[PATCH v3 05/21] read_packed_refs(): use mmap to read the `packed-refs` file
- From
Michael Haggerty <mhagger@alum.mit.edu>
- Date
- Sep 25, 2017, 08:00 UTC
- Message-ID
- <9a4914af7f6abfed196986c59abd9875e64b0a9d.1506325610.git.mhagger@alum.mit.edu>
- In-Reply-To
- <cover.1506325610.git.mhagger@alum.mit.edu>
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> --- refs/packed-backend.c | 42 ++++++++++++++++++++++++++++++++---------- 1 file changed, 32 insertions(+), 10 deletions(-)
diff --git a/refs/packed-backend.c b/refs/packed-backend.c index 5c50c223ef..154abbd83a 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -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; }
-- 2.14.1