#include "storage/spin.h"
#include "utils/hsearch.h"

Include dependency graph for shmem.h:

This graph shows which files directly or indirectly include this file:

Data Structures
struct	ShmemIndexEnt

Macros
#define	SHMEM_INDEX_KEYSIZE (48)

#define	SHMEM_INDEX_SIZE (64)

Functions
void	InitShmemAccess (void *seghdr)

void	InitShmemAllocation (void)

void *	ShmemAlloc (Size size)

void *	ShmemAllocNoError (Size size)

void *	ShmemAllocUnlocked (Size size)

bool	ShmemAddrIsValid (const void *addr)

void	InitShmemIndex (void)

HTAB *	ShmemInitHash (const char name, long init_size, long max_size, HASHCTL infoP, int hash_flags)

void *	ShmemInitStruct (const char name, Size size, bool foundPtr)

Size	add_size (Size s1, Size s2)

Size	mul_size (Size s1, Size s2)

void	RequestAddinShmemSpace (Size size)

Variables
PGDLLIMPORT slock_t *	ShmemLock

Macro Definition Documentation

◆ SHMEM_INDEX_KEYSIZE

#define SHMEM_INDEX_KEYSIZE (48)

Definition at line 48 of file shmem.h.

◆ SHMEM_INDEX_SIZE

#define SHMEM_INDEX_SIZE (64)

Definition at line 50 of file shmem.h.

Function Documentation

◆ add_size()

Size add_size	(	Size	s1,
		Size	s2
	)

Definition at line 493 of file shmem.c.

 {
     Size        result;
  
     result = s1 + s2;
     /* We are assuming Size is an unsigned type here... */
     if (result < s1 || result < s2)
         ereport(ERROR,
                 (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                  errmsg("requested shared memory size overflows size_t")));
     return result;
 }

References ereport, errcode(), errmsg(), ERROR, s1, and s2.

Referenced by _brin_parallel_estimate_shared(), _bt_parallel_estimate_shared(), ApplyLauncherShmemSize(), AsyncShmemInit(), AsyncShmemSize(), AutoVacuumShmemSize(), BackendStatusShmemSize(), BackgroundWorkerShmemSize(), BTreeShmemSize(), BufferManagerShmemSize(), CalculateShmemSize(), CheckpointerShmemSize(), estimate_variable_size(), EstimateClientConnectionInfoSpace(), EstimateComboCIDStateSpace(), EstimateGUCStateSpace(), EstimateLibraryStateSpace(), EstimateParamExecSpace(), EstimateParamListSpace(), EstimateSnapshotSpace(), EstimateTransactionStateSpace(), ExecAggEstimate(), ExecAppendEstimate(), ExecBitmapHeapEstimate(), ExecBitmapHeapInitializeDSM(), ExecHashEstimate(), ExecIncrementalSortEstimate(), ExecMemoizeEstimate(), ExecSortEstimate(), expand_planner_arrays(), hash_estimate_size(), index_parallelscan_estimate(), index_parallelscan_initialize(), InitializeShmemGUCs(), InjectionPointShmemSize(), LockManagerShmemSize(), LWLockShmemSize(), MultiXactShmemSize(), PgArchShmemSize(), pgss_memsize(), PMSignalShmemSize(), PredicateLockShmemSize(), ProcArrayShmemInit(), ProcArrayShmemSize(), ProcGlobalShmemSize(), ProcSignalShmemSize(), ReplicationOriginShmemSize(), ReplicationSlotsShmemSize(), RequestAddinShmemSpace(), SerializeTransactionState(), SharedInvalShmemSize(), shm_toc_estimate(), StatsShmemSize(), StrategyShmemSize(), table_parallelscan_estimate(), tuplesort_estimate_shared(), TwoPhaseShmemSize(), WaitEventCustomShmemSize(), WaitLSNShmemSize(), WalRcvShmemSize(), WalSndShmemSize(), and XLOGShmemSize().

◆ InitShmemAccess()

void InitShmemAccess ( void * seghdr )

Definition at line 100 of file shmem.c.

 {
     PGShmemHeader *shmhdr = (PGShmemHeader *) seghdr;
  
     ShmemSegHdr = shmhdr;
     ShmemBase = (void *) shmhdr;
     ShmemEnd = (char *) ShmemBase + shmhdr->totalsize;
 }

References ShmemBase, ShmemEnd, ShmemSegHdr, and PGShmemHeader::totalsize.

Referenced by CreateSharedMemoryAndSemaphores().

◆ InitShmemAllocation()

void InitShmemAllocation ( void )

Definition at line 115 of file shmem.c.

 {
     PGShmemHeader *shmhdr = ShmemSegHdr;
     char       *aligned;
  
     Assert(shmhdr != NULL);
  
     /*
      * Initialize the spinlock used by ShmemAlloc.  We must use
      * ShmemAllocUnlocked, since obviously ShmemAlloc can't be called yet.
      */
     ShmemLock = (slock_t *) ShmemAllocUnlocked(sizeof(slock_t));
  
     SpinLockInit(ShmemLock);
  
     /*
      * Allocations after this point should go through ShmemAlloc, which
      * expects to allocate everything on cache line boundaries.  Make sure the
      * first allocation begins on a cache line boundary.
      */
     aligned = (char *)
         (CACHELINEALIGN((((char *) shmhdr) + shmhdr->freeoffset)));
     shmhdr->freeoffset = aligned - (char *) shmhdr;
  
     /* ShmemIndex can't be set up yet (need LWLocks first) */
     shmhdr->index = NULL;
     ShmemIndex = (HTAB *) NULL;
 }

References Assert, CACHELINEALIGN, PGShmemHeader::freeoffset, PGShmemHeader::index, ShmemAllocUnlocked(), ShmemIndex, ShmemLock, ShmemSegHdr, and SpinLockInit.

Referenced by CreateSharedMemoryAndSemaphores().

◆ InitShmemIndex()

void InitShmemIndex ( void )

Definition at line 283 of file shmem.c.

 {
     HASHCTL     info;
  
     /*
      * Create the shared memory shmem index.
      *
      * Since ShmemInitHash calls ShmemInitStruct, which expects the ShmemIndex
      * hashtable to exist already, we have a bit of a circularity problem in
      * initializing the ShmemIndex itself.  The special "ShmemIndex" hash
      * table name will tell ShmemInitStruct to fake it.
      */
     info.keysize = SHMEM_INDEX_KEYSIZE;
     info.entrysize = sizeof(ShmemIndexEnt);
  
     ShmemIndex = ShmemInitHash("ShmemIndex",
                                SHMEM_INDEX_SIZE, SHMEM_INDEX_SIZE,
                                &info,
                                HASH_ELEM | HASH_STRINGS);
 }

References HASHCTL::entrysize, HASH_ELEM, HASH_STRINGS, HASHCTL::keysize, SHMEM_INDEX_KEYSIZE, SHMEM_INDEX_SIZE, ShmemIndex, and ShmemInitHash().

Referenced by CreateOrAttachShmemStructs().

◆ mul_size()

Size mul_size	(	Size	s1,
		Size	s2
	)

Definition at line 510 of file shmem.c.

 {
     Size        result;
  
     if (s1 == 0 || s2 == 0)
         return 0;
     result = s1 * s2;
     /* We are assuming Size is an unsigned type here... */
     if (result / s2 != s1)
         ereport(ERROR,
                 (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                  errmsg("requested shared memory size overflows size_t")));
     return result;
 }

References ereport, errcode(), errmsg(), ERROR, s1, and s2.

Referenced by _brin_begin_parallel(), _bt_begin_parallel(), ApplyLauncherShmemSize(), AsyncShmemInit(), AsyncShmemSize(), AutoVacuumShmemSize(), BackendStatusShmemInit(), BackendStatusShmemSize(), BackgroundWorkerShmemSize(), BTreeShmemSize(), BufferManagerShmemSize(), CheckpointerShmemSize(), EstimateComboCIDStateSpace(), EstimatePendingSyncsSpace(), EstimateReindexStateSpace(), EstimateSnapshotSpace(), EstimateTransactionStateSpace(), ExecAggEstimate(), ExecBitmapHeapEstimate(), ExecBitmapHeapInitializeDSM(), ExecHashEstimate(), ExecIncrementalSortEstimate(), ExecInitParallelPlan(), ExecMemoizeEstimate(), ExecParallelRetrieveInstrumentation(), ExecParallelRetrieveJitInstrumentation(), ExecParallelSetupTupleQueues(), ExecSortEstimate(), hash_estimate_size(), InitializeParallelDSM(), LWLockShmemSize(), parallel_vacuum_init(), PGSemaphoreShmemSize(), PMSignalShmemSize(), PredicateLockShmemInit(), PredicateLockShmemSize(), ProcArrayShmemInit(), ProcArrayShmemSize(), ProcGlobalShmemSize(), ProcSignalShmemSize(), ReplicationOriginShmemSize(), ReplicationSlotsShmemSize(), SharedInvalShmemSize(), shm_toc_estimate(), tuplesort_estimate_shared(), TwoPhaseShmemSize(), WaitLSNShmemSize(), WalSndShmemSize(), and XLOGShmemSize().

◆ RequestAddinShmemSpace()

void RequestAddinShmemSpace ( Size size )

Definition at line 76 of file ipci.c.

 {
     if (!process_shmem_requests_in_progress)
         elog(FATAL, "cannot request additional shared memory outside shmem_request_hook");
     total_addin_request = add_size(total_addin_request, size);
 }

References add_size(), elog, FATAL, process_shmem_requests_in_progress, size, and total_addin_request.

Referenced by injection_shmem_request(), pgss_shmem_request(), and test_slru_shmem_request().

◆ ShmemAddrIsValid()

bool ShmemAddrIsValid ( const void * addr )

Definition at line 274 of file shmem.c.

 {
     return (addr >= ShmemBase) && (addr < ShmemEnd);
 }

References ShmemBase, and ShmemEnd.

Referenced by ReleasePredXact(), and ShmemInitStruct().

◆ ShmemAlloc()

void* ShmemAlloc ( Size size )

Definition at line 152 of file shmem.c.

 {
     void       *newSpace;
     Size        allocated_size;
  
     newSpace = ShmemAllocRaw(size, &allocated_size);
     if (!newSpace)
         ereport(ERROR,
                 (errcode(ERRCODE_OUT_OF_MEMORY),
                  errmsg("out of shared memory (%zu bytes requested)",
                         size)));
     return newSpace;
 }

References ereport, errcode(), errmsg(), ERROR, ShmemAllocRaw(), and size.

Referenced by CreateLWLocks(), InitProcGlobal(), PredicateLockShmemInit(), ShmemInitStruct(), and StatsShmemInit().

◆ ShmemAllocNoError()

void* ShmemAllocNoError ( Size size )

Definition at line 172 of file shmem.c.

 {
     Size        allocated_size;
  
     return ShmemAllocRaw(size, &allocated_size);
 }

References ShmemAllocRaw(), and size.

Referenced by ShmemInitHash().

◆ ShmemAllocUnlocked()

void* ShmemAllocUnlocked ( Size size )

Definition at line 238 of file shmem.c.

 {
     Size        newStart;
     Size        newFree;
     void       *newSpace;
  
     /*
      * Ensure allocated space is adequately aligned.
      */
     size = MAXALIGN(size);
  
     Assert(ShmemSegHdr != NULL);
  
     newStart = ShmemSegHdr->freeoffset;
  
     newFree = newStart + size;
     if (newFree > ShmemSegHdr->totalsize)
         ereport(ERROR,
                 (errcode(ERRCODE_OUT_OF_MEMORY),
                  errmsg("out of shared memory (%zu bytes requested)",
                         size)));
     ShmemSegHdr->freeoffset = newFree;
  
     newSpace = (void *) ((char *) ShmemBase + newStart);
  
     Assert(newSpace == (void *) MAXALIGN(newSpace));
  
     return newSpace;
 }

References Assert, ereport, errcode(), errmsg(), ERROR, PGShmemHeader::freeoffset, MAXALIGN, ShmemBase, ShmemSegHdr, size, and PGShmemHeader::totalsize.

Referenced by InitShmemAllocation(), and PGReserveSemaphores().

◆ ShmemInitHash()

HTAB* ShmemInitHash	(	const char *	name,
		long	init_size,
		long	max_size,
		HASHCTL *	infoP,
		int	hash_flags
	)

Definition at line 332 of file shmem.c.

 {
     bool        found;
     void       *location;
  
     /*
      * Hash tables allocated in shared memory have a fixed directory; it can't
      * grow or other backends wouldn't be able to find it. So, make sure we
      * make it big enough to start with.
      *
      * The shared memory allocator must be specified too.
      */
     infoP->dsize = infoP->max_dsize = hash_select_dirsize(max_size);
     infoP->alloc = ShmemAllocNoError;
     hash_flags |= HASH_SHARED_MEM | HASH_ALLOC | HASH_DIRSIZE;
  
     /* look it up in the shmem index */
     location = ShmemInitStruct(name,
                                hash_get_shared_size(infoP, hash_flags),
                                &found);
  
     /*
      * if it already exists, attach to it rather than allocate and initialize
      * new space
      */
     if (found)
         hash_flags |= HASH_ATTACH;
  
     /* Pass location of hashtable header to hash_create */
     infoP->hctl = (HASHHDR *) location;
  
     return hash_create(name, init_size, infoP, hash_flags);
 }

References HASHCTL::alloc, HASHCTL::dsize, HASH_ALLOC, HASH_ATTACH, hash_create(), HASH_DIRSIZE, hash_get_shared_size(), hash_select_dirsize(), HASH_SHARED_MEM, HASHCTL::hctl, HASHCTL::max_dsize, name, ShmemAllocNoError(), and ShmemInitStruct().

Referenced by InitBufTable(), InitShmemIndex(), LockManagerShmemInit(), pgss_shmem_startup(), PredicateLockShmemInit(), and WaitEventCustomShmemInit().

◆ ShmemInitStruct()

void* ShmemInitStruct	(	const char *	name,
		Size	size,
		bool *	foundPtr
	)

Definition at line 387 of file shmem.c.

 {
     ShmemIndexEnt *result;
     void       *structPtr;
  
     LWLockAcquire(ShmemIndexLock, LW_EXCLUSIVE);
  
     if (!ShmemIndex)
     {
         PGShmemHeader *shmemseghdr = ShmemSegHdr;
  
         /* Must be trying to create/attach to ShmemIndex itself */
         Assert(strcmp(name, "ShmemIndex") == 0);
  
         if (IsUnderPostmaster)
         {
             /* Must be initializing a (non-standalone) backend */
             Assert(shmemseghdr->index != NULL);
             structPtr = shmemseghdr->index;
             *foundPtr = true;
         }
         else
         {
             /*
              * If the shmem index doesn't exist, we are bootstrapping: we must
              * be trying to init the shmem index itself.
              *
              * Notice that the ShmemIndexLock is released before the shmem
              * index has been initialized.  This should be OK because no other
              * process can be accessing shared memory yet.
              */
             Assert(shmemseghdr->index == NULL);
             structPtr = ShmemAlloc(size);
             shmemseghdr->index = structPtr;
             *foundPtr = false;
         }
         LWLockRelease(ShmemIndexLock);
         return structPtr;
     }
  
     /* look it up in the shmem index */
     result = (ShmemIndexEnt *)
         hash_search(ShmemIndex, name, HASH_ENTER_NULL, foundPtr);
  
     if (!result)
     {
         LWLockRelease(ShmemIndexLock);
         ereport(ERROR,
                 (errcode(ERRCODE_OUT_OF_MEMORY),
                  errmsg("could not create ShmemIndex entry for data structure \"%s\"",
                         name)));
     }
  
     if (*foundPtr)
     {
         /*
          * Structure is in the shmem index so someone else has allocated it
          * already.  The size better be the same as the size we are trying to
          * initialize to, or there is a name conflict (or worse).
          */
         if (result->size != size)
         {
             LWLockRelease(ShmemIndexLock);
             ereport(ERROR,
                     (errmsg("ShmemIndex entry size is wrong for data structure"
                             " \"%s\": expected %zu, actual %zu",
                             name, size, result->size)));
         }
         structPtr = result->location;
     }
     else
     {
         Size        allocated_size;
  
         /* It isn't in the table yet. allocate and initialize it */
         structPtr = ShmemAllocRaw(size, &allocated_size);
         if (structPtr == NULL)
         {
             /* out of memory; remove the failed ShmemIndex entry */
             hash_search(ShmemIndex, name, HASH_REMOVE, NULL);
             LWLockRelease(ShmemIndexLock);
             ereport(ERROR,
                     (errcode(ERRCODE_OUT_OF_MEMORY),
                      errmsg("not enough shared memory for data structure"
                             " \"%s\" (%zu bytes requested)",
                             name, size)));
         }
         result->size = size;
         result->allocated_size = allocated_size;
         result->location = structPtr;
     }
  
     LWLockRelease(ShmemIndexLock);
  
     Assert(ShmemAddrIsValid(structPtr));
  
     Assert(structPtr == (void *) CACHELINEALIGN(structPtr));
  
     return structPtr;
 }

References ShmemIndexEnt::allocated_size, Assert, CACHELINEALIGN, ereport, errcode(), errmsg(), ERROR, HASH_ENTER_NULL, HASH_REMOVE, hash_search(), PGShmemHeader::index, IsUnderPostmaster, ShmemIndexEnt::location, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), name, ShmemAddrIsValid(), ShmemAlloc(), ShmemAllocRaw(), ShmemIndex, ShmemSegHdr, size, and ShmemIndexEnt::size.

Referenced by ApplyLauncherShmemInit(), AsyncShmemInit(), AutoVacuumShmemInit(), BackendStatusShmemInit(), BackgroundWorkerShmemInit(), BTreeShmemInit(), BufferManagerShmemInit(), CheckpointerShmemInit(), CommitTsShmemInit(), dsm_shmem_init(), DSMRegistryShmemInit(), InitProcGlobal(), injection_shmem_startup(), InjectionPointShmemInit(), LockManagerShmemInit(), MultiXactShmemInit(), PgArchShmemInit(), pgss_shmem_startup(), PMSignalShmemInit(), PredicateLockShmemInit(), ProcArrayShmemInit(), ProcSignalShmemInit(), ReplicationOriginShmemInit(), ReplicationSlotsShmemInit(), SerialInit(), SharedInvalShmemInit(), ShmemInitHash(), SimpleLruInit(), SlotSyncShmemInit(), StatsShmemInit(), StrategyInitialize(), SyncScanShmemInit(), TwoPhaseShmemInit(), VarsupShmemInit(), WaitEventCustomShmemInit(), WaitLSNShmemInit(), WalRcvShmemInit(), WalSndShmemInit(), WalSummarizerShmemInit(), XLogPrefetchShmemInit(), XLogRecoveryShmemInit(), and XLOGShmemInit().

Variable Documentation

◆ ShmemLock

PGDLLIMPORT slock_t* ShmemLock

extern

Definition at line 87 of file shmem.c.

Referenced by InitShmemAllocation(), LWLockNewTrancheId(), and ShmemAllocRaw().

Data Structures

Macros

Functions

Variables