Age Owner TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * procsignal.c
4 : * Routines for interprocess signaling
5 : *
6 : *
7 : * Portions Copyright (c) 1996-2023, 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 "port/pg_bitutils.h"
22 : #include "commands/async.h"
23 : #include "miscadmin.h"
24 : #include "pgstat.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/proc.h"
31 : #include "storage/shmem.h"
32 : #include "storage/smgr.h"
33 : #include "storage/sinval.h"
34 : #include "tcop/tcopprot.h"
35 : #include "utils/memutils.h"
36 :
37 : /*
38 : * The SIGUSR1 signal is multiplexed to support signaling multiple event
39 : * types. The specific reason is communicated via flags in shared memory.
40 : * We keep a boolean flag for each possible "reason", so that different
41 : * reasons can be signaled to a process concurrently. (However, if the same
42 : * reason is signaled more than once nearly simultaneously, the process may
43 : * observe it only once.)
44 : *
45 : * Each process that wants to receive signals registers its process ID
46 : * in the ProcSignalSlots array. The array is indexed by backend ID to make
47 : * slot allocation simple, and to avoid having to search the array when you
48 : * know the backend ID of the process you're signaling. (We do support
49 : * signaling without backend ID, but it's a bit less efficient.)
50 : *
51 : * The flags are actually declared as "volatile sig_atomic_t" for maximum
52 : * portability. This should ensure that loads and stores of the flag
53 : * values are atomic, allowing us to dispense with any explicit locking.
54 : *
55 : * pss_signalFlags are intended to be set in cases where we don't need to
56 : * keep track of whether or not the target process has handled the signal,
57 : * but sometimes we need confirmation, as when making a global state change
58 : * that cannot be considered complete until all backends have taken notice
59 : * of it. For such use cases, we set a bit in pss_barrierCheckMask and then
60 : * increment the current "barrier generation"; when the new barrier generation
61 : * (or greater) appears in the pss_barrierGeneration flag of every process,
62 : * we know that the message has been received everywhere.
63 : */
64 : typedef struct
65 : {
66 : volatile pid_t pss_pid;
67 : volatile sig_atomic_t pss_signalFlags[NUM_PROCSIGNALS];
68 : pg_atomic_uint64 pss_barrierGeneration;
69 : pg_atomic_uint32 pss_barrierCheckMask;
70 : ConditionVariable pss_barrierCV;
71 : } ProcSignalSlot;
72 :
73 : /*
74 : * Information that is global to the entire ProcSignal system can be stored
75 : * here.
76 : *
77 : * psh_barrierGeneration is the highest barrier generation in existence.
78 : */
79 : typedef struct
80 : {
81 : pg_atomic_uint64 psh_barrierGeneration;
82 : ProcSignalSlot psh_slot[FLEXIBLE_ARRAY_MEMBER];
83 : } ProcSignalHeader;
84 :
85 : /*
86 : * We reserve a slot for each possible BackendId, plus one for each
87 : * possible auxiliary process type. (This scheme assumes there is not
88 : * more than one of any auxiliary process type at a time.)
89 : */
90 : #define NumProcSignalSlots (MaxBackends + NUM_AUXPROCTYPES)
91 :
92 : /* Check whether the relevant type bit is set in the flags. */
93 : #define BARRIER_SHOULD_CHECK(flags, type) \
94 : (((flags) & (((uint32) 1) << (uint32) (type))) != 0)
95 :
96 : /* Clear the relevant type bit from the flags. */
97 : #define BARRIER_CLEAR_BIT(flags, type) \
98 : ((flags) &= ~(((uint32) 1) << (uint32) (type)))
99 :
100 : static ProcSignalHeader *ProcSignal = NULL;
101 : static ProcSignalSlot *MyProcSignalSlot = NULL;
102 :
103 : static bool CheckProcSignal(ProcSignalReason reason);
104 : static void CleanupProcSignalState(int status, Datum arg);
105 : static void ResetProcSignalBarrierBits(uint32 flags);
106 :
107 : /*
108 : * ProcSignalShmemSize
109 : * Compute space needed for ProcSignal's shared memory
110 : */
111 : Size
5000 tgl 112 GIC 4564 : ProcSignalShmemSize(void)
5000 tgl 113 ECB : {
114 : Size size;
115 :
362 rhaas 116 GIC 4564 : size = mul_size(NumProcSignalSlots, sizeof(ProcSignalSlot));
1207 rhaas 117 CBC 4564 : size = add_size(size, offsetof(ProcSignalHeader, psh_slot));
118 4564 : return size;
5000 tgl 119 ECB : }
120 :
121 : /*
122 : * ProcSignalShmemInit
123 : * Allocate and initialize ProcSignal's shared memory
124 : */
125 : void
5000 tgl 126 GIC 1826 : ProcSignalShmemInit(void)
5000 tgl 127 ECB : {
5000 tgl 128 GIC 1826 : Size size = ProcSignalShmemSize();
5000 tgl 129 ECB : bool found;
130 :
1207 rhaas 131 GIC 1826 : ProcSignal = (ProcSignalHeader *)
1207 rhaas 132 CBC 1826 : ShmemInitStruct("ProcSignal", size, &found);
5000 tgl 133 ECB :
134 : /* If we're first, initialize. */
5000 tgl 135 GIC 1826 : if (!found)
1207 rhaas 136 ECB : {
137 : int i;
138 :
1207 rhaas 139 GIC 1826 : pg_atomic_init_u64(&ProcSignal->psh_barrierGeneration, 0);
1207 rhaas 140 ECB :
362 rhaas 141 GIC 204159 : for (i = 0; i < NumProcSignalSlots; ++i)
1207 rhaas 142 ECB : {
1207 rhaas 143 GIC 202333 : ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
1207 rhaas 144 ECB :
1207 rhaas 145 GIC 202333 : slot->pss_pid = 0;
1207 rhaas 146 CBC 202333 : MemSet(slot->pss_signalFlags, 0, sizeof(slot->pss_signalFlags));
147 202333 : pg_atomic_init_u64(&slot->pss_barrierGeneration, PG_UINT64_MAX);
148 202333 : pg_atomic_init_u32(&slot->pss_barrierCheckMask, 0);
769 tmunro 149 202333 : ConditionVariableInit(&slot->pss_barrierCV);
1207 rhaas 150 ECB : }
151 : }
5000 tgl 152 GIC 1826 : }
5000 tgl 153 ECB :
154 : /*
155 : * ProcSignalInit
156 : * Register the current process in the ProcSignal array
157 : *
158 : * The passed index should be my BackendId if the process has one,
159 : * or MaxBackends + aux process type if not.
160 : */
161 : void
5000 tgl 162 GIC 13282 : ProcSignalInit(int pss_idx)
5000 tgl 163 ECB : {
164 : ProcSignalSlot *slot;
165 : uint64 barrier_generation;
166 :
362 rhaas 167 GIC 13282 : Assert(pss_idx >= 1 && pss_idx <= NumProcSignalSlots);
5000 tgl 168 ECB :
1207 rhaas 169 GIC 13282 : slot = &ProcSignal->psh_slot[pss_idx - 1];
5000 tgl 170 ECB :
171 : /* sanity check */
5000 tgl 172 GIC 13282 : if (slot->pss_pid != 0)
5000 tgl 173 LBC 0 : elog(LOG, "process %d taking over ProcSignal slot %d, but it's not empty",
5000 tgl 174 EUB : MyProcPid, pss_idx);
175 :
176 : /* Clear out any leftover signal reasons */
5000 tgl 177 GIC 13282 : MemSet(slot->pss_signalFlags, 0, NUM_PROCSIGNALS * sizeof(sig_atomic_t));
5000 tgl 178 ECB :
179 : /*
180 : * Initialize barrier state. Since we're a brand-new process, there
181 : * shouldn't be any leftover backend-private state that needs to be
182 : * updated. Therefore, we can broadcast the latest barrier generation and
183 : * disregard any previously-set check bits.
184 : *
185 : * NB: This only works if this initialization happens early enough in the
186 : * startup sequence that we haven't yet cached any state that might need
187 : * to be invalidated. That's also why we have a memory barrier here, to be
188 : * sure that any later reads of memory happen strictly after this.
189 : */
1207 rhaas 190 GIC 13282 : pg_atomic_write_u32(&slot->pss_barrierCheckMask, 0);
1207 rhaas 191 ECB : barrier_generation =
1207 rhaas 192 GIC 13282 : pg_atomic_read_u64(&ProcSignal->psh_barrierGeneration);
1207 rhaas 193 CBC 13282 : pg_atomic_write_u64(&slot->pss_barrierGeneration, barrier_generation);
194 13282 : pg_memory_barrier();
1207 rhaas 195 ECB :
196 : /* Mark slot with my PID */
5000 tgl 197 GIC 13282 : slot->pss_pid = MyProcPid;
5000 tgl 198 ECB :
199 : /* Remember slot location for CheckProcSignal */
5000 tgl 200 GIC 13282 : MyProcSignalSlot = slot;
5000 tgl 201 ECB :
202 : /* Set up to release the slot on process exit */
5000 tgl 203 GIC 13282 : on_shmem_exit(CleanupProcSignalState, Int32GetDatum(pss_idx));
5000 tgl 204 CBC 13282 : }
5000 tgl 205 ECB :
206 : /*
207 : * CleanupProcSignalState
208 : * Remove current process from ProcSignal mechanism
209 : *
210 : * This function is called via on_shmem_exit() during backend shutdown.
211 : */
212 : static void
5000 tgl 213 GIC 13282 : CleanupProcSignalState(int status, Datum arg)
5000 tgl 214 ECB : {
5000 tgl 215 GIC 13282 : int pss_idx = DatumGetInt32(arg);
769 tmunro 216 ECB : ProcSignalSlot *slot;
217 :
1207 rhaas 218 GIC 13282 : slot = &ProcSignal->psh_slot[pss_idx - 1];
5000 tgl 219 CBC 13282 : Assert(slot == MyProcSignalSlot);
5000 tgl 220 ECB :
221 : /*
222 : * Clear MyProcSignalSlot, so that a SIGUSR1 received after this point
223 : * won't try to access it after it's no longer ours (and perhaps even
224 : * after we've unmapped the shared memory segment).
225 : */
3355 rhaas 226 GIC 13282 : MyProcSignalSlot = NULL;
3355 rhaas 227 ECB :
228 : /* sanity check */
5000 tgl 229 GIC 13282 : if (slot->pss_pid != MyProcPid)
5000 tgl 230 ECB : {
231 : /*
232 : * don't ERROR here. We're exiting anyway, and don't want to get into
233 : * infinite loop trying to exit
234 : */
5000 tgl 235 UIC 0 : elog(LOG, "process %d releasing ProcSignal slot %d, but it contains %d",
5000 tgl 236 EUB : MyProcPid, pss_idx, (int) slot->pss_pid);
5000 tgl 237 UIC 0 : return; /* XXX better to zero the slot anyway? */
5000 tgl 238 EUB : }
239 :
240 : /*
241 : * Make this slot look like it's absorbed all possible barriers, so that
242 : * no barrier waits block on it.
243 : */
1207 rhaas 244 GIC 13282 : pg_atomic_write_u64(&slot->pss_barrierGeneration, PG_UINT64_MAX);
769 tmunro 245 CBC 13282 : ConditionVariableBroadcast(&slot->pss_barrierCV);
1207 rhaas 246 ECB :
5000 tgl 247 GIC 13282 : slot->pss_pid = 0;
5000 tgl 248 ECB : }
249 :
250 : /*
251 : * SendProcSignal
252 : * Send a signal to a Postgres process
253 : *
254 : * Providing backendId is optional, but it will speed up the operation.
255 : *
256 : * On success (a signal was sent), zero is returned.
257 : * On error, -1 is returned, and errno is set (typically to ESRCH or EPERM).
258 : *
259 : * Not to be confused with ProcSendSignal
260 : */
261 : int
5000 tgl 262 GIC 6650 : SendProcSignal(pid_t pid, ProcSignalReason reason, BackendId backendId)
5000 tgl 263 ECB : {
264 : volatile ProcSignalSlot *slot;
265 :
5000 tgl 266 GIC 6650 : if (backendId != InvalidBackendId)
5000 tgl 267 ECB : {
1207 rhaas 268 GIC 6600 : slot = &ProcSignal->psh_slot[backendId - 1];
5000 tgl 269 ECB :
270 : /*
271 : * Note: Since there's no locking, it's possible that the target
272 : * process detaches from shared memory and exits right after this
273 : * test, before we set the flag and send signal. And the signal slot
274 : * might even be recycled by a new process, so it's remotely possible
275 : * that we set a flag for a wrong process. That's OK, all the signals
276 : * are such that no harm is done if they're mistakenly fired.
277 : */
5000 tgl 278 GIC 6600 : if (slot->pss_pid == pid)
5000 tgl 279 ECB : {
280 : /* Atomically set the proper flag */
5000 tgl 281 GIC 6600 : slot->pss_signalFlags[reason] = true;
5000 tgl 282 ECB : /* Send signal */
5000 tgl 283 GIC 6600 : return kill(pid, SIGUSR1);
5000 tgl 284 ECB : }
285 : }
286 : else
287 : {
288 : /*
289 : * BackendId not provided, so search the array using pid. We search
290 : * the array back to front so as to reduce search overhead. Passing
291 : * InvalidBackendId means that the target is most likely an auxiliary
292 : * process, which will have a slot near the end of the array.
293 : */
294 : int i;
295 :
362 rhaas 296 GIC 1654 : for (i = NumProcSignalSlots - 1; i >= 0; i--)
5000 tgl 297 ECB : {
1207 rhaas 298 GIC 1644 : slot = &ProcSignal->psh_slot[i];
5000 tgl 299 ECB :
5000 tgl 300 GIC 1644 : if (slot->pss_pid == pid)
5000 tgl 301 ECB : {
302 : /* the above note about race conditions applies here too */
303 :
304 : /* Atomically set the proper flag */
5000 tgl 305 GIC 40 : slot->pss_signalFlags[reason] = true;
5000 tgl 306 ECB : /* Send signal */
5000 tgl 307 GIC 40 : return kill(pid, SIGUSR1);
5000 tgl 308 ECB : }
309 : }
310 : }
311 :
5000 tgl 312 GIC 10 : errno = ESRCH;
5000 tgl 313 CBC 10 : return -1;
5000 tgl 314 ECB : }
315 :
316 : /*
317 : * EmitProcSignalBarrier
318 : * Send a signal to every Postgres process
319 : *
320 : * The return value of this function is the barrier "generation" created
321 : * by this operation. This value can be passed to WaitForProcSignalBarrier
322 : * to wait until it is known that every participant in the ProcSignal
323 : * mechanism has absorbed the signal (or started afterwards).
324 : *
325 : * Note that it would be a bad idea to use this for anything that happens
326 : * frequently, as interrupting every backend could cause a noticeable
327 : * performance hit.
328 : *
329 : * Callers are entitled to assume that this function will not throw ERROR
330 : * or FATAL.
331 : */
332 : uint64
1207 rhaas 333 GIC 56 : EmitProcSignalBarrier(ProcSignalBarrierType type)
1207 rhaas 334 ECB : {
1028 andres 335 GIC 56 : uint32 flagbit = 1 << (uint32) type;
1060 tgl 336 ECB : uint64 generation;
337 :
338 : /*
339 : * Set all the flags.
340 : *
341 : * Note that pg_atomic_fetch_or_u32 has full barrier semantics, so this is
342 : * totally ordered with respect to anything the caller did before, and
343 : * anything that we do afterwards. (This is also true of the later call to
344 : * pg_atomic_add_fetch_u64.)
345 : */
362 rhaas 346 GIC 3706 : for (int i = 0; i < NumProcSignalSlots; i++)
1207 rhaas 347 ECB : {
1207 rhaas 348 GIC 3650 : volatile ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
1207 rhaas 349 ECB :
1207 rhaas 350 GIC 3650 : pg_atomic_fetch_or_u32(&slot->pss_barrierCheckMask, flagbit);
1207 rhaas 351 ECB : }
352 :
353 : /*
354 : * Increment the generation counter.
355 : */
356 : generation =
1207 rhaas 357 GIC 56 : pg_atomic_add_fetch_u64(&ProcSignal->psh_barrierGeneration, 1);
1207 rhaas 358 ECB :
359 : /*
360 : * Signal all the processes, so that they update their advertised barrier
361 : * generation.
362 : *
363 : * Concurrency is not a problem here. Backends that have exited don't
364 : * matter, and new backends that have joined since we entered this
365 : * function must already have current state, since the caller is
366 : * responsible for making sure that the relevant state is entirely visible
367 : * before calling this function in the first place. We still have to wake
368 : * them up - because we can't distinguish between such backends and older
369 : * backends that need to update state - but they won't actually need to
370 : * change any state.
371 : */
362 rhaas 372 GIC 3706 : for (int i = NumProcSignalSlots - 1; i >= 0; i--)
1207 rhaas 373 ECB : {
1207 rhaas 374 GIC 3650 : volatile ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
1060 tgl 375 CBC 3650 : pid_t pid = slot->pss_pid;
1207 rhaas 376 ECB :
1207 rhaas 377 GIC 3650 : if (pid != 0)
1028 andres 378 ECB : {
379 : /* see SendProcSignal for details */
1028 andres 380 GIC 333 : slot->pss_signalFlags[PROCSIG_BARRIER] = true;
1207 rhaas 381 CBC 333 : kill(pid, SIGUSR1);
1028 andres 382 ECB : }
383 : }
384 :
1207 rhaas 385 GIC 56 : return generation;
1207 rhaas 386 ECB : }
387 :
388 : /*
389 : * WaitForProcSignalBarrier - wait until it is guaranteed that all changes
390 : * requested by a specific call to EmitProcSignalBarrier() have taken effect.
391 : */
392 : void
1207 rhaas 393 GIC 56 : WaitForProcSignalBarrier(uint64 generation)
1207 rhaas 394 ECB : {
1028 andres 395 GIC 56 : Assert(generation <= pg_atomic_read_u64(&ProcSignal->psh_barrierGeneration));
1028 andres 396 ECB :
333 tmunro 397 GIC 56 : elog(DEBUG1,
333 tmunro 398 ECB : "waiting for all backends to process ProcSignalBarrier generation "
399 : UINT64_FORMAT,
400 : generation);
401 :
362 rhaas 402 GIC 3706 : for (int i = NumProcSignalSlots - 1; i >= 0; i--)
1207 rhaas 403 ECB : {
769 tmunro 404 GIC 3650 : ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
1060 tgl 405 ECB : uint64 oldval;
406 :
407 : /*
408 : * It's important that we check only pss_barrierGeneration here and
409 : * not pss_barrierCheckMask. Bits in pss_barrierCheckMask get cleared
410 : * before the barrier is actually absorbed, but pss_barrierGeneration
411 : * is updated only afterward.
412 : */
1207 rhaas 413 GIC 3650 : oldval = pg_atomic_read_u64(&slot->pss_barrierGeneration);
1207 rhaas 414 CBC 3827 : while (oldval < generation)
1207 rhaas 415 ECB : {
333 tmunro 416 GIC 177 : if (ConditionVariableTimedSleep(&slot->pss_barrierCV,
333 tmunro 417 ECB : 5000,
418 : WAIT_EVENT_PROC_SIGNAL_BARRIER))
333 tmunro 419 UIC 0 : ereport(LOG,
420 : (errmsg("still waiting for backend with PID %d to accept ProcSignalBarrier",
421 : (int) slot->pss_pid)));
1207 rhaas 422 GIC 177 : oldval = pg_atomic_read_u64(&slot->pss_barrierGeneration);
1207 rhaas 423 ECB : }
769 tmunro 424 GIC 3650 : ConditionVariableCancelSleep();
1207 rhaas 425 ECB : }
426 :
333 tmunro 427 GIC 56 : elog(DEBUG1,
333 tmunro 428 ECB : "finished waiting for all backends to process ProcSignalBarrier generation "
429 : UINT64_FORMAT,
430 : generation);
431 :
432 : /*
433 : * The caller is probably calling this function because it wants to read
434 : * the shared state or perform further writes to shared state once all
435 : * backends are known to have absorbed the barrier. However, the read of
436 : * pss_barrierGeneration was performed unlocked; insert a memory barrier
437 : * to separate it from whatever follows.
438 : */
1207 rhaas 439 GIC 56 : pg_memory_barrier();
1207 rhaas 440 CBC 56 : }
1207 rhaas 441 ECB :
442 : /*
443 : * Handle receipt of an interrupt indicating a global barrier event.
444 : *
445 : * All the actual work is deferred to ProcessProcSignalBarrier(), because we
446 : * cannot safely access the barrier generation inside the signal handler as
447 : * 64bit atomics might use spinlock based emulation, even for reads. As this
448 : * routine only gets called when PROCSIG_BARRIER is sent that won't cause a
449 : * lot of unnecessary work.
450 : */
451 : static void
1028 andres 452 GIC 248 : HandleProcSignalBarrierInterrupt(void)
1028 andres 453 ECB : {
1028 andres 454 GIC 248 : InterruptPending = true;
1028 andres 455 CBC 248 : ProcSignalBarrierPending = true;
1028 andres 456 ECB : /* latch will be set by procsignal_sigusr1_handler */
1028 andres 457 GIC 248 : }
1028 andres 458 ECB :
459 : /*
460 : * Perform global barrier related interrupt checking.
461 : *
462 : * Any backend that participates in ProcSignal signaling must arrange to
463 : * call this function periodically. It is called from CHECK_FOR_INTERRUPTS(),
464 : * which is enough for normal backends, but not necessarily for all types of
465 : * background processes.
466 : */
467 : void
1207 rhaas 468 GIC 248 : ProcessProcSignalBarrier(void)
1207 rhaas 469 ECB : {
470 : uint64 local_gen;
471 : uint64 shared_gen;
472 : volatile uint32 flags;
473 :
1028 andres 474 GIC 248 : Assert(MyProcSignalSlot);
1028 andres 475 ECB :
476 : /* Exit quickly if there's no work to do. */
1207 rhaas 477 GIC 248 : if (!ProcSignalBarrierPending)
1207 rhaas 478 LBC 0 : return;
1207 rhaas 479 GBC 248 : ProcSignalBarrierPending = false;
1207 rhaas 480 ECB :
481 : /*
482 : * It's not unlikely to process multiple barriers at once, before the
483 : * signals for all the barriers have arrived. To avoid unnecessary work in
484 : * response to subsequent signals, exit early if we already have processed
485 : * all of them.
486 : */
1028 andres 487 GIC 248 : local_gen = pg_atomic_read_u64(&MyProcSignalSlot->pss_barrierGeneration);
1028 andres 488 CBC 248 : shared_gen = pg_atomic_read_u64(&ProcSignal->psh_barrierGeneration);
1028 andres 489 ECB :
1028 andres 490 GIC 248 : Assert(local_gen <= shared_gen);
1028 andres 491 ECB :
1028 andres 492 GIC 248 : if (local_gen == shared_gen)
1028 andres 493 LBC 0 : return;
1028 andres 494 EUB :
495 : /*
496 : * Get and clear the flags that are set for this backend. Note that
497 : * pg_atomic_exchange_u32 is a full barrier, so we're guaranteed that the
498 : * read of the barrier generation above happens before we atomically
499 : * extract the flags, and that any subsequent state changes happen
500 : * afterward.
501 : *
502 : * NB: In order to avoid race conditions, we must zero
503 : * pss_barrierCheckMask first and only afterwards try to do barrier
504 : * processing. If we did it in the other order, someone could send us
505 : * another barrier of some type right after we called the
506 : * barrier-processing function but before we cleared the bit. We would
507 : * have no way of knowing that the bit needs to stay set in that case, so
508 : * the need to call the barrier-processing function again would just get
509 : * forgotten. So instead, we tentatively clear all the bits and then put
510 : * back any for which we don't manage to successfully absorb the barrier.
511 : */
1207 rhaas 512 GIC 248 : flags = pg_atomic_exchange_u32(&MyProcSignalSlot->pss_barrierCheckMask, 0);
1207 rhaas 513 ECB :
514 : /*
515 : * If there are no flags set, then we can skip doing any real work.
516 : * Otherwise, establish a PG_TRY block, so that we don't lose track of
517 : * which types of barrier processing are needed if an ERROR occurs.
518 : */
811 rhaas 519 GIC 248 : if (flags != 0)
811 rhaas 520 ECB : {
697 tgl 521 GIC 248 : bool success = true;
811 rhaas 522 ECB :
811 rhaas 523 GIC 248 : PG_TRY();
811 rhaas 524 ECB : {
525 : /*
526 : * Process each type of barrier. The barrier-processing functions
527 : * should normally return true, but may return false if the
528 : * barrier can't be absorbed at the current time. This should be
529 : * rare, because it's pretty expensive. Every single
530 : * CHECK_FOR_INTERRUPTS() will return here until we manage to
531 : * absorb the barrier, and that cost will add up in a hurry.
532 : *
533 : * NB: It ought to be OK to call the barrier-processing functions
534 : * unconditionally, but it's more efficient to call only the ones
535 : * that might need us to do something based on the flags.
536 : */
811 rhaas 537 GIC 744 : while (flags != 0)
811 rhaas 538 ECB : {
539 : ProcSignalBarrierType type;
697 tgl 540 GIC 248 : bool processed = true;
811 rhaas 541 ECB :
811 rhaas 542 GIC 248 : type = (ProcSignalBarrierType) pg_rightmost_one_pos32(flags);
811 rhaas 543 CBC 248 : switch (type)
811 rhaas 544 ECB : {
421 tmunro 545 GIC 248 : case PROCSIGNAL_BARRIER_SMGRRELEASE:
421 tmunro 546 CBC 248 : processed = ProcessBarrierSmgrRelease();
811 rhaas 547 248 : break;
811 rhaas 548 ECB : }
549 :
550 : /*
551 : * To avoid an infinite loop, we must always unset the bit in
552 : * flags.
553 : */
811 rhaas 554 GIC 248 : BARRIER_CLEAR_BIT(flags, type);
811 rhaas 555 ECB :
556 : /*
557 : * If we failed to process the barrier, reset the shared bit
558 : * so we try again later, and set a flag so that we don't bump
559 : * our generation.
560 : */
811 rhaas 561 GIC 248 : if (!processed)
811 rhaas 562 ECB : {
811 rhaas 563 UIC 0 : ResetProcSignalBarrierBits(((uint32) 1) << type);
811 rhaas 564 UBC 0 : success = false;
811 rhaas 565 EUB : }
566 : }
567 : }
811 rhaas 568 UIC 0 : PG_CATCH();
811 rhaas 569 EUB : {
570 : /*
571 : * If an ERROR occurred, we'll need to try again later to handle
572 : * that barrier type and any others that haven't been handled yet
573 : * or weren't successfully absorbed.
574 : */
811 rhaas 575 UIC 0 : ResetProcSignalBarrierBits(flags);
811 rhaas 576 UBC 0 : PG_RE_THROW();
811 rhaas 577 EUB : }
811 rhaas 578 GIC 248 : PG_END_TRY();
811 rhaas 579 ECB :
580 : /*
581 : * If some barrier types were not successfully absorbed, we will have
582 : * to try again later.
583 : */
811 rhaas 584 GIC 248 : if (!success)
811 rhaas 585 LBC 0 : return;
811 rhaas 586 EUB : }
587 :
588 : /*
589 : * State changes related to all types of barriers that might have been
590 : * emitted have now been handled, so we can update our notion of the
591 : * generation to the one we observed before beginning the updates. If
592 : * things have changed further, it'll get fixed up when this function is
593 : * next called.
594 : */
1028 andres 595 GIC 248 : pg_atomic_write_u64(&MyProcSignalSlot->pss_barrierGeneration, shared_gen);
769 tmunro 596 CBC 248 : ConditionVariableBroadcast(&MyProcSignalSlot->pss_barrierCV);
1207 rhaas 597 ECB : }
598 :
599 : /*
600 : * If it turns out that we couldn't absorb one or more barrier types, either
601 : * because the barrier-processing functions returned false or due to an error,
602 : * arrange for processing to be retried later.
603 : */
604 : static void
811 rhaas 605 UIC 0 : ResetProcSignalBarrierBits(uint32 flags)
811 rhaas 606 EUB : {
811 rhaas 607 UIC 0 : pg_atomic_fetch_or_u32(&MyProcSignalSlot->pss_barrierCheckMask, flags);
811 rhaas 608 UBC 0 : ProcSignalBarrierPending = true;
609 0 : InterruptPending = true;
610 0 : }
811 rhaas 611 EUB :
612 : /*
613 : * CheckProcSignal - check to see if a particular reason has been
614 : * signaled, and clear the signal flag. Should be called after receiving
615 : * SIGUSR1.
616 : */
617 : static bool
5000 tgl 618 GIC 135394 : CheckProcSignal(ProcSignalReason reason)
5000 tgl 619 ECB : {
5000 tgl 620 GIC 135394 : volatile ProcSignalSlot *slot = MyProcSignalSlot;
5000 tgl 621 ECB :
5000 tgl 622 GIC 135394 : if (slot != NULL)
5000 tgl 623 ECB : {
624 : /* Careful here --- don't clear flag if we haven't seen it set */
5000 tgl 625 GIC 135296 : if (slot->pss_signalFlags[reason])
5000 tgl 626 ECB : {
5000 tgl 627 GIC 5690 : slot->pss_signalFlags[reason] = false;
5000 tgl 628 CBC 5690 : return true;
5000 tgl 629 ECB : }
630 : }
631 :
5000 tgl 632 GIC 129704 : return false;
5000 tgl 633 ECB : }
634 :
635 : /*
636 : * procsignal_sigusr1_handler - handle SIGUSR1 signal.
637 : */
638 : void
5000 tgl 639 GIC 9671 : procsignal_sigusr1_handler(SIGNAL_ARGS)
5000 tgl 640 ECB : {
4790 bruce 641 GIC 9671 : int save_errno = errno;
5000 tgl 642 ECB :
5000 tgl 643 GIC 9671 : if (CheckProcSignal(PROCSIG_CATCHUP_INTERRUPT))
5000 tgl 644 CBC 2651 : HandleCatchupInterrupt();
5000 tgl 645 ECB :
5000 tgl 646 GIC 9671 : if (CheckProcSignal(PROCSIG_NOTIFY_INTERRUPT))
5000 tgl 647 CBC 20 : HandleNotifyInterrupt();
5000 tgl 648 ECB :
2901 rhaas 649 GIC 9671 : if (CheckProcSignal(PROCSIG_PARALLEL_MESSAGE))
2901 rhaas 650 CBC 2711 : HandleParallelMessageInterrupt();
2901 rhaas 651 ECB :
2134 andres 652 GIC 9671 : if (CheckProcSignal(PROCSIG_WALSND_INIT_STOPPING))
2134 andres 653 CBC 27 : HandleWalSndInitStopping();
2134 andres 654 ECB :
1028 andres 655 GIC 9671 : if (CheckProcSignal(PROCSIG_BARRIER))
1028 andres 656 CBC 248 : HandleProcSignalBarrierInterrupt();
1028 andres 657 ECB :
733 fujii 658 GIC 9671 : if (CheckProcSignal(PROCSIG_LOG_MEMORY_CONTEXT))
733 fujii 659 CBC 9 : HandleLogMemoryContextInterrupt();
733 fujii 660 ECB :
90 akapila 661 GNC 9671 : if (CheckProcSignal(PROCSIG_PARALLEL_APPLY_MESSAGE))
662 5 : HandleParallelApplyMessageInterrupt();
663 :
4831 simon 664 GIC 9671 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_DATABASE))
4831 simon 665 CBC 2 : RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_DATABASE);
4831 simon 666 ECB :
4831 simon 667 GIC 9671 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_TABLESPACE))
4831 simon 668 CBC 1 : RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_TABLESPACE);
4831 simon 669 ECB :
4831 simon 670 GIC 9671 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_LOCK))
4831 simon 671 CBC 1 : RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_LOCK);
4831 simon 672 ECB :
4831 simon 673 GIC 9671 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT))
4831 simon 674 CBC 1 : RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT);
4831 simon 675 ECB :
2 andres 676 GNC 9671 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_LOGICALSLOT))
677 5 : RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_LOGICALSLOT);
678 :
4803 simon 679 GIC 9671 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK))
4803 simon 680 CBC 8 : RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
4803 simon 681 ECB :
4824 simon 682 GIC 9671 : if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))
4824 simon 683 CBC 1 : RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
4824 simon 684 ECB :
2739 rhaas 685 GIC 9671 : SetLatch(MyLatch);
3511 rhaas 686 ECB :
5000 tgl 687 CBC 9671 : errno = save_errno;
5000 tgl 688 GIC 9671 : }
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