PostgreSQL Source Code  git master
ipc.c File Reference
#include "postgres.h"
#include <signal.h>
#include <unistd.h>
#include <sys/stat.h>
#include "miscadmin.h"
#include "storage/dsm.h"
#include "storage/ipc.h"
#include "tcop/tcopprot.h"
Include dependency graph for ipc.c:

Go to the source code of this file.

Data Structures

struct  ONEXIT
 

Macros

#define MAX_ON_EXITS   20
 

Functions

static void proc_exit_prepare (int code)
 
void proc_exit (int code)
 
void shmem_exit (int code)
 
static void atexit_callback (void)
 
void on_proc_exit (pg_on_exit_callback function, Datum arg)
 
void before_shmem_exit (pg_on_exit_callback function, Datum arg)
 
void on_shmem_exit (pg_on_exit_callback function, Datum arg)
 
void cancel_before_shmem_exit (pg_on_exit_callback function, Datum arg)
 
void on_exit_reset (void)
 
void check_on_shmem_exit_lists_are_empty (void)
 

Variables

bool proc_exit_inprogress = false
 
bool shmem_exit_inprogress = false
 
static bool atexit_callback_setup = false
 
static struct ONEXIT on_proc_exit_list [MAX_ON_EXITS]
 
static struct ONEXIT on_shmem_exit_list [MAX_ON_EXITS]
 
static struct ONEXIT before_shmem_exit_list [MAX_ON_EXITS]
 
static int on_proc_exit_index
 
static int on_shmem_exit_index
 
static int before_shmem_exit_index
 

Macro Definition Documentation

◆ MAX_ON_EXITS

#define MAX_ON_EXITS   20

Definition at line 71 of file ipc.c.

Function Documentation

◆ atexit_callback()

static void atexit_callback ( void  )
static

Definition at line 294 of file ipc.c.

295 {
296  /* Clean up everything that must be cleaned up */
297  /* ... too bad we don't know the real exit code ... */
298  proc_exit_prepare(-1);
299 }
static void proc_exit_prepare(int code)
Definition: ipc.c:165

References proc_exit_prepare().

Referenced by before_shmem_exit(), on_proc_exit(), and on_shmem_exit().

◆ before_shmem_exit()

void before_shmem_exit ( pg_on_exit_callback  function,
Datum  arg 
)

Definition at line 337 of file ipc.c.

338 {
340  ereport(FATAL,
341  (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
342  errmsg_internal("out of before_shmem_exit slots")));
343 
346 
348 
350  {
351  atexit(atexit_callback);
352  atexit_callback_setup = true;
353  }
354 }
int errmsg_internal(const char *fmt,...)
Definition: elog.c:1157
int errcode(int sqlerrcode)
Definition: elog.c:857
#define FATAL
Definition: elog.h:41
#define ereport(elevel,...)
Definition: elog.h:149
static bool atexit_callback_setup
Definition: ipc.c:51
static void atexit_callback(void)
Definition: ipc.c:294
#define MAX_ON_EXITS
Definition: ipc.c:71
static int before_shmem_exit_index
Definition: ipc.c:85
static struct ONEXIT before_shmem_exit_list[MAX_ON_EXITS]
Definition: ipc.c:81
void * arg
Datum arg
Definition: ipc.c:76
pg_on_exit_callback function
Definition: ipc.c:75

References ONEXIT::arg, arg, atexit_callback(), atexit_callback_setup, before_shmem_exit_index, before_shmem_exit_list, ereport, errcode(), errmsg_internal(), FATAL, ONEXIT::function, and MAX_ON_EXITS.

Referenced by ApplyLauncherMain(), AtEOXact_Namespace(), autoprewarm_main(), AuxiliaryProcessMainCommon(), CheckpointerMain(), Exec_ListenPreCommit(), InitPostgres(), InitTemporaryFileAccess(), injection_points_set_local(), LoadArchiveLibrary(), LockGXact(), logicalrep_worker_attach(), MarkAsPreparing(), ParallelApplyWorkerMain(), ParallelWorkerMain(), pgstat_initialize(), register_persistent_abort_backup_handler(), ReplicationSlotInitialize(), and ReplSlotSyncWorkerMain().

◆ cancel_before_shmem_exit()

void cancel_before_shmem_exit ( pg_on_exit_callback  function,
Datum  arg 
)

Definition at line 394 of file ipc.c.

395 {
396  if (before_shmem_exit_index > 0 &&
398  == function &&
401  else
402  elog(ERROR, "before_shmem_exit callback (%p,0x%llx) is not the latest entry",
403  function, (long long) arg);
404 }
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:224

References arg, before_shmem_exit_index, before_shmem_exit_list, elog, and ERROR.

◆ check_on_shmem_exit_lists_are_empty()

void check_on_shmem_exit_lists_are_empty ( void  )

Definition at line 432 of file ipc.c.

433 {
435  elog(FATAL, "before_shmem_exit has been called prematurely");
437  elog(FATAL, "on_shmem_exit has been called prematurely");
438  /* Checking DSM detach state seems unnecessary given the above */
439 }
static int on_shmem_exit_index
Definition: ipc.c:84

References before_shmem_exit_index, elog, FATAL, and on_shmem_exit_index.

Referenced by BackendInitialize().

◆ on_exit_reset()

void on_exit_reset ( void  )

Definition at line 416 of file ipc.c.

417 {
420  on_proc_exit_index = 0;
422 }
void reset_on_dsm_detach(void)
Definition: dsm.c:1170
static int on_proc_exit_index
Definition: ipc.c:83

References before_shmem_exit_index, on_proc_exit_index, on_shmem_exit_index, and reset_on_dsm_detach().

Referenced by InitPostmasterChild().

◆ on_proc_exit()

void on_proc_exit ( pg_on_exit_callback  function,
Datum  arg 
)

Definition at line 309 of file ipc.c.

310 {
312  ereport(FATAL,
313  (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
314  errmsg_internal("out of on_proc_exit slots")));
315 
318 
320 
322  {
323  atexit(atexit_callback);
324  atexit_callback_setup = true;
325  }
326 }
static struct ONEXIT on_proc_exit_list[MAX_ON_EXITS]
Definition: ipc.c:79

References ONEXIT::arg, arg, atexit_callback(), atexit_callback_setup, ereport, errcode(), errmsg_internal(), FATAL, ONEXIT::function, MAX_ON_EXITS, on_proc_exit_index, and on_proc_exit_list.

Referenced by CreateLockFile(), InitCatCache(), llvm_session_initialize(), PostgresMain(), PostmasterMain(), pq_init(), select_perl_context(), sepgsql_avc_init(), and smgrinit().

◆ on_shmem_exit()

◆ proc_exit()

void proc_exit ( int  code)

Definition at line 104 of file ipc.c.

105 {
106  /* not safe if forked by system(), etc. */
107  if (MyProcPid != (int) getpid())
108  elog(PANIC, "proc_exit() called in child process");
109 
110  /* Clean up everything that must be cleaned up */
111  proc_exit_prepare(code);
112 
113 #ifdef PROFILE_PID_DIR
114  {
115  /*
116  * If we are profiling ourself then gprof's mcleanup() is about to
117  * write out a profile to ./gmon.out. Since mcleanup() always uses a
118  * fixed file name, each backend will overwrite earlier profiles. To
119  * fix that, we create a separate subdirectory for each backend
120  * (./gprof/pid) and 'cd' to that subdirectory before we exit() - that
121  * forces mcleanup() to write each profile into its own directory. We
122  * end up with something like: $PGDATA/gprof/8829/gmon.out
123  * $PGDATA/gprof/8845/gmon.out ...
124  *
125  * To avoid undesirable disk space bloat, autovacuum workers are
126  * discriminated against: all their gmon.out files go into the same
127  * subdirectory. Without this, an installation that is "just sitting
128  * there" nonetheless eats megabytes of disk space every few seconds.
129  *
130  * Note that we do this here instead of in an on_proc_exit() callback
131  * because we want to ensure that this code executes last - we don't
132  * want to interfere with any other on_proc_exit() callback. For the
133  * same reason, we do not include it in proc_exit_prepare ... so if
134  * you are exiting in the "wrong way" you won't drop your profile in a
135  * nice place.
136  */
137  char gprofDirName[32];
138 
140  snprintf(gprofDirName, 32, "gprof/avworker");
141  else
142  snprintf(gprofDirName, 32, "gprof/%d", (int) getpid());
143 
144  /*
145  * Use mkdir() instead of MakePGDirectory() since we aren't making a
146  * PG directory here.
147  */
148  mkdir("gprof", S_IRWXU | S_IRWXG | S_IRWXO);
149  mkdir(gprofDirName, S_IRWXU | S_IRWXG | S_IRWXO);
150  chdir(gprofDirName);
151  }
152 #endif
153 
154  elog(DEBUG3, "exit(%d)", code);
155 
156  exit(code);
157 }
#define DEBUG3
Definition: elog.h:28
#define PANIC
Definition: elog.h:42
int MyProcPid
Definition: globals.c:45
exit(1)
#define AmAutoVacuumWorkerProcess()
Definition: miscadmin.h:375
#define snprintf
Definition: port.h:238
#define S_IRWXG
Definition: win32_port.h:310
#define S_IRWXO
Definition: win32_port.h:322
#define mkdir(a, b)
Definition: win32_port.h:80
#define S_IRWXU
Definition: win32_port.h:298

References AmAutoVacuumWorkerProcess, DEBUG3, elog, exit(), mkdir, MyProcPid, PANIC, proc_exit_prepare(), S_IRWXG, S_IRWXO, S_IRWXU, and snprintf.

Referenced by apply_worker_exit(), ApplyWorkerMain(), auth_failed(), AutoVacWorkerMain(), BackendInitialize(), BackgroundWorkerMain(), BootstrapModeMain(), CheckerModeMain(), DisableSubscriptionAndExit(), errfinish(), ExitPostmaster(), HandleCheckpointerInterrupts(), HandleMainLoopInterrupts(), HandlePgArchInterrupts(), HandleStartupProcInterrupts(), HandleWalSummarizerInterrupts(), InitializeLogRepWorker(), maybe_reread_subscription(), PerformWalRecovery(), pg_attribute_noreturn(), PgArchiverMain(), PostgresMain(), PostgresSingleUserMain(), PreRestoreCommand(), process_syncing_tables_for_apply(), ProcessInterrupts(), ProcessParallelApplyInterrupts(), ProcessRepliesIfAny(), ProcessSlotSyncInterrupts(), ProcessStandbyMessage(), ReplSlotSyncWorkerMain(), RestoreArchivedFile(), slotsync_reread_config(), StartLogicalReplication(), StartReplication(), StartupProcessMain(), StartupProcShutdownHandler(), SysLoggerMain(), test_shm_mq_main(), WaitEventSetWaitBlock(), WalRcvWaitForStartPosition(), WalReceiverMain(), WalSndDone(), WalSndErrorCleanup(), WalSndWait(), and WalSummarizerMain().

◆ proc_exit_prepare()

static void proc_exit_prepare ( int  code)
static

Definition at line 165 of file ipc.c.

166 {
167  /*
168  * Once we set this flag, we are committed to exit. Any ereport() will
169  * NOT send control back to the main loop, but right back here.
170  */
171  proc_exit_inprogress = true;
172 
173  /*
174  * Forget any pending cancel or die requests; we're doing our best to
175  * close up shop already. Note that the signal handlers will not set
176  * these flags again, now that proc_exit_inprogress is set.
177  */
178  InterruptPending = false;
179  ProcDiePending = false;
180  QueryCancelPending = false;
182  CritSectionCount = 0;
183 
184  /*
185  * Also clear the error context stack, to prevent error callbacks from
186  * being invoked by any elog/ereport calls made during proc_exit. Whatever
187  * context they might want to offer is probably not relevant, and in any
188  * case they are likely to fail outright after we've done things like
189  * aborting any open transaction. (In normal exit scenarios the context
190  * stack should be empty anyway, but it might not be in the case of
191  * elog(FATAL) for example.)
192  */
193  error_context_stack = NULL;
194  /* For the same reason, reset debug_query_string before it's clobbered */
195  debug_query_string = NULL;
196 
197  /* do our shared memory exits first */
198  shmem_exit(code);
199 
200  elog(DEBUG3, "proc_exit(%d): %d callbacks to make",
201  code, on_proc_exit_index);
202 
203  /*
204  * call all the registered callbacks.
205  *
206  * Note that since we decrement on_proc_exit_index each time, if a
207  * callback calls ereport(ERROR) or ereport(FATAL) then it won't be
208  * invoked again when control comes back here (nor will the
209  * previously-completed callbacks). So, an infinite loop should not be
210  * possible.
211  */
212  while (--on_proc_exit_index >= 0)
215 
216  on_proc_exit_index = 0;
217 }
ErrorContextCallback * error_context_stack
Definition: elog.c:94
volatile sig_atomic_t InterruptPending
Definition: globals.c:30
volatile uint32 InterruptHoldoffCount
Definition: globals.c:41
volatile uint32 CritSectionCount
Definition: globals.c:43
volatile sig_atomic_t QueryCancelPending
Definition: globals.c:31
volatile sig_atomic_t ProcDiePending
Definition: globals.c:32
bool proc_exit_inprogress
Definition: ipc.c:40
void shmem_exit(int code)
Definition: ipc.c:228
const char * debug_query_string
Definition: postgres.c:87

References arg, CritSectionCount, DEBUG3, debug_query_string, elog, error_context_stack, ONEXIT::function, InterruptHoldoffCount, InterruptPending, on_proc_exit_index, on_proc_exit_list, proc_exit_inprogress, ProcDiePending, QueryCancelPending, and shmem_exit().

Referenced by atexit_callback(), and proc_exit().

◆ shmem_exit()

void shmem_exit ( int  code)

Definition at line 228 of file ipc.c.

229 {
230  shmem_exit_inprogress = true;
231 
232  /*
233  * Call before_shmem_exit callbacks.
234  *
235  * These should be things that need most of the system to still be up and
236  * working, such as cleanup of temp relations, which requires catalog
237  * access; or things that need to be completed because later cleanup steps
238  * depend on them, such as releasing lwlocks.
239  */
240  elog(DEBUG3, "shmem_exit(%d): %d before_shmem_exit callbacks to make",
242  while (--before_shmem_exit_index >= 0)
246 
247  /*
248  * Call dynamic shared memory callbacks.
249  *
250  * These serve the same purpose as late callbacks, but for dynamic shared
251  * memory segments rather than the main shared memory segment.
252  * dsm_backend_shutdown() has the same kind of progressive logic we use
253  * for the main shared memory segment; namely, it unregisters each
254  * callback before invoking it, so that we don't get stuck in an infinite
255  * loop if one of those callbacks itself throws an ERROR or FATAL.
256  *
257  * Note that explicitly calling this function here is quite different from
258  * registering it as an on_shmem_exit callback for precisely this reason:
259  * if one dynamic shared memory callback errors out, the remaining
260  * callbacks will still be invoked. Thus, hard-coding this call puts it
261  * equal footing with callbacks for the main shared memory segment.
262  */
264 
265  /*
266  * Call on_shmem_exit callbacks.
267  *
268  * These are generally releasing low-level shared memory resources. In
269  * some cases, this is a backstop against the possibility that the early
270  * callbacks might themselves fail, leading to re-entry to this routine;
271  * in other cases, it's cleanup that only happens at process exit.
272  */
273  elog(DEBUG3, "shmem_exit(%d): %d on_shmem_exit callbacks to make",
274  code, on_shmem_exit_index);
275  while (--on_shmem_exit_index >= 0)
279 
280  shmem_exit_inprogress = false;
281 }
void dsm_backend_shutdown(void)
Definition: dsm.c:757
bool shmem_exit_inprogress
Definition: ipc.c:45

References arg, before_shmem_exit_index, before_shmem_exit_list, DEBUG3, dsm_backend_shutdown(), elog, ONEXIT::function, on_shmem_exit_index, on_shmem_exit_list, and shmem_exit_inprogress.

Referenced by PostmasterStateMachine(), and proc_exit_prepare().

Variable Documentation

◆ atexit_callback_setup

bool atexit_callback_setup = false
static

Definition at line 51 of file ipc.c.

Referenced by before_shmem_exit(), on_proc_exit(), and on_shmem_exit().

◆ before_shmem_exit_index

int before_shmem_exit_index
static

◆ before_shmem_exit_list

struct ONEXIT before_shmem_exit_list[MAX_ON_EXITS]
static

Definition at line 54 of file ipc.c.

Referenced by before_shmem_exit(), cancel_before_shmem_exit(), and shmem_exit().

◆ on_proc_exit_index

int on_proc_exit_index
static

Definition at line 83 of file ipc.c.

Referenced by on_exit_reset(), on_proc_exit(), and proc_exit_prepare().

◆ on_proc_exit_list

struct ONEXIT on_proc_exit_list[MAX_ON_EXITS]
static

Definition at line 54 of file ipc.c.

Referenced by on_proc_exit(), and proc_exit_prepare().

◆ on_shmem_exit_index

int on_shmem_exit_index
static

◆ on_shmem_exit_list

struct ONEXIT on_shmem_exit_list[MAX_ON_EXITS]
static

Definition at line 54 of file ipc.c.

Referenced by on_shmem_exit(), and shmem_exit().

◆ proc_exit_inprogress

◆ shmem_exit_inprogress

bool shmem_exit_inprogress = false

Definition at line 45 of file ipc.c.

Referenced by AtAbort_Portals(), and shmem_exit().