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dblink: Replace WAIT_EVENT_EXTENSION with custom wait events

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Two custom wait events are added here:
- "DblinkConnect", when waiting to establish a connection to a remote
server.
- "DblinkGetConnect", when waiting to establish a connection to a remote
server but it could not be found in the list of already-opened ones.

Author: Masahiro Ikeda
Discussion: https://postgr.es/m/197bce267fa691a0ac62c86c4ab904c4@oss.nttdata.com
This commit is contained in:
Michael Paquier 2023-10-05 10:23:22 +09:00
parent d61f2538a3
commit c789f0f6cc
2 changed files with 40 additions and 2 deletions
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16
contrib/dblink/dblink.c
View File

@ -130,6 +130,10 @@ static void restoreLocalGucs(int nestlevel);
static remoteConn *pconn = NULL;
static HTAB *remoteConnHash = NULL;
/* custom wait event values, retrieved from shared memory */
static uint32 dblink_we_connect = 0;
static uint32 dblink_we_get_conn = 0;
/*
* Following is list that holds multiple remote connections.
* Calling convention of each dblink function changes to accept
@ -202,8 +206,12 @@ dblink_get_conn(char *conname_or_str,
connstr = conname_or_str;
dblink_connstr_check(connstr);
/* first time, allocate or get the custom wait event */
if (dblink_we_get_conn == 0)
dblink_we_get_conn = WaitEventExtensionNew("DblinkGetConnect");
/* OK to make connection */
conn = libpqsrv_connect(connstr, WAIT_EVENT_EXTENSION);
conn = libpqsrv_connect(connstr, dblink_we_get_conn);
if (PQstatus(conn) == CONNECTION_BAD)
{
@ -292,8 +300,12 @@ dblink_connect(PG_FUNCTION_ARGS)
/* check password in connection string if not superuser */
dblink_connstr_check(connstr);
/* first time, allocate or get the custom wait event */
if (dblink_we_connect == 0)
dblink_we_connect = WaitEventExtensionNew("DblinkConnect");
/* OK to make connection */
conn = libpqsrv_connect(connstr, WAIT_EVENT_EXTENSION);
conn = libpqsrv_connect(connstr, dblink_we_connect);
if (PQstatus(conn) == CONNECTION_BAD)
{

26
doc/src/sgml/dblink.sgml
View File

@ -13,6 +13,32 @@
session.
</para>
<para>
<filename>dblink</filename> can report the following wait events under the wait
event type <literal>Extension</literal>.
</para>
<variablelist>
<varlistentry>
<term><literal>DblinkConnect</literal></term>
<listitem>
<para>
Waiting to establish a connection to a remote server.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DblinkGetConnect</literal></term>
<listitem>
<para>
Waiting to establish a connection to a remote server when it could not
be found in the list of already-opened connections.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
See also <xref linkend="postgres-fdw"/>, which provides roughly the same
functionality using a more modern and standards-compliant infrastructure.