[Tarantool-patches] [PATCH v2 1/6] box: add a single execution guard to clear_synchro_queue
Serge Petrenko
sergepetrenko at tarantool.org
Wed Dec 23 14:59:19 MSK 2020
Clear_synchro_queue isn't meant to be called multiple times on a single
instance.
Multiple simultaneous invocations of clear_synhcro_queue() shouldn't
hurt now, since clear_synchro_queue simply exits on an empty limbo, but
may be harmful in future, when clear_synchro_queue is reworked.
Prohibit such misuse by introducing an execution guard and raising an
error once duplicate invocation is detected.
Prerequisite #5435
---
src/box/box.cc | 18 +++++++++++++++---
src/box/box.h | 2 +-
src/box/lua/ctl.c | 4 ++--
src/box/raft.c | 9 +++++++--
4 files changed, 25 insertions(+), 8 deletions(-)
diff --git a/src/box/box.cc b/src/box/box.cc
index 306db7c37..2d403fc9a 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -1002,15 +1002,24 @@ box_set_replication_anon(void)
}
-void
+int
box_clear_synchro_queue(bool try_wait)
{
+ /* A guard to block multiple simultaneous function invocations. */
+ static bool in_clear_synchro_queue = false;
+ if (in_clear_synchro_queue) {
+ diag_set(ClientError, ER_UNSUPPORTED, "clear_synchro_queue",
+ "simultaneous invocations");
+ return -1;
+ }
if (!is_box_configured || txn_limbo_is_empty(&txn_limbo))
- return;
+ return 0;
uint32_t former_leader_id = txn_limbo.owner_id;
assert(former_leader_id != REPLICA_ID_NIL);
if (former_leader_id == instance_id)
- return;
+ return 0;
+
+ in_clear_synchro_queue = true;
if (try_wait) {
/* Wait until pending confirmations/rollbacks reach us. */
@@ -1051,6 +1060,9 @@ box_clear_synchro_queue(bool try_wait)
txn_limbo_force_empty(&txn_limbo, confirm_lsn);
assert(txn_limbo_is_empty(&txn_limbo));
}
+
+ in_clear_synchro_queue = false;
+ return 0;
}
void
diff --git a/src/box/box.h b/src/box/box.h
index b47a220b7..95336688b 100644
--- a/src/box/box.h
+++ b/src/box/box.h
@@ -266,7 +266,7 @@ extern "C" {
typedef struct tuple box_tuple_t;
-void
+int
box_clear_synchro_queue(bool try_wait);
/* box_select is private and used only by FFI */
diff --git a/src/box/lua/ctl.c b/src/box/lua/ctl.c
index bb4841994..b44474b12 100644
--- a/src/box/lua/ctl.c
+++ b/src/box/lua/ctl.c
@@ -83,8 +83,8 @@ lbox_ctl_on_schema_init(struct lua_State *L)
static int
lbox_ctl_clear_synchro_queue(struct lua_State *L)
{
- (void) L;
- box_clear_synchro_queue(true);
+ if (box_clear_synchro_queue(true) != 0)
+ return luaT_error(L);
return 0;
}
diff --git a/src/box/raft.c b/src/box/raft.c
index 8f32a9662..1942df952 100644
--- a/src/box/raft.c
+++ b/src/box/raft.c
@@ -89,9 +89,14 @@ box_raft_update_synchro_queue(struct raft *raft)
* If the node became a leader, it means it will ignore all records from
* all the other nodes, and won't get late CONFIRM messages anyway. Can
* clear the queue without waiting for confirmations.
+ * It's alright that the user may have called clear_synchro_queue
+ * manually. In this case the call below will exit immediately and we'll
+ * simply log a warning.
*/
- if (raft->state == RAFT_STATE_LEADER)
- box_clear_synchro_queue(false);
+ if (raft->state == RAFT_STATE_LEADER) {
+ if (box_clear_synchro_queue(false) != 0)
+ diag_log();
+ }
}
static int
--
2.24.3 (Apple Git-128)
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