diff options
Diffstat (limited to 'src/backend/storage')
| -rw-r--r-- | src/backend/storage/ipc/Makefile | 1 | ||||
| -rw-r--r-- | src/backend/storage/ipc/dsm_registry.c | 198 | ||||
| -rw-r--r-- | src/backend/storage/ipc/ipci.c | 3 | ||||
| -rw-r--r-- | src/backend/storage/ipc/meson.build | 1 | ||||
| -rw-r--r-- | src/backend/storage/lmgr/lwlock.c | 4 | ||||
| -rw-r--r-- | src/backend/storage/lmgr/lwlocknames.txt | 1 |
6 files changed, 208 insertions, 0 deletions
diff --git a/src/backend/storage/ipc/Makefile b/src/backend/storage/ipc/Makefile index 6d5b921038c..d8a1653eb6a 100644 --- a/src/backend/storage/ipc/Makefile +++ b/src/backend/storage/ipc/Makefile @@ -12,6 +12,7 @@ OBJS = \ barrier.o \ dsm.o \ dsm_impl.o \ + dsm_registry.o \ ipc.o \ ipci.o \ latch.o \ diff --git a/src/backend/storage/ipc/dsm_registry.c b/src/backend/storage/ipc/dsm_registry.c new file mode 100644 index 00000000000..ac11f51375e --- /dev/null +++ b/src/backend/storage/ipc/dsm_registry.c @@ -0,0 +1,198 @@ +/*------------------------------------------------------------------------- + * + * dsm_registry.c + * Functions for interfacing with the dynamic shared memory registry. + * + * This provides a way for libraries to use shared memory without needing + * to request it at startup time via a shmem_request_hook. The registry + * stores dynamic shared memory (DSM) segment handles keyed by a + * library-specified string. + * + * The registry is accessed by calling GetNamedDSMSegment(). If a segment + * with the provided name does not yet exist, it is created and initialized + * with the provided init_callback callback function. Otherwise, + * GetNamedDSMSegment() simply ensures that the segment is attached to the + * current backend. This function guarantees that only one backend + * initializes the segment and that all other backends just attach it. + * + * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * IDENTIFICATION + * src/backend/storage/ipc/dsm_registry.c + * + *------------------------------------------------------------------------- + */ + +#include "postgres.h" + +#include "lib/dshash.h" +#include "storage/dsm_registry.h" +#include "storage/lwlock.h" +#include "storage/shmem.h" +#include "utils/memutils.h" + +typedef struct DSMRegistryCtxStruct +{ + dsa_handle dsah; + dshash_table_handle dshh; +} DSMRegistryCtxStruct; + +static DSMRegistryCtxStruct *DSMRegistryCtx; + +typedef struct DSMRegistryEntry +{ + char name[64]; + dsm_handle handle; + size_t size; +} DSMRegistryEntry; + +static const dshash_parameters dsh_params = { + offsetof(DSMRegistryEntry, handle), + sizeof(DSMRegistryEntry), + dshash_memcmp, + dshash_memhash, + LWTRANCHE_DSM_REGISTRY_HASH +}; + +static dsa_area *dsm_registry_dsa; +static dshash_table *dsm_registry_table; + +Size +DSMRegistryShmemSize(void) +{ + return MAXALIGN(sizeof(DSMRegistryCtxStruct)); +} + +void +DSMRegistryShmemInit(void) +{ + bool found; + + DSMRegistryCtx = (DSMRegistryCtxStruct *) + ShmemInitStruct("DSM Registry Data", + DSMRegistryShmemSize(), + &found); + + if (!found) + { + DSMRegistryCtx->dsah = DSA_HANDLE_INVALID; + DSMRegistryCtx->dshh = DSHASH_HANDLE_INVALID; + } +} + +/* + * Initialize or attach to the dynamic shared hash table that stores the DSM + * registry entries, if not already done. This must be called before accessing + * the table. + */ +static void +init_dsm_registry(void) +{ + /* Quick exit if we already did this. */ + if (dsm_registry_table) + return; + + /* Otherwise, use a lock to ensure only one process creates the table. */ + LWLockAcquire(DSMRegistryLock, LW_EXCLUSIVE); + + if (DSMRegistryCtx->dshh == DSHASH_HANDLE_INVALID) + { + /* Initialize dynamic shared hash table for registry. */ + dsm_registry_dsa = dsa_create(LWTRANCHE_DSM_REGISTRY_DSA); + dsa_pin(dsm_registry_dsa); + dsa_pin_mapping(dsm_registry_dsa); + dsm_registry_table = dshash_create(dsm_registry_dsa, &dsh_params, NULL); + + /* Store handles in shared memory for other backends to use. */ + DSMRegistryCtx->dsah = dsa_get_handle(dsm_registry_dsa); + DSMRegistryCtx->dshh = dshash_get_hash_table_handle(dsm_registry_table); + } + else + { + /* Attach to existing dynamic shared hash table. */ + dsm_registry_dsa = dsa_attach(DSMRegistryCtx->dsah); + dsa_pin_mapping(dsm_registry_dsa); + dsm_registry_table = dshash_attach(dsm_registry_dsa, &dsh_params, + DSMRegistryCtx->dshh, NULL); + } + + LWLockRelease(DSMRegistryLock); +} + +/* + * Initialize or attach a named DSM segment. + * + * This routine returns the address of the segment. init_callback is called to + * initialize the segment when it is first created. + */ +void * +GetNamedDSMSegment(const char *name, size_t size, + void (*init_callback) (void *ptr), bool *found) +{ + DSMRegistryEntry *entry; + MemoryContext oldcontext; + char name_padded[offsetof(DSMRegistryEntry, handle)] = {0}; + void *ret; + + Assert(found); + + if (!name || *name == '\0') + ereport(ERROR, + (errmsg("DSM segment name cannot be empty"))); + + if (strlen(name) >= offsetof(DSMRegistryEntry, handle)) + ereport(ERROR, + (errmsg("DSM segment name too long"))); + + if (size == 0) + ereport(ERROR, + (errmsg("DSM segment size must be nonzero"))); + + /* Be sure any local memory allocated by DSM/DSA routines is persistent. */ + oldcontext = MemoryContextSwitchTo(TopMemoryContext); + + /* Connect to the registry. */ + init_dsm_registry(); + + strcpy(name_padded, name); + entry = dshash_find_or_insert(dsm_registry_table, name_padded, found); + if (!(*found)) + { + /* Initialize the segment. */ + dsm_segment *seg = dsm_create(size, 0); + + dsm_pin_segment(seg); + dsm_pin_mapping(seg); + entry->handle = dsm_segment_handle(seg); + entry->size = size; + ret = dsm_segment_address(seg); + + if (init_callback) + (*init_callback) (ret); + } + else if (entry->size != size) + { + ereport(ERROR, + (errmsg("requested DSM segment size does not match size of " + "existing segment"))); + } + else if (!dsm_find_mapping(entry->handle)) + { + /* Attach to existing segment. */ + dsm_segment *seg = dsm_attach(entry->handle); + + dsm_pin_mapping(seg); + ret = dsm_segment_address(seg); + } + else + { + /* Return address of an already-attached segment. */ + ret = dsm_segment_address(dsm_find_mapping(entry->handle)); + } + + dshash_release_lock(dsm_registry_table, entry); + MemoryContextSwitchTo(oldcontext); + + return ret; +} diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index e5119ed55dd..fbc62b15637 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -40,6 +40,7 @@ #include "replication/walsender.h" #include "storage/bufmgr.h" #include "storage/dsm.h" +#include "storage/dsm_registry.h" #include "storage/ipc.h" #include "storage/pg_shmem.h" #include "storage/pmsignal.h" @@ -115,6 +116,7 @@ CalculateShmemSize(int *num_semaphores) size = add_size(size, hash_estimate_size(SHMEM_INDEX_SIZE, sizeof(ShmemIndexEnt))); size = add_size(size, dsm_estimate_size()); + size = add_size(size, DSMRegistryShmemSize()); size = add_size(size, BufferShmemSize()); size = add_size(size, LockShmemSize()); size = add_size(size, PredicateLockShmemSize()); @@ -289,6 +291,7 @@ CreateOrAttachShmemStructs(void) InitShmemIndex(); dsm_shmem_init(); + DSMRegistryShmemInit(); /* * Set up xlog, clog, and buffers diff --git a/src/backend/storage/ipc/meson.build b/src/backend/storage/ipc/meson.build index 08bdc718b83..5a936171f73 100644 --- a/src/backend/storage/ipc/meson.build +++ b/src/backend/storage/ipc/meson.build @@ -4,6 +4,7 @@ backend_sources += files( 'barrier.c', 'dsm.c', 'dsm_impl.c', + 'dsm_registry.c', 'ipc.c', 'ipci.c', 'latch.c', diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c index b4b989ac569..2f2de5a5624 100644 --- a/src/backend/storage/lmgr/lwlock.c +++ b/src/backend/storage/lmgr/lwlock.c @@ -190,6 +190,10 @@ static const char *const BuiltinTrancheNames[] = { "LogicalRepLauncherDSA", /* LWTRANCHE_LAUNCHER_HASH: */ "LogicalRepLauncherHash", + /* LWTRANCHE_DSM_REGISTRY_DSA: */ + "DSMRegistryDSA", + /* LWTRANCHE_DSM_REGISTRY_HASH: */ + "DSMRegistryHash", }; StaticAssertDecl(lengthof(BuiltinTrancheNames) == diff --git a/src/backend/storage/lmgr/lwlocknames.txt b/src/backend/storage/lmgr/lwlocknames.txt index d621f5507f3..ef8542de469 100644 --- a/src/backend/storage/lmgr/lwlocknames.txt +++ b/src/backend/storage/lmgr/lwlocknames.txt @@ -55,3 +55,4 @@ WrapLimitsVacuumLock 46 NotifyQueueTailLock 47 WaitEventExtensionLock 48 WALSummarizerLock 49 +DSMRegistryLock 50 |