From 862a5b9a8a27995157a8b71b8f3ce09bf6ed17c5 Mon Sep 17 00:00:00 2001 From: Julien Rouhaud Date: Fri, 25 Mar 2022 11:05:24 +0800 Subject: [PATCH v3 2/2] Add a new shmem_request_hook hook. Currently, preloaded libraries are expected to request additional shared memory in _PG_init(). However, it is not unusal for such requests to depend on MaxBackends, which won't be initialized at that time. This introduces a new hook where modules can use MaxBackends to request additional shared memory. Author: Julien Rouhaud Discussion: https://postgr.es/m/20220412210112.GA2065815%40nathanxps13 --- src/backend/storage/ipc/ipci.c | 15 +++++++++++++++ src/include/storage/ipc.h | 2 ++ src/tools/pgindent/typedefs.list | 1 + 3 files changed, 18 insertions(+) diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index 75e456360b..fdd72175d5 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -52,6 +52,7 @@ /* GUCs */ int shared_memory_type = DEFAULT_SHARED_MEMORY_TYPE; +shmem_request_hook_type shmem_request_hook = NULL; shmem_startup_hook_type shmem_startup_hook = NULL; static Size total_addin_request = 0; @@ -152,6 +153,20 @@ CalculateShmemSize(int *num_semaphores) size = add_size(size, ShmemBackendArraySize()); #endif + /* + * Final chance for modules to request additional shared memory. + * + * Ordinarily, modules call RequestAddinShmemSpace() in _PG_init(), but it + * is not unusal for such requests to depend on MaxBackends, which won't be + * initialized at that time. This hook provides an opportunity for modules + * to use MaxBackends when requesting shared memory. + */ + if (addin_request_allowed && shmem_request_hook) + { + Assert(MaxBackends > 0); + shmem_request_hook(); + } + /* freeze the addin request size and include it */ addin_request_allowed = false; size = add_size(size, total_addin_request); diff --git a/src/include/storage/ipc.h b/src/include/storage/ipc.h index fade4dbe63..5f2c6683db 100644 --- a/src/include/storage/ipc.h +++ b/src/include/storage/ipc.h @@ -19,6 +19,7 @@ #define IPC_H typedef void (*pg_on_exit_callback) (int code, Datum arg); +typedef void (*shmem_request_hook_type) (void); typedef void (*shmem_startup_hook_type) (void); /*---------- @@ -75,6 +76,7 @@ extern void on_exit_reset(void); extern void check_on_shmem_exit_lists_are_empty(void); /* ipci.c */ +extern PGDLLIMPORT shmem_request_hook_type shmem_request_hook; extern PGDLLIMPORT shmem_startup_hook_type shmem_startup_hook; extern Size CalculateShmemSize(int *num_semaphores); diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 87ee7bf866..71a97654e0 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -3549,6 +3549,7 @@ shm_mq_result shm_toc shm_toc_entry shm_toc_estimator +shmem_request_hook_type shmem_startup_hook_type sig_atomic_t sigjmp_buf -- 2.25.1