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AlterSubscription_refresh: avoid stomping on global variable

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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
This commit is contained in:
Alvaro Herrera 2021-05-07 11:46:37 -04:00
parent f518c3df4e
commit ef70b6f8e2
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GPG Key ID: 1C20ACB9D5C564AE
1 changed files with 2 additions and 1 deletions
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3
src/backend/commands/subscriptioncmds.c
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@ -517,6 +517,7 @@ AlterSubscription_refresh(Subscription *sub, bool copy_data)
List *subrel_states; List *subrel_states;
Oid *subrel_local_oids; Oid *subrel_local_oids;
Oid *pubrel_local_oids; Oid *pubrel_local_oids;
WalReceiverConn *wrconn;
ListCell *lc; ListCell *lc;
int off; int off;
@ -835,7 +836,7 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
char originname[NAMEDATALEN]; char originname[NAMEDATALEN];
char *err = NULL; char *err = NULL;
RepOriginId originid; RepOriginId originid;
WalReceiverConn *wrconn = NULL; WalReceiverConn *wrconn;
StringInfoData cmd; StringInfoData cmd;
Form_pg_subscription form; Form_pg_subscription form;