From: Michael Paquier Date: Wed, 19 Oct 2022 05:06:56 +0000 (+0900) Subject: Rework shutdown callback of archiver modules X-Git-Tag: REL_16_BETA1~1451 X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=9668c4a6618cc4a7a94f4bc0ad5685dd596bab63;p=postgresql.git Rework shutdown callback of archiver modules As currently designed, with a callback registered in a ERROR_CLEANUP block, the shutdown callback would get called twice when updating archive_library on SIGHUP, which is something that we want to avoid to ease the life of extension writers. Anyway, an ERROR in the archiver process is treated as a FATAL, stopping it immediately, hence there is no need for a ERROR_CLEANUP block. Instead of that, the shutdown callback is not called upon before_shmem_exit(), giving to the modules the opportunity to do any cleanup actions before the server shuts down its subsystems. While on it, this commit adds some testing coverage for the shutdown callback. Neither shell_archive nor basic_archive have been using it, and one is added to shell_archive, whose trigger is checked in a TAP test through a shutdown sequence. Author: Nathan Bossart, Bharath Rupireddy Reviewed-by: Kyotaro Horiguchi, Michael Paquier Discussion: https://postgr.es/m/20221015221328.GB1821022@nathanxps13 Backpatch-through: 15 --- diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 66312b53b81..6c649336e16 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3625,8 +3625,9 @@ include_dir 'conf.d' The library to use for archiving completed WAL file segments. If set to an empty string (the default), archiving via shell is enabled, and is used. Otherwise, the specified - shared library is used for archiving. For more information, see - and + shared library is used for archiving. The WAL archiver process is + restarted by the postmaster when this parameter changes. For more + information, see and . diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c index 3868cd7bd35..2670e41666a 100644 --- a/src/backend/postmaster/pgarch.c +++ b/src/backend/postmaster/pgarch.c @@ -144,7 +144,7 @@ static void pgarch_die(int code, Datum arg); static void HandlePgArchInterrupts(void); static int ready_file_comparator(Datum a, Datum b, void *arg); static void LoadArchiveLibrary(void); -static void call_archive_module_shutdown_callback(int code, Datum arg); +static void pgarch_call_module_shutdown_cb(int code, Datum arg); /* Report shared memory space needed by PgArchShmemInit */ Size @@ -252,13 +252,7 @@ PgArchiverMain(void) /* Load the archive_library. */ LoadArchiveLibrary(); - PG_ENSURE_ERROR_CLEANUP(call_archive_module_shutdown_callback, 0); - { - pgarch_MainLoop(); - } - PG_END_ENSURE_ERROR_CLEANUP(call_archive_module_shutdown_callback, 0); - - call_archive_module_shutdown_callback(0, 0); + pgarch_MainLoop(); proc_exit(0); } @@ -803,19 +797,14 @@ HandlePgArchInterrupts(void) if (archiveLibChanged) { - /* - * Call the currently loaded archive module's shutdown callback, - * if one is defined. - */ - call_archive_module_shutdown_callback(0, 0); - /* * Ideally, we would simply unload the previous archive module and * load the new one, but there is presently no mechanism for * unloading a library (see the comment above * internal_load_library()). To deal with this, we simply restart * the archiver. The new archive module will be loaded when the - * new archiver process starts up. + * new archiver process starts up. Note that this triggers the + * module's shutdown callback, if defined. */ ereport(LOG, (errmsg("restarting archiver process because value of " @@ -858,15 +847,15 @@ LoadArchiveLibrary(void) if (ArchiveContext.archive_file_cb == NULL) ereport(ERROR, (errmsg("archive modules must register an archive callback"))); + + before_shmem_exit(pgarch_call_module_shutdown_cb, 0); } /* - * call_archive_module_shutdown_callback - * - * Calls the loaded archive module's shutdown callback, if one is defined. + * Call the shutdown callback of the loaded archive module, if defined. */ static void -call_archive_module_shutdown_callback(int code, Datum arg) +pgarch_call_module_shutdown_cb(int code, Datum arg) { if (ArchiveContext.shutdown_cb != NULL) ArchiveContext.shutdown_cb(); diff --git a/src/backend/postmaster/shell_archive.c b/src/backend/postmaster/shell_archive.c index 8a54d02e7bb..71d567065a2 100644 --- a/src/backend/postmaster/shell_archive.c +++ b/src/backend/postmaster/shell_archive.c @@ -23,6 +23,7 @@ static bool shell_archive_configured(void); static bool shell_archive_file(const char *file, const char *path); +static void shell_archive_shutdown(void); void shell_archive_init(ArchiveModuleCallbacks *cb) @@ -31,6 +32,7 @@ shell_archive_init(ArchiveModuleCallbacks *cb) cb->check_configured_cb = shell_archive_configured; cb->archive_file_cb = shell_archive_file; + cb->shutdown_cb = shell_archive_shutdown; } static bool @@ -156,3 +158,9 @@ shell_archive_file(const char *file, const char *path) elog(DEBUG1, "archived write-ahead log file \"%s\"", file); return true; } + +static void +shell_archive_shutdown(void) +{ + elog(DEBUG1, "archiver process shutting down"); +} diff --git a/src/test/recovery/t/020_archive_status.pl b/src/test/recovery/t/020_archive_status.pl index 550fb37cb68..2108d50073a 100644 --- a/src/test/recovery/t/020_archive_status.pl +++ b/src/test/recovery/t/020_archive_status.pl @@ -234,4 +234,18 @@ ok( -f "$standby2_data/$segment_path_1_done" ".done files created after archive success with archive_mode=always on standby" ); +# Check that the archiver process calls the shell archive module's shutdown +# callback. +$standby2->append_conf('postgresql.conf', "log_min_messages = debug1"); +$standby2->reload; + +# Run a query to make sure that the reload has taken effect. +$standby2->safe_psql('postgres', q{SELECT 1}); +my $log_location = -s $standby2->logfile; + +$standby2->stop; +my $logfile = slurp_file($standby2->logfile, $log_location); +ok( $logfile =~ qr/archiver process shutting down/, + 'check shutdown callback of shell archive module'); + done_testing();