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dsm.h File Reference
#include "storage/dsm_impl.h"
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Macros

#define DSM_CREATE_NULL_IF_MAXSEGMENTS   0x0001
 
#define DSM_HANDLE_INVALID   0
 

Typedefs

typedef struct dsm_segment dsm_segment
 
typedef void(* on_dsm_detach_callback )(dsm_segment *, Datum arg)
 

Functions

void dsm_cleanup_using_control_segment (dsm_handle old_control_handle)
 
void dsm_postmaster_startup (struct PGShmemHeader *)
 
void dsm_backend_shutdown (void)
 
void dsm_detach_all (void)
 
dsm_segmentdsm_create (Size size, int flags)
 
dsm_segmentdsm_attach (dsm_handle h)
 
void * dsm_resize (dsm_segment *seg, Size size)
 
void * dsm_remap (dsm_segment *seg)
 
void dsm_detach (dsm_segment *seg)
 
void dsm_pin_mapping (dsm_segment *seg)
 
void dsm_unpin_mapping (dsm_segment *seg)
 
void dsm_pin_segment (dsm_segment *seg)
 
void dsm_unpin_segment (dsm_handle h)
 
dsm_segmentdsm_find_mapping (dsm_handle h)
 
void * dsm_segment_address (dsm_segment *seg)
 
Size dsm_segment_map_length (dsm_segment *seg)
 
dsm_handle dsm_segment_handle (dsm_segment *seg)
 
void on_dsm_detach (dsm_segment *seg, on_dsm_detach_callback function, Datum arg)
 
void cancel_on_dsm_detach (dsm_segment *seg, on_dsm_detach_callback function, Datum arg)
 
void reset_on_dsm_detach (void)
 

Macro Definition Documentation

#define DSM_CREATE_NULL_IF_MAXSEGMENTS   0x0001

Definition at line 20 of file dsm.h.

Referenced by dsm_create(), and InitializeParallelDSM().

Typedef Documentation

Definition at line 18 of file dsm.h.

typedef void(* on_dsm_detach_callback)(dsm_segment *, Datum arg)

Definition at line 56 of file dsm.h.

Function Documentation

void cancel_on_dsm_detach ( dsm_segment seg,
on_dsm_detach_callback  function,
Datum  arg 
)

Definition at line 1052 of file dsm.c.

References dsm_segment_detach_callback::arg, slist_mutable_iter::cur, dsm_segment_detach_callback::function, dsm_segment::on_detach, pfree(), slist_container, slist_delete_current(), and slist_foreach_modify.

Referenced by test_shm_mq_setup().

1054 {
1055  slist_mutable_iter iter;
1056 
1057  slist_foreach_modify(iter, &seg->on_detach)
1058  {
1060 
1062  if (cb->function == function && cb->arg == arg)
1063  {
1064  slist_delete_current(&iter);
1065  pfree(cb);
1066  break;
1067  }
1068  }
1069 }
slist_node * cur
Definition: ilist.h:241
#define slist_foreach_modify(iter, lhead)
Definition: ilist.h:716
void pfree(void *pointer)
Definition: mcxt.c:950
on_dsm_detach_callback function
Definition: dsm.c:61
slist_head on_detach
Definition: dsm.c:76
#define slist_container(type, membername, ptr)
Definition: ilist.h:674
void * arg
static void slist_delete_current(slist_mutable_iter *iter)
Definition: ilist.h:652
dsm_segment* dsm_attach ( dsm_handle  h)

Definition at line 561 of file dsm.c.

References Assert, dsm_segment::control_slot, dlist_iter::cur, dlist_container, dlist_foreach, dsm_backend_startup(), dsm_create_descriptor(), dsm_detach(), dsm_impl_op(), dsm_init_done, DSM_OP_ATTACH, elog, ERROR, dsm_segment::handle, dsm_control_item::handle, i, dsm_segment::impl_private, INVALID_CONTROL_SLOT, IsUnderPostmaster, dsm_control_header::item, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), dsm_segment::mapped_address, dsm_segment::mapped_size, dsm_control_header::nitems, NULL, and dsm_control_item::refcnt.

Referenced by dsa_attach(), get_segment_by_index(), ParallelWorkerMain(), and test_shm_mq_main().

562 {
563  dsm_segment *seg;
564  dlist_iter iter;
565  uint32 i;
566  uint32 nitems;
567 
568  /* Unsafe in postmaster (and pointless in a stand-alone backend). */
570 
571  if (!dsm_init_done)
573 
574  /*
575  * Since this is just a debugging cross-check, we could leave it out
576  * altogether, or include it only in assert-enabled builds. But since the
577  * list of attached segments should normally be very short, let's include
578  * it always for right now.
579  *
580  * If you're hitting this error, you probably want to attempt to find an
581  * existing mapping via dsm_find_mapping() before calling dsm_attach() to
582  * create a new one.
583  */
585  {
586  seg = dlist_container(dsm_segment, node, iter.cur);
587  if (seg->handle == h)
588  elog(ERROR, "can't attach the same segment more than once");
589  }
590 
591  /* Create a new segment descriptor. */
592  seg = dsm_create_descriptor();
593  seg->handle = h;
594 
595  /* Bump reference count for this segment in shared memory. */
596  LWLockAcquire(DynamicSharedMemoryControlLock, LW_EXCLUSIVE);
597  nitems = dsm_control->nitems;
598  for (i = 0; i < nitems; ++i)
599  {
600  /* If the reference count is 0, the slot is actually unused. */
601  if (dsm_control->item[i].refcnt == 0)
602  continue;
603 
604  /* If the handle doesn't match, it's not the slot we want. */
605  if (dsm_control->item[i].handle != seg->handle)
606  continue;
607 
608  /*
609  * If the reference count is 1, the slot is still in use, but the
610  * segment is in the process of going away. Treat that as if we
611  * didn't find a match.
612  */
613  if (dsm_control->item[i].refcnt == 1)
614  break;
615 
616  /* Otherwise we've found a match. */
617  dsm_control->item[i].refcnt++;
618  seg->control_slot = i;
619  break;
620  }
621  LWLockRelease(DynamicSharedMemoryControlLock);
622 
623  /*
624  * If we didn't find the handle we're looking for in the control segment,
625  * it probably means that everyone else who had it mapped, including the
626  * original creator, died before we got to this point. It's up to the
627  * caller to decide what to do about that.
628  */
630  {
631  dsm_detach(seg);
632  return NULL;
633  }
634 
635  /* Here's where we actually try to map the segment. */
637  &seg->mapped_address, &seg->mapped_size, ERROR);
638 
639  return seg;
640 }
Size mapped_size
Definition: dsm.c:75
dsm_handle handle
Definition: dsm.c:82
#define dlist_foreach(iter, lhead)
Definition: ilist.h:507
static void dsm_backend_startup(void)
Definition: dsm.c:405
static dlist_head dsm_segment_list
Definition: dsm.c:124
uint32 nitems
Definition: dsm.c:92
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
#define dlist_container(type, membername, ptr)
Definition: ilist.h:477
#define ERROR
Definition: elog.h:43
bool IsUnderPostmaster
Definition: globals.c:101
dsm_control_item item[FLEXIBLE_ARRAY_MEMBER]
Definition: dsm.c:94
unsigned int uint32
Definition: c.h:268
void * mapped_address
Definition: dsm.c:74
dsm_handle handle
Definition: dsm.c:71
dlist_node * cur
Definition: ilist.h:161
static dsm_control_header * dsm_control
Definition: dsm.c:134
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
void * impl_private
Definition: dsm.c:73
uint32 control_slot
Definition: dsm.c:72
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1111
static dsm_segment * dsm_create_descriptor(void)
Definition: dsm.c:1106
uint32 refcnt
Definition: dsm.c:83
static bool dsm_init_done
Definition: dsm.c:105
void dsm_detach(dsm_segment *seg)
Definition: dsm.c:726
int i
#define INVALID_CONTROL_SLOT
Definition: dsm.c:56
#define elog
Definition: elog.h:219
bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size, void **impl_private, void **mapped_address, Size *mapped_size, int elevel)
Definition: dsm_impl.c:162
void dsm_backend_shutdown ( void  )

Definition at line 648 of file dsm.c.

References dlist_head_element, dlist_is_empty(), and dsm_detach().

Referenced by shmem_exit().

649 {
651  {
652  dsm_segment *seg;
653 
655  dsm_detach(seg);
656  }
657 }
static dlist_head dsm_segment_list
Definition: dsm.c:124
#define dlist_head_element(type, membername, lhead)
Definition: ilist.h:487
static bool dlist_is_empty(dlist_head *head)
Definition: ilist.h:289
void dsm_detach(dsm_segment *seg)
Definition: dsm.c:726
void dsm_cleanup_using_control_segment ( dsm_handle  old_control_handle)

Definition at line 210 of file dsm.c.

References DEBUG1, DEBUG2, dsm_control_segment_sane(), DSM_IMPL_NONE, dsm_impl_op(), DSM_OP_ATTACH, DSM_OP_DESTROY, DSM_OP_DETACH, dynamic_shared_memory_type, elog, dsm_control_item::handle, i, dsm_control_header::item, LOG, dsm_control_header::nitems, NULL, and dsm_control_item::refcnt.

Referenced by PGSharedMemoryCreate().

211 {
212  void *mapped_address = NULL;
213  void *junk_mapped_address = NULL;
214  void *impl_private = NULL;
215  void *junk_impl_private = NULL;
216  Size mapped_size = 0;
217  Size junk_mapped_size = 0;
218  uint32 nitems;
219  uint32 i;
220  dsm_control_header *old_control;
221 
222  /* If dynamic shared memory is disabled, there's nothing to do. */
224  return;
225 
226  /*
227  * Try to attach the segment. If this fails, it probably just means that
228  * the operating system has been rebooted and the segment no longer
229  * exists, or an unrelated process has used the same shm ID. So just fall
230  * out quietly.
231  */
232  if (!dsm_impl_op(DSM_OP_ATTACH, old_control_handle, 0, &impl_private,
233  &mapped_address, &mapped_size, DEBUG1))
234  return;
235 
236  /*
237  * We've managed to reattach it, but the contents might not be sane. If
238  * they aren't, we disregard the segment after all.
239  */
240  old_control = (dsm_control_header *) mapped_address;
241  if (!dsm_control_segment_sane(old_control, mapped_size))
242  {
243  dsm_impl_op(DSM_OP_DETACH, old_control_handle, 0, &impl_private,
244  &mapped_address, &mapped_size, LOG);
245  return;
246  }
247 
248  /*
249  * OK, the control segment looks basically valid, so we can use it to get
250  * a list of segments that need to be removed.
251  */
252  nitems = old_control->nitems;
253  for (i = 0; i < nitems; ++i)
254  {
255  dsm_handle handle;
256  uint32 refcnt;
257 
258  /* If the reference count is 0, the slot is actually unused. */
259  refcnt = old_control->item[i].refcnt;
260  if (refcnt == 0)
261  continue;
262 
263  /* Log debugging information. */
264  handle = old_control->item[i].handle;
265  elog(DEBUG2, "cleaning up orphaned dynamic shared memory with ID %u (reference count %u)",
266  handle, refcnt);
267 
268  /* Destroy the referenced segment. */
269  dsm_impl_op(DSM_OP_DESTROY, handle, 0, &junk_impl_private,
270  &junk_mapped_address, &junk_mapped_size, LOG);
271  }
272 
273  /* Destroy the old control segment, too. */
274  elog(DEBUG2,
275  "cleaning up dynamic shared memory control segment with ID %u",
276  old_control_handle);
277  dsm_impl_op(DSM_OP_DESTROY, old_control_handle, 0, &impl_private,
278  &mapped_address, &mapped_size, LOG);
279 }
#define DEBUG1
Definition: elog.h:25
uint32 dsm_handle
Definition: dsm_impl.h:55
dsm_handle handle
Definition: dsm.c:82
#define LOG
Definition: elog.h:26
uint32 nitems
Definition: dsm.c:92
#define DEBUG2
Definition: elog.h:24
dsm_control_item item[FLEXIBLE_ARRAY_MEMBER]
Definition: dsm.c:94
int dynamic_shared_memory_type
Definition: dsm_impl.c:112
unsigned int uint32
Definition: c.h:268
static bool dsm_control_segment_sane(dsm_control_header *control, Size mapped_size)
Definition: dsm.c:1142
#define NULL
Definition: c.h:229
#define DSM_IMPL_NONE
Definition: dsm_impl.h:17
size_t Size
Definition: c.h:356
uint32 refcnt
Definition: dsm.c:83
int i
#define elog
Definition: elog.h:219
bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size, void **impl_private, void **mapped_address, Size *mapped_size, int elevel)
Definition: dsm_impl.c:162
dsm_segment* dsm_create ( Size  size,
int  flags 
)

Definition at line 465 of file dsm.c.

References Assert, dsm_segment::control_slot, dlist_delete(), dsm_backend_startup(), dsm_create_descriptor(), DSM_CREATE_NULL_IF_MAXSEGMENTS, DSM_HANDLE_INVALID, dsm_impl_op(), dsm_init_done, DSM_OP_CREATE, DSM_OP_DESTROY, ereport, errcode(), errmsg(), ERROR, dsm_segment::handle, dsm_control_item::handle, i, dsm_segment::impl_private, dsm_control_item::impl_private_pm_handle, IsUnderPostmaster, dsm_control_header::item, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), dsm_segment::mapped_address, dsm_segment::mapped_size, dsm_control_header::maxitems, dsm_control_header::nitems, dsm_segment::node, NULL, pfree(), dsm_control_item::pinned, random(), dsm_control_item::refcnt, ResourceOwnerForgetDSM(), dsm_segment::resowner, and WARNING.

Referenced by dsa_create(), InitializeParallelDSM(), make_new_segment(), and setup_dynamic_shared_memory().

466 {
467  dsm_segment *seg;
468  uint32 i;
469  uint32 nitems;
470 
471  /* Unsafe in postmaster (and pointless in a stand-alone backend). */
473 
474  if (!dsm_init_done)
476 
477  /* Create a new segment descriptor. */
478  seg = dsm_create_descriptor();
479 
480  /* Loop until we find an unused segment identifier. */
481  for (;;)
482  {
483  Assert(seg->mapped_address == NULL && seg->mapped_size == 0);
484  seg->handle = random();
485  if (seg->handle == DSM_HANDLE_INVALID) /* Reserve sentinel */
486  continue;
487  if (dsm_impl_op(DSM_OP_CREATE, seg->handle, size, &seg->impl_private,
488  &seg->mapped_address, &seg->mapped_size, ERROR))
489  break;
490  }
491 
492  /* Lock the control segment so we can register the new segment. */
493  LWLockAcquire(DynamicSharedMemoryControlLock, LW_EXCLUSIVE);
494 
495  /* Search the control segment for an unused slot. */
496  nitems = dsm_control->nitems;
497  for (i = 0; i < nitems; ++i)
498  {
499  if (dsm_control->item[i].refcnt == 0)
500  {
501  dsm_control->item[i].handle = seg->handle;
502  /* refcnt of 1 triggers destruction, so start at 2 */
503  dsm_control->item[i].refcnt = 2;
505  dsm_control->item[i].pinned = false;
506  seg->control_slot = i;
507  LWLockRelease(DynamicSharedMemoryControlLock);
508  return seg;
509  }
510  }
511 
512  /* Verify that we can support an additional mapping. */
513  if (nitems >= dsm_control->maxitems)
514  {
515  if ((flags & DSM_CREATE_NULL_IF_MAXSEGMENTS) != 0)
516  {
517  LWLockRelease(DynamicSharedMemoryControlLock);
519  &seg->mapped_address, &seg->mapped_size, WARNING);
520  if (seg->resowner != NULL)
521  ResourceOwnerForgetDSM(seg->resowner, seg);
522  dlist_delete(&seg->node);
523  pfree(seg);
524  return NULL;
525  }
526  ereport(ERROR,
527  (errcode(ERRCODE_INSUFFICIENT_RESOURCES),
528  errmsg("too many dynamic shared memory segments")));
529  }
530 
531  /* Enter the handle into a new array slot. */
532  dsm_control->item[nitems].handle = seg->handle;
533  /* refcnt of 1 triggers destruction, so start at 2 */
534  dsm_control->item[nitems].refcnt = 2;
536  dsm_control->item[nitems].pinned = false;
537  seg->control_slot = nitems;
538  dsm_control->nitems++;
539  LWLockRelease(DynamicSharedMemoryControlLock);
540 
541  return seg;
542 }
dlist_node node
Definition: dsm.c:69
uint32 maxitems
Definition: dsm.c:93
Size mapped_size
Definition: dsm.c:75
dsm_handle handle
Definition: dsm.c:82
long random(void)
Definition: random.c:22
int errcode(int sqlerrcode)
Definition: elog.c:575
static void dsm_backend_startup(void)
Definition: dsm.c:405
uint32 nitems
Definition: dsm.c:92
bool pinned
Definition: dsm.c:85
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
#define DSM_HANDLE_INVALID
Definition: dsm.h:23
void pfree(void *pointer)
Definition: mcxt.c:950
#define ERROR
Definition: elog.h:43
#define DSM_CREATE_NULL_IF_MAXSEGMENTS
Definition: dsm.h:20
bool IsUnderPostmaster
Definition: globals.c:101
dsm_control_item item[FLEXIBLE_ARRAY_MEMBER]
Definition: dsm.c:94
unsigned int uint32
Definition: c.h:268
void * mapped_address
Definition: dsm.c:74
static void dlist_delete(dlist_node *node)
Definition: ilist.h:358
#define ereport(elevel, rest)
Definition: elog.h:122
#define WARNING
Definition: elog.h:40
dsm_handle handle
Definition: dsm.c:71
static dsm_control_header * dsm_control
Definition: dsm.c:134
ResourceOwner resowner
Definition: dsm.c:70
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
void * impl_private
Definition: dsm.c:73
void ResourceOwnerForgetDSM(ResourceOwner owner, dsm_segment *seg)
Definition: resowner.c:1254
uint32 control_slot
Definition: dsm.c:72
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1111
static dsm_segment * dsm_create_descriptor(void)
Definition: dsm.c:1106
uint32 refcnt
Definition: dsm.c:83
static bool dsm_init_done
Definition: dsm.c:105
int errmsg(const char *fmt,...)
Definition: elog.c:797
int i
void * impl_private_pm_handle
Definition: dsm.c:84
bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size, void **impl_private, void **mapped_address, Size *mapped_size, int elevel)
Definition: dsm_impl.c:162
void dsm_detach ( dsm_segment seg)

Definition at line 726 of file dsm.c.

References arg, dsm_segment_detach_callback::arg, Assert, dsm_segment::control_slot, dlist_delete(), dsm_impl_op(), DSM_OP_DESTROY, DSM_OP_DETACH, dsm_segment_detach_callback::function, dsm_segment::handle, dsm_control_item::handle, dsm_segment::impl_private, INVALID_CONTROL_SLOT, dsm_control_header::item, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), dsm_segment::mapped_address, dsm_segment::mapped_size, dsm_segment::node, NULL, dsm_segment::on_detach, pfree(), dsm_control_item::pinned, dsm_control_item::refcnt, ResourceOwnerForgetDSM(), dsm_segment::resowner, slist_container, slist_is_empty(), slist_pop_head_node(), and WARNING.

Referenced by check_for_freed_segments(), destroy_superblock(), DestroyParallelContext(), dsa_detach(), dsm_attach(), dsm_backend_shutdown(), dsm_detach_all(), ResourceOwnerReleaseInternal(), test_shm_mq(), test_shm_mq_main(), and test_shm_mq_pipelined().

727 {
728  /*
729  * Invoke registered callbacks. Just in case one of those callbacks
730  * throws a further error that brings us back here, pop the callback
731  * before invoking it, to avoid infinite error recursion.
732  */
733  while (!slist_is_empty(&seg->on_detach))
734  {
735  slist_node *node;
737  on_dsm_detach_callback function;
738  Datum arg;
739 
740  node = slist_pop_head_node(&seg->on_detach);
742  function = cb->function;
743  arg = cb->arg;
744  pfree(cb);
745 
746  function(seg, arg);
747  }
748 
749  /*
750  * Try to remove the mapping, if one exists. Normally, there will be, but
751  * maybe not, if we failed partway through a create or attach operation.
752  * We remove the mapping before decrementing the reference count so that
753  * the process that sees a zero reference count can be certain that no
754  * remaining mappings exist. Even if this fails, we pretend that it
755  * works, because retrying is likely to fail in the same way.
756  */
757  if (seg->mapped_address != NULL)
758  {
760  &seg->mapped_address, &seg->mapped_size, WARNING);
761  seg->impl_private = NULL;
762  seg->mapped_address = NULL;
763  seg->mapped_size = 0;
764  }
765 
766  /* Reduce reference count, if we previously increased it. */
768  {
769  uint32 refcnt;
770  uint32 control_slot = seg->control_slot;
771 
772  LWLockAcquire(DynamicSharedMemoryControlLock, LW_EXCLUSIVE);
773  Assert(dsm_control->item[control_slot].handle == seg->handle);
774  Assert(dsm_control->item[control_slot].refcnt > 1);
775  refcnt = --dsm_control->item[control_slot].refcnt;
777  LWLockRelease(DynamicSharedMemoryControlLock);
778 
779  /* If new reference count is 1, try to destroy the segment. */
780  if (refcnt == 1)
781  {
782  /* A pinned segment should never reach 1. */
783  Assert(!dsm_control->item[control_slot].pinned);
784 
785  /*
786  * If we fail to destroy the segment here, or are killed before we
787  * finish doing so, the reference count will remain at 1, which
788  * will mean that nobody else can attach to the segment. At
789  * postmaster shutdown time, or when a new postmaster is started
790  * after a hard kill, another attempt will be made to remove the
791  * segment.
792  *
793  * The main case we're worried about here is being killed by a
794  * signal before we can finish removing the segment. In that
795  * case, it's important to be sure that the segment still gets
796  * removed. If we actually fail to remove the segment for some
797  * other reason, the postmaster may not have any better luck than
798  * we did. There's not much we can do about that, though.
799  */
800  if (dsm_impl_op(DSM_OP_DESTROY, seg->handle, 0, &seg->impl_private,
801  &seg->mapped_address, &seg->mapped_size, WARNING))
802  {
803  LWLockAcquire(DynamicSharedMemoryControlLock, LW_EXCLUSIVE);
804  Assert(dsm_control->item[control_slot].handle == seg->handle);
805  Assert(dsm_control->item[control_slot].refcnt == 1);
806  dsm_control->item[control_slot].refcnt = 0;
807  LWLockRelease(DynamicSharedMemoryControlLock);
808  }
809  }
810  }
811 
812  /* Clean up our remaining backend-private data structures. */
813  if (seg->resowner != NULL)
814  ResourceOwnerForgetDSM(seg->resowner, seg);
815  dlist_delete(&seg->node);
816  pfree(seg);
817 }
dlist_node node
Definition: dsm.c:69
Size mapped_size
Definition: dsm.c:75
dsm_handle handle
Definition: dsm.c:82
void(* on_dsm_detach_callback)(dsm_segment *, Datum arg)
Definition: dsm.h:56
bool pinned
Definition: dsm.c:85
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
void pfree(void *pointer)
Definition: mcxt.c:950
on_dsm_detach_callback function
Definition: dsm.c:61
dsm_control_item item[FLEXIBLE_ARRAY_MEMBER]
Definition: dsm.c:94
unsigned int uint32
Definition: c.h:268
void * mapped_address
Definition: dsm.c:74
static void dlist_delete(dlist_node *node)
Definition: ilist.h:358
static slist_node * slist_pop_head_node(slist_head *head)
Definition: ilist.h:596
slist_head on_detach
Definition: dsm.c:76
static bool slist_is_empty(slist_head *head)
Definition: ilist.h:563
#define WARNING
Definition: elog.h:40
dsm_handle handle
Definition: dsm.c:71
#define slist_container(type, membername, ptr)
Definition: ilist.h:674
uintptr_t Datum
Definition: postgres.h:372
static dsm_control_header * dsm_control
Definition: dsm.c:134
ResourceOwner resowner
Definition: dsm.c:70
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
void * impl_private
Definition: dsm.c:73
void ResourceOwnerForgetDSM(ResourceOwner owner, dsm_segment *seg)
Definition: resowner.c:1254
uint32 control_slot
Definition: dsm.c:72
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1111
uint32 refcnt
Definition: dsm.c:83
void * arg
#define INVALID_CONTROL_SLOT
Definition: dsm.c:56
bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size, void **impl_private, void **mapped_address, Size *mapped_size, int elevel)
Definition: dsm_impl.c:162
void dsm_detach_all ( void  )

Definition at line 666 of file dsm.c.

References dlist_head_element, dlist_is_empty(), dsm_control, dsm_control_handle, dsm_control_impl_private, dsm_control_mapped_size, dsm_detach(), dsm_impl_op(), DSM_OP_DETACH, ERROR, and NULL.

Referenced by pgarch_start(), pgstat_start(), StartBackgroundWorker(), and SysLogger_Start().

667 {
668  void *control_address = dsm_control;
669 
671  {
672  dsm_segment *seg;
673 
675  dsm_detach(seg);
676  }
677 
678  if (control_address != NULL)
680  &dsm_control_impl_private, &control_address,
682 }
static void * dsm_control_impl_private
Definition: dsm.c:136
static dsm_handle dsm_control_handle
Definition: dsm.c:133
static dlist_head dsm_segment_list
Definition: dsm.c:124
#define ERROR
Definition: elog.h:43
#define dlist_head_element(type, membername, lhead)
Definition: ilist.h:487
static dsm_control_header * dsm_control
Definition: dsm.c:134
#define NULL
Definition: c.h:229
static bool dlist_is_empty(dlist_head *head)
Definition: ilist.h:289
void dsm_detach(dsm_segment *seg)
Definition: dsm.c:726
static Size dsm_control_mapped_size
Definition: dsm.c:135
bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size, void **impl_private, void **mapped_address, Size *mapped_size, int elevel)
Definition: dsm_impl.c:162
dsm_segment* dsm_find_mapping ( dsm_handle  h)

Definition at line 981 of file dsm.c.

References dlist_iter::cur, dlist_container, dlist_foreach, dsm_segment::handle, and NULL.

982 {
983  dlist_iter iter;
984  dsm_segment *seg;
985 
987  {
988  seg = dlist_container(dsm_segment, node, iter.cur);
989  if (seg->handle == h)
990  return seg;
991  }
992 
993  return NULL;
994 }
#define dlist_foreach(iter, lhead)
Definition: ilist.h:507
static dlist_head dsm_segment_list
Definition: dsm.c:124
#define dlist_container(type, membername, ptr)
Definition: ilist.h:477
dsm_handle handle
Definition: dsm.c:71
dlist_node * cur
Definition: ilist.h:161
#define NULL
Definition: c.h:229
void dsm_pin_mapping ( dsm_segment seg)

Definition at line 827 of file dsm.c.

References NULL, ResourceOwnerForgetDSM(), and dsm_segment::resowner.

Referenced by dsa_pin_mapping(), get_segment_by_index(), and make_new_segment().

828 {
829  if (seg->resowner != NULL)
830  {
831  ResourceOwnerForgetDSM(seg->resowner, seg);
832  seg->resowner = NULL;
833  }
834 }
ResourceOwner resowner
Definition: dsm.c:70
#define NULL
Definition: c.h:229
void ResourceOwnerForgetDSM(ResourceOwner owner, dsm_segment *seg)
Definition: resowner.c:1254
void dsm_pin_segment ( dsm_segment seg)

Definition at line 867 of file dsm.c.

References dsm_segment::control_slot, dsm_impl_pin_segment(), elog, ERROR, dsm_segment::handle, dsm_segment::impl_private, dsm_control_item::impl_private_pm_handle, dsm_control_header::item, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), dsm_control_item::pinned, and dsm_control_item::refcnt.

Referenced by dsa_create(), and make_new_segment().

868 {
869  void *handle;
870 
871  /*
872  * Bump reference count for this segment in shared memory. This will
873  * ensure that even if there is no session which is attached to this
874  * segment, it will remain until postmaster shutdown or an explicit call
875  * to unpin.
876  */
877  LWLockAcquire(DynamicSharedMemoryControlLock, LW_EXCLUSIVE);
878  if (dsm_control->item[seg->control_slot].pinned)
879  elog(ERROR, "cannot pin a segment that is already pinned");
880  dsm_impl_pin_segment(seg->handle, seg->impl_private, &handle);
881  dsm_control->item[seg->control_slot].pinned = true;
884  LWLockRelease(DynamicSharedMemoryControlLock);
885 }
bool pinned
Definition: dsm.c:85
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
#define ERROR
Definition: elog.h:43
dsm_control_item item[FLEXIBLE_ARRAY_MEMBER]
Definition: dsm.c:94
dsm_handle handle
Definition: dsm.c:71
static dsm_control_header * dsm_control
Definition: dsm.c:134
void * impl_private
Definition: dsm.c:73
uint32 control_slot
Definition: dsm.c:72
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1111
uint32 refcnt
Definition: dsm.c:83
void dsm_impl_pin_segment(dsm_handle handle, void *impl_private, void **impl_private_pm_handle)
Definition: dsm_impl.c:1009
void * impl_private_pm_handle
Definition: dsm.c:84
#define elog
Definition: elog.h:219
void dsm_postmaster_startup ( struct PGShmemHeader )

Definition at line 145 of file dsm.c.

References Assert, DEBUG2, dsm_cleanup_for_mmap(), PGShmemHeader::dsm_control, dsm_control_bytes_needed(), dsm_control_handle, dsm_control_impl_private, dsm_control_mapped_size, DSM_HANDLE_INVALID, DSM_IMPL_MMAP, DSM_IMPL_NONE, dsm_impl_op(), DSM_OP_CREATE, dsm_postmaster_shutdown(), dynamic_shared_memory_type, elog, ERROR, IsUnderPostmaster, dsm_control_header::magic, MaxBackends, dsm_control_header::maxitems, dsm_control_header::nitems, NULL, on_shmem_exit(), PG_DYNSHMEM_CONTROL_MAGIC, PG_DYNSHMEM_FIXED_SLOTS, PG_DYNSHMEM_SLOTS_PER_BACKEND, PointerGetDatum, and random().

Referenced by CreateSharedMemoryAndSemaphores().

146 {
147  void *dsm_control_address = NULL;
148  uint32 maxitems;
149  Size segsize;
150 
152 
153  /* If dynamic shared memory is disabled, there's nothing to do. */
155  return;
156 
157  /*
158  * If we're using the mmap implementations, clean up any leftovers.
159  * Cleanup isn't needed on Windows, and happens earlier in startup for
160  * POSIX and System V shared memory, via a direct call to
161  * dsm_cleanup_using_control_segment.
162  */
165 
166  /* Determine size for new control segment. */
167  maxitems = PG_DYNSHMEM_FIXED_SLOTS
169  elog(DEBUG2, "dynamic shared memory system will support %u segments",
170  maxitems);
171  segsize = dsm_control_bytes_needed(maxitems);
172 
173  /*
174  * Loop until we find an unused identifier for the new control segment. We
175  * sometimes use 0 as a sentinel value indicating that no control segment
176  * is known to exist, so avoid using that value for a real control
177  * segment.
178  */
179  for (;;)
180  {
181  Assert(dsm_control_address == NULL);
185  continue;
187  &dsm_control_impl_private, &dsm_control_address,
189  break;
190  }
191  dsm_control = dsm_control_address;
193  elog(DEBUG2,
194  "created dynamic shared memory control segment %u (%zu bytes)",
195  dsm_control_handle, segsize);
196  shim->dsm_control = dsm_control_handle;
197 
198  /* Initialize control segment. */
200  dsm_control->nitems = 0;
201  dsm_control->maxitems = maxitems;
202 }
static void * dsm_control_impl_private
Definition: dsm.c:136
#define DSM_IMPL_MMAP
Definition: dsm_impl.h:21
uint32 maxitems
Definition: dsm.c:93
#define PG_DYNSHMEM_SLOTS_PER_BACKEND
Definition: dsm.c:54
#define PG_DYNSHMEM_FIXED_SLOTS
Definition: dsm.c:53
#define PointerGetDatum(X)
Definition: postgres.h:562
long random(void)
Definition: random.c:22
static dsm_handle dsm_control_handle
Definition: dsm.c:133
static uint64 dsm_control_bytes_needed(uint32 nitems)
Definition: dsm.c:1160
uint32 nitems
Definition: dsm.c:92
#define DSM_HANDLE_INVALID
Definition: dsm.h:23
#define ERROR
Definition: elog.h:43
uint32 magic
Definition: dsm.c:91
int MaxBackends
Definition: globals.c:127
#define DEBUG2
Definition: elog.h:24
void on_shmem_exit(pg_on_exit_callback function, Datum arg)
Definition: ipc.c:348
bool IsUnderPostmaster
Definition: globals.c:101
static void dsm_postmaster_shutdown(int code, Datum arg)
Definition: dsm.c:343
int dynamic_shared_memory_type
Definition: dsm_impl.c:112
unsigned int uint32
Definition: c.h:268
static void dsm_cleanup_for_mmap(void)
Definition: dsm.c:292
static dsm_control_header * dsm_control
Definition: dsm.c:134
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
#define DSM_IMPL_NONE
Definition: dsm_impl.h:17
size_t Size
Definition: c.h:356
static Size dsm_control_mapped_size
Definition: dsm.c:135
#define elog
Definition: elog.h:219
bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size, void **impl_private, void **mapped_address, Size *mapped_size, int elevel)
Definition: dsm_impl.c:162
#define PG_DYNSHMEM_CONTROL_MAGIC
Definition: dsm.c:46
void* dsm_remap ( dsm_segment seg)

Definition at line 708 of file dsm.c.

References dsm_impl_op(), DSM_OP_ATTACH, ERROR, dsm_segment::handle, dsm_segment::impl_private, dsm_segment::mapped_address, and dsm_segment::mapped_size.

709 {
711  &seg->mapped_address, &seg->mapped_size, ERROR);
712 
713  return seg->mapped_address;
714 }
Size mapped_size
Definition: dsm.c:75
#define ERROR
Definition: elog.h:43
void * mapped_address
Definition: dsm.c:74
dsm_handle handle
Definition: dsm.c:71
void * impl_private
Definition: dsm.c:73
bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size, void **impl_private, void **mapped_address, Size *mapped_size, int elevel)
Definition: dsm_impl.c:162
void* dsm_resize ( dsm_segment seg,
Size  size 
)

Definition at line 691 of file dsm.c.

References Assert, dsm_segment::control_slot, dsm_impl_op(), DSM_OP_RESIZE, ERROR, dsm_segment::handle, dsm_segment::impl_private, INVALID_CONTROL_SLOT, dsm_segment::mapped_address, and dsm_segment::mapped_size.

692 {
694  dsm_impl_op(DSM_OP_RESIZE, seg->handle, size, &seg->impl_private,
695  &seg->mapped_address, &seg->mapped_size, ERROR);
696  return seg->mapped_address;
697 }
Size mapped_size
Definition: dsm.c:75
#define ERROR
Definition: elog.h:43
void * mapped_address
Definition: dsm.c:74
dsm_handle handle
Definition: dsm.c:71
#define Assert(condition)
Definition: c.h:675
void * impl_private
Definition: dsm.c:73
uint32 control_slot
Definition: dsm.c:72
#define INVALID_CONTROL_SLOT
Definition: dsm.c:56
bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size, void **impl_private, void **mapped_address, Size *mapped_size, int elevel)
Definition: dsm_impl.c:162
void* dsm_segment_address ( dsm_segment seg)

Definition at line 1000 of file dsm.c.

References Assert, dsm_segment::mapped_address, and NULL.

Referenced by dsa_attach(), dsa_create(), get_segment_by_index(), InitializeParallelDSM(), make_new_segment(), ParallelWorkerMain(), setup_dynamic_shared_memory(), and test_shm_mq_main().

1001 {
1002  Assert(seg->mapped_address != NULL);
1003  return seg->mapped_address;
1004 }
void * mapped_address
Definition: dsm.c:74
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
dsm_handle dsm_segment_handle ( dsm_segment seg)

Definition at line 1028 of file dsm.c.

References dsm_segment::handle.

Referenced by destroy_superblock(), dsa_create(), LaunchParallelWorkers(), make_new_segment(), PrintDSMLeakWarning(), ResourceOwnerForgetDSM(), and setup_background_workers().

1029 {
1030  return seg->handle;
1031 }
dsm_handle handle
Definition: dsm.c:71
Size dsm_segment_map_length ( dsm_segment seg)

Definition at line 1010 of file dsm.c.

References Assert, dsm_segment::mapped_address, dsm_segment::mapped_size, and NULL.

1011 {
1012  Assert(seg->mapped_address != NULL);
1013  return seg->mapped_size;
1014 }
Size mapped_size
Definition: dsm.c:75
void * mapped_address
Definition: dsm.c:74
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
void dsm_unpin_mapping ( dsm_segment seg)

Definition at line 846 of file dsm.c.

References Assert, CurrentResourceOwner, NULL, ResourceOwnerEnlargeDSMs(), ResourceOwnerRememberDSM(), and dsm_segment::resowner.

847 {
848  Assert(seg->resowner == NULL);
852 }
void ResourceOwnerRememberDSM(ResourceOwner owner, dsm_segment *seg)
Definition: resowner.c:1245
ResourceOwner CurrentResourceOwner
Definition: resowner.c:138
void ResourceOwnerEnlargeDSMs(ResourceOwner owner)
Definition: resowner.c:1234
ResourceOwner resowner
Definition: dsm.c:70
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
void dsm_unpin_segment ( dsm_handle  h)

Definition at line 899 of file dsm.c.

References Assert, dsm_impl_op(), dsm_impl_unpin_segment(), DSM_OP_DESTROY, elog, ERROR, dsm_control_item::handle, i, dsm_control_item::impl_private_pm_handle, INVALID_CONTROL_SLOT, dsm_control_header::item, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), dsm_control_header::nitems, NULL, dsm_control_item::pinned, dsm_control_item::refcnt, and WARNING.

Referenced by destroy_superblock(), and dsa_release_in_place().

900 {
901  uint32 control_slot = INVALID_CONTROL_SLOT;
902  bool destroy = false;
903  uint32 i;
904 
905  /* Find the control slot for the given handle. */
906  LWLockAcquire(DynamicSharedMemoryControlLock, LW_EXCLUSIVE);
907  for (i = 0; i < dsm_control->nitems; ++i)
908  {
909  /* Skip unused slots. */
910  if (dsm_control->item[i].refcnt == 0)
911  continue;
912 
913  /* If we've found our handle, we can stop searching. */
914  if (dsm_control->item[i].handle == handle)
915  {
916  control_slot = i;
917  break;
918  }
919  }
920 
921  /*
922  * We should definitely have found the slot, and it should not already be
923  * in the process of going away, because this function should only be
924  * called on a segment which is pinned.
925  */
926  if (control_slot == INVALID_CONTROL_SLOT)
927  elog(ERROR, "cannot unpin unknown segment handle");
928  if (!dsm_control->item[control_slot].pinned)
929  elog(ERROR, "cannot unpin a segment that is not pinned");
930  Assert(dsm_control->item[control_slot].refcnt > 1);
931 
932  /*
933  * Allow implementation-specific code to run. We have to do this before
934  * releasing the lock, because impl_private_pm_handle may get modified by
935  * dsm_impl_unpin_segment.
936  */
937  dsm_impl_unpin_segment(handle,
938  &dsm_control->item[control_slot].impl_private_pm_handle);
939 
940  /* Note that 1 means no references (0 means unused slot). */
941  if (--dsm_control->item[control_slot].refcnt == 1)
942  destroy = true;
943  dsm_control->item[control_slot].pinned = false;
944 
945  /* Now we can release the lock. */
946  LWLockRelease(DynamicSharedMemoryControlLock);
947 
948  /* Clean up resources if that was the last reference. */
949  if (destroy)
950  {
951  void *junk_impl_private = NULL;
952  void *junk_mapped_address = NULL;
953  Size junk_mapped_size = 0;
954 
955  /*
956  * For an explanation of how error handling works in this case, see
957  * comments in dsm_detach. Note that if we reach this point, the
958  * current process certainly does not have the segment mapped, because
959  * if it did, the reference count would have still been greater than 1
960  * even after releasing the reference count held by the pin. The fact
961  * that there can't be a dsm_segment for this handle makes it OK to
962  * pass the mapped size, mapped address, and private data as NULL
963  * here.
964  */
965  if (dsm_impl_op(DSM_OP_DESTROY, handle, 0, &junk_impl_private,
966  &junk_mapped_address, &junk_mapped_size, WARNING))
967  {
968  LWLockAcquire(DynamicSharedMemoryControlLock, LW_EXCLUSIVE);
969  Assert(dsm_control->item[control_slot].handle == handle);
970  Assert(dsm_control->item[control_slot].refcnt == 1);
971  dsm_control->item[control_slot].refcnt = 0;
972  LWLockRelease(DynamicSharedMemoryControlLock);
973  }
974  }
975 }
void dsm_impl_unpin_segment(dsm_handle handle, void **impl_private)
Definition: dsm_impl.c:1059
dsm_handle handle
Definition: dsm.c:82
uint32 nitems
Definition: dsm.c:92
bool pinned
Definition: dsm.c:85
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
#define ERROR
Definition: elog.h:43
dsm_control_item item[FLEXIBLE_ARRAY_MEMBER]
Definition: dsm.c:94
unsigned int uint32
Definition: c.h:268
#define WARNING
Definition: elog.h:40
static dsm_control_header * dsm_control
Definition: dsm.c:134
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
size_t Size
Definition: c.h:356
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1111
uint32 refcnt
Definition: dsm.c:83
int i
void * impl_private_pm_handle
Definition: dsm.c:84
#define INVALID_CONTROL_SLOT
Definition: dsm.c:56
#define elog
Definition: elog.h:219
bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size, void **impl_private, void **mapped_address, Size *mapped_size, int elevel)
Definition: dsm_impl.c:162
void on_dsm_detach ( dsm_segment seg,
on_dsm_detach_callback  function,
Datum  arg 
)

Definition at line 1037 of file dsm.c.

References arg, dsm_segment_detach_callback::arg, dsm_segment_detach_callback::function, MemoryContextAlloc(), dsm_segment_detach_callback::node, dsm_segment::on_detach, slist_push_head(), and TopMemoryContext.

Referenced by dsa_attach(), dsa_attach_in_place(), dsa_create(), dsa_create_in_place(), pq_redirect_to_shm_mq(), setup_background_workers(), and shm_mq_attach().

1038 {
1040 
1042  sizeof(dsm_segment_detach_callback));
1043  cb->function = function;
1044  cb->arg = arg;
1045  slist_push_head(&seg->on_detach, &cb->node);
1046 }
static void slist_push_head(slist_head *head, slist_node *node)
Definition: ilist.h:574
on_dsm_detach_callback function
Definition: dsm.c:61
MemoryContext TopMemoryContext
Definition: mcxt.c:43
slist_head on_detach
Definition: dsm.c:76
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:707
void * arg
void reset_on_dsm_detach ( void  )

Definition at line 1075 of file dsm.c.

References dsm_segment::control_slot, dlist_iter::cur, dlist_container, dlist_foreach, INVALID_CONTROL_SLOT, dsm_segment::on_detach, pfree(), slist_container, slist_is_empty(), and slist_pop_head_node().

Referenced by on_exit_reset().

1076 {
1077  dlist_iter iter;
1078 
1080  {
1081  dsm_segment *seg = dlist_container(dsm_segment, node, iter.cur);
1082 
1083  /* Throw away explicit on-detach actions one by one. */
1084  while (!slist_is_empty(&seg->on_detach))
1085  {
1086  slist_node *node;
1088 
1089  node = slist_pop_head_node(&seg->on_detach);
1090  cb = slist_container(dsm_segment_detach_callback, node, node);
1091  pfree(cb);
1092  }
1093 
1094  /*
1095  * Decrementing the reference count is a sort of implicit on-detach
1096  * action; make sure we don't do that, either.
1097  */
1099  }
1100 }
#define dlist_foreach(iter, lhead)
Definition: ilist.h:507
static dlist_head dsm_segment_list
Definition: dsm.c:124
#define dlist_container(type, membername, ptr)
Definition: ilist.h:477
void pfree(void *pointer)
Definition: mcxt.c:950
static slist_node * slist_pop_head_node(slist_head *head)
Definition: ilist.h:596
slist_head on_detach
Definition: dsm.c:76
static bool slist_is_empty(slist_head *head)
Definition: ilist.h:563
#define slist_container(type, membername, ptr)
Definition: ilist.h:674
dlist_node * cur
Definition: ilist.h:161
uint32 control_slot
Definition: dsm.c:72
#define INVALID_CONTROL_SLOT
Definition: dsm.c:56