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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) 1996-2021, 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/heapam.h"
20 #include "access/multixact.h"
21 #include "access/nbtree.h"
22 #include "access/subtrans.h"
23 #include "access/syncscan.h"
24 #include "access/twophase.h"
25 #include "commands/async.h"
26 #include "miscadmin.h"
27 #include "pgstat.h"
28 #include "postmaster/autovacuum.h"
30 #include "postmaster/bgwriter.h"
31 #include "postmaster/postmaster.h"
33 #include "replication/origin.h"
34 #include "replication/slot.h"
36 #include "replication/walsender.h"
37 #include "storage/bufmgr.h"
38 #include "storage/dsm.h"
39 #include "storage/ipc.h"
40 #include "storage/pg_shmem.h"
41 #include "storage/pmsignal.h"
42 #include "storage/predicate.h"
43 #include "storage/proc.h"
44 #include "storage/procarray.h"
45 #include "storage/procsignal.h"
46 #include "storage/sinvaladt.h"
47 #include "storage/spin.h"
48 #include "utils/snapmgr.h"
49 
50 /* GUCs */
52 
54 
56 static bool addin_request_allowed = true;
57 
58 
59 /*
60  * RequestAddinShmemSpace
61  * Request that extra shmem space be allocated for use by
62  * a loadable module.
63  *
64  * This is only useful if called from the _PG_init hook of a library that
65  * is loaded into the postmaster via shared_preload_libraries. Once
66  * shared memory has been allocated, calls will be ignored. (We could
67  * raise an error, but it seems better to make it a no-op, so that
68  * libraries containing such calls can be reloaded if needed.)
69  */
70 void
72 {
74  return; /* too late */
76 }
77 
78 
79 /*
80  * CreateSharedMemoryAndSemaphores
81  * Creates and initializes shared memory and semaphores.
82  *
83  * This is called by the postmaster or by a standalone backend.
84  * It is also called by a backend forked from the postmaster in the
85  * EXEC_BACKEND case. In the latter case, the shared memory segment
86  * already exists and has been physically attached to, but we have to
87  * initialize pointers in local memory that reference the shared structures,
88  * because we didn't inherit the correct pointer values from the postmaster
89  * as we do in the fork() scenario. The easiest way to do that is to run
90  * through the same code as before. (Note that the called routines mostly
91  * check IsUnderPostmaster, rather than EXEC_BACKEND, to detect this case.
92  * This is a bit code-wasteful and could be cleaned up.)
93  */
94 void
96 {
97  PGShmemHeader *shim = NULL;
98 
99  if (!IsUnderPostmaster)
100  {
101  PGShmemHeader *seghdr;
102  Size size;
103  int numSemas;
104 
105  /* Compute number of semaphores we'll need */
106  numSemas = ProcGlobalSemas();
107  numSemas += SpinlockSemas();
108 
109  /*
110  * Size of the Postgres shared-memory block is estimated via
111  * moderately-accurate estimates for the big hogs, plus 100K for the
112  * stuff that's too small to bother with estimating.
113  *
114  * We take some care during this phase to ensure that the total size
115  * request doesn't overflow size_t. If this gets through, we don't
116  * need to be so careful during the actual allocation phase.
117  */
118  size = 100000;
119  size = add_size(size, PGSemaphoreShmemSize(numSemas));
120  size = add_size(size, SpinlockSemaSize());
122  sizeof(ShmemIndexEnt)));
123  size = add_size(size, dsm_estimate_size());
124  size = add_size(size, BufferShmemSize());
125  size = add_size(size, LockShmemSize());
126  size = add_size(size, PredicateLockShmemSize());
127  size = add_size(size, ProcGlobalShmemSize());
128  size = add_size(size, XLOGShmemSize());
129  size = add_size(size, CLOGShmemSize());
130  size = add_size(size, CommitTsShmemSize());
131  size = add_size(size, SUBTRANSShmemSize());
132  size = add_size(size, TwoPhaseShmemSize());
133  size = add_size(size, BackgroundWorkerShmemSize());
134  size = add_size(size, MultiXactShmemSize());
135  size = add_size(size, LWLockShmemSize());
136  size = add_size(size, ProcArrayShmemSize());
137  size = add_size(size, BackendStatusShmemSize());
138  size = add_size(size, SInvalShmemSize());
139  size = add_size(size, PMSignalShmemSize());
140  size = add_size(size, ProcSignalShmemSize());
141  size = add_size(size, CheckpointerShmemSize());
142  size = add_size(size, AutoVacuumShmemSize());
143  size = add_size(size, ReplicationSlotsShmemSize());
144  size = add_size(size, ReplicationOriginShmemSize());
145  size = add_size(size, WalSndShmemSize());
146  size = add_size(size, WalRcvShmemSize());
147  size = add_size(size, PgArchShmemSize());
148  size = add_size(size, ApplyLauncherShmemSize());
149  size = add_size(size, SnapMgrShmemSize());
150  size = add_size(size, BTreeShmemSize());
151  size = add_size(size, SyncScanShmemSize());
152  size = add_size(size, AsyncShmemSize());
153 #ifdef EXEC_BACKEND
154  size = add_size(size, ShmemBackendArraySize());
155 #endif
156 
157  /* freeze the addin request size and include it */
158  addin_request_allowed = false;
159  size = add_size(size, total_addin_request);
160 
161  /* might as well round it off to a multiple of a typical page size */
162  size = add_size(size, 8192 - (size % 8192));
163 
164  elog(DEBUG3, "invoking IpcMemoryCreate(size=%zu)", size);
165 
166  /*
167  * Create the shmem segment
168  */
169  seghdr = PGSharedMemoryCreate(size, &shim);
170 
171  InitShmemAccess(seghdr);
172 
173  /*
174  * Create semaphores
175  */
176  PGReserveSemaphores(numSemas);
177 
178  /*
179  * If spinlocks are disabled, initialize emulation layer (which
180  * depends on semaphores, so the order is important here).
181  */
182 #ifndef HAVE_SPINLOCKS
184 #endif
185  }
186  else
187  {
188  /*
189  * We are reattaching to an existing shared memory segment. This
190  * should only be reached in the EXEC_BACKEND case.
191  */
192 #ifndef EXEC_BACKEND
193  elog(PANIC, "should be attached to shared memory already");
194 #endif
195  }
196 
197  /*
198  * Set up shared memory allocation mechanism
199  */
200  if (!IsUnderPostmaster)
202 
203  /*
204  * Now initialize LWLocks, which do shared memory allocation and are
205  * needed for InitShmemIndex.
206  */
207  CreateLWLocks();
208 
209  /*
210  * Set up shmem.c index hashtable
211  */
212  InitShmemIndex();
213 
214  dsm_shmem_init();
215 
216  /*
217  * Set up xlog, clog, and buffers
218  */
219  XLOGShmemInit();
220  CLOGShmemInit();
224  InitBufferPool();
225 
226  /*
227  * Set up lock manager
228  */
229  InitLocks();
230 
231  /*
232  * Set up predicate lock manager
233  */
235 
236  /*
237  * Set up process table
238  */
239  if (!IsUnderPostmaster)
240  InitProcGlobal();
245 
246  /*
247  * Set up shared-inval messaging
248  */
250 
251  /*
252  * Set up interprocess signaling mechanisms
253  */
260  WalSndShmemInit();
261  WalRcvShmemInit();
262  PgArchShmemInit();
264 
265  /*
266  * Set up other modules that need some shared memory space
267  */
268  SnapMgrInit();
269  BTreeShmemInit();
271  AsyncShmemInit();
272 
273 #ifdef EXEC_BACKEND
274 
275  /*
276  * Alloc the win32 shared backend array
277  */
278  if (!IsUnderPostmaster)
279  ShmemBackendArrayAllocation();
280 #endif
281 
282  /* Initialize dynamic shared memory facilities. */
283  if (!IsUnderPostmaster)
285 
286  /*
287  * Now give loadable modules a chance to set up their shmem allocations
288  */
289  if (shmem_startup_hook)
291 }
void dsm_postmaster_startup(PGShmemHeader *shim)
Definition: dsm.c:149
Size SInvalShmemSize(void)
Definition: sinvaladt.c:203
Size PgArchShmemSize(void)
Definition: pgarch.c:109
PGShmemHeader * PGSharedMemoryCreate(Size size, PGShmemHeader **shim)
Definition: sysv_shmem.c:651
void RequestAddinShmemSpace(Size size)
Definition: ipci.c:71
void BTreeShmemInit(void)
Definition: nbtutils.c:2076
Size PMSignalShmemSize(void)
Definition: pmsignal.c:119
Size ReplicationSlotsShmemSize(void)
Definition: slot.c:114
#define SHMEM_INDEX_SIZE
Definition: shmem.h:55
void dsm_shmem_init(void)
Definition: dsm.c:450
void SUBTRANSShmemInit(void)
Definition: subtrans.c:191
#define DEBUG3
Definition: elog.h:23
Size SpinlockSemaSize(void)
Definition: spin.c:55
void InitShmemAccess(void *seghdr)
Definition: shmem.c:101
void AsyncShmemInit(void)
Definition: async.c:526
void CreateSharedInvalidationState(void)
Definition: sinvaladt.c:218
Size SyncScanShmemSize(void)
Definition: syncscan.c:126
Size WalSndShmemSize(void)
Definition: walsender.c:3068
int shared_memory_type
Definition: ipci.c:51
void PgArchShmemInit(void)
Definition: pgarch.c:120
void CheckpointerShmemInit(void)
Definition: checkpointer.c:884
Size PredicateLockShmemSize(void)
Definition: predicate.c:1355
Size TwoPhaseShmemSize(void)
Definition: twophase.c:236
void ReplicationOriginShmemInit(void)
Definition: origin.c:510
Size BackendStatusShmemSize(void)
void WalRcvShmemInit(void)
#define PANIC
Definition: elog.h:50
void XLOGShmemInit(void)
Definition: xlog.c:5126
Size BackgroundWorkerShmemSize(void)
Definition: bgworker.c:142
void ReplicationSlotsShmemInit(void)
Definition: slot.c:132
Size LWLockShmemSize(void)
Definition: lwlock.c:432
Size BTreeShmemSize(void)
Definition: nbtutils.c:2063
void InitProcGlobal(void)
Definition: proc.c:159
void BackgroundWorkerShmemInit(void)
Definition: bgworker.c:158
void MultiXactShmemInit(void)
Definition: multixact.c:1844
void PMSignalShmemInit(void)
Definition: pmsignal.c:134
Size XLOGShmemSize(void)
Definition: xlog.c:5085
void SpinlockSemaInit(void)
Definition: spin.c:77
size_t dsm_estimate_size(void)
Definition: dsm.c:441
bool IsUnderPostmaster
Definition: globals.c:112
void(* shmem_startup_hook_type)(void)
Definition: ipc.h:22
Size ApplyLauncherShmemSize(void)
Definition: launcher.c:683
void InitBufferPool(void)
Definition: buf_init.c:67
void SnapMgrInit(void)
Definition: snapmgr.c:213
void InitLocks(void)
Definition: lock.c:404
Size ProcGlobalShmemSize(void)
Definition: proc.c:102
static bool addin_request_allowed
Definition: ipci.c:56
Size ProcSignalShmemSize(void)
Definition: procsignal.c:111
shmem_startup_hook_type shmem_startup_hook
Definition: ipci.c:53
Size hash_estimate_size(long num_entries, Size entrysize)
Definition: dynahash.c:780
void TwoPhaseShmemInit(void)
Definition: twophase.c:252
int SpinlockSemas(void)
Definition: spin.c:64
static Size total_addin_request
Definition: ipci.c:55
Size add_size(Size s1, Size s2)
Definition: shmem.c:502
Size AutoVacuumShmemSize(void)
Definition: autovacuum.c:3465
Size ReplicationOriginShmemSize(void)
Definition: origin.c:490
Size CheckpointerShmemSize(void)
Definition: checkpointer.c:865
Size CLOGShmemSize(void)
Definition: clog.c:685
void PGReserveSemaphores(int maxSemas)
Definition: posix_sema.c:196
Size WalRcvShmemSize(void)
void CreateLWLocks(void)
Definition: lwlock.c:465
void SyncScanShmemInit(void)
Definition: syncscan.c:135
void CreateSharedProcArray(void)
Definition: procarray.c:394
Size AsyncShmemSize(void)
Definition: async.c:509
size_t Size
Definition: c.h:540
Size CommitTsShmemSize(void)
Definition: commit_ts.c:523
void ApplyLauncherShmemInit(void)
Definition: launcher.c:731
Size MultiXactShmemSize(void)
Definition: multixact.c:1827
void CreateSharedMemoryAndSemaphores(void)
Definition: ipci.c:95
void CreateSharedBackendStatus(void)
Size LockShmemSize(void)
Definition: lock.c:3523
Size SUBTRANSShmemSize(void)
Definition: subtrans.c:185
Size BufferShmemSize(void)
Definition: buf_init.c:156
#define elog(elevel,...)
Definition: elog.h:232
void WalSndShmemInit(void)
Definition: walsender.c:3080
void CLOGShmemInit(void)
Definition: clog.c:691
Size PGSemaphoreShmemSize(int maxSemas)
Definition: posix_sema.c:165
void ProcSignalShmemInit(void)
Definition: procsignal.c:125
void InitShmemIndex(void)
Definition: shmem.c:292
void InitPredicateLocks(void)
Definition: predicate.c:1153
void AutoVacuumShmemInit(void)
Definition: autovacuum.c:3484
Size SnapMgrShmemSize(void)
Definition: snapmgr.c:197
#define DEFAULT_SHARED_MEMORY_TYPE
Definition: pg_shmem.h:74
Size ProcArrayShmemSize(void)
Definition: procarray.c:352
int ProcGlobalSemas(void)
Definition: proc.c:124
void InitShmemAllocation(void)
Definition: shmem.c:116
void CommitTsShmemInit(void)
Definition: commit_ts.c:534