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meta: md with I and x removes value
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If `md` is given the `x` flags it will remove the value but leave the
item. When combined with 'I' it will mark this new item as stale as
well.

This allows the user to create a tombstone of a previous value with a
new TTL.
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@dormando
dormando committed Apr 8, 2024
1 parent 22480de commit 702ecb5
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Showing 2 changed files with 67 additions and 9 deletions.
38 changes: 34 additions & 4 deletions proto_text.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -918,6 +918,7 @@ struct _meta_flags {
unsigned int has_cas_in :1;
unsigned int new_ttl :1;
unsigned int key_binary:1;
unsigned int remove_val:1;
char mode; // single character mode switch, common to ms/ma
rel_time_t exptime;
rel_time_t autoviv_exptime;
Expand Down Expand Up @@ -1016,6 +1017,9 @@ static int _meta_flag_preparse(token_t *tokens, const size_t start,
case 'q':
of->no_reply = 1;
break;
case 'x':
of->remove_val = 1;
break;
// mset-related.
case 'F':
if (!safe_strtoflags(tokens[i].value+1, &of->client_flags)) {
Expand Down Expand Up @@ -1610,7 +1614,7 @@ static void process_mdelete_command(conn *c, token_t *tokens, const size_t ntoke
size_t nkey;
item *it = NULL;
int i;
uint32_t hv;
uint32_t hv = 0;
struct _meta_flags of = {0}; // option bitflags.
char *errstr = "CLIENT_ERROR bad command line format";
assert(c != NULL);
Expand Down Expand Up @@ -1676,6 +1680,25 @@ static void process_mdelete_command(conn *c, token_t *tokens, const size_t ntoke
goto cleanup;
}

// If requested, create a new empty tombstone item.
if (of.remove_val) {
item *new_it = item_alloc(key, nkey, of.client_flags, of.exptime, 2);
if (new_it != NULL) {
memcpy(ITEM_data(new_it), "\r\n", 2);
if (do_store_item(new_it, NREAD_SET, c->thread, hv, NULL, NULL, ITEM_get_cas(it), CAS_NO_STALE)) {
do_item_remove(it);
it = new_it;
} else {
do_item_remove(new_it);
memcpy(resp->wbuf, "NS", 2);
goto cleanup;
}
} else {
errstr = "SERVER_ERROR out of memory";
goto error;
}
}

// If we're to set this item as stale, we don't actually want to
// delete it. We mark the stale bit, bump CAS, and update exptime if
// we were supplied a new TTL.
Expand All @@ -1688,19 +1711,21 @@ static void process_mdelete_command(conn *c, token_t *tokens, const size_t ntoke
it->it_flags &= ~ITEM_TOKEN_SENT;

ITEM_set_cas(it, of.has_cas_in ? of.cas_id_in : get_cas_id());

// Clients can noreply nominal responses.
if (c->noreply)
resp->skip = true;

memcpy(resp->wbuf, "HD", 2);
} else {
pthread_mutex_lock(&c->thread->stats.mutex);
c->thread->stats.slab_stats[ITEM_clsid(it)].delete_hits++;
pthread_mutex_unlock(&c->thread->stats.mutex);

LOGGER_LOG(NULL, LOG_DELETIONS, LOGGER_DELETIONS, it, LOG_TYPE_META_DELETE);
do_item_unlink(it, hv);
STORAGE_delete(c->thread->storage, it);
if (!of.remove_val) {
do_item_unlink(it, hv);
STORAGE_delete(c->thread->storage, it);
}
if (c->noreply)
resp->skip = true;
memcpy(resp->wbuf, "HD", 2);
Expand All @@ -1727,6 +1752,11 @@ static void process_mdelete_command(conn *c, token_t *tokens, const size_t ntoke
conn_set_state(c, conn_new_cmd);
return;
error:
// cleanup if an error happens after we fetched an item.
if (it) {
do_item_remove(it);
item_unlock(hv);
}
out_errstring(c, errstr);
}

Expand Down
38 changes: 33 additions & 5 deletions proxy_internal.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -589,6 +589,7 @@ struct _meta_flags {
unsigned int has_cas_in :1;
unsigned int new_ttl :1;
unsigned int key_binary:1;
unsigned int remove_val:1;
char mode; // single character mode switch, common to ms/ma
rel_time_t exptime;
rel_time_t autoviv_exptime;
Expand Down Expand Up @@ -689,6 +690,9 @@ static int _meta_flag_preparse(mcp_parser_t *pr, const size_t start,
case 'q':
of->no_reply = 1;
break;
case 'x':
of->remove_val = 1;
break;
// mset-related.
case 'F':
if (!safe_strtoflags(&pr->request[pr->tokens[i]+1], &of->client_flags)) {
Expand Down Expand Up @@ -1323,6 +1327,25 @@ static void process_mdelete_cmd(LIBEVENT_THREAD *t, mcp_parser_t *pr, mc_resp *r
goto cleanup;
}

// If requested, create a new empty tombstone item.
if (of.remove_val) {
item *new_it = item_alloc(key, nkey, of.client_flags, of.exptime, 2);
if (new_it != NULL) {
memcpy(ITEM_data(new_it), "\r\n", 2);
if (do_store_item(new_it, NREAD_SET, t, hv, NULL, NULL, ITEM_get_cas(it), CAS_NO_STALE)) {
do_item_remove(it);
it = new_it;
} else {
do_item_remove(new_it);
memcpy(resp->wbuf, "NS", 2);
goto cleanup;
}
} else {
errstr = "SERVER_ERROR out of memory";
goto error;
}
}

// If we're to set this item as stale, we don't actually want to
// delete it. We mark the stale bit, bump CAS, and update exptime if
// we were supplied a new TTL.
Expand All @@ -1335,18 +1358,18 @@ static void process_mdelete_cmd(LIBEVENT_THREAD *t, mcp_parser_t *pr, mc_resp *r
it->it_flags &= ~ITEM_TOKEN_SENT;

ITEM_set_cas(it, of.has_cas_in ? of.cas_id_in : get_cas_id());

// Clients can noreply nominal responses.
if (of.no_reply)
resp->skip = true;

memcpy(resp->wbuf, "HD", 2);
} else {
pthread_mutex_lock(&t->stats.mutex);
t->stats.slab_stats[ITEM_clsid(it)].delete_hits++;
pthread_mutex_unlock(&t->stats.mutex);

do_item_unlink(it, hv);
STORAGE_delete(t->storage, it);
if (!of.remove_val) {
do_item_unlink(it, hv);
STORAGE_delete(t->storage, it);
}
if (of.no_reply)
resp->skip = true;
memcpy(resp->wbuf, "HD", 2);
Expand All @@ -1373,6 +1396,11 @@ static void process_mdelete_cmd(LIBEVENT_THREAD *t, mcp_parser_t *pr, mc_resp *r
//conn_set_state(c, conn_new_cmd);
return;
error:
// cleanup if an error happens after we fetched an item.
if (it) {
do_item_remove(it);
item_unlock(hv);
}
pout_errstring(resp, errstr);
}

Expand Down

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