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auxprocess.c
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1 /*-------------------------------------------------------------------------
2  * auxprocess.c
3  * functions related to auxiliary processes.
4  *
5  *
6  * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  * IDENTIFICATION
10  * src/backend/postmaster/auxprocess.c
11  *-------------------------------------------------------------------------
12  */
13 #include "postgres.h"
14 
15 #include <unistd.h>
16 #include <signal.h>
17 
18 #include "libpq/pqsignal.h"
19 #include "miscadmin.h"
20 #include "pgstat.h"
21 #include "postmaster/auxprocess.h"
22 #include "postmaster/bgwriter.h"
23 #include "postmaster/startup.h"
24 #include "postmaster/walwriter.h"
26 #include "storage/bufmgr.h"
27 #include "storage/bufpage.h"
29 #include "storage/ipc.h"
30 #include "storage/proc.h"
31 #include "tcop/tcopprot.h"
32 #include "utils/memutils.h"
33 #include "utils/ps_status.h"
34 #include "utils/rel.h"
35 
36 
37 static void ShutdownAuxiliaryProcess(int code, Datum arg);
38 
39 
40 /* ----------------
41  * global variables
42  * ----------------
43  */
44 
45 AuxProcType MyAuxProcType = NotAnAuxProcess; /* declared in miscadmin.h */
46 
47 
48 /*
49  * AuxiliaryProcessMain
50  *
51  * The main entry point for auxiliary processes, such as the bgwriter,
52  * walwriter, walreceiver, bootstrapper and the shared memory checker code.
53  *
54  * This code is here just because of historical reasons.
55  */
56 void
58 {
60 
61  MyAuxProcType = auxtype;
62 
63  switch (MyAuxProcType)
64  {
65  case StartupProcess:
67  break;
68  case ArchiverProcess:
70  break;
71  case BgWriterProcess:
73  break;
76  break;
77  case WalWriterProcess:
79  break;
80  case WalReceiverProcess:
82  break;
83  default:
84  elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
86  }
87 
88  init_ps_display(NULL);
89 
91  IgnoreSystemIndexes = true;
92 
93  /*
94  * As an auxiliary process, we aren't going to do the full InitPostgres
95  * pushups, but there are a couple of things that need to get lit up even
96  * in an auxiliary process.
97  */
98 
99  /*
100  * Create a PGPROC so we can use LWLocks and access shared memory.
101  */
103 
104  BaseInit();
105 
106  /*
107  * Assign the ProcSignalSlot for an auxiliary process. Since it doesn't
108  * have a BackendId, the slot is statically allocated based on the
109  * auxiliary process type (MyAuxProcType). Backends use slots indexed in
110  * the range from 1 to MaxBackends (inclusive), so we use MaxBackends +
111  * AuxProcType + 1 as the index of the slot for an auxiliary process.
112  *
113  * This will need rethinking if we ever want more than one of a particular
114  * auxiliary process type.
115  */
117 
118  /*
119  * Auxiliary processes don't run transactions, but they may need a
120  * resource owner anyway to manage buffer pins acquired outside
121  * transactions (and, perhaps, other things in future).
122  */
124 
125 
126  /* Initialize backend status information */
127  pgstat_beinit();
128  pgstat_bestart();
129 
130  /* register a before-shutdown callback for LWLock cleanup */
132 
134 
135  switch (MyAuxProcType)
136  {
137  case StartupProcess:
139  proc_exit(1);
140 
141  case ArchiverProcess:
142  PgArchiverMain();
143  proc_exit(1);
144 
145  case BgWriterProcess:
147  proc_exit(1);
148 
149  case CheckpointerProcess:
151  proc_exit(1);
152 
153  case WalWriterProcess:
154  WalWriterMain();
155  proc_exit(1);
156 
157  case WalReceiverProcess:
158  WalReceiverMain();
159  proc_exit(1);
160 
161  default:
162  elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
163  proc_exit(1);
164  }
165 }
166 
167 /*
168  * Begin shutdown of an auxiliary process. This is approximately the equivalent
169  * of ShutdownPostgres() in postinit.c. We can't run transactions in an
170  * auxiliary process, so most of the work of AbortTransaction() is not needed,
171  * but we do need to make sure we've released any LWLocks we are holding.
172  * (This is only critical during an error exit.)
173  */
174 static void
176 {
180 }
AuxProcType MyAuxProcType
Definition: auxprocess.c:45
void AuxiliaryProcessMain(AuxProcType auxtype)
Definition: auxprocess.c:57
static void ShutdownAuxiliaryProcess(int code, Datum arg)
Definition: auxprocess.c:175
void StartupProcessMain(void)
Definition: startup.c:244
void pgstat_beinit(void)
void pgstat_bestart(void)
void BackgroundWriterMain(void)
Definition: bgwriter.c:91
void CheckpointerMain(void)
Definition: checkpointer.c:172
bool ConditionVariableCancelSleep(void)
#define PANIC
Definition: elog.h:42
bool IsUnderPostmaster
Definition: globals.c:115
int MaxBackends
Definition: globals.c:142
void before_shmem_exit(pg_on_exit_callback function, Datum arg)
Definition: ipc.c:337
void proc_exit(int code)
Definition: ipc.c:104
Assert(fmt[strlen(fmt) - 1] !='\n')
void LWLockReleaseAll(void)
Definition: lwlock.c:1903
@ NormalProcessing
Definition: miscadmin.h:408
@ BootstrapProcessing
Definition: miscadmin.h:406
#define SetProcessingMode(mode)
Definition: miscadmin.h:419
@ B_WAL_WRITER
Definition: miscadmin.h:339
@ B_WAL_RECEIVER
Definition: miscadmin.h:337
@ B_CHECKPOINTER
Definition: miscadmin.h:333
@ B_STARTUP
Definition: miscadmin.h:336
@ B_INVALID
Definition: miscadmin.h:326
@ B_BG_WRITER
Definition: miscadmin.h:332
@ B_ARCHIVER
Definition: miscadmin.h:327
AuxProcType
Definition: miscadmin.h:437
@ BgWriterProcess
Definition: miscadmin.h:440
@ StartupProcess
Definition: miscadmin.h:439
@ NotAnAuxProcess
Definition: miscadmin.h:438
@ ArchiverProcess
Definition: miscadmin.h:441
@ WalWriterProcess
Definition: miscadmin.h:443
@ WalReceiverProcess
Definition: miscadmin.h:444
@ CheckpointerProcess
Definition: miscadmin.h:442
bool IgnoreSystemIndexes
Definition: miscinit.c:80
BackendType MyBackendType
Definition: miscinit.c:63
void * arg
void PgArchiverMain(void)
Definition: pgarch.c:212
uintptr_t Datum
Definition: postgres.h:64
void BaseInit(void)
Definition: postinit.c:629
void ProcSignalInit(int pss_idx)
Definition: procsignal.c:162
void init_ps_display(const char *fixed_part)
Definition: ps_status.c:242
void CreateAuxProcessResourceOwner(void)
Definition: resowner.c:983
void InitAuxiliaryProcess(void)
Definition: proc.c:519
static void pgstat_report_wait_end(void)
Definition: wait_event.h:104
void WalReceiverMain(void)
Definition: walreceiver.c:186
void WalWriterMain(void)
Definition: walwriter.c:91