1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
/*-------------------------------------------------------------------------
*
* ipci.c
* POSTGRES inter-process communication initialization code.
*
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.74 2004/12/31 22:00:56 pgsql Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/clog.h"
#include "access/subtrans.h"
#include "access/xlog.h"
#include "miscadmin.h"
#include "postmaster/bgwriter.h"
#include "postmaster/postmaster.h"
#include "storage/bufmgr.h"
#include "storage/freespace.h"
#include "storage/ipc.h"
#include "storage/lmgr.h"
#include "storage/lwlock.h"
#include "storage/pg_sema.h"
#include "storage/pg_shmem.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/sinval.h"
#include "storage/spin.h"
/*
* CreateSharedMemoryAndSemaphores
* Creates and initializes shared memory and semaphores.
*
* This is called by the postmaster or by a standalone backend.
* It is also called by a backend forked from the postmaster in the
* EXEC_BACKEND case. In the latter case, the shared memory segment
* already exists and has been physically attached to, but we have to
* initialize pointers in local memory that reference the shared structures,
* because we didn't inherit the correct pointer values from the postmaster
* as we do in the fork() scenario. The easiest way to do that is to run
* through the same code as before. (Note that the called routines mostly
* check IsUnderPostmaster, rather than EXEC_BACKEND, to detect this case.
* This is a bit code-wasteful and could be cleaned up.)
*
* If "makePrivate" is true then we only need private memory, not shared
* memory. This is true for a standalone backend, false for a postmaster.
*/
void
CreateSharedMemoryAndSemaphores(bool makePrivate,
int maxBackends,
int port)
{
PGShmemHeader *seghdr = NULL;
if (!IsUnderPostmaster)
{
int size;
int numSemas;
/*
* Size of the Postgres shared-memory block is estimated via
* moderately-accurate estimates for the big hogs, plus 100K for
* the stuff that's too small to bother with estimating.
*/
size = hash_estimate_size(SHMEM_INDEX_SIZE, sizeof(ShmemIndexEnt));
size += BufferShmemSize();
size += LockShmemSize(maxBackends);
size += ProcGlobalShmemSize(maxBackends);
size += XLOGShmemSize();
size += CLOGShmemSize();
size += SUBTRANSShmemSize();
size += LWLockShmemSize();
size += SInvalShmemSize(maxBackends);
size += FreeSpaceShmemSize();
size += BgWriterShmemSize();
#ifdef EXEC_BACKEND
size += ShmemBackendArraySize();
#endif
size += 100000;
/* might as well round it off to a multiple of a typical page size */
size += 8192 - (size % 8192);
elog(DEBUG3, "invoking IpcMemoryCreate(size=%d)", size);
/*
* Create the shmem segment
*/
seghdr = PGSharedMemoryCreate(size, makePrivate, port);
/*
* Create semaphores
*/
numSemas = ProcGlobalSemas(maxBackends);
numSemas += SpinlockSemas();
PGReserveSemaphores(numSemas, port);
}
else
{
/*
* We are reattaching to an existing shared memory segment.
* This should only be reached in the EXEC_BACKEND case, and
* even then only with makePrivate == false.
*/
#ifdef EXEC_BACKEND
Assert(!makePrivate);
Assert(UsedShmemSegAddr != NULL);
seghdr = UsedShmemSegAddr;
#else
elog(PANIC, "should be attached to shared memory already");
#endif
}
/*
* Set up shared memory allocation mechanism
*/
InitShmemAllocation(seghdr, !IsUnderPostmaster);
/*
* Now initialize LWLocks, which do shared memory allocation and are
* needed for InitShmemIndex.
*/
if (!IsUnderPostmaster)
CreateLWLocks();
/*
* Set up shmem.c index hashtable
*/
InitShmemIndex();
/*
* Set up xlog, clog, and buffers
*/
XLOGShmemInit();
CLOGShmemInit();
SUBTRANSShmemInit();
InitBufferPool();
/*
* Set up lock manager
*/
InitLocks();
InitLockTable(maxBackends);
/*
* Set up process table
*/
InitProcGlobal(maxBackends);
/*
* Set up shared-inval messaging
*/
CreateSharedInvalidationState(maxBackends);
/*
* Set up free-space map
*/
InitFreeSpaceMap();
/*
* Set up interprocess signaling mechanisms
*/
PMSignalInit();
BgWriterShmemInit();
#ifdef EXEC_BACKEND
/*
* Alloc the win32 shared backend array
*/
if (!IsUnderPostmaster)
ShmemBackendArrayAllocation();
#endif
}
|
