Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * procsignal.c
4 : : * Routines for interprocess signaling
5 : : *
6 : : *
7 : : * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
8 : : * Portions Copyright (c) 1994, Regents of the University of California
9 : : *
10 : : * IDENTIFICATION
11 : : * src/backend/storage/ipc/procsignal.c
12 : : *
13 : : *-------------------------------------------------------------------------
14 : : */
15 : : #include "postgres.h"
16 : :
17 : : #include <signal.h>
18 : : #include <unistd.h>
19 : :
20 : : #include "access/parallel.h"
21 : : #include "commands/async.h"
22 : : #include "miscadmin.h"
23 : : #include "pgstat.h"
24 : : #include "port/pg_bitutils.h"
25 : : #include "replication/logicalworker.h"
26 : : #include "replication/walsender.h"
27 : : #include "storage/condition_variable.h"
28 : : #include "storage/ipc.h"
29 : : #include "storage/latch.h"
30 : : #include "storage/shmem.h"
31 : : #include "storage/sinval.h"
32 : : #include "storage/smgr.h"
33 : : #include "tcop/tcopprot.h"
34 : : #include "utils/memutils.h"
35 : :
36 : : /*
37 : : * The SIGUSR1 signal is multiplexed to support signaling multiple event
38 : : * types. The specific reason is communicated via flags in shared memory.
39 : : * We keep a boolean flag for each possible "reason", so that different
40 : : * reasons can be signaled to a process concurrently. (However, if the same
41 : : * reason is signaled more than once nearly simultaneously, the process may
42 : : * observe it only once.)
43 : : *
44 : : * Each process that wants to receive signals registers its process ID
45 : : * in the ProcSignalSlots array. The array is indexed by ProcNumber to make
46 : : * slot allocation simple, and to avoid having to search the array when you
47 : : * know the ProcNumber of the process you're signaling. (We do support
48 : : * signaling without ProcNumber, but it's a bit less efficient.)
49 : : *
50 : : * The flags are actually declared as "volatile sig_atomic_t" for maximum
51 : : * portability. This should ensure that loads and stores of the flag
52 : : * values are atomic, allowing us to dispense with any explicit locking.
53 : : *
54 : : * pss_signalFlags are intended to be set in cases where we don't need to
55 : : * keep track of whether or not the target process has handled the signal,
56 : : * but sometimes we need confirmation, as when making a global state change
57 : : * that cannot be considered complete until all backends have taken notice
58 : : * of it. For such use cases, we set a bit in pss_barrierCheckMask and then
59 : : * increment the current "barrier generation"; when the new barrier generation
60 : : * (or greater) appears in the pss_barrierGeneration flag of every process,
61 : : * we know that the message has been received everywhere.
62 : : */
63 : : typedef struct
64 : : {
65 : : volatile pid_t pss_pid;
66 : : volatile sig_atomic_t pss_signalFlags[NUM_PROCSIGNALS];
67 : : pg_atomic_uint64 pss_barrierGeneration;
68 : : pg_atomic_uint32 pss_barrierCheckMask;
69 : : ConditionVariable pss_barrierCV;
70 : : } ProcSignalSlot;
71 : :
72 : : /*
73 : : * Information that is global to the entire ProcSignal system can be stored
74 : : * here.
75 : : *
76 : : * psh_barrierGeneration is the highest barrier generation in existence.
77 : : */
78 : : typedef struct
79 : : {
80 : : pg_atomic_uint64 psh_barrierGeneration;
81 : : ProcSignalSlot psh_slot[FLEXIBLE_ARRAY_MEMBER];
82 : : } ProcSignalHeader;
83 : :
84 : : /*
85 : : * We reserve a slot for each possible ProcNumber, plus one for each
86 : : * possible auxiliary process type. (This scheme assumes there is not
87 : : * more than one of any auxiliary process type at a time.)
88 : : */
89 : : #define NumProcSignalSlots (MaxBackends + NUM_AUXILIARY_PROCS)
90 : :
91 : : /* Check whether the relevant type bit is set in the flags. */
92 : : #define BARRIER_SHOULD_CHECK(flags, type) \
93 : : (((flags) & (((uint32) 1) << (uint32) (type))) != 0)
94 : :
95 : : /* Clear the relevant type bit from the flags. */
96 : : #define BARRIER_CLEAR_BIT(flags, type) \
97 : : ((flags) &= ~(((uint32) 1) << (uint32) (type)))
98 : :
99 : : static ProcSignalHeader *ProcSignal = NULL;
100 : : static ProcSignalSlot *MyProcSignalSlot = NULL;
101 : :
102 : : static bool CheckProcSignal(ProcSignalReason reason);
103 : : static void CleanupProcSignalState(int status, Datum arg);
104 : : static void ResetProcSignalBarrierBits(uint32 flags);
105 : :
106 : : /*
107 : : * ProcSignalShmemSize
108 : : * Compute space needed for ProcSignal's shared memory
109 : : */
110 : : Size
5371 tgl@sss.pgh.pa.us 111 :CBC 2577 : ProcSignalShmemSize(void)
112 : : {
113 : : Size size;
114 : :
733 rhaas@postgresql.org 115 : 2577 : size = mul_size(NumProcSignalSlots, sizeof(ProcSignalSlot));
1578 116 : 2577 : size = add_size(size, offsetof(ProcSignalHeader, psh_slot));
117 : 2577 : return size;
118 : : }
119 : :
120 : : /*
121 : : * ProcSignalShmemInit
122 : : * Allocate and initialize ProcSignal's shared memory
123 : : */
124 : : void
5371 tgl@sss.pgh.pa.us 125 : 898 : ProcSignalShmemInit(void)
126 : : {
127 : 898 : Size size = ProcSignalShmemSize();
128 : : bool found;
129 : :
1578 rhaas@postgresql.org 130 : 898 : ProcSignal = (ProcSignalHeader *)
131 : 898 : ShmemInitStruct("ProcSignal", size, &found);
132 : :
133 : : /* If we're first, initialize. */
5371 tgl@sss.pgh.pa.us 134 [ + - ]: 898 : if (!found)
135 : : {
136 : : int i;
137 : :
1578 rhaas@postgresql.org 138 : 898 : pg_atomic_init_u64(&ProcSignal->psh_barrierGeneration, 0);
139 : :
733 140 [ + + ]: 80720 : for (i = 0; i < NumProcSignalSlots; ++i)
141 : : {
1578 142 : 79822 : ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
143 : :
144 : 79822 : slot->pss_pid = 0;
145 [ - + - - : 79822 : MemSet(slot->pss_signalFlags, 0, sizeof(slot->pss_signalFlags));
- - - - -
- ]
146 : 79822 : pg_atomic_init_u64(&slot->pss_barrierGeneration, PG_UINT64_MAX);
147 : 79822 : pg_atomic_init_u32(&slot->pss_barrierCheckMask, 0);
1140 tmunro@postgresql.or 148 : 79822 : ConditionVariableInit(&slot->pss_barrierCV);
149 : : }
150 : : }
5371 tgl@sss.pgh.pa.us 151 : 898 : }
152 : :
153 : : /*
154 : : * ProcSignalInit
155 : : * Register the current process in the ProcSignal array
156 : : */
157 : : void
42 heikki.linnakangas@i 158 :GNC 19567 : ProcSignalInit(void)
159 : : {
160 : : ProcSignalSlot *slot;
161 : : uint64 barrier_generation;
162 : :
163 [ - + ]: 19567 : if (MyProcNumber < 0)
42 heikki.linnakangas@i 164 [ # # ]:UNC 0 : elog(ERROR, "MyProcNumber not set");
42 heikki.linnakangas@i 165 [ - + ]:GNC 19567 : if (MyProcNumber >= NumProcSignalSlots)
42 heikki.linnakangas@i 166 [ # # ]:UNC 0 : elog(ERROR, "unexpected MyProcNumber %d in ProcSignalInit (max %d)", MyProcNumber, NumProcSignalSlots);
42 heikki.linnakangas@i 167 :GNC 19567 : slot = &ProcSignal->psh_slot[MyProcNumber];
168 : :
169 : : /* sanity check */
5371 tgl@sss.pgh.pa.us 170 [ - + ]:CBC 19567 : if (slot->pss_pid != 0)
5371 tgl@sss.pgh.pa.us 171 [ # # ]:UBC 0 : elog(LOG, "process %d taking over ProcSignal slot %d, but it's not empty",
172 : : MyProcPid, MyProcNumber);
173 : :
174 : : /* Clear out any leftover signal reasons */
5371 tgl@sss.pgh.pa.us 175 [ - + - - :CBC 19567 : MemSet(slot->pss_signalFlags, 0, NUM_PROCSIGNALS * sizeof(sig_atomic_t));
- - - - -
- ]
176 : :
177 : : /*
178 : : * Initialize barrier state. Since we're a brand-new process, there
179 : : * shouldn't be any leftover backend-private state that needs to be
180 : : * updated. Therefore, we can broadcast the latest barrier generation and
181 : : * disregard any previously-set check bits.
182 : : *
183 : : * NB: This only works if this initialization happens early enough in the
184 : : * startup sequence that we haven't yet cached any state that might need
185 : : * to be invalidated. That's also why we have a memory barrier here, to be
186 : : * sure that any later reads of memory happen strictly after this.
187 : : */
1578 rhaas@postgresql.org 188 : 19567 : pg_atomic_write_u32(&slot->pss_barrierCheckMask, 0);
189 : : barrier_generation =
190 : 19567 : pg_atomic_read_u64(&ProcSignal->psh_barrierGeneration);
191 : 19567 : pg_atomic_write_u64(&slot->pss_barrierGeneration, barrier_generation);
192 : 19567 : pg_memory_barrier();
193 : :
194 : : /* Mark slot with my PID */
5371 tgl@sss.pgh.pa.us 195 : 19567 : slot->pss_pid = MyProcPid;
196 : :
197 : : /* Remember slot location for CheckProcSignal */
198 : 19567 : MyProcSignalSlot = slot;
199 : :
200 : : /* Set up to release the slot on process exit */
42 heikki.linnakangas@i 201 :GNC 19567 : on_shmem_exit(CleanupProcSignalState, (Datum) 0);
5371 tgl@sss.pgh.pa.us 202 :CBC 19567 : }
203 : :
204 : : /*
205 : : * CleanupProcSignalState
206 : : * Remove current process from ProcSignal mechanism
207 : : *
208 : : * This function is called via on_shmem_exit() during backend shutdown.
209 : : */
210 : : static void
211 : 18038 : CleanupProcSignalState(int status, Datum arg)
212 : : {
42 heikki.linnakangas@i 213 :GNC 18038 : ProcSignalSlot *slot = MyProcSignalSlot;
214 : :
215 : : /*
216 : : * Clear MyProcSignalSlot, so that a SIGUSR1 received after this point
217 : : * won't try to access it after it's no longer ours (and perhaps even
218 : : * after we've unmapped the shared memory segment).
219 : : */
220 [ - + ]: 18038 : Assert(MyProcSignalSlot != NULL);
3726 rhaas@postgresql.org 221 :CBC 18038 : MyProcSignalSlot = NULL;
222 : :
223 : : /* sanity check */
5371 tgl@sss.pgh.pa.us 224 [ - + ]: 18038 : if (slot->pss_pid != MyProcPid)
225 : : {
226 : : /*
227 : : * don't ERROR here. We're exiting anyway, and don't want to get into
228 : : * infinite loop trying to exit
229 : : */
5371 tgl@sss.pgh.pa.us 230 [ # # ]:UBC 0 : elog(LOG, "process %d releasing ProcSignal slot %d, but it contains %d",
231 : : MyProcPid, (int) (slot - ProcSignal->psh_slot), (int) slot->pss_pid);
232 : 0 : return; /* XXX better to zero the slot anyway? */
233 : : }
234 : :
235 : : /*
236 : : * Make this slot look like it's absorbed all possible barriers, so that
237 : : * no barrier waits block on it.
238 : : */
1578 rhaas@postgresql.org 239 :CBC 18038 : pg_atomic_write_u64(&slot->pss_barrierGeneration, PG_UINT64_MAX);
1140 tmunro@postgresql.or 240 : 18038 : ConditionVariableBroadcast(&slot->pss_barrierCV);
241 : :
5371 tgl@sss.pgh.pa.us 242 : 18038 : slot->pss_pid = 0;
243 : : }
244 : :
245 : : /*
246 : : * SendProcSignal
247 : : * Send a signal to a Postgres process
248 : : *
249 : : * Providing procNumber is optional, but it will speed up the operation.
250 : : *
251 : : * On success (a signal was sent), zero is returned.
252 : : * On error, -1 is returned, and errno is set (typically to ESRCH or EPERM).
253 : : *
254 : : * Not to be confused with ProcSendSignal
255 : : */
256 : : int
42 heikki.linnakangas@i 257 :GNC 5032 : SendProcSignal(pid_t pid, ProcSignalReason reason, ProcNumber procNumber)
258 : : {
259 : : volatile ProcSignalSlot *slot;
260 : :
261 [ + + ]: 5032 : if (procNumber != INVALID_PROC_NUMBER)
262 : : {
263 : 4981 : slot = &ProcSignal->psh_slot[procNumber];
264 : :
265 : : /*
266 : : * Note: Since there's no locking, it's possible that the target
267 : : * process detaches from shared memory and exits right after this
268 : : * test, before we set the flag and send signal. And the signal slot
269 : : * might even be recycled by a new process, so it's remotely possible
270 : : * that we set a flag for a wrong process. That's OK, all the signals
271 : : * are such that no harm is done if they're mistakenly fired.
272 : : */
5371 tgl@sss.pgh.pa.us 273 [ + - ]:CBC 4981 : if (slot->pss_pid == pid)
274 : : {
275 : : /* Atomically set the proper flag */
276 : 4981 : slot->pss_signalFlags[reason] = true;
277 : : /* Send signal */
278 : 4981 : return kill(pid, SIGUSR1);
279 : : }
280 : : }
281 : : else
282 : : {
283 : : /*
284 : : * Pronumber not provided, so search the array using pid. We search
285 : : * the array back to front so as to reduce search overhead. Passing
286 : : * INVALID_PROC_NUMBER means that the target is most likely an
287 : : * auxiliary process, which will have a slot near the end of the
288 : : * array.
289 : : */
290 : : int i;
291 : :
733 rhaas@postgresql.org 292 [ + - ]: 625 : for (i = NumProcSignalSlots - 1; i >= 0; i--)
293 : : {
1578 294 : 625 : slot = &ProcSignal->psh_slot[i];
295 : :
5371 tgl@sss.pgh.pa.us 296 [ + + ]: 625 : if (slot->pss_pid == pid)
297 : : {
298 : : /* the above note about race conditions applies here too */
299 : :
300 : : /* Atomically set the proper flag */
301 : 51 : slot->pss_signalFlags[reason] = true;
302 : : /* Send signal */
303 : 51 : return kill(pid, SIGUSR1);
304 : : }
305 : : }
306 : : }
307 : :
5371 tgl@sss.pgh.pa.us 308 :UBC 0 : errno = ESRCH;
309 : 0 : return -1;
310 : : }
311 : :
312 : : /*
313 : : * EmitProcSignalBarrier
314 : : * Send a signal to every Postgres process
315 : : *
316 : : * The return value of this function is the barrier "generation" created
317 : : * by this operation. This value can be passed to WaitForProcSignalBarrier
318 : : * to wait until it is known that every participant in the ProcSignal
319 : : * mechanism has absorbed the signal (or started afterwards).
320 : : *
321 : : * Note that it would be a bad idea to use this for anything that happens
322 : : * frequently, as interrupting every backend could cause a noticeable
323 : : * performance hit.
324 : : *
325 : : * Callers are entitled to assume that this function will not throw ERROR
326 : : * or FATAL.
327 : : */
328 : : uint64
1578 rhaas@postgresql.org 329 :CBC 106 : EmitProcSignalBarrier(ProcSignalBarrierType type)
330 : : {
1399 andres@anarazel.de 331 : 106 : uint32 flagbit = 1 << (uint32) type;
332 : : uint64 generation;
333 : :
334 : : /*
335 : : * Set all the flags.
336 : : *
337 : : * Note that pg_atomic_fetch_or_u32 has full barrier semantics, so this is
338 : : * totally ordered with respect to anything the caller did before, and
339 : : * anything that we do afterwards. (This is also true of the later call to
340 : : * pg_atomic_add_fetch_u64.)
341 : : */
733 rhaas@postgresql.org 342 [ + + ]: 6140 : for (int i = 0; i < NumProcSignalSlots; i++)
343 : : {
1578 344 : 6034 : volatile ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
345 : :
346 : 6034 : pg_atomic_fetch_or_u32(&slot->pss_barrierCheckMask, flagbit);
347 : : }
348 : :
349 : : /*
350 : : * Increment the generation counter.
351 : : */
352 : : generation =
353 : 106 : pg_atomic_add_fetch_u64(&ProcSignal->psh_barrierGeneration, 1);
354 : :
355 : : /*
356 : : * Signal all the processes, so that they update their advertised barrier
357 : : * generation.
358 : : *
359 : : * Concurrency is not a problem here. Backends that have exited don't
360 : : * matter, and new backends that have joined since we entered this
361 : : * function must already have current state, since the caller is
362 : : * responsible for making sure that the relevant state is entirely visible
363 : : * before calling this function in the first place. We still have to wake
364 : : * them up - because we can't distinguish between such backends and older
365 : : * backends that need to update state - but they won't actually need to
366 : : * change any state.
367 : : */
733 368 [ + + ]: 6140 : for (int i = NumProcSignalSlots - 1; i >= 0; i--)
369 : : {
1578 370 : 6034 : volatile ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
1431 tgl@sss.pgh.pa.us 371 : 6034 : pid_t pid = slot->pss_pid;
372 : :
1578 rhaas@postgresql.org 373 [ + + ]: 6034 : if (pid != 0)
374 : : {
375 : : /* see SendProcSignal for details */
1399 andres@anarazel.de 376 : 524 : slot->pss_signalFlags[PROCSIG_BARRIER] = true;
1578 rhaas@postgresql.org 377 : 524 : kill(pid, SIGUSR1);
378 : : }
379 : : }
380 : :
381 : 106 : return generation;
382 : : }
383 : :
384 : : /*
385 : : * WaitForProcSignalBarrier - wait until it is guaranteed that all changes
386 : : * requested by a specific call to EmitProcSignalBarrier() have taken effect.
387 : : */
388 : : void
389 : 106 : WaitForProcSignalBarrier(uint64 generation)
390 : : {
1399 andres@anarazel.de 391 [ - + ]: 106 : Assert(generation <= pg_atomic_read_u64(&ProcSignal->psh_barrierGeneration));
392 : :
704 tmunro@postgresql.or 393 [ + + ]: 106 : elog(DEBUG1,
394 : : "waiting for all backends to process ProcSignalBarrier generation "
395 : : UINT64_FORMAT,
396 : : generation);
397 : :
733 rhaas@postgresql.org 398 [ + + ]: 6140 : for (int i = NumProcSignalSlots - 1; i >= 0; i--)
399 : : {
1140 tmunro@postgresql.or 400 : 6034 : ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
401 : : uint64 oldval;
402 : :
403 : : /*
404 : : * It's important that we check only pss_barrierGeneration here and
405 : : * not pss_barrierCheckMask. Bits in pss_barrierCheckMask get cleared
406 : : * before the barrier is actually absorbed, but pss_barrierGeneration
407 : : * is updated only afterward.
408 : : */
1578 rhaas@postgresql.org 409 : 6034 : oldval = pg_atomic_read_u64(&slot->pss_barrierGeneration);
410 [ + + ]: 6386 : while (oldval < generation)
411 : : {
704 tmunro@postgresql.or 412 [ - + ]: 352 : if (ConditionVariableTimedSleep(&slot->pss_barrierCV,
413 : : 5000,
414 : : WAIT_EVENT_PROC_SIGNAL_BARRIER))
704 tmunro@postgresql.or 415 [ # # ]:UBC 0 : ereport(LOG,
416 : : (errmsg("still waiting for backend with PID %d to accept ProcSignalBarrier",
417 : : (int) slot->pss_pid)));
1578 rhaas@postgresql.org 418 :CBC 352 : oldval = pg_atomic_read_u64(&slot->pss_barrierGeneration);
419 : : }
1140 tmunro@postgresql.or 420 : 6034 : ConditionVariableCancelSleep();
421 : : }
422 : :
704 423 [ + + ]: 106 : elog(DEBUG1,
424 : : "finished waiting for all backends to process ProcSignalBarrier generation "
425 : : UINT64_FORMAT,
426 : : generation);
427 : :
428 : : /*
429 : : * The caller is probably calling this function because it wants to read
430 : : * the shared state or perform further writes to shared state once all
431 : : * backends are known to have absorbed the barrier. However, the read of
432 : : * pss_barrierGeneration was performed unlocked; insert a memory barrier
433 : : * to separate it from whatever follows.
434 : : */
1578 rhaas@postgresql.org 435 : 106 : pg_memory_barrier();
436 : 106 : }
437 : :
438 : : /*
439 : : * Handle receipt of an interrupt indicating a global barrier event.
440 : : *
441 : : * All the actual work is deferred to ProcessProcSignalBarrier(), because we
442 : : * cannot safely access the barrier generation inside the signal handler as
443 : : * 64bit atomics might use spinlock based emulation, even for reads. As this
444 : : * routine only gets called when PROCSIG_BARRIER is sent that won't cause a
445 : : * lot of unnecessary work.
446 : : */
447 : : static void
1399 andres@anarazel.de 448 : 542 : HandleProcSignalBarrierInterrupt(void)
449 : : {
450 : 542 : InterruptPending = true;
451 : 542 : ProcSignalBarrierPending = true;
452 : : /* latch will be set by procsignal_sigusr1_handler */
453 : 542 : }
454 : :
455 : : /*
456 : : * Perform global barrier related interrupt checking.
457 : : *
458 : : * Any backend that participates in ProcSignal signaling must arrange to
459 : : * call this function periodically. It is called from CHECK_FOR_INTERRUPTS(),
460 : : * which is enough for normal backends, but not necessarily for all types of
461 : : * background processes.
462 : : */
463 : : void
1578 rhaas@postgresql.org 464 : 542 : ProcessProcSignalBarrier(void)
465 : : {
466 : : uint64 local_gen;
467 : : uint64 shared_gen;
468 : : volatile uint32 flags;
469 : :
1399 andres@anarazel.de 470 [ - + ]: 542 : Assert(MyProcSignalSlot);
471 : :
472 : : /* Exit quickly if there's no work to do. */
1578 rhaas@postgresql.org 473 [ - + ]: 542 : if (!ProcSignalBarrierPending)
1578 rhaas@postgresql.org 474 :UBC 0 : return;
1578 rhaas@postgresql.org 475 :CBC 542 : ProcSignalBarrierPending = false;
476 : :
477 : : /*
478 : : * It's not unlikely to process multiple barriers at once, before the
479 : : * signals for all the barriers have arrived. To avoid unnecessary work in
480 : : * response to subsequent signals, exit early if we already have processed
481 : : * all of them.
482 : : */
1399 andres@anarazel.de 483 : 542 : local_gen = pg_atomic_read_u64(&MyProcSignalSlot->pss_barrierGeneration);
484 : 542 : shared_gen = pg_atomic_read_u64(&ProcSignal->psh_barrierGeneration);
485 : :
486 [ - + ]: 542 : Assert(local_gen <= shared_gen);
487 : :
488 [ - + ]: 542 : if (local_gen == shared_gen)
1399 andres@anarazel.de 489 :UBC 0 : return;
490 : :
491 : : /*
492 : : * Get and clear the flags that are set for this backend. Note that
493 : : * pg_atomic_exchange_u32 is a full barrier, so we're guaranteed that the
494 : : * read of the barrier generation above happens before we atomically
495 : : * extract the flags, and that any subsequent state changes happen
496 : : * afterward.
497 : : *
498 : : * NB: In order to avoid race conditions, we must zero
499 : : * pss_barrierCheckMask first and only afterwards try to do barrier
500 : : * processing. If we did it in the other order, someone could send us
501 : : * another barrier of some type right after we called the
502 : : * barrier-processing function but before we cleared the bit. We would
503 : : * have no way of knowing that the bit needs to stay set in that case, so
504 : : * the need to call the barrier-processing function again would just get
505 : : * forgotten. So instead, we tentatively clear all the bits and then put
506 : : * back any for which we don't manage to successfully absorb the barrier.
507 : : */
1578 rhaas@postgresql.org 508 :CBC 542 : flags = pg_atomic_exchange_u32(&MyProcSignalSlot->pss_barrierCheckMask, 0);
509 : :
510 : : /*
511 : : * If there are no flags set, then we can skip doing any real work.
512 : : * Otherwise, establish a PG_TRY block, so that we don't lose track of
513 : : * which types of barrier processing are needed if an ERROR occurs.
514 : : */
1182 515 [ + - ]: 542 : if (flags != 0)
516 : : {
1068 tgl@sss.pgh.pa.us 517 : 542 : bool success = true;
518 : :
1182 rhaas@postgresql.org 519 [ + - ]: 542 : PG_TRY();
520 : : {
521 : : /*
522 : : * Process each type of barrier. The barrier-processing functions
523 : : * should normally return true, but may return false if the
524 : : * barrier can't be absorbed at the current time. This should be
525 : : * rare, because it's pretty expensive. Every single
526 : : * CHECK_FOR_INTERRUPTS() will return here until we manage to
527 : : * absorb the barrier, and that cost will add up in a hurry.
528 : : *
529 : : * NB: It ought to be OK to call the barrier-processing functions
530 : : * unconditionally, but it's more efficient to call only the ones
531 : : * that might need us to do something based on the flags.
532 : : */
533 [ + + ]: 1626 : while (flags != 0)
534 : : {
535 : : ProcSignalBarrierType type;
1068 tgl@sss.pgh.pa.us 536 : 542 : bool processed = true;
537 : :
1182 rhaas@postgresql.org 538 : 542 : type = (ProcSignalBarrierType) pg_rightmost_one_pos32(flags);
539 [ + - ]: 542 : switch (type)
540 : : {
792 tmunro@postgresql.or 541 : 542 : case PROCSIGNAL_BARRIER_SMGRRELEASE:
542 : 542 : processed = ProcessBarrierSmgrRelease();
1182 rhaas@postgresql.org 543 : 542 : break;
544 : : }
545 : :
546 : : /*
547 : : * To avoid an infinite loop, we must always unset the bit in
548 : : * flags.
549 : : */
550 : 542 : BARRIER_CLEAR_BIT(flags, type);
551 : :
552 : : /*
553 : : * If we failed to process the barrier, reset the shared bit
554 : : * so we try again later, and set a flag so that we don't bump
555 : : * our generation.
556 : : */
557 [ + - ]: 542 : if (!processed)
558 : : {
1182 rhaas@postgresql.org 559 :UBC 0 : ResetProcSignalBarrierBits(((uint32) 1) << type);
560 : 0 : success = false;
561 : : }
562 : : }
563 : : }
564 : 0 : PG_CATCH();
565 : : {
566 : : /*
567 : : * If an ERROR occurred, we'll need to try again later to handle
568 : : * that barrier type and any others that haven't been handled yet
569 : : * or weren't successfully absorbed.
570 : : */
571 : 0 : ResetProcSignalBarrierBits(flags);
572 : 0 : PG_RE_THROW();
573 : : }
1182 rhaas@postgresql.org 574 [ - + ]:CBC 542 : PG_END_TRY();
575 : :
576 : : /*
577 : : * If some barrier types were not successfully absorbed, we will have
578 : : * to try again later.
579 : : */
580 [ - + ]: 542 : if (!success)
1182 rhaas@postgresql.org 581 :UBC 0 : return;
582 : : }
583 : :
584 : : /*
585 : : * State changes related to all types of barriers that might have been
586 : : * emitted have now been handled, so we can update our notion of the
587 : : * generation to the one we observed before beginning the updates. If
588 : : * things have changed further, it'll get fixed up when this function is
589 : : * next called.
590 : : */
1399 andres@anarazel.de 591 :CBC 542 : pg_atomic_write_u64(&MyProcSignalSlot->pss_barrierGeneration, shared_gen);
1140 tmunro@postgresql.or 592 : 542 : ConditionVariableBroadcast(&MyProcSignalSlot->pss_barrierCV);
593 : : }
594 : :
595 : : /*
596 : : * If it turns out that we couldn't absorb one or more barrier types, either
597 : : * because the barrier-processing functions returned false or due to an error,
598 : : * arrange for processing to be retried later.
599 : : */
600 : : static void
1182 rhaas@postgresql.org 601 :UBC 0 : ResetProcSignalBarrierBits(uint32 flags)
602 : : {
603 : 0 : pg_atomic_fetch_or_u32(&MyProcSignalSlot->pss_barrierCheckMask, flags);
604 : 0 : ProcSignalBarrierPending = true;
605 : 0 : InterruptPending = true;
606 : 0 : }
607 : :
608 : : /*
609 : : * CheckProcSignal - check to see if a particular reason has been
610 : : * signaled, and clear the signal flag. Should be called after receiving
611 : : * SIGUSR1.
612 : : */
613 : : static bool
5371 tgl@sss.pgh.pa.us 614 :CBC 129150 : CheckProcSignal(ProcSignalReason reason)
615 : : {
616 : 129150 : volatile ProcSignalSlot *slot = MyProcSignalSlot;
617 : :
618 [ + + ]: 129150 : if (slot != NULL)
619 : : {
620 : : /* Careful here --- don't clear flag if we haven't seen it set */
621 [ + + ]: 129052 : if (slot->pss_signalFlags[reason])
622 : : {
623 : 4527 : slot->pss_signalFlags[reason] = false;
624 : 4527 : return true;
625 : : }
626 : : }
627 : :
628 : 124623 : return false;
629 : : }
630 : :
631 : : /*
632 : : * procsignal_sigusr1_handler - handle SIGUSR1 signal.
633 : : */
634 : : void
635 : 9225 : procsignal_sigusr1_handler(SIGNAL_ARGS)
636 : : {
637 [ + + ]: 9225 : if (CheckProcSignal(PROCSIG_CATCHUP_INTERRUPT))
638 : 2286 : HandleCatchupInterrupt();
639 : :
640 [ + + ]: 9225 : if (CheckProcSignal(PROCSIG_NOTIFY_INTERRUPT))
641 : 20 : HandleNotifyInterrupt();
642 : :
3272 rhaas@postgresql.org 643 [ + + ]: 9225 : if (CheckProcSignal(PROCSIG_PARALLEL_MESSAGE))
644 : 1607 : HandleParallelMessageInterrupt();
645 : :
2505 andres@anarazel.de 646 [ + + ]: 9225 : if (CheckProcSignal(PROCSIG_WALSND_INIT_STOPPING))
647 : 31 : HandleWalSndInitStopping();
648 : :
1399 649 [ + + ]: 9225 : if (CheckProcSignal(PROCSIG_BARRIER))
650 : 542 : HandleProcSignalBarrierInterrupt();
651 : :
1104 fujii@postgresql.org 652 [ + + ]: 9225 : if (CheckProcSignal(PROCSIG_LOG_MEMORY_CONTEXT))
653 : 9 : HandleLogMemoryContextInterrupt();
654 : :
461 akapila@postgresql.o 655 [ + + ]: 9225 : if (CheckProcSignal(PROCSIG_PARALLEL_APPLY_MESSAGE))
656 : 13 : HandleParallelApplyMessageInterrupt();
657 : :
5202 simon@2ndQuadrant.co 658 [ + + ]: 9225 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_DATABASE))
220 tmunro@postgresql.or 659 :GNC 2 : HandleRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_DATABASE);
660 : :
5202 simon@2ndQuadrant.co 661 [ + + ]:CBC 9225 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_TABLESPACE))
220 tmunro@postgresql.or 662 :GNC 1 : HandleRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_TABLESPACE);
663 : :
5202 simon@2ndQuadrant.co 664 [ + + ]:CBC 9225 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_LOCK))
220 tmunro@postgresql.or 665 :GNC 1 : HandleRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_LOCK);
666 : :
5202 simon@2ndQuadrant.co 667 [ + + ]:CBC 9225 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT))
220 tmunro@postgresql.or 668 :GNC 1 : HandleRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT);
669 : :
373 andres@anarazel.de 670 [ + + ]:CBC 9225 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_LOGICALSLOT))
220 tmunro@postgresql.or 671 :GNC 5 : HandleRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_LOGICALSLOT);
672 : :
5174 simon@2ndQuadrant.co 673 [ + + ]:CBC 9225 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK))
220 tmunro@postgresql.or 674 :GNC 8 : HandleRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
675 : :
5195 simon@2ndQuadrant.co 676 [ + + ]:CBC 9225 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))
220 tmunro@postgresql.or 677 :GNC 1 : HandleRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
678 : :
3110 rhaas@postgresql.org 679 :CBC 9225 : SetLatch(MyLatch);
5371 tgl@sss.pgh.pa.us 680 : 9225 : }
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