git.postgresql.org Git - postgresql.git/commitdiff

git projects / postgresql.git / commitdiff

AlterSubscription_refresh: avoid stomping on global variable

author Alvaro Herrera <alvherre@alvh.no-ip.org>

Fri, 7 May 2021 15:46:37 +0000 (11:46 -0400)

committer Alvaro Herrera <alvherre@alvh.no-ip.org>

Fri, 7 May 2021 15:46:37 +0000 (11:46 -0400)

This patch replaces use of the global "wrconn" variable in
AlterSubscription_refresh with a local variable of the same name, making
it consistent with other functions in subscriptioncmds.c (e.g.
DropSubscription).

The global wrconn is only meant to be used for logical apply/tablesync worker.
Abusing it this way is known to cause trouble if an apply worker
manages to do a subscription refresh, such as reported by Jeremy Finzel
and diagnosed by Andres Freund back in November 2020, at
https://www.postgresql.org/message-id/20201111215820.qihhrz7fayu6myfi@alap3.anarazel.de

Backpatch to 10. In branch master, also move the connection establishment
to occur outside the PG_TRY block; this way we can remove a test for NULL in
PG_FINALLY, and it also makes the code more consistent with similar code in
the same file.

Author: Peter Smith <peter.b.smith@fujitsu.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Discussion: https://postgr.es/m/CAHut+Pu7Jv9L2BOEx_Z0UtJxfDevQSAUW2mJqWU+CtmDrEZVAg@mail.gmail.com

src/backend/commands/subscriptioncmds.c patch | blob | blame | history

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c

index 517c8edd3b2602a9bee0f684fddd891f2b7c550c..bbb2f5d029ea779b9ab11539de8feedcec74fabe 100644 (file)

--- a/src/backend/commands/subscriptioncmds.c

+++ b/src/backend/commands/subscriptioncmds.c

@@ -556,18 +556,19 @@ AlterSubscription_refresh(Subscription *sub, bool copy_data)

char state;

} SubRemoveRels;

SubRemoveRels *sub_remove_rels;

+ WalReceiverConn *wrconn;

/* Load the library providing us libpq calls. */

load_file("libpqwalreceiver", false);

+ /* Try to connect to the publisher. */

+ wrconn = walrcv_connect(sub->conninfo, true, sub->name, &err);

+ if (!wrconn)

+ ereport(ERROR,

+ (errmsg("could not connect to the publisher: %s", err)));

PG_TRY();

{

- /* Try to connect to the publisher. */

- wrconn = walrcv_connect(sub->conninfo, true, sub->name, &err);

- if (!wrconn)

- ereport(ERROR,

- (errmsg("could not connect to the publisher: %s", err)));

/* Get the table list from publisher. */

pubrel_names = fetch_table_list(wrconn, sub->publications);

@@ -737,8 +738,7 @@ AlterSubscription_refresh(Subscription *sub, bool copy_data)

}

PG_FINALLY();

{

- if (wrconn)

- walrcv_disconnect(wrconn);

+ walrcv_disconnect(wrconn);

}

PG_END_TRY();

@@ -1062,7 +1062,7 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)

ListCell *lc;

char originname[NAMEDATALEN];

char *err = NULL;

- WalReceiverConn *wrconn = NULL;

+ WalReceiverConn *wrconn;

Form_pg_subscription form;

List *rstates;

This is the main PostgreSQL git repository.

RSS Atom