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Don't let libpq PGEVT_CONNRESET callbacks break a PGconn.

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As currently implemented, failure of a PGEVT_CONNRESET callback
forces the PGconn into the CONNECTION_BAD state (without closing
the socket, which is inconsistent with other failure paths), and
prevents later callbacks from being called.  This seems highly
questionable, and indeed is questioned by comments in the source.

Instead, let's just ignore the result value of PGEVT_CONNRESET
calls.  Like the preceding commit, this converts event callbacks
into "pure observers" that cannot affect libpq's processing logic.

Discussion: https://postgr.es/m/3185105.1644960083@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2022-02-18 11:43:04 -05:00
parent ce1e7a2f71
commit 2e372869aa
2 changed files with 11 additions and 28 deletions
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11
doc/src/sgml/libpq.sgml
View File

@ -7183,12 +7183,11 @@ typedef struct
<para>
The connection reset event is fired on completion of
<xref linkend="libpq-PQreset"/> or <function>PQresetPoll</function>. In
both cases, the event is only fired if the reset was successful. If
the event procedure fails, the entire connection reset will fail; the
<structname>PGconn</structname> is put into
<literal>CONNECTION_BAD</literal> status and
<function>PQresetPoll</function> will return
<literal>PGRES_POLLING_FAILED</literal>.
both cases, the event is only fired if the reset was successful.
The return value of the event procedure is ignored
in <productname>PostgreSQL</productname> v15 and later.
With earlier versions, however, it's important to return success
(nonzero) or the connection will be aborted.
<synopsis>
typedef struct

28
src/interfaces/libpq/fe-connect.c
View File

@ -4276,8 +4276,7 @@ PQreset(PGconn *conn)
if (connectDBStart(conn) && connectDBComplete(conn))
{
/*
* Notify event procs of successful reset. We treat an event proc
* failure as disabling the connection ... good idea?
* Notify event procs of successful reset.
*/
int i;
@ -4286,15 +4285,8 @@ PQreset(PGconn *conn)
PGEventConnReset evt;
evt.conn = conn;
if (!conn->events[i].proc(PGEVT_CONNRESET, &evt,
conn->events[i].passThrough))
{
conn->status = CONNECTION_BAD;
appendPQExpBuffer(&conn->errorMessage,
libpq_gettext("PGEventProc \"%s\" failed during PGEVT_CONNRESET event\n"),
conn->events[i].name);
break;
}
(void) conn->events[i].proc(PGEVT_CONNRESET, &evt,
conn->events[i].passThrough);
}
}
}
@ -4336,8 +4328,7 @@ PQresetPoll(PGconn *conn)
if (status == PGRES_POLLING_OK)
{
/*
* Notify event procs of successful reset. We treat an event proc
* failure as disabling the connection ... good idea?
* Notify event procs of successful reset.
*/
int i;
@ -4346,15 +4337,8 @@ PQresetPoll(PGconn *conn)
PGEventConnReset evt;
evt.conn = conn;
if (!conn->events[i].proc(PGEVT_CONNRESET, &evt,
conn->events[i].passThrough))
{
conn->status = CONNECTION_BAD;
appendPQExpBuffer(&conn->errorMessage,
libpq_gettext("PGEventProc \"%s\" failed during PGEVT_CONNRESET event\n"),
conn->events[i].name);
return PGRES_POLLING_FAILED;
}
(void) conn->events[i].proc(PGEVT_CONNRESET, &evt,
conn->events[i].passThrough);
}
}