git/promisor-remote.c
Jonathan Tan 603960b50e promisor-remote: remove fetch_if_missing=0
Commit 6462d5eb9a ("fetch: remove fetch_if_missing=0", 2019-11-08)
strove to remove the need for fetch_if_missing=0 from the fetching
mechanism, so it is plausible to attempt removing fetch_if_missing=0
from the lazy-fetching mechanism in promisor-remote as well.

But doing so reveals a bug - when the server does not send an object
pointed to by a tag object, an infinite loop occurs: Git attempts to
fetch the missing object, which causes a deferencing of all refs (for
negotiation), which causes a lazy fetch of that missing object, and so
on. This bug is because of unnecessary use of the fetch negotiator
during lazy fetching - it is not used after initialization, but it is
still initialized (which causes the dereferencing of all refs).

Thus, when the negotiator is not used during fetching, refrain from
initializing it. Then, remove fetch_if_missing from promisor-remote.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-13 11:50:58 +09:00

266 lines
5.5 KiB
C

#include "cache.h"
#include "object-store.h"
#include "promisor-remote.h"
#include "config.h"
#include "transport.h"
static char *repository_format_partial_clone;
static const char *core_partial_clone_filter_default;
void set_repository_format_partial_clone(char *partial_clone)
{
repository_format_partial_clone = xstrdup_or_null(partial_clone);
}
static int fetch_refs(const char *remote_name, struct ref *ref)
{
struct remote *remote;
struct transport *transport;
int res;
remote = remote_get(remote_name);
if (!remote->url[0])
die(_("Remote with no URL"));
transport = transport_get(remote, remote->url[0]);
transport_set_option(transport, TRANS_OPT_FROM_PROMISOR, "1");
transport_set_option(transport, TRANS_OPT_NO_DEPENDENTS, "1");
res = transport_fetch_refs(transport, ref);
return res;
}
static int fetch_objects(const char *remote_name,
const struct object_id *oids,
int oid_nr)
{
struct ref *ref = NULL;
int i;
for (i = 0; i < oid_nr; i++) {
struct ref *new_ref = alloc_ref(oid_to_hex(&oids[i]));
oidcpy(&new_ref->old_oid, &oids[i]);
new_ref->exact_oid = 1;
new_ref->next = ref;
ref = new_ref;
}
return fetch_refs(remote_name, ref);
}
static struct promisor_remote *promisors;
static struct promisor_remote **promisors_tail = &promisors;
static struct promisor_remote *promisor_remote_new(const char *remote_name)
{
struct promisor_remote *r;
if (*remote_name == '/') {
warning(_("promisor remote name cannot begin with '/': %s"),
remote_name);
return NULL;
}
FLEX_ALLOC_STR(r, name, remote_name);
*promisors_tail = r;
promisors_tail = &r->next;
return r;
}
static struct promisor_remote *promisor_remote_lookup(const char *remote_name,
struct promisor_remote **previous)
{
struct promisor_remote *r, *p;
for (p = NULL, r = promisors; r; p = r, r = r->next)
if (!strcmp(r->name, remote_name)) {
if (previous)
*previous = p;
return r;
}
return NULL;
}
static void promisor_remote_move_to_tail(struct promisor_remote *r,
struct promisor_remote *previous)
{
if (r->next == NULL)
return;
if (previous)
previous->next = r->next;
else
promisors = r->next ? r->next : r;
r->next = NULL;
*promisors_tail = r;
promisors_tail = &r->next;
}
static int promisor_remote_config(const char *var, const char *value, void *data)
{
const char *name;
int namelen;
const char *subkey;
if (!strcmp(var, "core.partialclonefilter"))
return git_config_string(&core_partial_clone_filter_default,
var, value);
if (parse_config_key(var, "remote", &name, &namelen, &subkey) < 0)
return 0;
if (!strcmp(subkey, "promisor")) {
char *remote_name;
if (!git_config_bool(var, value))
return 0;
remote_name = xmemdupz(name, namelen);
if (!promisor_remote_lookup(remote_name, NULL))
promisor_remote_new(remote_name);
free(remote_name);
return 0;
}
if (!strcmp(subkey, "partialclonefilter")) {
struct promisor_remote *r;
char *remote_name = xmemdupz(name, namelen);
r = promisor_remote_lookup(remote_name, NULL);
if (!r)
r = promisor_remote_new(remote_name);
free(remote_name);
if (!r)
return 0;
return git_config_string(&r->partial_clone_filter, var, value);
}
return 0;
}
static int initialized;
static void promisor_remote_init(void)
{
if (initialized)
return;
initialized = 1;
git_config(promisor_remote_config, NULL);
if (repository_format_partial_clone) {
struct promisor_remote *o, *previous;
o = promisor_remote_lookup(repository_format_partial_clone,
&previous);
if (o)
promisor_remote_move_to_tail(o, previous);
else
promisor_remote_new(repository_format_partial_clone);
}
}
static void promisor_remote_clear(void)
{
while (promisors) {
struct promisor_remote *r = promisors;
promisors = promisors->next;
free(r);
}
promisors_tail = &promisors;
}
void promisor_remote_reinit(void)
{
initialized = 0;
promisor_remote_clear();
promisor_remote_init();
}
struct promisor_remote *promisor_remote_find(const char *remote_name)
{
promisor_remote_init();
if (!remote_name)
return promisors;
return promisor_remote_lookup(remote_name, NULL);
}
int has_promisor_remote(void)
{
return !!promisor_remote_find(NULL);
}
static int remove_fetched_oids(struct repository *repo,
struct object_id **oids,
int oid_nr, int to_free)
{
int i, remaining_nr = 0;
int *remaining = xcalloc(oid_nr, sizeof(*remaining));
struct object_id *old_oids = *oids;
struct object_id *new_oids;
for (i = 0; i < oid_nr; i++)
if (oid_object_info_extended(repo, &old_oids[i], NULL,
OBJECT_INFO_SKIP_FETCH_OBJECT)) {
remaining[i] = 1;
remaining_nr++;
}
if (remaining_nr) {
int j = 0;
new_oids = xcalloc(remaining_nr, sizeof(*new_oids));
for (i = 0; i < oid_nr; i++)
if (remaining[i])
oidcpy(&new_oids[j++], &old_oids[i]);
*oids = new_oids;
if (to_free)
free(old_oids);
}
free(remaining);
return remaining_nr;
}
int promisor_remote_get_direct(struct repository *repo,
const struct object_id *oids,
int oid_nr)
{
struct promisor_remote *r;
struct object_id *remaining_oids = (struct object_id *)oids;
int remaining_nr = oid_nr;
int to_free = 0;
int res = -1;
promisor_remote_init();
for (r = promisors; r; r = r->next) {
if (fetch_objects(r->name, remaining_oids, remaining_nr) < 0) {
if (remaining_nr == 1)
continue;
remaining_nr = remove_fetched_oids(repo, &remaining_oids,
remaining_nr, to_free);
if (remaining_nr) {
to_free = 1;
continue;
}
}
res = 0;
break;
}
if (to_free)
free(remaining_oids);
return res;
}