diff options
| author | Evan Huus <eapache@gmail.com> | 2014-05-02 09:53:33 -0400 |
|---|---|---|
| committer | Anders Broman <a.broman58@gmail.com> | 2014-05-02 14:34:50 +0000 |
| commit | f181756640f2ac6e14a2034637b00eb4faa28aee (patch) | |
| tree | f50d701ca4e7f0a30241e2006427e404025db47f /epan/wmem | |
| parent | 34fa16971919e9f71ef7dde018253e5b3c0e0bc5 (diff) | |
Optimize wmem_strbuf_grow.
As suggested by Anders, in the case of repeated calls to wmem_strbuf_append_c
(and other functions which append very little data) the growth check was a
substantial portion of the over-all running time. By short-circuiting the check
in the case where growth isn't needed (as opposed to letting it fall-through
naturally) we shave ~25% off the cost of such repeated calls in my benchmarks.
The function (wmem_strbuf_grow) is inline, so the compiler should be able to
optimize each caller individually for the short-circuit.
Change-Id: I76419020f4d8fa675906eb77798969b6c61c7732
Reviewed-on: https://code.wireshark.org/review/1467
Reviewed-by: Anders Broman <a.broman58@gmail.com>
Diffstat (limited to 'epan/wmem')
| -rw-r--r-- | epan/wmem/wmem_strbuf.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/epan/wmem/wmem_strbuf.c b/epan/wmem/wmem_strbuf.c index 41f13a9aff..bd074e7584 100644 --- a/epan/wmem/wmem_strbuf.c +++ b/epan/wmem/wmem_strbuf.c @@ -106,6 +106,14 @@ wmem_strbuf_grow(wmem_strbuf_t *strbuf, const gsize to_add) { gsize new_alloc_len, new_len; + /* short-circuit for efficiency if we have room already; greatly speeds up + * repeated calls to wmem_strbuf_append_c and others which grow a little bit + * at a time. + */ + if (WMEM_STRBUF_ROOM(strbuf) >= to_add) { + return; + } + new_alloc_len = strbuf->alloc_len; new_len = strbuf->len + to_add; |