ls-refs: reuse buffer when sending refs

In the initial reference advertisement, the Git server will first
announce all of its references to the client. The logic is handled in
`send_ref()`, which will allocate a new buffer for each refline it is
about to send. This is quite wasteful: instead of allocating a new
buffer each time, we can just reuse a buffer.

Improve this by passing in a buffer via the `ls_refs_data` struct which
is then reused on each reference.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/ls-refs.c b/ls-refs.c
index 88f6c3f60d8ef61373a1bfed33f49c877b6af320..84021416ca5561c937e920fc83d6a1fdede034f5 100644 (file)
--- a/ls-refs.c
+++ b/ls-refs.c
@@ -65,6 +65,7 @@ struct ls_refs_data {
        unsigned peel;
        unsigned symrefs;
        struct strvec prefixes;
+       struct strbuf buf;
        unsigned unborn : 1;
 };
 
@@ -73,7 +74,8 @@ static int send_ref(const char *refname, const struct object_id *oid,
 {
        struct ls_refs_data *data = cb_data;
        const char *refname_nons = strip_namespace(refname);
-       struct strbuf refline = STRBUF_INIT;
+
+       strbuf_reset(&data->buf);
 
        if (ref_is_hidden(refname_nons, refname))
                return 0;
@@ -82,9 +84,9 @@ static int send_ref(const char *refname, const struct object_id *oid,
                return 0;
 
        if (oid)
-               strbuf_addf(&refline, "%s %s", oid_to_hex(oid), refname_nons);
+               strbuf_addf(&data->buf, "%s %s", oid_to_hex(oid), refname_nons);
        else
-               strbuf_addf(&refline, "unborn %s", refname_nons);
+               strbuf_addf(&data->buf, "unborn %s", refname_nons);
        if (data->symrefs && flag & REF_ISSYMREF) {
                struct object_id unused;
                const char *symref_target = resolve_ref_unsafe(refname, 0,
@@ -94,20 +96,19 @@ static int send_ref(const char *refname, const struct object_id *oid,
                if (!symref_target)
                        die("'%s' is a symref but it is not?", refname);
 
-               strbuf_addf(&refline, " symref-target:%s",
+               strbuf_addf(&data->buf, " symref-target:%s",
                            strip_namespace(symref_target));
        }
 
        if (data->peel && oid) {
                struct object_id peeled;
                if (!peel_iterated_oid(oid, &peeled))
-                       strbuf_addf(&refline, " peeled:%s", oid_to_hex(&peeled));
+                       strbuf_addf(&data->buf, " peeled:%s", oid_to_hex(&peeled));
        }
 
-       strbuf_addch(&refline, '\n');
-       packet_write(1, refline.buf, refline.len);
+       strbuf_addch(&data->buf, '\n');
+       packet_write(1, data->buf.buf, data->buf.len);
 
-       strbuf_release(&refline);
        return 0;
 }
 
@@ -145,6 +146,7 @@ int ls_refs(struct repository *r, struct strvec *keys,
 
        memset(&data, 0, sizeof(data));
        strvec_init(&data.prefixes);
+       strbuf_init(&data.buf, 0);
 
        ensure_config_read();
        git_config(ls_refs_config, NULL);
@@ -173,6 +175,7 @@ int ls_refs(struct repository *r, struct strvec *keys,
                                     send_ref, &data, 0);
        packet_flush(1);
        strvec_clear(&data.prefixes);
+       strbuf_release(&data.buf);
        return 0;
 }