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Minor refactor of distributed xact handling

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Cleanup some inconsistencies and address nits in abort handlers for
distributed transactions.
This commit is contained in:
Erik Nordström 2019-11-28 16:51:47 +01:00 committed by Erik Nordström
parent 506b1189b1
commit c0e0f673b8
5 changed files with 61 additions and 34 deletions
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33
tsl/src/remote/dist_txn.c
View File

@ -146,7 +146,16 @@ dist_txn_xact_callback_1pc_pre_commit()
dist_txn_deallocate_prepared_stmts_if_needed();
}
/* On abort on the frontend send aborts to all of the remote endpoints */
/*
* Abort on the access node.
*
* The access node needs to send aborts to all of the remote endpoints. This
* code should not throw errors itself, since we are already in abort due to a
* previous error. Instead, we try to emit errors as warnings. For safety, we
* should probaby try-catch and swallow any potential lower-layer errors given
* that we're doing remote calls over the network. But the semantics for
* capturing and proceeding after such recursive errors are unclear.
*/
static void
dist_txn_xact_callback_abort()
{
@ -493,15 +502,19 @@ dist_txn_subxact_callback(SubXactEvent event, SubTransactionId mySubid,
if (store == NULL)
return;
/* Nothing to do at subxact start, nor after commit. */
if (!(event == SUBXACT_EVENT_PRE_COMMIT_SUB || event == SUBXACT_EVENT_ABORT_SUB))
return;
if (event == SUBXACT_EVENT_PRE_COMMIT_SUB)
reject_transactions_with_incomplete_transitions();
if (event == SUBXACT_EVENT_ABORT_SUB)
eventcallback(DTXN_EVENT_SUB_XACT_ABORT);
switch (event)
{
case SUBXACT_EVENT_START_SUB:
case SUBXACT_EVENT_COMMIT_SUB:
/* Nothing to do at subxact start, nor after commit. */
return;
case SUBXACT_EVENT_PRE_COMMIT_SUB:
reject_transactions_with_incomplete_transitions();
break;
case SUBXACT_EVENT_ABORT_SUB:
eventcallback(DTXN_EVENT_SUB_XACT_ABORT);
break;
}
curlevel = GetCurrentTransactionNestLevel();

2
tsl/src/remote/dist_txn.h
View File

@ -45,7 +45,7 @@ extern void remote_dist_txn_set_event_handler(const DistTransactionEventHandler
extern DistTransactionEvent remote_dist_txn_event_from_name(const char *eventname);
extern const char *remote_dist_txn_event_name(const DistTransactionEvent event);
#endif
#endif /* DEBUG */
void _remote_dist_txn_init(void);
void _remote_dist_txn_fini(void);

36
tsl/src/remote/txn.c
View File

@ -3,6 +3,7 @@
* Please see the included NOTICE for copyright information and
* LICENSE-TIMESCALE for a copy of the license.
*/
#include "libpq-fe.h"
#include <postgres.h>
#include <access/xact.h>
#include <utils/builtins.h>
@ -299,28 +300,35 @@ remote_txn_check_for_leaked_prepared_statements(RemoteTxn *entry)
{
PGresult *res;
char *count_string;
ExecStatusType status;
if (PQTRANS_IDLE != PQtransactionStatus(remote_connection_get_pg_conn(entry->conn)))
return;
res = remote_connection_exec(entry->conn, "SELECT count(*) FROM pg_prepared_statements");
if (PQresultStatus(res) == PGRES_TUPLES_OK)
status = PQresultStatus(res);
switch (status)
{
if (PQntuples(res) == 1 && PQnfields(res) == 1)
{
count_string = PQgetvalue(res, 0, 0);
if (strcmp("0", count_string) != 0)
elog(WARNING, "leak check: connection leaked prepared statement");
}
else
{
remote_result_close(res);
elog(ERROR, "leak check: incorrect number of rows or columns returned");
}
case PGRES_TUPLES_OK:
if (PQntuples(res) == 1 && PQnfields(res) == 1)
{
count_string = PQgetvalue(res, 0, 0);
if (strcmp("0", count_string) != 0)
elog(WARNING, "leak check: connection leaked prepared statement");
}
else
elog(ERROR, "leak check: unexpected number of rows or columns returned");
break;
case PGRES_FATAL_ERROR:
case PGRES_NONFATAL_ERROR:
elog(WARNING, "leak check: ERROR [\"%s\"]", PQresultErrorMessage(res));
break;
default:
elog(WARNING, "leak check: unexpected result state %u", status);
break;
}
else
elog(WARNING, "leak check: unexpected result \"%s\"", PQresultErrorMessage(res));
remote_result_close(res);
}

13
tsl/test/src/remote/connection.c
View File

@ -25,10 +25,6 @@
#include "test_utils.h"
#include "connection.h"
static const char *sql_get_backend_pid = "SELECT pg_backend_pid()";
static const char *sql_get_application_name =
"SELECT application_name from pg_stat_activity where pid = pg_backend_pid()";
TSConnection *
get_connection()
{
@ -250,10 +246,10 @@ remote_connection_get_remote_pid(const TSConnection *conn)
char *pid_string;
unsigned long pid_long;
res = PQexec(remote_connection_get_pg_conn(conn), sql_get_backend_pid);
res = PQexec(remote_connection_get_pg_conn(conn), "SELECT pg_backend_pid()");
if (PQresultStatus(res) != PGRES_TUPLES_OK)
return 0;
return -1;
Assert(1 == PQntuples(res));
Assert(1 == PQnfields(res));
@ -271,7 +267,10 @@ remote_connection_get_application_name(const TSConnection *conn)
PGresult *res;
char *app_name;
res = PQexec(remote_connection_get_pg_conn(conn), sql_get_application_name);
res = PQexec(remote_connection_get_pg_conn(conn),
"SELECT application_name "
"FROM pg_stat_activity "
"WHERE pid = pg_backend_pid()");
if (PQresultStatus(res) != PGRES_TUPLES_OK)
return 0;

11
tsl/test/src/remote/node_killer.c
View File

@ -51,9 +51,14 @@ void
remote_node_killer_init(RemoteNodeKiller *rnk, const TSConnection *conn,
const DistTransactionEvent event)
{
int remote_pid = remote_connection_get_remote_pid(conn);
if (remote_pid == -1)
elog(ERROR, "could not get PID of remote backend process");
MemSet(rnk, 0, sizeof(*rnk));
rnk->conn = conn;
rnk->pid = remote_connection_get_remote_pid(conn);
rnk->pid = remote_pid;
rnk->killevent = event;
}
@ -118,10 +123,12 @@ remote_node_killer_kill(RemoteNodeKiller *rnk)
elog(WARNING, "timeout while waiting for killed backend to exit");
break;
}
wait_count--;
pg_usleep(100L);
}
/* Once PG registered the backend as gone, wait some additional time
* for it to really exit */
pg_usleep(500L);
}
}