
refs/packed-backend.c
View file

@ -215,8 +215,12 @@ static NORETURN void die_invalid_line(const char *path,
*/
static struct packed_ref_cache *read_packed_refs(struct packed_ref_store *refs)
{
FILE *f;
struct packed_ref_cache *packed_refs = xcalloc(1, sizeof(*packed_refs));
int fd;
struct stat st;
size_t size;
char *buf;
const char *pos, *eol, *eof;
struct ref_entry *last = NULL;
struct strbuf line = STRBUF_INIT;
enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
@ -227,8 +231,8 @@ static struct packed_ref_cache *read_packed_refs(struct packed_ref_store *refs)
packed_refs->cache = create_ref_cache(NULL, NULL);
packed_refs->cache->root->flag &= ~REF_INCOMPLETE;
f = fopen(refs->path, "r");
if (!f) {
fd = open(refs->path, O_RDONLY);
if (fd < 0) {
if (errno == ENOENT) {
/*
* This is OK; it just means that no
@ -241,16 +245,27 @@ static struct packed_ref_cache *read_packed_refs(struct packed_ref_store *refs)
}
}
stat_validity_update(&packed_refs->validity, fileno(f));
stat_validity_update(&packed_refs->validity, fd);
if (fstat(fd, &st) < 0)
die_errno("couldn't stat %s", refs->path);
size = xsize_t(st.st_size);
buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
pos = buf;
eof = buf + size;
dir = get_ref_dir(packed_refs->cache->root);
while (strbuf_getwholeline(&line, f, '\n') != EOF) {
while (pos < eof) {
struct object_id oid;
const char *refname;
const char *traits;
if (!line.len || line.buf[line.len - 1] != '\n')
die_unterminated_line(refs->path, line.buf, line.len);
eol = memchr(pos, '\n', eof - pos);
if (!eol)
die_unterminated_line(refs->path, pos, eof - pos);
strbuf_add(&line, pos, eol + 1 - pos);
if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
if (strstr(traits, " fully-peeled "))
@ -258,7 +273,7 @@ static struct packed_ref_cache *read_packed_refs(struct packed_ref_store *refs)
else if (strstr(traits, " peeled "))
peeled = PEELED_TAGS;
/* perhaps other traits later as well */
continue;
goto next_line;
}
refname = parse_ref_line(&line, &oid);
@ -291,11 +306,18 @@ static struct packed_ref_cache *read_packed_refs(struct packed_ref_store *refs)
} else {
die_invalid_line(refs->path, line.buf, line.len);
}
next_line:
/* The "+ 1" is for the LF character. */
pos = eol + 1;
strbuf_reset(&line);
}
fclose(f);
strbuf_release(&line);
if (munmap(buf, size))
die_errno("error ummapping packed-refs file");
close(fd);
strbuf_release(&line);
return packed_refs;
}