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Login event trigger documentation wordsmithing

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Minor wordsmithing on the login trigger documentation and code
comments to improve readability, as well as fixing a few small
incorrect statements in the comments.

Author: Robert Treat <rob@xzilla.net>
Discussion: https://postgr.es/m/CAJSLCQ0aMWUh1m6E9YdjeqV61baQ=EhteJX8XOxXg8H_2Lcr0Q@mail.gmail.com
This commit is contained in:
Daniel Gustafsson 2024-03-14 23:35:35 +01:00
parent b4a71cf65d
commit 4665cebc8a
2 changed files with 14 additions and 14 deletions
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10
doc/src/sgml/event-trigger.sgml
View File

@ -39,10 +39,10 @@
<para> <para>
The <literal>login</literal> event occurs when an authenticated user logs The <literal>login</literal> event occurs when an authenticated user logs
into the system. Any bug in a trigger procedure for this event may into the system. Any bug in a trigger procedure for this event may
prevent successful login to the system. Such bugs may be fixed by prevent successful login to the system. Such bugs may be worked around by
setting <xref linkend="guc-event-triggers"/> is set to <literal>false</literal> setting <xref linkend="guc-event-triggers"/> to <literal>false</literal>
either in a connection string or configuration file. Alternative is either in a connection string or configuration file. Alternatively, you can
restarting the system in single-user mode (as event triggers are restart the system in single-user mode (as event triggers are
disabled in this mode). See the <xref linkend="app-postgres"/> reference disabled in this mode). See the <xref linkend="app-postgres"/> reference
page for details about using single-user mode. page for details about using single-user mode.
The <literal>login</literal> event will also fire on standby servers. The <literal>login</literal> event will also fire on standby servers.
@ -50,7 +50,7 @@
writing anything to the database when running on a standby. writing anything to the database when running on a standby.
Also, it's recommended to avoid long-running queries in Also, it's recommended to avoid long-running queries in
<literal>login</literal> event triggers. Note that, for instance, <literal>login</literal> event triggers. Note that, for instance,
canceling connection in <application>psql</application> wouldn't cancel canceling a connection in <application>psql</application> will not cancel
the in-progress <literal>login</literal> trigger. the in-progress <literal>login</literal> trigger.
</para> </para>

18
src/backend/commands/event_trigger.c
View File

@ -174,7 +174,7 @@ CreateEventTrigger(CreateEventTrigStmt *stmt)
else if (strcmp(stmt->eventname, "login") == 0 && tags != NULL) else if (strcmp(stmt->eventname, "login") == 0 && tags != NULL)
ereport(ERROR, ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED), (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("tag filtering is not supported for login event trigger"))); errmsg("tag filtering is not supported for login event triggers")));
/* /*
* Give user a nice error message if an event trigger of the same name * Give user a nice error message if an event trigger of the same name
@ -307,7 +307,7 @@ insert_event_trigger_tuple(const char *trigname, const char *eventname, Oid evtO
heap_freetuple(tuple); heap_freetuple(tuple);
/* /*
* Login event triggers have an additional flag in pg_database to avoid * Login event triggers have an additional flag in pg_database to enable
* faster lookups in hot codepaths. Set the flag unless already True. * faster lookups in hot codepaths. Set the flag unless already True.
*/ */
if (strcmp(eventname, "login") == 0) if (strcmp(eventname, "login") == 0)
@ -376,7 +376,7 @@ filter_list_to_array(List *filterlist)
/* /*
* Set pg_database.dathasloginevt flag for current database indicating that * Set pg_database.dathasloginevt flag for current database indicating that
* current database has on login triggers. * current database has on login event triggers.
*/ */
void void
SetDatatabaseHasLoginEventTriggers(void) SetDatatabaseHasLoginEventTriggers(void)
@ -444,7 +444,7 @@ AlterEventTrigger(AlterEventTrigStmt *stmt)
CatalogTupleUpdate(tgrel, &tup->t_self, tup); CatalogTupleUpdate(tgrel, &tup->t_self, tup);
/* /*
* Login event triggers have an additional flag in pg_database to avoid * Login event triggers have an additional flag in pg_database to enable
* faster lookups in hot codepaths. Set the flag unless already True. * faster lookups in hot codepaths. Set the flag unless already True.
*/ */
if (namestrcmp(&evtForm->evtevent, "login") == 0 && if (namestrcmp(&evtForm->evtevent, "login") == 0 &&
@ -695,7 +695,7 @@ EventTriggerCommonSetup(Node *parsetree,
} }
} }
/* don't spend any more time on this if no functions to run */ /* Don't spend any more time on this if no functions to run */
if (runlist == NIL) if (runlist == NIL)
return NIL; return NIL;
@ -878,7 +878,7 @@ EventTriggerSQLDrop(Node *parsetree)
/* /*
* Fire login event triggers if any are present. The dathasloginevt * Fire login event triggers if any are present. The dathasloginevt
* pg_database flag is left when an event trigger is dropped, to avoid * pg_database flag is left unchanged when an event trigger is dropped to avoid
* complicating the codepath in the case of multiple event triggers. This * complicating the codepath in the case of multiple event triggers. This
* function will instead unset the flag if no trigger is defined. * function will instead unset the flag if no trigger is defined.
*/ */
@ -891,7 +891,7 @@ EventTriggerOnLogin(void)
/* /*
* See EventTriggerDDLCommandStart for a discussion about why event * See EventTriggerDDLCommandStart for a discussion about why event
* triggers are disabled in single user mode or via a GUC. We also need a * triggers are disabled in single user mode or via a GUC. We also need a
* database connection (some background workers doesn't have it). * database connection (some background workers don't have it).
*/ */
if (!IsUnderPostmaster || !event_triggers || if (!IsUnderPostmaster || !event_triggers ||
!OidIsValid(MyDatabaseId) || !MyDatabaseHasLoginEventTriggers) !OidIsValid(MyDatabaseId) || !MyDatabaseHasLoginEventTriggers)
@ -920,7 +920,7 @@ EventTriggerOnLogin(void)
/* /*
* There is no active login event trigger, but our * There is no active login event trigger, but our
* pg_database.dathasloginevt was set. Try to unset this flag. We use the * pg_database.dathasloginevt is set. Try to unset this flag. We use the
* lock to prevent concurrent SetDatatabaseHasLoginEventTriggers(), but we * lock to prevent concurrent SetDatatabaseHasLoginEventTriggers(), but we
* don't want to hang the connection waiting on the lock. Thus, we are * don't want to hang the connection waiting on the lock. Thus, we are
* just trying to acquire the lock conditionally. * just trying to acquire the lock conditionally.
@ -931,7 +931,7 @@ EventTriggerOnLogin(void)
/* /*
* The lock is held. Now we need to recheck that login event triggers * The lock is held. Now we need to recheck that login event triggers
* list is still empty. Once the list is empty, we know that even if * list is still empty. Once the list is empty, we know that even if
* there is a backend, which concurrently inserts/enables login * there is a backend which concurrently inserts/enables a login event
* trigger, it will update pg_database.dathasloginevt *afterwards*. * trigger, it will update pg_database.dathasloginevt *afterwards*.
*/ */
runlist = EventTriggerCommonSetup(NULL, runlist = EventTriggerCommonSetup(NULL,