From ea55eca0d105597b08d9a77f1055bbb088972515 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Thu, 2 Apr 2026 00:18:05 +0300 Subject: [PATCH v20260405 06/15] Convert lwlock.c to use the new interface It seems like a good candidate to convert first because it needs to initialized before any other subsystem, but other than that it's nothing special. --- src/backend/storage/ipc/ipci.c | 13 ------ src/backend/storage/lmgr/lwlock.c | 71 +++++++++++++++-------------- src/include/storage/lwlock.h | 2 - src/include/storage/subsystemlist.h | 9 +++- 4 files changed, 45 insertions(+), 50 deletions(-) diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index e4a6a52f12d..de65a9ef33c 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -121,7 +121,6 @@ CalculateShmemSize(void) size = add_size(size, TwoPhaseShmemSize()); size = add_size(size, BackgroundWorkerShmemSize()); size = add_size(size, MultiXactShmemSize()); - size = add_size(size, LWLockShmemSize()); size = add_size(size, ProcArrayShmemSize()); size = add_size(size, BackendStatusShmemSize()); size = add_size(size, SharedInvalShmemSize()); @@ -179,11 +178,6 @@ AttachSharedMemoryStructs(void) */ InitializeFastPathLocks(); - /* - * Attach to LWLocks first. They are needed by most other subsystems. - */ - LWLockShmemInit(); - /* Establish pointers to all shared memory areas in this backend */ ShmemAttachRequested(); CreateOrAttachShmemStructs(); @@ -230,13 +224,6 @@ CreateSharedMemoryAndSemaphores(void) */ InitShmemAllocator(seghdr); - /* - * Initialize LWLocks first, in case any of the shmem init function use - * LWLocks. (Nothing else can be running during startup, so they don't - * need to do any locking yet, but we nevertheless allow it.) - */ - LWLockShmemInit(); - /* Initialize all shmem areas */ ShmemInitRequested(); diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c index 5cb696490d6..30b715ab051 100644 --- a/src/backend/storage/lmgr/lwlock.c +++ b/src/backend/storage/lmgr/lwlock.c @@ -84,6 +84,7 @@ #include "storage/proclist.h" #include "storage/procnumber.h" #include "storage/spin.h" +#include "storage/subsystems.h" #include "utils/memutils.h" #include "utils/wait_event.h" @@ -212,6 +213,15 @@ typedef struct NamedLWLockTrancheRequest static List *NamedLWLockTrancheRequests = NIL; +static void LWLockShmemRequest(void *arg); +static void LWLockShmemInit(void *arg); + +const ShmemCallbacks LWLockCallbacks = { + .request_fn = LWLockShmemRequest, + .init_fn = LWLockShmemInit, +}; + + static void InitializeLWLocks(int numLocks); static inline void LWLockReportWaitStart(LWLock *lock); static inline void LWLockReportWaitEnd(void); @@ -401,58 +411,51 @@ NumLWLocksForNamedTranches(void) } /* - * Compute shmem space needed for user-defined tranches and the main LWLock - * array. + * Request shmem space for user-defined tranches and the main LWLock array. */ -Size -LWLockShmemSize(void) +static void +LWLockShmemRequest(void *arg) { - Size size; int numLocks; + Size size; + + numLocks = NUM_FIXED_LWLOCKS + NumLWLocksForNamedTranches(); /* Space for user-defined tranches */ size = sizeof(LWLockTrancheShmemData); - - /* Space for the LWLock array */ - numLocks = NUM_FIXED_LWLOCKS + NumLWLocksForNamedTranches(); size = add_size(size, mul_size(numLocks, sizeof(LWLockPadded))); + ShmemRequestStruct(.name = "LWLock tranches", + .size = size, + .ptr = (void **) &LWLockTranches, + ); - return size; + /* Space for the LWLock array */ + ShmemRequestStruct(.name = "Main LWLock array", + .size = numLocks * sizeof(LWLockPadded), + .ptr = (void **) &MainLWLockArray, + ); } /* - * Allocate shmem space for user-defined tranches and the main LWLock array, - * and initialize it. + * Initialize shmem space for user-defined tranches and the main LWLock array. */ -void -LWLockShmemInit(void) +static void +LWLockShmemInit(void *arg) { int numLocks; - bool found; - LWLockTranches = (LWLockTrancheShmemData *) - ShmemInitStruct("LWLock tranches", sizeof(LWLockTrancheShmemData), &found); - if (!found) - { - /* Calculate total number of locks needed in the main array */ - LWLockTranches->num_main_array_locks = - NUM_FIXED_LWLOCKS + NumLWLocksForNamedTranches(); + numLocks = NUM_FIXED_LWLOCKS + NumLWLocksForNamedTranches(); - /* Initialize the dynamic-allocation counter for tranches */ - LWLockTranches->num_user_defined = 0; + /* Remember total number of locks needed in the main array */ + LWLockTranches->num_main_array_locks = numLocks; - SpinLockInit(&LWLockTranches->lock); - } + /* Initialize the dynamic-allocation counter for tranches */ + LWLockTranches->num_user_defined = 0; - /* Allocate and initialize the main array */ - numLocks = LWLockTranches->num_main_array_locks; - MainLWLockArray = (LWLockPadded *) - ShmemInitStruct("Main LWLock array", numLocks * sizeof(LWLockPadded), &found); - if (!found) - { - /* Initialize all LWLocks */ - InitializeLWLocks(numLocks); - } + SpinLockInit(&LWLockTranches->lock); + + /* Allocate and initialize all LWLocks in the main array */ + InitializeLWLocks(numLocks); } /* diff --git a/src/include/storage/lwlock.h b/src/include/storage/lwlock.h index 61f0dbe749a..efa5b427e9f 100644 --- a/src/include/storage/lwlock.h +++ b/src/include/storage/lwlock.h @@ -126,8 +126,6 @@ extern bool LWLockHeldByMeInMode(LWLock *lock, LWLockMode mode); extern bool LWLockWaitForVar(LWLock *lock, pg_atomic_uint64 *valptr, uint64 oldval, uint64 *newval); extern void LWLockUpdateVar(LWLock *lock, pg_atomic_uint64 *valptr, uint64 val); -extern Size LWLockShmemSize(void); -extern void LWLockShmemInit(void); extern void InitLWLockAccess(void); extern const char *GetLWLockIdentifier(uint32 classId, uint16 eventId); diff --git a/src/include/storage/subsystemlist.h b/src/include/storage/subsystemlist.h index ed43c90bcc3..f0cf01f5a85 100644 --- a/src/include/storage/subsystemlist.h +++ b/src/include/storage/subsystemlist.h @@ -20,4 +20,11 @@ * of these matter. */ -/* TODO: empty for now */ +/* + * LWLocks first, in case any of the other shmem init functions use LWLocks. + * (Nothing else can be running during startup, so they don't need to do any + * locking yet, but we nevertheless allow it.) + */ +PG_SHMEM_SUBSYSTEM(LWLockCallbacks) + +/* TODO: nothing else for now */ -- 2.34.1