/*
* ProcSendSignal - send a signal to a backend identified by PID
*/
void
ProcSendSignal(int pid)
{
PGPROC *proc = NULL;
if (RecoveryInProgress())
{
/* use volatile pointer to prevent code rearrangement */
volatile PROC_HDR *procglobal = ProcGlobal;
SpinLockAcquire(ProcStructLock);
/*
* Check to see whether it is the Startup process we wish to signal.
* This call is made by the buffer manager when it wishes to wake up a
* process that has been waiting for a pin in so it can obtain a
* cleanup lock using LockBufferForCleanup(). Startup is not a normal
* backend, so BackendPidGetProc() will not return any pid at all. So
* we remember the information for this special case.
*/
if (pid == procglobal->startupProcPid)
proc = procglobal->startupProc;
SpinLockRelease(ProcStructLock);
}
if (proc == NULL)
proc = BackendPidGetProc(pid);
if (proc != NULL)
{
SetLatch(&proc->procLatch);
}
}
/*
* ProcSendSignal - send a signal to a backend identified by PID
*/
void
ProcSendSignal(int pid)
{
PGPROC *proc = BackendPidGetProc(pid);
if (proc != NULL)
PGSemaphoreUnlock(&proc->sem);
}
static int
pg_signal_backend(int pid, int sig)
{
PGPROC *proc;
if (!superuser())
{
/*
* Since the user is not superuser, check for matching roles. Trust
* that BackendPidGetProc will return NULL if the pid isn't valid,
* even though the check for whether it's a backend process is below.
* The IsBackendPid check can't be relied on as definitive even if it
* was first. The process might end between successive checks
* regardless of their order. There's no way to acquire a lock on an
* arbitrary process to prevent that. But since so far all the callers
* of this mechanism involve some request for ending the process
* anyway, that it might end on its own first is not a problem.
*/
proc = BackendPidGetProc(pid);
if (proc == NULL || proc->roleId != GetUserId())
return SIGNAL_BACKEND_NOPERMISSION;
}
if (!IsBackendPid(pid))
{
/*
* This is just a warning so a loop-through-resultset will not abort
* if one backend terminated on it's own during the run
*/
ereport(WARNING,
(errmsg("PID %d is not a PostgreSQL server process", pid)));
return SIGNAL_BACKEND_ERROR;
}
/*
* Can the process we just validated above end, followed by the pid being
* recycled for a new process, before reaching here? Then we'd be trying
* to kill the wrong thing. Seems near impossible when sequential pid
* assignment and wraparound is used. Perhaps it could happen on a system
* where pid re-use is randomized. That race condition possibility seems
* too unlikely to worry about.
*/
/* If we have setsid(), signal the backend's whole process group */
#ifdef HAVE_SETSID
if (kill(-pid, sig))
#else
if (kill(pid, sig))
#endif
{
/* Again, just a warning to allow loops */
ereport(WARNING,
(errmsg("could not send signal to process %d: %m", pid)));
return SIGNAL_BACKEND_ERROR;
}
return SIGNAL_BACKEND_SUCCESS;
}
static int
pg_signal_backend(int pid, int sig)
{
PGPROC *proc = BackendPidGetProc(pid);
/*
* BackendPidGetProc returns NULL if the pid isn't valid; but by the time
* we reach kill(), a process for which we get a valid proc here might
* have terminated on its own. There's no way to acquire a lock on an
* arbitrary process to prevent that. But since so far all the callers of
* this mechanism involve some request for ending the process anyway, that
* it might end on its own first is not a problem.
*/
if (proc == NULL)
{
/*
* This is just a warning so a loop-through-resultset will not abort
* if one backend terminated on its own during the run.
*/
ereport(WARNING,
(errmsg("PID %d is not a PostgreSQL server process", pid)));
return SIGNAL_BACKEND_ERROR;
}
/* Only allow superusers to signal superuser-owned backends. */
if (superuser_arg(proc->roleId) && !superuser())
return SIGNAL_BACKEND_NOSUPERUSER;
/* Users can signal backends they have role membership in. */
if (!has_privs_of_role(GetUserId(), proc->roleId) &&
!has_privs_of_role(GetUserId(), DEFAULT_ROLE_SIGNAL_BACKENDID))
return SIGNAL_BACKEND_NOPERMISSION;
/*
* Can the process we just validated above end, followed by the pid being
* recycled for a new process, before reaching here? Then we'd be trying
* to kill the wrong thing. Seems near impossible when sequential pid
* assignment and wraparound is used. Perhaps it could happen on a system
* where pid re-use is randomized. That race condition possibility seems
* too unlikely to worry about.
*/
/* If we have setsid(), signal the backend's whole process group */
#ifdef HAVE_SETSID
if (kill(-pid, sig))
#else
if (kill(pid, sig))
#endif
{
/* Again, just a warning to allow loops */
ereport(WARNING,
(errmsg("could not send signal to process %d: %m", pid)));
return SIGNAL_BACKEND_ERROR;
}
return SIGNAL_BACKEND_SUCCESS;
}
Datum
pg_stat_get_backend_wait_event_type(PG_FUNCTION_ARGS)
{
int32 beid = PG_GETARG_INT32(0);
PgBackendStatus *beentry;
PGPROC *proc;
const char *wait_event_type;
if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
wait_event_type = "<backend information not available>";
else if (!has_privs_of_role(GetUserId(), beentry->st_userid))
wait_event_type = "<insufficient privilege>";
else
{
proc = BackendPidGetProc(beentry->st_procpid);
wait_event_type = pgstat_get_wait_event_type(proc->wait_event_info);
}
if (!wait_event_type)
PG_RETURN_NULL();
PG_RETURN_TEXT_P(cstring_to_text(wait_event_type));
}
/*
* Background worker entrypoint.
*
* This is intended to demonstrate how a background worker can be used to
* facilitate a parallel computation. Most of the logic here is fairly
* boilerplate stuff, designed to attach to the shared memory segment,
* notify the user backend that we're alive, and so on. The
* application-specific bits of logic that you'd replace for your own worker
* are attach_to_queues() and copy_messages().
*/
void
test_shm_mq_main(Datum main_arg)
{
dsm_segment *seg;
shm_toc *toc;
shm_mq_handle *inqh;
shm_mq_handle *outqh;
volatile test_shm_mq_header *hdr;
int myworkernumber;
PGPROC *registrant;
/*
* Establish signal handlers.
*
* We want CHECK_FOR_INTERRUPTS() to kill off this worker process just as
* it would a normal user backend. To make that happen, we establish a
* signal handler that is a stripped-down version of die(). We don't have
* any equivalent of the backend's command-read loop, where interrupts can
* be processed immediately, so make sure ImmediateInterruptOK is turned
* off.
*/
pqsignal(SIGTERM, handle_sigterm);
ImmediateInterruptOK = false;
BackgroundWorkerUnblockSignals();
/*
* Connect to the dynamic shared memory segment.
*
* The backend that registered this worker passed us the ID of a shared
* memory segment to which we must attach for further instructions. In
* order to attach to dynamic shared memory, we need a resource owner.
* Once we've mapped the segment in our address space, attach to the table
* of contents so we can locate the various data structures we'll need to
* find within the segment.
*/
CurrentResourceOwner = ResourceOwnerCreate(NULL, "test_shm_mq worker");
seg = dsm_attach(DatumGetInt32(main_arg));
if (seg == NULL)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("unable to map dynamic shared memory segment")));
toc = shm_toc_attach(PG_TEST_SHM_MQ_MAGIC, dsm_segment_address(seg));
if (toc == NULL)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("bad magic number in dynamic shared memory segment")));
/*
* Acquire a worker number.
*
* By convention, the process registering this background worker should
* have stored the control structure at key 0. We look up that key to
* find it. Our worker number gives our identity: there may be just one
* worker involved in this parallel operation, or there may be many.
*/
hdr = shm_toc_lookup(toc, 0);
SpinLockAcquire(&hdr->mutex);
myworkernumber = ++hdr->workers_attached;
SpinLockRelease(&hdr->mutex);
if (myworkernumber > hdr->workers_total)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("too many message queue testing workers already")));
/*
* Attach to the appropriate message queues.
*/
attach_to_queues(seg, toc, myworkernumber, &inqh, &outqh);
/*
* Indicate that we're fully initialized and ready to begin the main part
* of the parallel operation.
*
* Once we signal that we're ready, the user backend is entitled to assume
* that our on_dsm_detach callbacks will fire before we disconnect from
* the shared memory segment and exit. Generally, that means we must have
* attached to all relevant dynamic shared memory data structures by now.
*/
SpinLockAcquire(&hdr->mutex);
++hdr->workers_ready;
SpinLockRelease(&hdr->mutex);
registrant = BackendPidGetProc(MyBgworkerEntry->bgw_notify_pid);
if (registrant == NULL)
{
elog(DEBUG1, "registrant backend has exited prematurely");
proc_exit(1);
}
SetLatch(®istrant->procLatch);
/* Do the work. */
copy_messages(inqh, outqh);
/*
* We're done. Explicitly detach the shared memory segment so that we
* don't get a resource leak warning at commit time. This will fire any
* on_dsm_detach callbacks we've registered, as well. Once that's done,
* we can go ahead and exit.
*/
dsm_detach(seg);
proc_exit(1);
}
static int
pg_signal_backend(int pid, int sig, char *msg)
{
PGPROC *proc = BackendPidGetProc(pid);
/*
* BackendPidGetProc returns NULL if the pid isn't valid; but by the time
* we reach kill(), a process for which we get a valid proc here might
* have terminated on its own. There's no way to acquire a lock on an
* arbitrary process to prevent that. But since so far all the callers of
* this mechanism involve some request for ending the process anyway, that
* it might end on its own first is not a problem.
*/
if (proc == NULL)
{
/*
* This is just a warning so a loop-through-resultset will not abort
* if one backend terminated on its own during the run.
*/
ereport(WARNING,
(errmsg("PID %d is not a PostgreSQL server process", pid)));
return SIGNAL_BACKEND_ERROR;
}
if (!(superuser() || proc->roleId == GetUserId()))
return SIGNAL_BACKEND_NOPERMISSION;
/* If the user supplied a message to the signalled backend */
if (msg != NULL)
{
int r;
r = SetBackendCancelMessage(pid, msg);
if (r != -1 && r != strlen(msg))
ereport(NOTICE,
(errmsg("message is too long and has been truncated")));
}
/*
* Can the process we just validated above end, followed by the pid being
* recycled for a new process, before reaching here? Then we'd be trying
* to kill the wrong thing. Seems near impossible when sequential pid
* assignment and wraparound is used. Perhaps it could happen on a system
* where pid re-use is randomized. That race condition possibility seems
* too unlikely to worry about.
*/
/* If we have setsid(), signal the backend's whole process group */
#ifdef HAVE_SETSID
if (kill(-pid, sig))
#else
if (kill(pid, sig))
#endif
{
/* Again, just a warning to allow loops */
ereport(WARNING,
(errmsg("could not send signal to process %d: %m", pid)));
return SIGNAL_BACKEND_ERROR;
}
return SIGNAL_BACKEND_SUCCESS;
}
void
worker_test_main(Datum main_arg)
{
dsm_segment *seg;
volatile test_shm_mq_header *hdr;
PGPROC *registrant;
pqsignal(SIGHUP, handle_sighup);
pqsignal(SIGTERM, handle_sigterm);
BackgroundWorkerUnblockSignals();
printf("worker_test_main: %d\n", DatumGetInt32(main_arg));
CurrentResourceOwner = ResourceOwnerCreate(NULL, "worker test");
seg = dsm_attach(DatumGetInt32(main_arg));
if (seg == NULL)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("unable to map dynamic shared memory segment")));
hdr = dsm_segment_address(seg);
/* 開始 */
SpinLockAcquire(&hdr->mutex);
hdr->workers_ready++;
hdr->workers_attached++;
SpinLockRelease(&hdr->mutex);
registrant = BackendPidGetProc(MyBgworkerEntry->bgw_notify_pid);
if (registrant == NULL)
{
elog(DEBUG1, "registrant backend has exited prematurely");
proc_exit(1);
}
SetLatch(®istrant->procLatch);
/* Do the work */
BackgroundWorkerInitializeConnection(hdr->dbname, NULL);
printf("DSM: %p\n", dsm_segment_address);
#if 0
SetCurrentStatementStartTimestamp();
StartTransactionCommand();
SPI_connect();
PushActiveSnapshot(GetTransactionSnapshot());
pgstat_report_activity(STATE_RUNNING, "initializing spi_worker schema");
SPI_finish();
PopActiveSnapshot();
CommitTransactionCommand();
pgstat_report_activity(STATE_IDLE, NULL);
#endif
dsm_detach(seg);
proc_exit(0);
}
/*
* Returns activity of PG backends.
*/
Datum
pg_stat_get_activity(PG_FUNCTION_ARGS)
{
#define PG_STAT_GET_ACTIVITY_COLS 23
int num_backends = pgstat_fetch_stat_numbackends();
int curr_backend;
int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
MemoryContext per_query_ctx;
MemoryContext oldcontext;
/* check to see if caller supports us returning a tuplestore */
if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-valued function called in context that cannot accept a set")));
if (!(rsinfo->allowedModes & SFRM_Materialize))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("materialize mode required, but it is not " \
"allowed in this context")));
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
oldcontext = MemoryContextSwitchTo(per_query_ctx);
tupstore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->returnMode = SFRM_Materialize;
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
/* 1-based index */
for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
{
/* for each row */
Datum values[PG_STAT_GET_ACTIVITY_COLS];
bool nulls[PG_STAT_GET_ACTIVITY_COLS];
LocalPgBackendStatus *local_beentry;
PgBackendStatus *beentry;
PGPROC *proc;
const char *wait_event_type;
const char *wait_event;
MemSet(values, 0, sizeof(values));
MemSet(nulls, 0, sizeof(nulls));
if (pid != -1)
{
/* Skip any which are not the one we're looking for. */
PgBackendStatus *be = pgstat_fetch_stat_beentry(curr_backend);
if (!be || be->st_procpid != pid)
continue;
}
/* Get the next one in the list */
local_beentry = pgstat_fetch_stat_local_beentry(curr_backend);
if (!local_beentry)
continue;
beentry = &local_beentry->backendStatus;
if (!beentry)
{
int i;
for (i = 0; i < sizeof(nulls) / sizeof(nulls[0]); i++)
nulls[i] = true;
nulls[5] = false;
values[5] = CStringGetTextDatum("<backend information not available>");
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
continue;
}
/* Values available to all callers */
values[0] = ObjectIdGetDatum(beentry->st_databaseid);
values[1] = Int32GetDatum(beentry->st_procpid);
values[2] = ObjectIdGetDatum(beentry->st_userid);
if (beentry->st_appname)
values[3] = CStringGetTextDatum(beentry->st_appname);
else
nulls[3] = true;
if (TransactionIdIsValid(local_beentry->backend_xid))
values[15] = TransactionIdGetDatum(local_beentry->backend_xid);
else
nulls[15] = true;
if (TransactionIdIsValid(local_beentry->backend_xmin))
values[16] = TransactionIdGetDatum(local_beentry->backend_xmin);
else
nulls[16] = true;
if (beentry->st_ssl)
{
values[17] = BoolGetDatum(true); /* ssl */
values[18] = CStringGetTextDatum(beentry->st_sslstatus->ssl_version);
values[19] = CStringGetTextDatum(beentry->st_sslstatus->ssl_cipher);
values[20] = Int32GetDatum(beentry->st_sslstatus->ssl_bits);
values[21] = BoolGetDatum(beentry->st_sslstatus->ssl_compression);
values[22] = CStringGetTextDatum(beentry->st_sslstatus->ssl_clientdn);
}
else
{
values[17] = BoolGetDatum(false); /* ssl */
nulls[18] = nulls[19] = nulls[20] = nulls[21] = nulls[22] = true;
}
/* Values only available to role member */
if (has_privs_of_role(GetUserId(), beentry->st_userid))
{
SockAddr zero_clientaddr;
switch (beentry->st_state)
{
case STATE_IDLE:
values[4] = CStringGetTextDatum("idle");
break;
case STATE_RUNNING:
values[4] = CStringGetTextDatum("active");
break;
case STATE_IDLEINTRANSACTION:
values[4] = CStringGetTextDatum("idle in transaction");
break;
case STATE_FASTPATH:
values[4] = CStringGetTextDatum("fastpath function call");
break;
case STATE_IDLEINTRANSACTION_ABORTED:
values[4] = CStringGetTextDatum("idle in transaction (aborted)");
break;
case STATE_DISABLED:
values[4] = CStringGetTextDatum("disabled");
break;
case STATE_UNDEFINED:
nulls[4] = true;
break;
}
values[5] = CStringGetTextDatum(beentry->st_activity);
proc = BackendPidGetProc(beentry->st_procpid);
wait_event_type = pgstat_get_wait_event_type(proc->wait_event_info);
if (wait_event_type)
values[6] = CStringGetTextDatum(wait_event_type);
else
nulls[6] = true;
wait_event = pgstat_get_wait_event(proc->wait_event_info);
if (wait_event)
values[7] = CStringGetTextDatum(wait_event);
else
nulls[7] = true;
if (beentry->st_xact_start_timestamp != 0)
values[8] = TimestampTzGetDatum(beentry->st_xact_start_timestamp);
else
nulls[8] = true;
if (beentry->st_activity_start_timestamp != 0)
values[9] = TimestampTzGetDatum(beentry->st_activity_start_timestamp);
else
nulls[9] = true;
if (beentry->st_proc_start_timestamp != 0)
values[10] = TimestampTzGetDatum(beentry->st_proc_start_timestamp);
else
nulls[10] = true;
if (beentry->st_state_start_timestamp != 0)
values[11] = TimestampTzGetDatum(beentry->st_state_start_timestamp);
else
nulls[11] = true;
/* A zeroed client addr means we don't know */
memset(&zero_clientaddr, 0, sizeof(zero_clientaddr));
if (memcmp(&(beentry->st_clientaddr), &zero_clientaddr,
sizeof(zero_clientaddr)) == 0)
{
nulls[12] = true;
nulls[13] = true;
nulls[14] = true;
}
else
{
if (beentry->st_clientaddr.addr.ss_family == AF_INET
#ifdef HAVE_IPV6
|| beentry->st_clientaddr.addr.ss_family == AF_INET6
#endif
)
{
char remote_host[NI_MAXHOST];
char remote_port[NI_MAXSERV];
int ret;
remote_host[0] = '\0';
remote_port[0] = '\0';
ret = pg_getnameinfo_all(&beentry->st_clientaddr.addr,
beentry->st_clientaddr.salen,
remote_host, sizeof(remote_host),
remote_port, sizeof(remote_port),
NI_NUMERICHOST | NI_NUMERICSERV);
if (ret == 0)
{
clean_ipv6_addr(beentry->st_clientaddr.addr.ss_family, remote_host);
values[12] = DirectFunctionCall1(inet_in,
CStringGetDatum(remote_host));
if (beentry->st_clienthostname &&
beentry->st_clienthostname[0])
values[13] = CStringGetTextDatum(beentry->st_clienthostname);
else
nulls[13] = true;
values[14] = Int32GetDatum(atoi(remote_port));
}
else
{
nulls[12] = true;
nulls[13] = true;
nulls[14] = true;
}
}
else if (beentry->st_clientaddr.addr.ss_family == AF_UNIX)
{
/*
* Unix sockets always reports NULL for host and -1 for
* port, so it's possible to tell the difference to
* connections we have no permissions to view, or with
* errors.
*/
nulls[12] = true;
nulls[13] = true;
values[14] = DatumGetInt32(-1);
}
else
{
/* Unknown address type, should never happen */
nulls[12] = true;
nulls[13] = true;
nulls[14] = true;
}
}
}
else
{
/* No permissions to view data about this session */
values[5] = CStringGetTextDatum("<insufficient privilege>");
nulls[4] = true;
nulls[6] = true;
nulls[7] = true;
nulls[8] = true;
nulls[9] = true;
nulls[10] = true;
nulls[11] = true;
nulls[12] = true;
nulls[13] = true;
nulls[14] = true;
}
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
/* If only a single backend was requested, and we found it, break. */
if (pid != -1)
break;
}
/* clean up and return the tuplestore */
tuplestore_donestoring(tupstore);
return (Datum) 0;
}