From 32531e697b1c653b9af9a4b98b0923894318ba0c Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Sun, 5 Apr 2026 19:52:28 +0300 Subject: [PATCH v12 05/13] Introduce registry of built-in subsystems To add a new built-in subsystem, add it to subsystemslist.h. That hooks up its shmem callbacks so that they get called at the right times during postmaster startup. For now this is unused, but will replace the current SubsystemShmemSize() and SubsystemShmemInit() calls in the next commits. Reviewed-by: Ashutosh Bapat Reviewed-by: Matthias van de Meent Reviewed-by: Daniel Gustafsson Discussion: https://www.postgresql.org/message-id/CAExHW5vM1bneLYfg0wGeAa=52UiJ3z4vKd3AJ72X8Fw6k3KKrg@mail.gmail.com --- src/backend/bootstrap/bootstrap.c | 2 ++ src/backend/postmaster/launch_backend.c | 2 ++ src/backend/postmaster/postmaster.c | 5 +++++ src/backend/storage/ipc/ipci.c | 21 +++++++++++++++++ src/backend/storage/ipc/shmem.c | 6 +++-- src/backend/tcop/postgres.c | 3 +++ src/include/storage/ipc.h | 1 + src/include/storage/subsystemlist.h | 23 +++++++++++++++++++ src/include/storage/subsystems.h | 30 +++++++++++++++++++++++++ src/tools/pginclude/headerscheck | 1 + 10 files changed, 92 insertions(+), 2 deletions(-) create mode 100644 src/include/storage/subsystemlist.h create mode 100644 src/include/storage/subsystems.h diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c index 3766d8231ac..63378ab3d8c 100644 --- a/src/backend/bootstrap/bootstrap.c +++ b/src/backend/bootstrap/bootstrap.c @@ -363,6 +363,8 @@ BootstrapModeMain(int argc, char *argv[], bool check_only) SetProcessingMode(BootstrapProcessing); IgnoreSystemIndexes = true; + RegisterBuiltinShmemCallbacks(); + InitializeMaxBackends(); /* diff --git a/src/backend/postmaster/launch_backend.c b/src/backend/postmaster/launch_backend.c index 0973010b7dc..ed0f4f2d234 100644 --- a/src/backend/postmaster/launch_backend.c +++ b/src/backend/postmaster/launch_backend.c @@ -664,6 +664,8 @@ SubPostmasterMain(int argc, char *argv[]) */ LocalProcessControlFile(false); + RegisterBuiltinShmemCallbacks(); + /* * Reload any libraries that were preloaded by the postmaster. Since we * exec'd this process, those libraries didn't come along with us; but we diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index 7a8ee19bdaf..a2de96a9a8e 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -922,6 +922,11 @@ PostmasterMain(int argc, char *argv[]) */ ApplyLauncherRegister(); + /* + * Register the shared memory needs of all core subsystems. + */ + RegisterBuiltinShmemCallbacks(); + /* * process any libraries that should be preloaded at postmaster start */ diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index 24422a80ab3..e4a6a52f12d 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -52,6 +52,7 @@ #include "storage/procsignal.h" #include "storage/shmem_internal.h" #include "storage/sinvaladt.h" +#include "storage/subsystems.h" #include "utils/guc.h" #include "utils/injection_point.h" #include "utils/wait_event.h" @@ -252,6 +253,26 @@ CreateSharedMemoryAndSemaphores(void) shmem_startup_hook(); } +/* + * Early initialization of various subsystems, giving them a chance to + * register their shared memory needs before the shared memory segment is + * allocated. + */ +void +RegisterBuiltinShmemCallbacks(void) +{ + /* + * Call RegisterShmemCallbacks(...) on each subsystem listed in + * subsystemslist.h + */ +#define PG_SHMEM_SUBSYSTEM(subsystem_callbacks) \ + RegisterShmemCallbacks(&(subsystem_callbacks)); + +#include "storage/subsystemlist.h" + +#undef PG_SHMEM_SUBSYSTEM +} + /* * Initialize various subsystems, setting up their data structures in * shared memory. diff --git a/src/backend/storage/ipc/shmem.c b/src/backend/storage/ipc/shmem.c index 5c7caf59360..601c618d86c 100644 --- a/src/backend/storage/ipc/shmem.c +++ b/src/backend/storage/ipc/shmem.c @@ -78,8 +78,10 @@ * }); * } * - * Register the callbacks by calling RegisterShmemCallbacks(&MyShmemCallbacks) - * in the extension's _PG_init() function. + * In builtin PostgreSQL code, add the callbacks to the list in + * src/include/storage/subsystemlist.h. In an add-in module, you can register + * the callbacks by calling RegisterShmemCallbacks(&MyShmemCallbacks) in the + * extension's _PG_init() function. * * Lifecycle * --------- diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index 93851269e43..6a9ff3ad225 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -4138,6 +4138,9 @@ PostgresSingleUserMain(int argc, char *argv[], /* read control file (error checking and contains config ) */ LocalProcessControlFile(false); + /* Register the shared memory needs of all core subsystems. */ + RegisterBuiltinShmemCallbacks(); + /* * process any libraries that should be preloaded at postmaster start */ diff --git a/src/include/storage/ipc.h b/src/include/storage/ipc.h index da32787ab51..b205b00e7a1 100644 --- a/src/include/storage/ipc.h +++ b/src/include/storage/ipc.h @@ -77,6 +77,7 @@ extern void check_on_shmem_exit_lists_are_empty(void); /* ipci.c */ extern PGDLLIMPORT shmem_startup_hook_type shmem_startup_hook; +extern void RegisterBuiltinShmemCallbacks(void); extern Size CalculateShmemSize(void); extern void CreateSharedMemoryAndSemaphores(void); #ifdef EXEC_BACKEND diff --git a/src/include/storage/subsystemlist.h b/src/include/storage/subsystemlist.h new file mode 100644 index 00000000000..ed43c90bcc3 --- /dev/null +++ b/src/include/storage/subsystemlist.h @@ -0,0 +1,23 @@ +/*--------------------------------------------------------------------------- + * subsystemlist.h + * + * List of initialization callbacks of built-in subsystems. This is kept in + * its own source file for possible use by automatic tools. + * PG_SHMEM_SUBSYSTEM is defined in the callers depending on how the list is + * used. + * + * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/storage/subsystemlist.h + *--------------------------------------------------------------------------- + */ + +/* there is deliberately not an #ifndef SUBSYSTEMLIST_H here */ + +/* + * Note: there are some inter-dependencies between these, so the order of some + * of these matter. + */ + +/* TODO: empty for now */ diff --git a/src/include/storage/subsystems.h b/src/include/storage/subsystems.h new file mode 100644 index 00000000000..38b735bec67 --- /dev/null +++ b/src/include/storage/subsystems.h @@ -0,0 +1,30 @@ +/*------------------------------------------------------------------------- + * + * subsystems.h + * Provide extern declarations for all the built-in subsystem callbacks + * + * + * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/storage/subsystems.h + * + *------------------------------------------------------------------------- + */ +#ifndef SUBSYSTEMS_H +#define SUBSYSTEMS_H + +#include "storage/shmem.h" + +/* + * Extern declarations of all the built-in subsystem callbacks + * + * The actual list is in subsystemlist.h, so that the same list can be used + * for other purposes. + */ +#define PG_SHMEM_SUBSYSTEM(callbacks) \ + extern const ShmemCallbacks callbacks; +#include "storage/subsystemlist.h" +#undef PG_SHMEM_SUBSYSTEM + +#endif /* SUBSYSTEMS_H */ diff --git a/src/tools/pginclude/headerscheck b/src/tools/pginclude/headerscheck index 14c466cc237..24f7416185e 100755 --- a/src/tools/pginclude/headerscheck +++ b/src/tools/pginclude/headerscheck @@ -131,6 +131,7 @@ do test "$f" = src/include/postmaster/proctypelist.h && continue test "$f" = src/include/regex/regerrs.h && continue test "$f" = src/include/storage/lwlocklist.h && continue + test "$f" = src/include/storage/subsystemlist.h && continue test "$f" = src/include/tcop/cmdtaglist.h && continue test "$f" = src/interfaces/ecpg/preproc/c_kwlist.h && continue test "$f" = src/interfaces/ecpg/preproc/ecpg_kwlist.h && continue -- 2.47.3