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ipci.c
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1 /*-------------------------------------------------------------------------
2  *
3  * ipci.c
4  * POSTGRES inter-process communication initialization code.
5  *
6  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  *
10  * IDENTIFICATION
11  * src/backend/storage/ipc/ipci.c
12  *
13  *-------------------------------------------------------------------------
14  */
15 #include "postgres.h"
16 
17 #include "access/clog.h"
18 #include "access/commit_ts.h"
19 #include "access/multixact.h"
20 #include "access/nbtree.h"
21 #include "access/subtrans.h"
22 #include "access/syncscan.h"
23 #include "access/transam.h"
24 #include "access/twophase.h"
25 #include "access/xlogprefetcher.h"
26 #include "access/xlogrecovery.h"
27 #include "commands/async.h"
28 #include "miscadmin.h"
29 #include "pgstat.h"
30 #include "postmaster/autovacuum.h"
32 #include "postmaster/bgwriter.h"
33 #include "postmaster/postmaster.h"
36 #include "replication/origin.h"
37 #include "replication/slot.h"
38 #include "replication/slotsync.h"
40 #include "replication/walsender.h"
41 #include "storage/bufmgr.h"
42 #include "storage/dsm.h"
43 #include "storage/dsm_registry.h"
44 #include "storage/ipc.h"
45 #include "storage/pg_shmem.h"
46 #include "storage/pmsignal.h"
47 #include "storage/predicate.h"
48 #include "storage/proc.h"
49 #include "storage/procarray.h"
50 #include "storage/procsignal.h"
51 #include "storage/sinvaladt.h"
52 #include "storage/spin.h"
53 #include "utils/guc.h"
54 #include "utils/injection_point.h"
55 
56 /* GUCs */
58 
60 
62 
63 static void CreateOrAttachShmemStructs(void);
64 
65 /*
66  * RequestAddinShmemSpace
67  * Request that extra shmem space be allocated for use by
68  * a loadable module.
69  *
70  * This may only be called via the shmem_request_hook of a library that is
71  * loaded into the postmaster via shared_preload_libraries. Calls from
72  * elsewhere will fail.
73  */
74 void
76 {
78  elog(FATAL, "cannot request additional shared memory outside shmem_request_hook");
80 }
81 
82 /*
83  * CalculateShmemSize
84  * Calculates the amount of shared memory and number of semaphores needed.
85  *
86  * If num_semaphores is not NULL, it will be set to the number of semaphores
87  * required.
88  */
89 Size
90 CalculateShmemSize(int *num_semaphores)
91 {
92  Size size;
93  int numSemas;
94 
95  /* Compute number of semaphores we'll need */
96  numSemas = ProcGlobalSemas();
97  numSemas += SpinlockSemas();
98 
99  /* Return the number of semaphores if requested by the caller */
100  if (num_semaphores)
101  *num_semaphores = numSemas;
102 
103  /*
104  * Size of the Postgres shared-memory block is estimated via moderately-
105  * accurate estimates for the big hogs, plus 100K for the stuff that's too
106  * small to bother with estimating.
107  *
108  * We take some care to ensure that the total size request doesn't
109  * overflow size_t. If this gets through, we don't need to be so careful
110  * during the actual allocation phase.
111  */
112  size = 100000;
113  size = add_size(size, PGSemaphoreShmemSize(numSemas));
116  sizeof(ShmemIndexEnt)));
155 #ifdef EXEC_BACKEND
156  size = add_size(size, ShmemBackendArraySize());
157 #endif
158 
159  /* include additional requested shmem from preload libraries */
161 
162  /* might as well round it off to a multiple of a typical page size */
163  size = add_size(size, 8192 - (size % 8192));
164 
165  return size;
166 }
167 
168 #ifdef EXEC_BACKEND
169 /*
170  * AttachSharedMemoryStructs
171  * Initialize a postmaster child process's access to shared memory
172  * structures.
173  *
174  * In !EXEC_BACKEND mode, we inherit everything through the fork, and this
175  * isn't needed.
176  */
177 void
178 AttachSharedMemoryStructs(void)
179 {
180  /* InitProcess must've been called already */
181  Assert(MyProc != NULL);
183 
185 
186  /*
187  * Now give loadable modules a chance to set up their shmem allocations
188  */
189  if (shmem_startup_hook)
191 }
192 #endif
193 
194 /*
195  * CreateSharedMemoryAndSemaphores
196  * Creates and initializes shared memory and semaphores.
197  */
198 void
200 {
201  PGShmemHeader *shim;
202  PGShmemHeader *seghdr;
203  Size size;
204  int numSemas;
205 
207 
208  /* Compute the size of the shared-memory block */
209  size = CalculateShmemSize(&numSemas);
210  elog(DEBUG3, "invoking IpcMemoryCreate(size=%zu)", size);
211 
212  /*
213  * Create the shmem segment
214  */
215  seghdr = PGSharedMemoryCreate(size, &shim);
216 
217  /*
218  * Make sure that huge pages are never reported as "unknown" while the
219  * server is running.
220  */
221  Assert(strcmp("unknown",
222  GetConfigOption("huge_pages_status", false, false)) != 0);
223 
224  InitShmemAccess(seghdr);
225 
226  /*
227  * Create semaphores
228  */
229  PGReserveSemaphores(numSemas);
230 
231  /*
232  * If spinlocks are disabled, initialize emulation layer (which depends on
233  * semaphores, so the order is important here).
234  */
235 #ifndef HAVE_SPINLOCKS
237 #endif
238 
239  /*
240  * Set up shared memory allocation mechanism
241  */
243 
244  /* Initialize subsystems */
246 
247 #ifdef EXEC_BACKEND
248 
249  /*
250  * Alloc the win32 shared backend array
251  */
252  ShmemBackendArrayAllocation();
253 #endif
254 
255  /* Initialize dynamic shared memory facilities. */
257 
258  /*
259  * Now give loadable modules a chance to set up their shmem allocations
260  */
261  if (shmem_startup_hook)
263 }
264 
265 /*
266  * Initialize various subsystems, setting up their data structures in
267  * shared memory.
268  *
269  * This is called by the postmaster or by a standalone backend.
270  * It is also called by a backend forked from the postmaster in the
271  * EXEC_BACKEND case. In the latter case, the shared memory segment
272  * already exists and has been physically attached to, but we have to
273  * initialize pointers in local memory that reference the shared structures,
274  * because we didn't inherit the correct pointer values from the postmaster
275  * as we do in the fork() scenario. The easiest way to do that is to run
276  * through the same code as before. (Note that the called routines mostly
277  * check IsUnderPostmaster, rather than EXEC_BACKEND, to detect this case.
278  * This is a bit code-wasteful and could be cleaned up.)
279  */
280 static void
282 {
283  /*
284  * Now initialize LWLocks, which do shared memory allocation and are
285  * needed for InitShmemIndex.
286  */
287  CreateLWLocks();
288 
289  /*
290  * Set up shmem.c index hashtable
291  */
292  InitShmemIndex();
293 
294  dsm_shmem_init();
296 
297  /*
298  * Set up xlog, clog, and buffers
299  */
300  VarsupShmemInit();
301  XLOGShmemInit();
304  CLOGShmemInit();
308  InitBufferPool();
309 
310  /*
311  * Set up lock manager
312  */
313  InitLocks();
314 
315  /*
316  * Set up predicate lock manager
317  */
319 
320  /*
321  * Set up process table
322  */
323  if (!IsUnderPostmaster)
324  InitProcGlobal();
329 
330  /*
331  * Set up shared-inval messaging
332  */
334 
335  /*
336  * Set up interprocess signaling mechanisms
337  */
344  WalSndShmemInit();
345  WalRcvShmemInit();
347  PgArchShmemInit();
350 
351  /*
352  * Set up other modules that need some shared memory space
353  */
354  BTreeShmemInit();
356  AsyncShmemInit();
357  StatsShmemInit();
360 }
361 
362 /*
363  * InitializeShmemGUCs
364  *
365  * This function initializes runtime-computed GUCs related to the amount of
366  * shared memory required for the current configuration.
367  */
368 void
370 {
371  char buf[64];
372  Size size_b;
373  Size size_mb;
374  Size hp_size;
375 
376  /*
377  * Calculate the shared memory size and round up to the nearest megabyte.
378  */
379  size_b = CalculateShmemSize(NULL);
380  size_mb = add_size(size_b, (1024 * 1024) - 1) / (1024 * 1024);
381  sprintf(buf, "%zu", size_mb);
382  SetConfigOption("shared_memory_size", buf,
384 
385  /*
386  * Calculate the number of huge pages required.
387  */
388  GetHugePageSize(&hp_size, NULL);
389  if (hp_size != 0)
390  {
391  Size hp_required;
392 
393  hp_required = add_size(size_b / hp_size, 1);
394  sprintf(buf, "%zu", hp_required);
395  SetConfigOption("shared_memory_size_in_huge_pages", buf,
397  }
398 }
Size AsyncShmemSize(void)
Definition: async.c:485
void AsyncShmemInit(void)
Definition: async.c:502
Size AutoVacuumShmemSize(void)
Definition: autovacuum.c:3237
void AutoVacuumShmemInit(void)
Definition: autovacuum.c:3256
void CreateSharedBackendStatus(void)
Size BackendStatusShmemSize(void)
void BackgroundWorkerShmemInit(void)
Definition: bgworker.c:162
Size BackgroundWorkerShmemSize(void)
Definition: bgworker.c:146
Size BufferShmemSize(void)
Definition: buf_init.c:160
void InitBufferPool(void)
Definition: buf_init.c:68
size_t Size
Definition: c.h:592
void CheckpointerShmemInit(void)
Definition: checkpointer.c:898
Size CheckpointerShmemSize(void)
Definition: checkpointer.c:879
void CLOGShmemInit(void)
Definition: clog.c:787
Size CLOGShmemSize(void)
Definition: clog.c:781
Size CommitTsShmemSize(void)
Definition: commit_ts.c:519
void CommitTsShmemInit(void)
Definition: commit_ts.c:530
size_t dsm_estimate_size(void)
Definition: dsm.c:470
void dsm_postmaster_startup(PGShmemHeader *shim)
Definition: dsm.c:177
void dsm_shmem_init(void)
Definition: dsm.c:479
void DSMRegistryShmemInit(void)
Definition: dsm_registry.c:69
Size DSMRegistryShmemSize(void)
Definition: dsm_registry.c:63
Size hash_estimate_size(long num_entries, Size entrysize)
Definition: dynahash.c:783
#define DEBUG3
Definition: elog.h:28
#define FATAL
Definition: elog.h:41
#define elog(elevel,...)
Definition: elog.h:224
bool IsUnderPostmaster
Definition: globals.c:117
void SetConfigOption(const char *name, const char *value, GucContext context, GucSource source)
Definition: guc.c:4275
const char * GetConfigOption(const char *name, bool missing_ok, bool restrict_privileged)
Definition: guc.c:4298
@ PGC_S_DYNAMIC_DEFAULT
Definition: guc.h:110
@ PGC_INTERNAL
Definition: guc.h:69
void InjectionPointShmemInit(void)
Size InjectionPointShmemSize(void)
void(* shmem_startup_hook_type)(void)
Definition: ipc.h:22
static Size total_addin_request
Definition: ipci.c:61
int shared_memory_type
Definition: ipci.c:57
shmem_startup_hook_type shmem_startup_hook
Definition: ipci.c:59
void RequestAddinShmemSpace(Size size)
Definition: ipci.c:75
Size CalculateShmemSize(int *num_semaphores)
Definition: ipci.c:90
void InitializeShmemGUCs(void)
Definition: ipci.c:369
static void CreateOrAttachShmemStructs(void)
Definition: ipci.c:281
void CreateSharedMemoryAndSemaphores(void)
Definition: ipci.c:199
Size ApplyLauncherShmemSize(void)
Definition: launcher.c:899
void ApplyLauncherShmemInit(void)
Definition: launcher.c:954
Assert(fmt[strlen(fmt) - 1] !='\n')
void InitLocks(void)
Definition: lock.c:392
Size LockShmemSize(void)
Definition: lock.c:3552
void CreateLWLocks(void)
Definition: lwlock.c:451
Size LWLockShmemSize(void)
Definition: lwlock.c:421
bool process_shmem_requests_in_progress
Definition: miscinit.c:1782
void MultiXactShmemInit(void)
Definition: multixact.c:1890
Size MultiXactShmemSize(void)
Definition: multixact.c:1873
void BTreeShmemInit(void)
Definition: nbtutils.c:2134
Size BTreeShmemSize(void)
Definition: nbtutils.c:2121
Size ReplicationOriginShmemSize(void)
Definition: origin.c:506
void ReplicationOriginShmemInit(void)
Definition: origin.c:526
#define DEFAULT_SHARED_MEMORY_TYPE
Definition: pg_shmem.h:75
static char * buf
Definition: pg_test_fsync.c:73
Size PgArchShmemSize(void)
Definition: pgarch.c:151
void PgArchShmemInit(void)
Definition: pgarch.c:162
void StatsShmemInit(void)
Definition: pgstat_shmem.c:141
Size StatsShmemSize(void)
Definition: pgstat_shmem.c:127
Size PMSignalShmemSize(void)
Definition: pmsignal.c:129
void PMSignalShmemInit(void)
Definition: pmsignal.c:144
#define sprintf
Definition: port.h:240
Size PGSemaphoreShmemSize(int maxSemas)
Definition: posix_sema.c:165
void PGReserveSemaphores(int maxSemas)
Definition: posix_sema.c:196
void InitPredicateLocks(void)
Definition: predicate.c:1135
Size PredicateLockShmemSize(void)
Definition: predicate.c:1337
Size ProcArrayShmemSize(void)
Definition: procarray.c:376
void CreateSharedProcArray(void)
Definition: procarray.c:418
void ProcSignalShmemInit(void)
Definition: procsignal.c:125
Size ProcSignalShmemSize(void)
Definition: procsignal.c:111
void InitShmemIndex(void)
Definition: shmem.c:283
Size add_size(Size s1, Size s2)
Definition: shmem.c:493
void InitShmemAllocation(void)
Definition: shmem.c:115
void InitShmemAccess(void *seghdr)
Definition: shmem.c:100
#define SHMEM_INDEX_SIZE
Definition: shmem.h:48
Size SInvalShmemSize(void)
Definition: sinvaladt.c:218
void CreateSharedInvalidationState(void)
Definition: sinvaladt.c:234
static pg_noinline void Size size
Definition: slab.c:607
void ReplicationSlotsShmemInit(void)
Definition: slot.c:189
Size ReplicationSlotsShmemSize(void)
Definition: slot.c:171
void SlotSyncShmemInit(void)
Definition: slotsync.c:1396
Size SlotSyncShmemSize(void)
Definition: slotsync.c:1387
Size SpinlockSemaSize(void)
Definition: spin.c:55
void SpinlockSemaInit(void)
Definition: spin.c:77
int SpinlockSemas(void)
Definition: spin.c:64
PGPROC * MyProc
Definition: proc.c:66
Size ProcGlobalShmemSize(void)
Definition: proc.c:100
int ProcGlobalSemas(void)
Definition: proc.c:122
void InitProcGlobal(void)
Definition: proc.c:157
void SUBTRANSShmemInit(void)
Definition: subtrans.c:220
Size SUBTRANSShmemSize(void)
Definition: subtrans.c:214
void SyncScanShmemInit(void)
Definition: syncscan.c:135
Size SyncScanShmemSize(void)
Definition: syncscan.c:126
PGShmemHeader * PGSharedMemoryCreate(Size size, PGShmemHeader **shim)
Definition: sysv_shmem.c:700
void GetHugePageSize(Size *hugepagesize, int *mmap_flags)
Definition: sysv_shmem.c:479
Size TwoPhaseShmemSize(void)
Definition: twophase.c:237
void TwoPhaseShmemInit(void)
Definition: twophase.c:253
Size VarsupShmemSize(void)
Definition: varsup.c:41
void VarsupShmemInit(void)
Definition: varsup.c:47
Size WaitEventExtensionShmemSize(void)
Definition: wait_event.c:104
void WaitEventExtensionShmemInit(void)
Definition: wait_event.c:120
void WalRcvShmemInit(void)
Size WalRcvShmemSize(void)
void WalSndShmemInit(void)
Definition: walsender.c:3621
Size WalSndShmemSize(void)
Definition: walsender.c:3609
Size WalSummarizerShmemSize(void)
void WalSummarizerShmemInit(void)
void XLOGShmemInit(void)
Definition: xlog.c:4808
Size XLOGShmemSize(void)
Definition: xlog.c:4758
size_t XLogPrefetchShmemSize(void)
void XLogPrefetchShmemInit(void)
Size XLogRecoveryShmemSize(void)
Definition: xlogrecovery.c:447
void XLogRecoveryShmemInit(void)
Definition: xlogrecovery.c:458