git/ls-refs.c
Jeff King c4716086d8 ls-refs: drop config caching
The code for the v2 ls-refs command has an ensure_config_read() function
that tries to read the lsrefs.unborn config only once and caches it in
some static global variables.

There's no real need for this caching. In any given process we'd only
need the value twice (once to decide whether to advertise, and once if
somebody runs the command). And since the config code already has its
own cache, each access is only incurring a hash lookup and string
comparison anyway.

Since the values we set are going to be specific to the_repository, the
globals we set are a mild anti-pattern. In practice it's not a bug (yet)
since the server-side v2 code only handles a single repository anyway.
But it doesn't hurt to take a small step in the right direction and
model a good approach.

Note that we currently set two booleans: advertise_unborn and
allow_unborn. But we can get away with a single value, since "advertise"
naturally implies "allow". That lets us just convert this to a function
with a return value.

Note that we still always read from the_repository; we'll deal with that
in a follow-on patch.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-02-24 09:13:28 -08:00

207 lines
5.1 KiB
C

#include "cache.h"
#include "repository.h"
#include "refs.h"
#include "remote.h"
#include "strvec.h"
#include "ls-refs.h"
#include "pkt-line.h"
#include "config.h"
#include "string-list.h"
static enum {
UNBORN_IGNORE = 0,
UNBORN_ALLOW,
UNBORN_ADVERTISE /* implies ALLOW */
} unborn_config(void)
{
const char *str = NULL;
if (repo_config_get_string_tmp(the_repository, "lsrefs.unborn", &str)) {
/*
* If there is no such config, advertise and allow it by
* default.
*/
return UNBORN_ADVERTISE;
} else {
if (!strcmp(str, "advertise")) {
return UNBORN_ADVERTISE;
} else if (!strcmp(str, "allow")) {
return UNBORN_ALLOW;
} else if (!strcmp(str, "ignore")) {
return UNBORN_IGNORE;
} else {
die(_("invalid value for '%s': '%s'"),
"lsrefs.unborn", str);
}
}
}
/*
* If we see this many or more "ref-prefix" lines from the client, we consider
* it "too many" and will avoid using the prefix feature entirely.
*/
#define TOO_MANY_PREFIXES 65536
/*
* Check if one of the prefixes is a prefix of the ref.
* If no prefixes were provided, all refs match.
*/
static int ref_match(const struct strvec *prefixes, const char *refname)
{
int i;
if (!prefixes->nr)
return 1; /* no restriction */
for (i = 0; i < prefixes->nr; i++) {
const char *prefix = prefixes->v[i];
if (starts_with(refname, prefix))
return 1;
}
return 0;
}
struct ls_refs_data {
unsigned peel;
unsigned symrefs;
struct strvec prefixes;
struct strbuf buf;
struct string_list hidden_refs;
unsigned unborn : 1;
};
static int send_ref(const char *refname, const struct object_id *oid,
int flag, void *cb_data)
{
struct ls_refs_data *data = cb_data;
const char *refname_nons = strip_namespace(refname);
strbuf_reset(&data->buf);
if (ref_is_hidden(refname_nons, refname, &data->hidden_refs))
return 0;
if (!ref_match(&data->prefixes, refname_nons))
return 0;
if (oid)
strbuf_addf(&data->buf, "%s %s", oid_to_hex(oid), refname_nons);
else
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,
&unused,
&flag);
if (!symref_target)
die("'%s' is a symref but it is not?", refname);
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(&data->buf, " peeled:%s", oid_to_hex(&peeled));
}
strbuf_addch(&data->buf, '\n');
packet_fwrite(stdout, data->buf.buf, data->buf.len);
return 0;
}
static void send_possibly_unborn_head(struct ls_refs_data *data)
{
struct strbuf namespaced = STRBUF_INIT;
struct object_id oid;
int flag;
int oid_is_null;
strbuf_addf(&namespaced, "%sHEAD", get_git_namespace());
if (!resolve_ref_unsafe(namespaced.buf, 0, &oid, &flag))
return; /* bad ref */
oid_is_null = is_null_oid(&oid);
if (!oid_is_null ||
(data->unborn && data->symrefs && (flag & REF_ISSYMREF)))
send_ref(namespaced.buf, oid_is_null ? NULL : &oid, flag, data);
strbuf_release(&namespaced);
}
static int ls_refs_config(const char *var, const char *value,
void *cb_data)
{
struct ls_refs_data *data = cb_data;
/*
* We only serve fetches over v2 for now, so respect only "uploadpack"
* config. This may need to eventually be expanded to "receive", but we
* don't yet know how that information will be passed to ls-refs.
*/
return parse_hide_refs_config(var, value, "uploadpack", &data->hidden_refs);
}
int ls_refs(struct repository *r, struct packet_reader *request)
{
struct ls_refs_data data;
memset(&data, 0, sizeof(data));
strvec_init(&data.prefixes);
strbuf_init(&data.buf, 0);
string_list_init_dup(&data.hidden_refs);
git_config(ls_refs_config, &data);
while (packet_reader_read(request) == PACKET_READ_NORMAL) {
const char *arg = request->line;
const char *out;
if (!strcmp("peel", arg))
data.peel = 1;
else if (!strcmp("symrefs", arg))
data.symrefs = 1;
else if (skip_prefix(arg, "ref-prefix ", &out)) {
if (data.prefixes.nr < TOO_MANY_PREFIXES)
strvec_push(&data.prefixes, out);
}
else if (!strcmp("unborn", arg))
data.unborn = !!unborn_config();
else
die(_("unexpected line: '%s'"), arg);
}
if (request->status != PACKET_READ_FLUSH)
die(_("expected flush after ls-refs arguments"));
/*
* If we saw too many prefixes, we must avoid using them at all; as
* soon as we have any prefix, they are meant to form a comprehensive
* list.
*/
if (data.prefixes.nr >= TOO_MANY_PREFIXES)
strvec_clear(&data.prefixes);
send_possibly_unborn_head(&data);
if (!data.prefixes.nr)
strvec_push(&data.prefixes, "");
refs_for_each_fullref_in_prefixes(get_main_ref_store(r),
get_git_namespace(), data.prefixes.v,
send_ref, &data);
packet_fflush(stdout);
strvec_clear(&data.prefixes);
strbuf_release(&data.buf);
string_list_clear(&data.hidden_refs, 0);
return 0;
}
int ls_refs_advertise(struct repository *r, struct strbuf *value)
{
if (value && unborn_config() == UNBORN_ADVERTISE)
strbuf_addstr(value, "unborn");
return 1;
}