/*
* emit a completed btree page, and release the working storage.
*/
static void
_bt_blwritepage(BTWriteState *wstate, Page page, BlockNumber blkno)
{
// Fetch gp_persistent_relation_node information that will be added to XLOG record.
RelationFetchGpRelationNodeForXLog(wstate->index);
/* Ensure rd_smgr is open (could have been closed by relcache flush!) */
RelationOpenSmgr(wstate->index);
/* XLOG stuff */
if (wstate->btws_use_wal)
{
_bt_lognewpage(wstate->index, page, blkno);
}
else
{
/* Leave the page LSN zero if not WAL-logged, but set TLI anyway */
PageSetTLI(page, ThisTimeLineID);
}
/*
* If we have to write pages nonsequentially, fill in the space with
* zeroes until we come back and overwrite. This is not logically
* necessary on standard Unix filesystems (unwritten space will read as
* zeroes anyway), but it should help to avoid fragmentation. The dummy
* pages aren't WAL-logged though.
*/
while (blkno > wstate->btws_pages_written)
{
if (!wstate->btws_zeropage)
wstate->btws_zeropage = (Page) palloc0(BLCKSZ);
// -------- MirroredLock ----------
// UNDONE: Unfortunately, I think we write temp relations to the mirror...
LWLockAcquire(MirroredLock, LW_SHARED);
smgrextend(wstate->index->rd_smgr, wstate->btws_pages_written++,
(char *) wstate->btws_zeropage,
true);
LWLockRelease(MirroredLock);
// -------- MirroredLock ----------
}
// -------- MirroredLock ----------
// UNDONE: Unfortunately, I think we write temp relations to the mirror...
LWLockAcquire(MirroredLock, LW_SHARED);
/*
* Now write the page. We say isTemp = true even if it's not a temp
* index, because there's no need for smgr to schedule an fsync for this
* write; we'll do it ourselves before ending the build.
*/
if (blkno == wstate->btws_pages_written)
{
/* extending the file... */
smgrextend(wstate->index->rd_smgr, blkno, (char *) page, true);
wstate->btws_pages_written++;
}
else
{
/* overwriting a block we zero-filled before */
smgrwrite(wstate->index->rd_smgr, blkno, (char *) page, true);
}
LWLockRelease(MirroredLock);
// -------- MirroredLock ----------
pfree(page);
}
/*
* Create a new___ replication slot and mark it as used by this backend.
*
* name: Name of the slot
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
*/
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency)
{
ReplicationSlot *slot = NULL;
int i;
Assert(MyReplicationSlot == NULL);
ReplicationSlotValidateName(name, ERROR);
/*
* If some other backend ran this code currently with us, we'd likely both
* allocate the same slot, and that would be bad. We'd also be at risk of
* missing a name collision. Also, we don't want to try to create a new___
* slot while somebody's busy cleaning up an old one, because we might
* both be monkeying with the same directory.
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
* Check for name collision, and identify an allocatable slot. We need to
* hold ReplicationSlotControlLock in shared mode for this, so that nobody
* else can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
for (i = 0; i < max_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
if (s->in_use && strcmp(name, NameStr(s->data.name)) == 0)
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
if (!s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
/* If all slots are in use, we're out of luck. */
if (slot == NULL)
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
errhint("Free one or increase max_replication_slots.")));
/*
* Since this slot is not in use, nobody should be looking at any part of
* it other than the in_use field unless they're trying to allocate it.
* And since we hold ReplicationSlotAllocationLock, nobody except us can
* be doing that. So it's safe to initialize the slot.
*/
Assert(!slot->in_use);
Assert(slot->active_pid == 0);
slot->data.persistency = persistency;
slot->data.xmin = InvalidTransactionId;
slot->effective_xmin = InvalidTransactionId;
StrNCpy(NameStr(slot->data.name), name, NAMEDATALEN);
slot->data.database = db_specific ? MyDatabaseId : InvalidOid;
slot->data.restart_lsn = InvalidXLogRecPtr;
/*
* Create the slot on disk. We haven't actually marked the slot allocated
* yet, so no special cleanup is required if this errors out.
*/
CreateSlotOnDisk(slot);
/*
* We need to briefly prevent any other backend from iterating over the
* slots while we flip the in_use flag. We also need to set the active
* flag while holding the ControlLock as otherwise a concurrent
* SlotAcquire() could acquire the slot as well.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_EXCLUSIVE);
slot->in_use = true;
/* We can now mark the slot active, and that makes it our slot. */
{
volatile ReplicationSlot *vslot = slot;
SpinLockAcquire(&slot->mutex);
Assert(vslot->active_pid == 0);
vslot->active_pid = MyProcPid;
SpinLockRelease(&slot->mutex);
MyReplicationSlot = slot;
}
LWLockRelease(ReplicationSlotControlLock);
/*
* Now that the slot has been marked as in_use and in_active, it's safe to
* let somebody else try to allocate a slot.
*/
LWLockRelease(ReplicationSlotAllocationLock);
}
/*
* Shared functionality between saving and creating a replication slot.
*/
static void
SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel)
{
char tmppath[MAXPGPATH];
char path[MAXPGPATH];
int fd;
ReplicationSlotOnDisk cp;
bool was_dirty;
/* first check whether there's something to write out */
{
volatile ReplicationSlot *vslot = slot;
SpinLockAcquire(&vslot->mutex);
was_dirty = vslot->dirty;
vslot->just_dirtied = false;
SpinLockRelease(&vslot->mutex);
}
/* and don't do anything if there's nothing to write */
if (!was_dirty)
return;
LWLockAcquire(slot->io_in_progress_lock, LW_EXCLUSIVE);
/* silence valgrind :( */
memset(&cp, 0, sizeof(ReplicationSlotOnDisk));
sprintf(tmppath, "%s/state.tmp", dir);
sprintf(path, "%s/state", dir);
fd = OpenTransientFile(tmppath,
O_CREAT | O_EXCL | O_WRONLY | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not create file \"%s\": %m",
tmppath)));
return;
}
cp.magic = SLOT_MAGIC;
INIT_CRC32C(cp.checksum);
cp.version = SLOT_VERSION;
cp.length = ReplicationSlotOnDiskV2Size;
SpinLockAcquire(&slot->mutex);
memcpy(&cp.slotdata, &slot->data, sizeof(ReplicationSlotPersistentData));
SpinLockRelease(&slot->mutex);
COMP_CRC32C(cp.checksum,
(char *) (&cp) + SnapBuildOnDiskNotChecksummedSize,
SnapBuildOnDiskChecksummedSize);
FIN_CRC32C(cp.checksum);
if ((write(fd, &cp, sizeof(cp))) != sizeof(cp))
{
int save_errno = errno;
CloseTransientFile(fd);
errno = save_errno;
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not write to file \"%s\": %m",
tmppath)));
return;
}
/* fsync the temporary file */
if (pg_fsync(fd) != 0)
{
int save_errno = errno;
CloseTransientFile(fd);
errno = save_errno;
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not fsync file \"%s\": %m",
tmppath)));
return;
}
CloseTransientFile(fd);
/* rename to permanent file, fsync file and directory */
if (rename(tmppath, path) != 0)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not rename file \"%s\" to \"%s\": %m",
tmppath, path)));
return;
}
/* Check CreateSlot() for the reasoning of using a crit. section. */
START_CRIT_SECTION();
fsync_fname(path, false);
fsync_fname((char *) dir, true);
fsync_fname("pg_replslot", true);
END_CRIT_SECTION();
/*
* Successfully wrote, unset dirty bit, unless somebody dirtied again
* already.
*/
{
volatile ReplicationSlot *vslot = slot;
SpinLockAcquire(&vslot->mutex);
if (!vslot->just_dirtied)
vslot->dirty = false;
SpinLockRelease(&vslot->mutex);
}
LWLockRelease(slot->io_in_progress_lock);
}
/*
* StrategyGetBuffer
*
* Called by the bufmgr to get the next candidate buffer to use in
* BufferAlloc(). The only hard requirement BufferAlloc() has is that
* the selected buffer must not currently be pinned by anyone.
*
* strategy is a BufferAccessStrategy object, or NULL for default strategy.
*
* To ensure that no one else can pin the buffer before we do, we must
* return the buffer with the buffer header spinlock still held. If
* *lock_held is set on exit, we have returned with the BufFreelistLock
* still held, as well; the caller must release that lock once the spinlock
* is dropped. We do it that way because releasing the BufFreelistLock
* might awaken other processes, and it would be bad to do the associated
* kernel calls while holding the buffer header spinlock.
*/
volatile BufferDesc *
StrategyGetBuffer(BufferAccessStrategy strategy, bool *lock_held)
{
volatile BufferDesc *buf;
int trycounter;
/*
* If given a strategy object, see whether it can select a buffer. We
* assume strategy objects don't need the BufFreelistLock.
*/
if (strategy != NULL)
{
buf = GetBufferFromRing(strategy);
if (buf != NULL)
{
*lock_held = false;
return buf;
}
}
/* Nope, so lock the freelist */
*lock_held = true;
LWLockAcquire(BufFreelistLock, LW_EXCLUSIVE);
/*
* We count buffer allocation requests so that the bgwriter can estimate
* the rate of buffer consumption. Note that buffers recycled by a
* strategy object are intentionally not counted here.
*/
StrategyControl->numBufferAllocs++;
/*
* Try to get a buffer from the freelist. Note that the freeNext fields
* are considered to be protected by the BufFreelistLock not the
* individual buffer spinlocks, so it's OK to manipulate them without
* holding the spinlock.
*/
while (StrategyControl->firstFreeBuffer >= 0)
{
buf = &BufferDescriptors[StrategyControl->firstFreeBuffer];
Assert(buf->freeNext != FREENEXT_NOT_IN_LIST);
/* Unconditionally remove buffer from freelist */
StrategyControl->firstFreeBuffer = buf->freeNext;
buf->freeNext = FREENEXT_NOT_IN_LIST;
/*
* If the buffer is pinned or has a nonzero usage_count, we cannot use
* it; discard it and retry. (This can only happen if VACUUM put a
* valid buffer in the freelist and then someone else used it before
* we got to it. It's probably impossible altogether as of 8.3, but
* we'd better check anyway.)
*/
LockBufHdr(buf);
if (buf->refcount == 0 && buf->usage_count == 0)
{
if (strategy != NULL)
AddBufferToRing(strategy, buf);
return buf;
}
UnlockBufHdr(buf);
}
/* Nothing on the freelist, so run the "clock sweep" algorithm */
trycounter = NBuffers;
for (;;)
{
buf = &BufferDescriptors[StrategyControl->nextVictimBuffer];
if (++StrategyControl->nextVictimBuffer >= NBuffers)
{
StrategyControl->nextVictimBuffer = 0;
StrategyControl->completePasses++;
}
/*
* If the buffer is pinned or has a nonzero usage_count, we cannot use
* it; decrement the usage_count (unless pinned) and keep scanning.
*/
LockBufHdr(buf);
if (buf->refcount == 0)
{
if (buf->usage_count > 0)
{
buf->usage_count--;
trycounter = NBuffers;
}
else
{
/* Found a usable buffer */
if (strategy != NULL)
AddBufferToRing(strategy, buf);
return buf;
}
}
else if (--trycounter == 0)
{
/*
* We've scanned all the buffers without making any state changes,
* so all the buffers are pinned (or were when we looked at them).
* We could hope that someone will free one eventually, but it's
* probably better to fail than to risk getting stuck in an
* infinite loop.
*/
UnlockBufHdr(buf);
elog(ERROR, "no unpinned buffers available");
}
UnlockBufHdr(buf);
}
/* not reached */
return NULL;
}
static void
DtmXactCallback(XactEvent event, void *arg)
{
//XTM_INFO("%d: DtmXactCallbackevent=%d nextxid=%d\n", getpid(), event, DtmNextXid);
switch (event)
{
case XACT_EVENT_START:
//XTM_INFO("%d: normal=%d, initialized=%d, replication=%d, bgw=%d, vacuum=%d\n",
// getpid(), IsNormalProcessingMode(), dtm->initialized, MMDoReplication, IsBackgroundWorker, IsAutoVacuumWorkerProcess());
if (IsNormalProcessingMode() && dtm->initialized && MMDoReplication && !am_walsender && !IsBackgroundWorker && !IsAutoVacuumWorkerProcess()) {
MMBeginTransaction();
}
break;
#if 0
case XACT_EVENT_PRE_COMMIT:
case XACT_EVENT_PARALLEL_PRE_COMMIT:
{
TransactionId xid = GetCurrentTransactionIdIfAny();
if (!MMIsDistributedTrans && TransactionIdIsValid(xid)) {
XTM_INFO("%d: Will ignore transaction %u\n", getpid(), xid);
MMMarkTransAsLocal(xid);
}
break;
}
#endif
case XACT_EVENT_COMMIT:
case XACT_EVENT_ABORT:
if (TransactionIdIsValid(DtmNextXid))
{
if (!DtmVoted) {
ArbiterSetTransStatus(DtmNextXid, TRANSACTION_STATUS_ABORTED, false);
}
if (event == XACT_EVENT_COMMIT)
{
/*
* Now transaction status is already written in CLOG,
* so we can remove information about it from hash table
*/
LWLockAcquire(dtm->hashLock, LW_EXCLUSIVE);
hash_search(xid_in_doubt, &DtmNextXid, HASH_REMOVE, NULL);
LWLockRelease(dtm->hashLock);
}
#if 0 /* should be handled now using DtmVoted flag */
else
{
/*
* Transaction at the node can be aborted because of transaction failure at some other node
* before it starts doing anything and assigned Xid, in this case Postgres is not calling SetTransactionStatus,
* so we have to send report to DTMD here
*/
if (!TransactionIdIsValid(GetCurrentTransactionIdIfAny())) {
XTM_INFO("%d: abort transation on DTMD\n", getpid());
ArbiterSetTransStatus(DtmNextXid, TRANSACTION_STATUS_ABORTED, false);
}
}
#endif
DtmNextXid = InvalidTransactionId;
DtmLastSnapshot = NULL;
}
MMIsDistributedTrans = false;
break;
default:
break;
}
}
/*
* ShmemInitStruct -- Create/attach to a structure in shared memory.
*
* This is called during initialization to find or allocate
* a data structure in shared memory. If no other process
* has created the structure, this routine allocates space
* for it. If it exists already, a pointer to the existing
* structure is returned.
*
* Returns: pointer to the object. *foundPtr is set TRUE if the object was
* already in the shmem index (hence, already initialized).
*
* Note: before Postgres 9.0, this function returned NULL for some failure
* cases. Now, it always throws error instead, so callers need not check
* for NULL.
*/
void *
ShmemInitStruct(const char *name, Size size, bool *foundPtr)
{
ShmemIndexEnt *result;
void *structPtr;
LWLockAcquire(ShmemIndexLock, LW_EXCLUSIVE);
if (!ShmemIndex)
{
PGShmemHeader *shmemseghdr = ShmemSegHdr;
/* Must be trying to create/attach to ShmemIndex itself */
Assert(strcmp(name, "ShmemIndex") == 0);
if (IsUnderPostmaster)
{
/* Must be initializing a (non-standalone) backend */
Assert(shmemseghdr->index != NULL);
structPtr = shmemseghdr->index;
*foundPtr = TRUE;
}
else
{
/*
* If the shmem index doesn't exist, we are bootstrapping: we must
* be trying to init the shmem index itself.
*
* Notice that the ShmemIndexLock is released before the shmem
* index has been initialized. This should be OK because no other
* process can be accessing shared memory yet.
*/
Assert(shmemseghdr->index == NULL);
structPtr = ShmemAlloc(size);
if (structPtr == NULL)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("not enough shared memory for data structure"
" \"%s\" (%zu bytes requested)",
name, size)));
shmemseghdr->index = structPtr;
*foundPtr = FALSE;
}
LWLockRelease(ShmemIndexLock);
return structPtr;
}
/* look it up in the shmem index */
result = (ShmemIndexEnt *)
hash_search(ShmemIndex, name, HASH_ENTER_NULL, foundPtr);
if (!result)
{
LWLockRelease(ShmemIndexLock);
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("could not create ShmemIndex entry for data structure \"%s\"",
name)));
}
if (*foundPtr)
{
/*
* Structure is in the shmem index so someone else has allocated it
* already. The size better be the same as the size we are trying to
* initialize to, or there is a name conflict (or worse).
*/
if (result->size != size)
{
LWLockRelease(ShmemIndexLock);
ereport(ERROR,
(errmsg("ShmemIndex entry size is wrong for data structure"
" \"%s\": expected %zu, actual %zu",
name, size, result->size)));
}
structPtr = result->location;
}
else
{
/* It isn't in the table yet. allocate and initialize it */
structPtr = ShmemAlloc(size);
if (structPtr == NULL)
{
/* out of memory; remove the failed ShmemIndex entry */
hash_search(ShmemIndex, name, HASH_REMOVE, NULL);
LWLockRelease(ShmemIndexLock);
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("not enough shared memory for data structure"
" \"%s\" (%zu bytes requested)",
name, size)));
}
result->size = size;
result->location = structPtr;
}
LWLockRelease(ShmemIndexLock);
Assert(ShmemAddrIsValid(structPtr));
return structPtr;
}
/*
* CheckDeadLock
*
* We only get to this routine if the DEADLOCK_TIMEOUT fired
* while waiting for a lock to be released by some other process. Look
* to see if there's a deadlock; if not, just return and continue waiting.
* (But signal ProcSleep to log a message, if log_lock_waits is true.)
* If we have a real deadlock, remove ourselves from the lock's wait queue
* and signal an error to ProcSleep.
*
* NB: this is run inside a signal handler, so be very wary about what is done
* here or in called routines.
*/
void
CheckDeadLock(void)
{
int i;
/*
* Acquire exclusive lock on the entire shared lock data structures. Must
* grab LWLocks in partition-number order to avoid LWLock deadlock.
*
* Note that the deadlock check interrupt had better not be enabled
* anywhere that this process itself holds lock partition locks, else this
* will wait forever. Also note that LWLockAcquire creates a critical
* section, so that this routine cannot be interrupted by cancel/die
* interrupts.
*/
for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
LWLockAcquire(FirstLockMgrLock + i, LW_EXCLUSIVE);
/*
* Check to see if we've been awoken by anyone in the interim.
*
* If we have, we can return and resume our transaction -- happy day.
* Before we are awoken the process releasing the lock grants it to us so
* we know that we don't have to wait anymore.
*
* We check by looking to see if we've been unlinked from the wait queue.
* This is quicker than checking our semaphore's state, since no kernel
* call is needed, and it is safe because we hold the lock partition lock.
*/
if (MyProc->links.prev == NULL ||
MyProc->links.next == NULL)
goto check_done;
#ifdef LOCK_DEBUG
if (Debug_deadlocks)
DumpAllLocks();
#endif
/* Run the deadlock check, and set deadlock_state for use by ProcSleep */
deadlock_state = DeadLockCheck(MyProc);
if (deadlock_state == DS_HARD_DEADLOCK)
{
/*
* Oops. We have a deadlock.
*
* Get this process out of wait state. (Note: we could do this more
* efficiently by relying on lockAwaited, but use this coding to
* preserve the flexibility to kill some other transaction than the
* one detecting the deadlock.)
*
* RemoveFromWaitQueue sets MyProc->waitStatus to STATUS_ERROR, so
* ProcSleep will report an error after we return from the signal
* handler.
*/
Assert(MyProc->waitLock != NULL);
RemoveFromWaitQueue(MyProc, LockTagHashCode(&(MyProc->waitLock->tag)));
/*
* Unlock my semaphore so that the interrupted ProcSleep() call can
* finish.
*/
PGSemaphoreUnlock(&MyProc->sem);
/*
* We're done here. Transaction abort caused by the error that
* ProcSleep will raise will cause any other locks we hold to be
* released, thus allowing other processes to wake up; we don't need
* to do that here. NOTE: an exception is that releasing locks we
* hold doesn't consider the possibility of waiters that were blocked
* behind us on the lock we just failed to get, and might now be
* wakable because we're not in front of them anymore. However,
* RemoveFromWaitQueue took care of waking up any such processes.
*/
}
else if (log_lock_waits || deadlock_state == DS_BLOCKED_BY_AUTOVACUUM)
{
/*
* Unlock my semaphore so that the interrupted ProcSleep() call can
* print the log message (we daren't do it here because we are inside
* a signal handler). It will then sleep again until someone releases
* the lock.
*
* If blocked by autovacuum, this wakeup will enable ProcSleep to send
* the canceling signal to the autovacuum worker.
*/
PGSemaphoreUnlock(&MyProc->sem);
}
/*
* And release locks. We do this in reverse order for two reasons: (1)
* Anyone else who needs more than one of the locks will be trying to lock
* them in increasing order; we don't want to release the other process
* until it can get all the locks it needs. (2) This avoids O(N^2)
* behavior inside LWLockRelease.
*/
check_done:
for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
LWLockRelease(FirstLockMgrLock + i);
}
/*
* Write a page from a shared buffer, if necessary.
* Does nothing if the specified slot is not dirty.
*
* NOTE: only one write attempt is made here. Hence, it is possible that
* the page is still dirty at exit (if someone else re-dirtied it during
* the write). However, we *do* attempt a fresh write even if the page
* is already being written; this is for checkpoints.
*
* Control lock must be held at entry, and will be held at exit.
*/
void
SimpleLruWritePage(SlruCtl ctl, int slotno, SlruFlush fdata)
{
SlruShared shared = ctl->shared;
int pageno = shared->page_number[slotno];
bool ok;
/* If a write is in progress, wait for it to finish */
while (shared->page_status[slotno] == SLRU_PAGE_WRITE_IN_PROGRESS &&
shared->page_number[slotno] == pageno)
{
SimpleLruWaitIO(ctl, slotno);
}
/*
* Do nothing if page is not dirty, or if buffer no longer contains the
* same page we were called for.
*/
if (!shared->page_dirty[slotno] ||
shared->page_status[slotno] != SLRU_PAGE_VALID ||
shared->page_number[slotno] != pageno)
return;
/*
* Mark the slot write-busy, and clear the dirtybit. After this point, a
* transaction status update on this page will mark it dirty again.
*/
shared->page_status[slotno] = SLRU_PAGE_WRITE_IN_PROGRESS;
shared->page_dirty[slotno] = false;
/* Acquire per-buffer lock (cannot deadlock, see notes at top) */
LWLockAcquire(shared->buffer_locks[slotno], LW_EXCLUSIVE);
/* Release control lock while doing I/O */
LWLockRelease(shared->ControlLock);
/* Do the write */
ok = SlruPhysicalWritePage(ctl, pageno, slotno, fdata);
/* If we failed, and we're in a flush, better close the files */
if (!ok && fdata)
{
int i;
for (i = 0; i < fdata->num_files; i++)
MirroredFlatFile_Close(&fdata->mirroredOpens[i]);
}
/* Re-acquire control lock and update page state */
LWLockAcquire(shared->ControlLock, LW_EXCLUSIVE);
Assert(shared->page_number[slotno] == pageno &&
shared->page_status[slotno] == SLRU_PAGE_WRITE_IN_PROGRESS);
/* If we failed to write, mark the page dirty again */
if (!ok)
shared->page_dirty[slotno] = true;
shared->page_status[slotno] = SLRU_PAGE_VALID;
LWLockRelease(shared->buffer_locks[slotno]);
/* Now it's okay to ereport if we failed */
if (!ok)
SlruReportIOError(ctl, pageno, InvalidTransactionId);
}
/*
* Drop a table space
*
* Be careful to check that the tablespace is empty.
*/
void
RemoveTableSpace(List *names, DropBehavior behavior, bool missing_ok)
{
char *tablespacename;
Relation rel;
HeapTuple tuple;
cqContext cqc;
cqContext *pcqCtx;
Oid tablespaceoid;
int32 count;
RelFileNode relfilenode;
DbDirNode dbDirNode;
PersistentFileSysState persistentState;
ItemPointerData persistentTid;
int64 persistentSerialNum;
/* don't call this in a transaction block */
// PreventTransactionChain((void *) stmt, "DROP TABLESPACE");
/*
* General DROP (object) syntax allows fully qualified names, but
* tablespaces are global objects that do not live in schemas, so
* it is a syntax error if a fully qualified name was given.
*/
if (list_length(names) != 1)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("tablespace name may not be qualified")));
tablespacename = strVal(linitial(names));
/* Disallow CASCADE */
if (behavior == DROP_CASCADE)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("syntax at or near \"cascade\"")));
/*
* Find the target tuple
*/
rel = heap_open(TableSpaceRelationId, RowExclusiveLock);
pcqCtx = caql_addrel(cqclr(&cqc), rel);
tuple = caql_getfirst(
pcqCtx,
cql("SELECT * FROM pg_tablespace "
" WHERE spcname = :1 "
" FOR UPDATE ",
CStringGetDatum(tablespacename)));
if (!HeapTupleIsValid(tuple))
{
/* No such tablespace, no need to hold the lock */
heap_close(rel, RowExclusiveLock);
if (!missing_ok)
{
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("tablespace \"%s\" does not exist",
tablespacename)));
}
else
{
ereport(NOTICE,
(errmsg("tablespace \"%s\" does not exist, skipping",
tablespacename)));
}
return;
}
tablespaceoid = HeapTupleGetOid(tuple);
/* Must be tablespace owner */
if (!pg_tablespace_ownercheck(tablespaceoid, GetUserId()))
aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_TABLESPACE,
tablespacename);
/* Disallow drop of the standard tablespaces, even by superuser */
if (tablespaceoid == GLOBALTABLESPACE_OID ||
tablespaceoid == DEFAULTTABLESPACE_OID)
aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_TABLESPACE,
tablespacename);
/*
* Check for any databases or relations defined in this tablespace, this
* is logically the same as checkSharedDependencies, however we don't
* actually track these in pg_shdepend, instead we lookup this information
* in the gp_persistent_database/relation_node tables.
*/
/* ... */
/*
* Remove the pg_tablespace tuple (this will roll back if we fail below)
*/
caql_delete_current(pcqCtx);
/*
* Remove any comments on this tablespace.
*/
DeleteSharedComments(tablespaceoid, TableSpaceRelationId);
/*
* Remove dependency on owner.
*
* If shared dependencies are added between filespace <=> tablespace
* they will be deleted as well.
*/
deleteSharedDependencyRecordsFor(TableSpaceRelationId, tablespaceoid);
/* MPP-6929: metadata tracking */
if (Gp_role == GP_ROLE_DISPATCH)
MetaTrackDropObject(TableSpaceRelationId,
tablespaceoid);
/*
* Acquire TablespaceCreateLock to ensure that no
* MirroredFileSysObj_JustInTimeDbDirCreate is running concurrently.
*/
LWLockAcquire(TablespaceCreateLock, LW_EXCLUSIVE);
/*
* Check for any relations still defined in the tablespace.
*/
PersistentRelation_CheckTablespace(tablespaceoid, &count, &relfilenode);
if (count > 0)
{
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("tablespace \"%s\" is not empty", tablespacename)));
}
/*
* Schedule the removal the physical infrastructure.
*
* Note: This only schedules the delete, the delete won't actually occur
* until after the transaction has comitted. This should however do
* everything it can to assure that the delete will occur sucessfully,
* e.g. check permissions etc.
*/
/*
* Schedule all persistent database directory removals for transaction commit.
*/
PersistentDatabase_DirIterateInit();
while (PersistentDatabase_DirIterateNext(
&dbDirNode,
&persistentState,
&persistentTid,
&persistentSerialNum))
{
if (dbDirNode.tablespace != tablespaceoid)
continue;
/*
* Database directory objects can linger in 'Drop Pending' state, etc,
* when the mirror is down and needs drop work. So only pay attention
* to 'Created' objects.
*/
if (persistentState != PersistentFileSysState_Created)
continue;
MirroredFileSysObj_ScheduleDropDbDir(
&dbDirNode,
&persistentTid,
persistentSerialNum);
}
/*
* Now schedule the tablespace directory removal.
*/
MirroredFileSysObj_ScheduleDropTablespaceDir(tablespaceoid);
/*
* Note: because we checked that the tablespace was empty, there should be
* no need to worry about flushing shared buffers or free space map
* entries for relations in the tablespace.
*
* CHECK THIS, also check if the lock makes any sense in this context.
*/
/*
* Allow MirroredFileSysObj_JustInTimeDbDirCreate again.
*/
LWLockRelease(TablespaceCreateLock);
/* We keep the lock on the row in pg_tablespace until commit */
heap_close(rel, NoLock);
/* Note: no need for dispatch, that is handled in utility.c */
return;
}
/*
* Remove all segments before the one holding the passed page number
*/
static void
SimpleLruTruncate_internal(SlruCtl ctl, int cutoffPage, bool lockHeld)
{
SlruShared shared = ctl->shared;
int slotno;
/*
* The cutoff point is the start of the segment containing cutoffPage.
*/
cutoffPage -= cutoffPage % SLRU_PAGES_PER_SEGMENT;
/*
* Scan shared memory and remove any pages preceding the cutoff page, to
* ensure we won't rewrite them later. (Since this is normally called in
* or just after a checkpoint, any dirty pages should have been flushed
* already ... we're just being extra careful here.)
*/
if (!lockHeld)
LWLockAcquire(shared->ControlLock, LW_EXCLUSIVE);
restart:;
/*
* While we are holding the lock, make an important safety check: the
* planned cutoff point must be <= the current endpoint page. Otherwise we
* have already wrapped around, and proceeding with the truncation would
* risk removing the current segment.
*/
if (ctl->PagePrecedes(shared->latest_page_number, cutoffPage))
{
if (!lockHeld)
LWLockRelease(shared->ControlLock);
ereport(LOG,
(errmsg("could not truncate directory \"%s\": apparent wraparound",
ctl->Dir)));
return;
}
for (slotno = 0; slotno < shared->num_slots; slotno++)
{
if (shared->page_status[slotno] == SLRU_PAGE_EMPTY)
continue;
if (!ctl->PagePrecedes(shared->page_number[slotno], cutoffPage))
continue;
/*
* If page is clean, just change state to EMPTY (expected case).
*/
if (shared->page_status[slotno] == SLRU_PAGE_VALID &&
!shared->page_dirty[slotno])
{
shared->page_status[slotno] = SLRU_PAGE_EMPTY;
continue;
}
/*
* Hmm, we have (or may have) I/O operations acting on the page, so
* we've got to wait for them to finish and then start again. This is
* the same logic as in SlruSelectLRUPage. (XXX if page is dirty,
* wouldn't it be OK to just discard it without writing it? For now,
* keep the logic the same as it was.)
*/
if (shared->page_status[slotno] == SLRU_PAGE_VALID)
SimpleLruWritePage(ctl, slotno, NULL);
else
SimpleLruWaitIO(ctl, slotno);
goto restart;
}
if (!lockHeld)
LWLockRelease(shared->ControlLock);
/* Now we can remove the old segment(s) */
(void) SlruScanDirectory(ctl, cutoffPage, true);
}
/*
* Find a page in a shared buffer, reading it in if necessary.
* The page number must correspond to an already-initialized page.
*
* The passed-in xid is used only for error reporting, and may be
* InvalidTransactionId if no specific xid is associated with the action.
*
* If the passed in pointer to valid is NULL, then log errors can be
* generated by this function. If valid is not NULL, then the function
* will not generate log errors, but will set the boolean value
* pointed to by valid to TRUE if it was able to read the page,
* or FALSE if the page read had error.
*
* Return value is the shared-buffer slot number now holding the page.
* The buffer's LRU access info is updated.
*
* Control lock must be held at entry, and will be held at exit.
*/
static int
SimpleLruReadPage_Internal(SlruCtl ctl, int pageno, TransactionId xid, bool *valid)
{
SlruShared shared = ctl->shared;
/* Outer loop handles restart if we must wait for someone else's I/O */
for (;;)
{
int slotno;
bool ok;
/* See if page already is in memory; if not, pick victim slot */
slotno = SlruSelectLRUPage(ctl, pageno);
/* Did we find the page in memory? */
if (shared->page_number[slotno] == pageno &&
shared->page_status[slotno] != SLRU_PAGE_EMPTY)
{
/* If page is still being read in, we must wait for I/O */
if (shared->page_status[slotno] == SLRU_PAGE_READ_IN_PROGRESS)
{
SimpleLruWaitIO(ctl, slotno);
/* Now we must recheck state from the top */
continue;
}
/* Otherwise, it's ready to use */
SlruRecentlyUsed(shared, slotno);
if (valid != NULL)
*valid = true;
return slotno;
}
/* We found no match; assert we selected a freeable slot */
Assert(shared->page_status[slotno] == SLRU_PAGE_EMPTY ||
(shared->page_status[slotno] == SLRU_PAGE_VALID &&
!shared->page_dirty[slotno]));
/* Mark the slot read-busy */
shared->page_number[slotno] = pageno;
shared->page_status[slotno] = SLRU_PAGE_READ_IN_PROGRESS;
shared->page_dirty[slotno] = false;
/* Acquire per-buffer lock (cannot deadlock, see notes at top) */
LWLockAcquire(shared->buffer_locks[slotno], LW_EXCLUSIVE);
/*
* Temporarily mark page as recently-used to discourage
* SlruSelectLRUPage from selecting it again for someone else.
*/
SlruRecentlyUsed(shared, slotno);
/* Release control lock while doing I/O */
LWLockRelease(shared->ControlLock);
/* Do the read */
ok = SlruPhysicalReadPage(ctl, pageno, slotno);
/* Re-acquire control lock and update page state */
LWLockAcquire(shared->ControlLock, LW_EXCLUSIVE);
Assert(shared->page_number[slotno] == pageno &&
shared->page_status[slotno] == SLRU_PAGE_READ_IN_PROGRESS &&
!shared->page_dirty[slotno]);
shared->page_status[slotno] = ok ? SLRU_PAGE_VALID : SLRU_PAGE_EMPTY;
LWLockRelease(shared->buffer_locks[slotno]);
/* Now it's okay to ereport if we failed */
if (!ok && valid == NULL)
SlruReportIOError(ctl, pageno, xid);
else if (valid != NULL)
{
if (!ok)
{
LWLockRelease(shared->ControlLock);
*valid = false;
return -1;
}
else
*valid = true;
}
SlruRecentlyUsed(shared, slotno);
return slotno;
}
}
/*
* Select the slot to re-use when we need a free slot.
*
* The target page number is passed because we need to consider the
* possibility that some other process reads in the target page while
* we are doing I/O to free a slot. Hence, check or recheck to see if
* any slot already holds the target page, and return that slot if so.
* Thus, the returned slot is *either* a slot already holding the pageno
* (could be any state except EMPTY), *or* a freeable slot (state EMPTY
* or CLEAN).
*
* Control lock must be held at entry, and will be held at exit.
*/
static int
SlruSelectLRUPage(SlruCtl ctl, int pageno)
{
SlruShared shared = ctl->shared;
/* Outer loop handles restart after I/O */
for (;;)
{
int slotno;
int bestslot = 0;
unsigned int bestcount = 0;
/* See if page already has a buffer assigned */
for (slotno = 0; slotno < NUM_SLRU_BUFFERS; slotno++)
{
if (shared->page_number[slotno] == pageno &&
shared->page_status[slotno] != SLRU_PAGE_EMPTY)
return slotno;
}
/*
* If we find any EMPTY slot, just select that one. Else locate the
* least-recently-used slot that isn't the latest page.
*/
for (slotno = 0; slotno < NUM_SLRU_BUFFERS; slotno++)
{
if (shared->page_status[slotno] == SLRU_PAGE_EMPTY)
return slotno;
if (shared->page_lru_count[slotno] > bestcount &&
shared->page_number[slotno] != shared->latest_page_number)
{
bestslot = slotno;
bestcount = shared->page_lru_count[slotno];
}
}
/*
* If the selected page is clean, we're set.
*/
if (shared->page_status[bestslot] == SLRU_PAGE_CLEAN)
return bestslot;
/*
* We need to do I/O. Normal case is that we have to write it out,
* but it's possible in the worst case to have selected a read-busy
* page. In that case we just wait for someone else to complete the
* I/O, which we can do by waiting for the per-buffer lock.
*/
if (shared->page_status[bestslot] == SLRU_PAGE_READ_IN_PROGRESS)
{
LWLockRelease(shared->ControlLock);
LWLockAcquire(shared->buffer_locks[bestslot], LW_SHARED);
LWLockRelease(shared->buffer_locks[bestslot]);
LWLockAcquire(shared->ControlLock, LW_EXCLUSIVE);
}
else
SimpleLruWritePage(ctl, bestslot, NULL);
/*
* Now loop back and try again. This is the easiest way of dealing
* with corner cases such as the victim page being re-dirtied while we
* wrote it.
*/
}
}
/*
* Write a page from a shared buffer, if necessary.
* Does nothing if the specified slot is not dirty.
*
* NOTE: only one write attempt is made here. Hence, it is possible that
* the page is still dirty at exit (if someone else re-dirtied it during
* the write). However, we *do* attempt a fresh write even if the page
* is already being written; this is for checkpoints.
*
* Control lock must be held at entry, and will be held at exit.
*/
void
SimpleLruWritePage(SlruCtl ctl, int slotno, SlruFlush fdata)
{
SlruShared shared = ctl->shared;
int pageno;
bool ok;
/* Do nothing if page does not need writing */
if (shared->page_status[slotno] != SLRU_PAGE_DIRTY &&
shared->page_status[slotno] != SLRU_PAGE_WRITE_IN_PROGRESS)
return;
pageno = shared->page_number[slotno];
/*
* We must grab the per-buffer lock to do I/O. To avoid deadlock, must
* release ControlLock while waiting for per-buffer lock. Fortunately,
* most of the time the per-buffer lock shouldn't be already held, so we
* can do this:
*/
if (!LWLockConditionalAcquire(shared->buffer_locks[slotno],
LW_EXCLUSIVE))
{
LWLockRelease(shared->ControlLock);
LWLockAcquire(shared->buffer_locks[slotno], LW_EXCLUSIVE);
LWLockAcquire(shared->ControlLock, LW_EXCLUSIVE);
}
/*
* Check to see if someone else already did the write, or took the buffer
* away from us. If so, do nothing. NOTE: we really should never see
* WRITE_IN_PROGRESS here, since that state should only occur while the
* writer is holding the buffer lock. But accept it so that we have a
* recovery path if a writer aborts.
*/
if (shared->page_number[slotno] != pageno ||
(shared->page_status[slotno] != SLRU_PAGE_DIRTY &&
shared->page_status[slotno] != SLRU_PAGE_WRITE_IN_PROGRESS))
{
LWLockRelease(shared->buffer_locks[slotno]);
return;
}
/*
* Mark the slot write-busy. After this point, a transaction status
* update on this page will mark it dirty again.
*/
shared->page_status[slotno] = SLRU_PAGE_WRITE_IN_PROGRESS;
/* Okay, release the control lock and do the write */
LWLockRelease(shared->ControlLock);
ok = SlruPhysicalWritePage(ctl, pageno, slotno, fdata);
/* If we failed, and we're in a flush, better close the files */
if (!ok && fdata)
{
int i;
for (i = 0; i < fdata->num_files; i++)
close(fdata->fd[i]);
}
/* Re-acquire shared control lock and update page state */
LWLockAcquire(shared->ControlLock, LW_EXCLUSIVE);
Assert(shared->page_number[slotno] == pageno &&
(shared->page_status[slotno] == SLRU_PAGE_WRITE_IN_PROGRESS ||
shared->page_status[slotno] == SLRU_PAGE_DIRTY));
/* Cannot set CLEAN if someone re-dirtied page since write started */
if (shared->page_status[slotno] == SLRU_PAGE_WRITE_IN_PROGRESS)
shared->page_status[slotno] = ok ? SLRU_PAGE_CLEAN : SLRU_PAGE_DIRTY;
LWLockRelease(shared->buffer_locks[slotno]);
/* Now it's okay to ereport if we failed */
if (!ok)
SlruReportIOError(ctl, pageno, InvalidTransactionId);
}
/*
* Find a page in a shared buffer, reading it in if necessary.
* The page number must correspond to an already-initialized page.
*
* The passed-in xid is used only for error reporting, and may be
* InvalidTransactionId if no specific xid is associated with the action.
*
* Return value is the shared-buffer slot number now holding the page.
* The buffer's LRU access info is updated.
*
* Control lock must be held at entry, and will be held at exit.
*/
int
SimpleLruReadPage(SlruCtl ctl, int pageno, TransactionId xid)
{
SlruShared shared = ctl->shared;
/* Outer loop handles restart if we lose the buffer to someone else */
for (;;)
{
int slotno;
bool ok;
/* See if page already is in memory; if not, pick victim slot */
slotno = SlruSelectLRUPage(ctl, pageno);
/* Did we find the page in memory? */
if (shared->page_number[slotno] == pageno &&
shared->page_status[slotno] != SLRU_PAGE_EMPTY)
{
/* If page is still being read in, we cannot use it yet */
if (shared->page_status[slotno] != SLRU_PAGE_READ_IN_PROGRESS)
{
/* otherwise, it's ready to use */
SlruRecentlyUsed(shared, slotno);
return slotno;
}
}
else
{
/* We found no match; assert we selected a freeable slot */
Assert(shared->page_status[slotno] == SLRU_PAGE_EMPTY ||
shared->page_status[slotno] == SLRU_PAGE_CLEAN);
}
/* Mark the slot read-busy (no-op if it already was) */
shared->page_number[slotno] = pageno;
shared->page_status[slotno] = SLRU_PAGE_READ_IN_PROGRESS;
/*
* Temporarily mark page as recently-used to discourage
* SlruSelectLRUPage from selecting it again for someone else.
*/
SlruRecentlyUsed(shared, slotno);
/*
* We must grab the per-buffer lock to do I/O. To avoid deadlock,
* must release ControlLock while waiting for per-buffer lock.
* Fortunately, most of the time the per-buffer lock shouldn't be
* already held, so we can do this:
*/
if (!LWLockConditionalAcquire(shared->buffer_locks[slotno],
LW_EXCLUSIVE))
{
LWLockRelease(shared->ControlLock);
LWLockAcquire(shared->buffer_locks[slotno], LW_EXCLUSIVE);
LWLockAcquire(shared->ControlLock, LW_EXCLUSIVE);
}
/*
* Check to see if someone else already did the read, or took the
* buffer away from us. If so, restart from the top.
*/
if (shared->page_number[slotno] != pageno ||
shared->page_status[slotno] != SLRU_PAGE_READ_IN_PROGRESS)
{
LWLockRelease(shared->buffer_locks[slotno]);
continue;
}
/* Okay, release control lock and do the read */
LWLockRelease(shared->ControlLock);
ok = SlruPhysicalReadPage(ctl, pageno, slotno);
/* Re-acquire shared control lock and update page state */
LWLockAcquire(shared->ControlLock, LW_EXCLUSIVE);
Assert(shared->page_number[slotno] == pageno &&
shared->page_status[slotno] == SLRU_PAGE_READ_IN_PROGRESS);
shared->page_status[slotno] = ok ? SLRU_PAGE_CLEAN : SLRU_PAGE_EMPTY;
LWLockRelease(shared->buffer_locks[slotno]);
/* Now it's okay to ereport if we failed */
if (!ok)
SlruReportIOError(ctl, pageno, xid);
SlruRecentlyUsed(shared, slotno);
return slotno;
}
}
/*
* Each database using a table space is isolated into its own name space
* by a subdirectory named for the database OID. On first creation of an
* object in the tablespace, create the subdirectory. If the subdirectory
* already exists, fall through quietly.
*
* isRedo indicates that we are creating an object during WAL replay.
* In this case we will cope with the possibility of the tablespace
* directory not being there either --- this could happen if we are
* replaying an operation on a table in a subsequently-dropped tablespace.
* We handle this by making a directory in the place where the tablespace
* symlink would normally be. This isn't an exact replay of course, but
* it's the best we can do given the available information.
*
* If tablespaces are not supported, we still need it in case we have to
* re-create a database subdirectory (of $PGDATA/base) during WAL replay.
*/
void
TablespaceCreateDbspace(Oid spcNode, Oid dbNode, bool isRedo)
{
struct stat st;
char *dir;
/*
* The global tablespace doesn't have per-database subdirectories, so
* nothing to do for it.
*/
if (spcNode == GLOBALTABLESPACE_OID)
return;
Assert(OidIsValid(spcNode));
Assert(OidIsValid(dbNode));
dir = GetDatabasePath(dbNode, spcNode);
if (stat(dir, &st) < 0)
{
/* Directory does not exist? */
if (errno == ENOENT)
{
/*
* Acquire TablespaceCreateLock to ensure that no DROP TABLESPACE
* or TablespaceCreateDbspace is running concurrently.
*/
LWLockAcquire(TablespaceCreateLock, LW_EXCLUSIVE);
/*
* Recheck to see if someone created the directory while we were
* waiting for lock.
*/
if (stat(dir, &st) == 0 && S_ISDIR(st.st_mode))
{
/* Directory was created */
}
else
{
/* Directory creation failed? */
if (mkdir(dir, S_IRWXU) < 0)
{
char *parentdir;
/* Failure other than not exists or not in WAL replay? */
if (errno != ENOENT || !isRedo)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not create directory \"%s\": %m",
dir)));
/*
* Parent directories are missing during WAL replay, so
* continue by creating simple parent directories rather
* than a symlink.
*/
/* create two parents up if not exist */
parentdir = pstrdup(dir);
get_parent_directory(parentdir);
get_parent_directory(parentdir);
/* Can't create parent and it doesn't already exist? */
if (mkdir(parentdir, S_IRWXU) < 0 && errno != EEXIST)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not create directory \"%s\": %m",
parentdir)));
pfree(parentdir);
/* create one parent up if not exist */
parentdir = pstrdup(dir);
get_parent_directory(parentdir);
/* Can't create parent and it doesn't already exist? */
if (mkdir(parentdir, S_IRWXU) < 0 && errno != EEXIST)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not create directory \"%s\": %m",
parentdir)));
pfree(parentdir);
/* Create database directory */
if (mkdir(dir, S_IRWXU) < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not create directory \"%s\": %m",
dir)));
}
}
LWLockRelease(TablespaceCreateLock);
}
else
{
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not stat directory \"%s\": %m", dir)));
}
}
else
{
/* Is it not a directory? */
if (!S_ISDIR(st.st_mode))
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("\"%s\" exists but is not a directory",
dir)));
}
pfree(dir);
}
/*
* Update the LSNs on each queue based upon our latest state. This
* implements a simple policy of first-valid-standby-releases-waiter.
*
* Other policies are possible, which would change what we do here and what
* perhaps also which information we store as well.
*/
void
SyncRepReleaseWaiters(void)
{
volatile WalSndCtlData *walsndctl = WalSndCtl;
volatile WalSnd *syncWalSnd = NULL;
int numprocs = 0;
int priority = 0;
int i;
/*
* If this WALSender is serving a standby that is not on the list of
* potential standbys then we have nothing to do. If we are still starting
* up or still running base backup, then leave quickly also.
*/
if (MyWalSnd->sync_standby_priority == 0 ||
MyWalSnd->state < WALSNDSTATE_STREAMING)
return;
/*
* We're a potential sync standby. Release waiters if we are the highest
* priority standby. If there are multiple standbys with same priorities
* then we use the first mentioned standby. If you change this, also
* change pg_stat_get_wal_senders().
*/
LWLockAcquire(SyncRepLock, LW_EXCLUSIVE);
for (i = 0; i < max_wal_senders; i++)
{
/* use volatile pointer to prevent code rearrangement */
volatile WalSnd *walsnd = &walsndctl->walsnds[i];
if (walsnd->pid != 0 &&
walsnd->sync_standby_priority > 0 &&
(priority == 0 ||
priority > walsnd->sync_standby_priority))
{
priority = walsnd->sync_standby_priority;
syncWalSnd = walsnd;
}
}
/*
* We should have found ourselves at least.
*/
Assert(syncWalSnd);
/*
* If we aren't managing the highest priority standby then just leave.
*/
if (syncWalSnd != MyWalSnd)
{
LWLockRelease(SyncRepLock);
announce_next_takeover = true;
return;
}
if (XLByteLT(walsndctl->lsn, MyWalSnd->flush))
{
/*
* Set the lsn first so that when we wake backends they will release
* up to this location.
*/
walsndctl->lsn = MyWalSnd->flush;
numprocs = SyncRepWakeQueue(false);
}
LWLockRelease(SyncRepLock);
elog(DEBUG3, "released %d procs up to %X/%X",
numprocs,
MyWalSnd->flush.xlogid,
MyWalSnd->flush.xrecoff);
/*
* If we are managing the highest priority standby, though we weren't
* prior to this, then announce we are now the sync standby.
*/
if (announce_next_takeover)
{
announce_next_takeover = false;
ereport(LOG,
(errmsg("standby \"%s\" is now the synchronous standby with priority %u",
application_name, MyWalSnd->sync_standby_priority)));
}
}
/*
* Drop a table space
*
* Be careful to check that the tablespace is empty.
*/
void
DropTableSpace(DropTableSpaceStmt *stmt)
{
#ifdef HAVE_SYMLINK
char *tablespacename = stmt->tablespacename;
HeapScanDesc scandesc;
Relation rel;
HeapTuple tuple;
ScanKeyData entry[1];
Oid tablespaceoid;
/*
* Find the target tuple
*/
rel = heap_open(TableSpaceRelationId, RowExclusiveLock);
ScanKeyInit(&entry[0],
Anum_pg_tablespace_spcname,
BTEqualStrategyNumber, F_NAMEEQ,
CStringGetDatum(tablespacename));
scandesc = heap_beginscan(rel, SnapshotNow, 1, entry);
tuple = heap_getnext(scandesc, ForwardScanDirection);
if (!HeapTupleIsValid(tuple))
{
if (!stmt->missing_ok)
{
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("tablespace \"%s\" does not exist",
tablespacename)));
}
else
{
ereport(NOTICE,
(errmsg("tablespace \"%s\" does not exist, skipping",
tablespacename)));
/* XXX I assume I need one or both of these next two calls */
heap_endscan(scandesc);
heap_close(rel, NoLock);
}
return;
}
tablespaceoid = HeapTupleGetOid(tuple);
/* Must be tablespace owner */
if (!pg_tablespace_ownercheck(tablespaceoid, GetUserId()))
aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_TABLESPACE,
tablespacename);
/* Disallow drop of the standard tablespaces, even by superuser */
if (tablespaceoid == GLOBALTABLESPACE_OID ||
tablespaceoid == DEFAULTTABLESPACE_OID)
aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_TABLESPACE,
tablespacename);
/*
* Remove the pg_tablespace tuple (this will roll back if we fail below)
*/
simple_heap_delete(rel, &tuple->t_self);
heap_endscan(scandesc);
/*
* Remove any comments or security labels on this tablespace.
*/
DeleteSharedComments(tablespaceoid, TableSpaceRelationId);
DeleteSharedSecurityLabel(tablespaceoid, TableSpaceRelationId);
/*
* Remove dependency on owner.
*/
deleteSharedDependencyRecordsFor(TableSpaceRelationId, tablespaceoid, 0);
/*
* Acquire TablespaceCreateLock to ensure that no TablespaceCreateDbspace
* is running concurrently.
*/
LWLockAcquire(TablespaceCreateLock, LW_EXCLUSIVE);
/*
* Try to remove the physical infrastructure.
*/
if (!destroy_tablespace_directories(tablespaceoid, false))
{
/*
* Not all files deleted? However, there can be lingering empty files
* in the directories, left behind by for example DROP TABLE, that
* have been scheduled for deletion at next checkpoint (see comments
* in mdunlink() for details). We could just delete them immediately,
* but we can't tell them apart from important data files that we
* mustn't delete. So instead, we force a checkpoint which will clean
* out any lingering files, and try again.
*/
RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT);
if (!destroy_tablespace_directories(tablespaceoid, false))
{
/* Still not empty, the files must be important then */
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("tablespace \"%s\" is not empty",
tablespacename)));
}
}
/* Record the filesystem change in XLOG */
{
xl_tblspc_drop_rec xlrec;
XLogRecData rdata[1];
xlrec.ts_id = tablespaceoid;
rdata[0].data = (char *) &xlrec;
rdata[0].len = sizeof(xl_tblspc_drop_rec);
rdata[0].buffer = InvalidBuffer;
rdata[0].next = NULL;
(void) XLogInsert(RM_TBLSPC_ID, XLOG_TBLSPC_DROP, rdata);
}
/*
* Note: because we checked that the tablespace was empty, there should be
* no need to worry about flushing shared buffers or free space map
* entries for relations in the tablespace.
*/
/*
* Force synchronous commit, to minimize the window between removing the
* files on-disk and marking the transaction committed. It's not great
* that there is any window at all, but definitely we don't want to make
* it larger than necessary.
*/
ForceSyncCommit();
/*
* Allow TablespaceCreateDbspace again.
*/
LWLockRelease(TablespaceCreateLock);
/* We keep the lock on pg_tablespace until commit */
heap_close(rel, NoLock);
#else /* !HAVE_SYMLINK */
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("tablespaces are not supported on this platform")));
#endif /* HAVE_SYMLINK */
}
/*
* Wait for synchronous replication, if requested by user.
*
* Initially backends start in state SYNC_REP_NOT_WAITING and then
* change that state to SYNC_REP_WAITING before adding ourselves
* to the wait queue. During SyncRepWakeQueue() a WALSender changes
* the state to SYNC_REP_WAIT_COMPLETE once replication is confirmed.
* This backend then resets its state to SYNC_REP_NOT_WAITING.
*/
void
SyncRepWaitForLSN(XLogRecPtr XactCommitLSN)
{
char *new_status = NULL;
const char *old_status;
/*
* Fast exit if user has not requested sync replication, or there are no
* sync replication standby names defined. Note that those standbys don't
* need to be connected.
*/
if (!SyncRepRequested() || !SyncStandbysDefined())
return;
Assert(SHMQueueIsDetached(&(MyProc->syncRepLinks)));
Assert(WalSndCtl != NULL);
LWLockAcquire(SyncRepLock, LW_EXCLUSIVE);
Assert(MyProc->syncRepState == SYNC_REP_NOT_WAITING);
/*
* We don't wait for sync rep if WalSndCtl->sync_standbys_defined is not
* set. See SyncRepUpdateSyncStandbysDefined.
*
* Also check that the standby hasn't already replied. Unlikely race
* condition but we'll be fetching that cache line anyway so its likely to
* be a low cost check.
*/
if (!WalSndCtl->sync_standbys_defined ||
XLByteLE(XactCommitLSN, WalSndCtl->lsn))
{
LWLockRelease(SyncRepLock);
return;
}
/*
* Set our waitLSN so WALSender will know when to wake us, and add
* ourselves to the queue.
*/
MyProc->waitLSN = XactCommitLSN;
MyProc->syncRepState = SYNC_REP_WAITING;
SyncRepQueueInsert();
Assert(SyncRepQueueIsOrderedByLSN());
LWLockRelease(SyncRepLock);
/* Alter ps display to show waiting for sync rep. */
if (update_process_title)
{
int len;
old_status = get_ps_display(&len);
new_status = (char *) palloc(len + 32 + 1);
memcpy(new_status, old_status, len);
sprintf(new_status + len, " waiting for %X/%X",
XactCommitLSN.xlogid, XactCommitLSN.xrecoff);
set_ps_display(new_status, false);
new_status[len] = '\0'; /* truncate off " waiting ..." */
}
/*
* Wait for specified LSN to be confirmed.
*
* Each proc has its own wait latch, so we perform a normal latch
* check/wait loop here.
*/
for (;;)
{
int syncRepState;
/* Must reset the latch before testing state. */
ResetLatch(&MyProc->procLatch);
/*
* Try checking the state without the lock first. There's no
* guarantee that we'll read the most up-to-date value, so if it looks
* like we're still waiting, recheck while holding the lock. But if
* it looks like we're done, we must really be done, because once
* walsender changes the state to SYNC_REP_WAIT_COMPLETE, it will
* never update it again, so we can't be seeing a stale value in that
* case.
*
* Note: on machines with weak memory ordering, the acquisition of
* the lock is essential to avoid race conditions: we cannot be sure
* the sender's state update has reached main memory until we acquire
* the lock. We could get rid of this dance if SetLatch/ResetLatch
* contained memory barriers.
*/
syncRepState = MyProc->syncRepState;
if (syncRepState == SYNC_REP_WAITING)
{
LWLockAcquire(SyncRepLock, LW_SHARED);
syncRepState = MyProc->syncRepState;
LWLockRelease(SyncRepLock);
}
if (syncRepState == SYNC_REP_WAIT_COMPLETE)
break;
/*
* If a wait for synchronous replication is pending, we can neither
* acknowledge the commit nor raise ERROR or FATAL. The latter would
* lead the client to believe that that the transaction aborted, which
* is not true: it's already committed locally. The former is no good
* either: the client has requested synchronous replication, and is
* entitled to assume that an acknowledged commit is also replicated,
* which might not be true. So in this case we issue a WARNING (which
* some clients may be able to interpret) and shut off further output.
* We do NOT reset ProcDiePending, so that the process will die after
* the commit is cleaned up.
*/
if (ProcDiePending)
{
ereport(WARNING,
(errcode(ERRCODE_ADMIN_SHUTDOWN),
errmsg("canceling the wait for synchronous replication and terminating connection due to administrator command"),
errdetail("The transaction has already committed locally, but might not have been replicated to the standby.")));
whereToSendOutput = DestNone;
SyncRepCancelWait();
break;
}
/*
* It's unclear what to do if a query cancel interrupt arrives. We
* can't actually abort at this point, but ignoring the interrupt
* altogether is not helpful, so we just terminate the wait with a
* suitable warning.
*/
if (QueryCancelPending)
{
QueryCancelPending = false;
ereport(WARNING,
(errmsg("canceling wait for synchronous replication due to user request"),
errdetail("The transaction has already committed locally, but might not have been replicated to the standby.")));
SyncRepCancelWait();
break;
}
/*
* If the postmaster dies, we'll probably never get an
* acknowledgement, because all the wal sender processes will exit. So
* just bail out.
*/
if (!PostmasterIsAlive())
{
ProcDiePending = true;
whereToSendOutput = DestNone;
SyncRepCancelWait();
break;
}
/*
* Wait on latch. Any condition that should wake us up will set
* the latch, so no need for timeout.
*/
WaitLatch(&MyProc->procLatch, WL_LATCH_SET | WL_POSTMASTER_DEATH, -1);
}
/*
* WalSender has checked our LSN and has removed us from queue. Clean up
* state and leave. It's OK to reset these shared memory fields without
* holding SyncRepLock, because any walsenders will ignore us anyway when
* we're not on the queue.
*/
Assert(SHMQueueIsDetached(&(MyProc->syncRepLinks)));
MyProc->syncRepState = SYNC_REP_NOT_WAITING;
MyProc->waitLSN.xlogid = 0;
MyProc->waitLSN.xrecoff = 0;
if (new_status)
{
/* Reset ps display */
set_ps_display(new_status, false);
pfree(new_status);
}
}
Datum
pg_buffercache_pages(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
Datum result;
MemoryContext oldcontext;
BufferCachePagesContext *fctx; /* User function context. */
TupleDesc tupledesc;
HeapTuple tuple;
if (SRF_IS_FIRSTCALL())
{
int i;
volatile BufferDesc *bufHdr;
funcctx = SRF_FIRSTCALL_INIT();
/* Switch context when allocating stuff to be used in later calls */
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/* Create a user function context for cross-call persistence */
fctx = (BufferCachePagesContext *) palloc(sizeof(BufferCachePagesContext));
/* Construct a tuple descriptor for the result rows. */
tupledesc = CreateTemplateTupleDesc(NUM_BUFFERCACHE_PAGES_ELEM, false);
TupleDescInitEntry(tupledesc, (AttrNumber) 1, "bufferid",
INT4OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 2, "relfilenode",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 3, "reltablespace",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 4, "reldatabase",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 5, "relforknumber",
INT2OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 6, "relblocknumber",
INT8OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 7, "isdirty",
BOOLOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 8, "usage_count",
INT2OID, -1, 0);
fctx->tupdesc = BlessTupleDesc(tupledesc);
/* Allocate NBuffers worth of BufferCachePagesRec records. */
fctx->record = (BufferCachePagesRec *) palloc(sizeof(BufferCachePagesRec) * NBuffers);
/* Set max calls and remember the user function context. */
funcctx->max_calls = NBuffers;
funcctx->user_fctx = fctx;
/* Return to original context when allocating transient memory */
MemoryContextSwitchTo(oldcontext);
/*
* To get a consistent picture of the buffer state, we must lock all
* partitions of the buffer map. Needless to say, this is horrible
* for concurrency. Must grab locks in increasing order to avoid
* possible deadlocks.
*/
for (i = 0; i < NUM_BUFFER_PARTITIONS; i++)
LWLockAcquire(FirstBufMappingLock + i, LW_SHARED);
/*
* Scan though all the buffers, saving the relevant fields in the
* fctx->record structure.
*/
for (i = 0, bufHdr = BufferDescriptors; i < NBuffers; i++, bufHdr++)
{
/* Lock each buffer header before inspecting. */
LockBufHdr(bufHdr);
fctx->record[i].bufferid = BufferDescriptorGetBuffer(bufHdr);
fctx->record[i].relfilenode = bufHdr->tag.rnode.relNode;
fctx->record[i].reltablespace = bufHdr->tag.rnode.spcNode;
fctx->record[i].reldatabase = bufHdr->tag.rnode.dbNode;
fctx->record[i].forknum = bufHdr->tag.forkNum;
fctx->record[i].blocknum = bufHdr->tag.blockNum;
fctx->record[i].usagecount = bufHdr->usage_count;
if (bufHdr->flags & BM_DIRTY)
fctx->record[i].isdirty = true;
else
fctx->record[i].isdirty = false;
/* Note if the buffer is valid, and has storage created */
if ((bufHdr->flags & BM_VALID) && (bufHdr->flags & BM_TAG_VALID))
fctx->record[i].isvalid = true;
else
fctx->record[i].isvalid = false;
UnlockBufHdr(bufHdr);
}
/*
* And release locks. We do this in reverse order for two reasons:
* (1) Anyone else who needs more than one of the locks will be trying
* to lock them in increasing order; we don't want to release the
* other process until it can get all the locks it needs. (2) This
* avoids O(N^2) behavior inside LWLockRelease.
*/
for (i = NUM_BUFFER_PARTITIONS; --i >= 0;)
LWLockRelease(FirstBufMappingLock + i);
}
funcctx = SRF_PERCALL_SETUP();
/* Get the saved state */
fctx = funcctx->user_fctx;
if (funcctx->call_cntr < funcctx->max_calls)
{
uint32 i = funcctx->call_cntr;
Datum values[NUM_BUFFERCACHE_PAGES_ELEM];
bool nulls[NUM_BUFFERCACHE_PAGES_ELEM];
values[0] = Int32GetDatum(fctx->record[i].bufferid);
nulls[0] = false;
/*
* Set all fields except the bufferid to null if the buffer is unused
* or not valid.
*/
if (fctx->record[i].blocknum == InvalidBlockNumber ||
fctx->record[i].isvalid == false)
{
nulls[1] = true;
nulls[2] = true;
nulls[3] = true;
nulls[4] = true;
nulls[5] = true;
nulls[6] = true;
nulls[7] = true;
}
else
{
values[1] = ObjectIdGetDatum(fctx->record[i].relfilenode);
nulls[1] = false;
values[2] = ObjectIdGetDatum(fctx->record[i].reltablespace);
nulls[2] = false;
values[3] = ObjectIdGetDatum(fctx->record[i].reldatabase);
nulls[3] = false;
values[4] = ObjectIdGetDatum(fctx->record[i].forknum);
nulls[4] = false;
values[5] = Int64GetDatum((int64) fctx->record[i].blocknum);
nulls[5] = false;
values[6] = BoolGetDatum(fctx->record[i].isdirty);
nulls[6] = false;
values[7] = Int16GetDatum(fctx->record[i].usagecount);
nulls[7] = false;
}
/* Build and return the tuple. */
tuple = heap_form_tuple(fctx->tupdesc, values, nulls);
result = HeapTupleGetDatum(tuple);
SRF_RETURN_NEXT(funcctx, result);
}
else
SRF_RETURN_DONE(funcctx);
}
/*
* Releases the pinCount of a SessionState entry. If the pinCount
* drops to 0, it puts the entry back to the freeList for reuse.
*/
static void
SessionState_Release(SessionState *acquired)
{
if (!sessionStateInited)
{
Assert(NULL == acquired);
return;
}
Assert(NULL != acquired);
Assert(0 < acquired->pinCount);
Assert(acquired->sessionId == gp_session_id || acquired->isModifiedSessionId);
LWLockAcquire(SessionStateLock, LW_EXCLUSIVE);
Assert(!isProcessActive);
Assert(acquired->activeProcessCount < acquired->pinCount);
int pinCount = pg_atomic_sub_fetch_u32((pg_atomic_uint32 *) &acquired->pinCount, 1);
ereport(gp_sessionstate_loglevel, (errmsg("SessionState_Release: pinCount: %d, activeProcessCount: %d",
pinCount, acquired->activeProcessCount), errprintstack(true)));
/* Before this point the process should have been deactivated */
Assert(acquired->activeProcessCount <= acquired->pinCount);
Assert(0 <= acquired->pinCount);
if (0 == acquired->pinCount)
{
RunawayCleaner_RunawayCleanupDoneForSession();
acquired->sessionId = INVALID_SESSION_ID;
Assert(acquired->runawayStatus == RunawayStatus_NotRunaway);
Assert(CLEANUP_COUNTDOWN_BEFORE_RUNAWAY == acquired->cleanupCountdown);
Assert(0 == acquired->activeProcessCount);
acquired->sessionVmem = 0;
acquired->runawayStatus = RunawayStatus_NotRunaway;
acquired->sessionVmemRunaway = 0;
acquired->commandCountRunaway = 0;
acquired->cleanupCountdown = CLEANUP_COUNTDOWN_BEFORE_RUNAWAY;
acquired->activeProcessCount = 0;
acquired->idle_start = 0;
acquired->resGroupSlot = NULL;
#ifdef USE_ASSERT_CHECKING
acquired->isModifiedSessionId = false;
#endif
SessionState *cur = AllSessionStateEntries->usedList;
SessionState *prev = NULL;
while (cur != acquired && cur != NULL)
{
prev = cur;
cur = cur->next;
}
Assert(cur == acquired);
/* grabbed is at the head of used list */
if (NULL == prev)
{
Assert(AllSessionStateEntries->usedList == acquired);
AllSessionStateEntries->usedList = acquired->next;
}
else
{
prev->next = cur->next;
}
acquired->next = AllSessionStateEntries->freeList;
AllSessionStateEntries->freeList = acquired;
AllSessionStateEntries->numSession--;
Assert(AllSessionStateEntries->numSession >= 0);
}
LWLockRelease(SessionStateLock);
}
/*
* ProcSleep -- put a process to sleep on the specified lock
*
* Caller must have set MyProc->heldLocks to reflect locks already held
* on the lockable object by this process (under all XIDs).
*
* The lock table's partition lock must be held at entry, and will be held
* at exit.
*
* Result: STATUS_OK if we acquired the lock, STATUS_ERROR if not (deadlock).
*
* ASSUME: that no one will fiddle with the queue until after
* we release the partition lock.
*
* NOTES: The process queue is now a priority queue for locking.
*
* P() on the semaphore should put us to sleep. The process
* semaphore is normally zero, so when we try to acquire it, we sleep.
*/
int
ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
{
LOCKMODE lockmode = locallock->tag.mode;
LOCK *lock = locallock->lock;
PROCLOCK *proclock = locallock->proclock;
uint32 hashcode = locallock->hashcode;
LWLockId partitionLock = LockHashPartitionLock(hashcode);
PROC_QUEUE *waitQueue = &(lock->waitProcs);
LOCKMASK myHeldLocks = MyProc->heldLocks;
bool early_deadlock = false;
bool allow_autovacuum_cancel = true;
int myWaitStatus;
PGPROC *proc;
int i;
/*
* Determine where to add myself in the wait queue.
*
* Normally I should go at the end of the queue. However, if I already
* hold locks that conflict with the request of any previous waiter, put
* myself in the queue just in front of the first such waiter. This is not
* a necessary step, since deadlock detection would move me to before that
* waiter anyway; but it's relatively cheap to detect such a conflict
* immediately, and avoid delaying till deadlock timeout.
*
* Special case: if I find I should go in front of some waiter, check to
* see if I conflict with already-held locks or the requests before that
* waiter. If not, then just grant myself the requested lock immediately.
* This is the same as the test for immediate grant in LockAcquire, except
* we are only considering the part of the wait queue before my insertion
* point.
*/
if (myHeldLocks != 0)
{
LOCKMASK aheadRequests = 0;
proc = (PGPROC *) waitQueue->links.next;
for (i = 0; i < waitQueue->size; i++)
{
/* Must he wait for me? */
if (lockMethodTable->conflictTab[proc->waitLockMode] & myHeldLocks)
{
/* Must I wait for him ? */
if (lockMethodTable->conflictTab[lockmode] & proc->heldLocks)
{
/*
* Yes, so we have a deadlock. Easiest way to clean up
* correctly is to call RemoveFromWaitQueue(), but we
* can't do that until we are *on* the wait queue. So, set
* a flag to check below, and break out of loop. Also,
* record deadlock info for later message.
*/
RememberSimpleDeadLock(MyProc, lockmode, lock, proc);
early_deadlock = true;
break;
}
/* I must go before this waiter. Check special case. */
if ((lockMethodTable->conflictTab[lockmode] & aheadRequests) == 0 &&
LockCheckConflicts(lockMethodTable,
lockmode,
lock,
proclock,
MyProc) == STATUS_OK)
{
/* Skip the wait and just grant myself the lock. */
GrantLock(lock, proclock, lockmode);
GrantAwaitedLock();
return STATUS_OK;
}
/* Break out of loop to put myself before him */
break;
}
/* Nope, so advance to next waiter */
aheadRequests |= LOCKBIT_ON(proc->waitLockMode);
proc = (PGPROC *) proc->links.next;
}
/*
* If we fall out of loop normally, proc points to waitQueue head, so
* we will insert at tail of queue as desired.
*/
}
else
{
/* I hold no locks, so I can't push in front of anyone. */
proc = (PGPROC *) &(waitQueue->links);
}
/*
* Insert self into queue, ahead of the given proc (or at tail of queue).
*/
SHMQueueInsertBefore(&(proc->links), &(MyProc->links));
waitQueue->size++;
lock->waitMask |= LOCKBIT_ON(lockmode);
/* Set up wait information in PGPROC object, too */
MyProc->waitLock = lock;
MyProc->waitProcLock = proclock;
MyProc->waitLockMode = lockmode;
MyProc->waitStatus = STATUS_WAITING;
/*
* If we detected deadlock, give up without waiting. This must agree with
* CheckDeadLock's recovery code, except that we shouldn't release the
* semaphore since we haven't tried to lock it yet.
*/
if (early_deadlock)
{
RemoveFromWaitQueue(MyProc, hashcode);
return STATUS_ERROR;
}
/* mark that we are waiting for a lock */
lockAwaited = locallock;
/*
* Release the lock table's partition lock.
*
* NOTE: this may also cause us to exit critical-section state, possibly
* allowing a cancel/die interrupt to be accepted. This is OK because we
* have recorded the fact that we are waiting for a lock, and so
* LockErrorCleanup will clean up if cancel/die happens.
*/
LWLockRelease(partitionLock);
/*
* Also, now that we will successfully clean up after an ereport, it's
* safe to check to see if there's a buffer pin deadlock against the
* Startup process. Of course, that's only necessary if we're doing Hot
* Standby and are not the Startup process ourselves.
*/
if (RecoveryInProgress() && !InRecovery)
CheckRecoveryConflictDeadlock();
/* Reset deadlock_state before enabling the timeout handler */
deadlock_state = DS_NOT_YET_CHECKED;
/*
* Set timer so we can wake up after awhile and check for a deadlock. If a
* deadlock is detected, the handler releases the process's semaphore and
* sets MyProc->waitStatus = STATUS_ERROR, allowing us to know that we
* must report failure rather than success.
*
* By delaying the check until we've waited for a bit, we can avoid
* running the rather expensive deadlock-check code in most cases.
*/
enable_timeout_after(DEADLOCK_TIMEOUT, DeadlockTimeout);
/*
* If someone wakes us between LWLockRelease and PGSemaphoreLock,
* PGSemaphoreLock will not block. The wakeup is "saved" by the semaphore
* implementation. While this is normally good, there are cases where a
* saved wakeup might be leftover from a previous operation (for example,
* we aborted ProcWaitForSignal just before someone did ProcSendSignal).
* So, loop to wait again if the waitStatus shows we haven't been granted
* nor denied the lock yet.
*
* We pass interruptOK = true, which eliminates a window in which
* cancel/die interrupts would be held off undesirably. This is a promise
* that we don't mind losing control to a cancel/die interrupt here. We
* don't, because we have no shared-state-change work to do after being
* granted the lock (the grantor did it all). We do have to worry about
* canceling the deadlock timeout and updating the locallock table, but if
* we lose control to an error, LockErrorCleanup will fix that up.
*/
do
{
PGSemaphoreLock(&MyProc->sem, true);
/*
* waitStatus could change from STATUS_WAITING to something else
* asynchronously. Read it just once per loop to prevent surprising
* behavior (such as missing log messages).
*/
myWaitStatus = MyProc->waitStatus;
/*
* If we are not deadlocked, but are waiting on an autovacuum-induced
* task, send a signal to interrupt it.
*/
if (deadlock_state == DS_BLOCKED_BY_AUTOVACUUM && allow_autovacuum_cancel)
{
PGPROC *autovac = GetBlockingAutoVacuumPgproc();
PGXACT *autovac_pgxact = &ProcGlobal->allPgXact[autovac->pgprocno];
LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
/*
* Only do it if the worker is not working to protect against Xid
* wraparound.
*/
if ((autovac != NULL) &&
(autovac_pgxact->vacuumFlags & PROC_IS_AUTOVACUUM) &&
!(autovac_pgxact->vacuumFlags & PROC_VACUUM_FOR_WRAPAROUND))
{
int pid = autovac->pid;
StringInfoData locktagbuf;
StringInfoData logbuf; /* errdetail for server log */
initStringInfo(&locktagbuf);
initStringInfo(&logbuf);
DescribeLockTag(&locktagbuf, &lock->tag);
appendStringInfo(&logbuf,
_("Process %d waits for %s on %s."),
MyProcPid,
GetLockmodeName(lock->tag.locktag_lockmethodid,
lockmode),
locktagbuf.data);
/* release lock as quickly as possible */
LWLockRelease(ProcArrayLock);
ereport(LOG,
(errmsg("sending cancel to blocking autovacuum PID %d",
pid),
errdetail_log("%s", logbuf.data)));
pfree(logbuf.data);
pfree(locktagbuf.data);
/* send the autovacuum worker Back to Old Kent Road */
if (kill(pid, SIGINT) < 0)
{
/* Just a warning to allow multiple callers */
ereport(WARNING,
(errmsg("could not send signal to process %d: %m",
pid)));
}
}
else
LWLockRelease(ProcArrayLock);
/* prevent signal from being resent more than once */
allow_autovacuum_cancel = false;
}
/*
* If awoken after the deadlock check interrupt has run, and
* log_lock_waits is on, then report about the wait.
*/
if (log_lock_waits && deadlock_state != DS_NOT_YET_CHECKED)
{
StringInfoData buf;
const char *modename;
long secs;
int usecs;
long msecs;
initStringInfo(&buf);
DescribeLockTag(&buf, &locallock->tag.lock);
modename = GetLockmodeName(locallock->tag.lock.locktag_lockmethodid,
lockmode);
TimestampDifference(get_timeout_start_time(DEADLOCK_TIMEOUT),
GetCurrentTimestamp(),
&secs, &usecs);
msecs = secs * 1000 + usecs / 1000;
usecs = usecs % 1000;
if (deadlock_state == DS_SOFT_DEADLOCK)
ereport(LOG,
(errmsg("process %d avoided deadlock for %s on %s by rearranging queue order after %ld.%03d ms",
MyProcPid, modename, buf.data, msecs, usecs)));
else if (deadlock_state == DS_HARD_DEADLOCK)
{
/*
* This message is a bit redundant with the error that will be
* reported subsequently, but in some cases the error report
* might not make it to the log (eg, if it's caught by an
* exception handler), and we want to ensure all long-wait
* events get logged.
*/
ereport(LOG,
(errmsg("process %d detected deadlock while waiting for %s on %s after %ld.%03d ms",
MyProcPid, modename, buf.data, msecs, usecs)));
}
if (myWaitStatus == STATUS_WAITING)
ereport(LOG,
(errmsg("process %d still waiting for %s on %s after %ld.%03d ms",
MyProcPid, modename, buf.data, msecs, usecs)));
else if (myWaitStatus == STATUS_OK)
ereport(LOG,
(errmsg("process %d acquired %s on %s after %ld.%03d ms",
MyProcPid, modename, buf.data, msecs, usecs)));
else
{
Assert(myWaitStatus == STATUS_ERROR);
/*
* Currently, the deadlock checker always kicks its own
* process, which means that we'll only see STATUS_ERROR when
* deadlock_state == DS_HARD_DEADLOCK, and there's no need to
* print redundant messages. But for completeness and
* future-proofing, print a message if it looks like someone
* else kicked us off the lock.
*/
if (deadlock_state != DS_HARD_DEADLOCK)
ereport(LOG,
(errmsg("process %d failed to acquire %s on %s after %ld.%03d ms",
MyProcPid, modename, buf.data, msecs, usecs)));
}
/*
* At this point we might still need to wait for the lock. Reset
* state so we don't print the above messages again.
*/
deadlock_state = DS_NO_DEADLOCK;
pfree(buf.data);
}
} while (myWaitStatus == STATUS_WAITING);
/*
* Disable the timer, if it's still running
*/
disable_timeout(DEADLOCK_TIMEOUT, false);
/*
* Re-acquire the lock table's partition lock. We have to do this to hold
* off cancel/die interrupts before we can mess with lockAwaited (else we
* might have a missed or duplicated locallock update).
*/
LWLockAcquire(partitionLock, LW_EXCLUSIVE);
/*
* We no longer want LockErrorCleanup to do anything.
*/
lockAwaited = NULL;
/*
* If we got the lock, be sure to remember it in the locallock table.
*/
if (MyProc->waitStatus == STATUS_OK)
GrantAwaitedLock();
/*
* We don't have to do anything else, because the awaker did all the
* necessary update of the lock table and MyProc.
*/
return MyProc->waitStatus;
}
/*
* Grabs one entry in the sessionStateArray for current session.
* If the current session already has an entry, it just returns the
* pointer to the previously grabbed entry.
*/
static SessionState*
SessionState_Acquire(int sessionId)
{
LWLockAcquire(SessionStateLock, LW_EXCLUSIVE);
SessionState *cur = AllSessionStateEntries->usedList;
while (cur != NULL && cur->sessionId != sessionId)
{
Assert(INVALID_SESSION_ID != cur->sessionId);
cur = cur->next;
}
if (NULL == cur && NULL == AllSessionStateEntries->freeList)
{
LWLockRelease(SessionStateLock);
ereport(FATAL,
(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
errmsg("Too many sessions."),
errdetail("Could not acquire resources for additional sessions."),
errhint("Disconnect some sessions and try again.")));
}
SessionState *acquired = cur;
/*
* Nothing was acquired for this session from any other processes. Therefore,
* acquire a new entry, and reset its properties.
*/
if (NULL == acquired)
{
acquired = AllSessionStateEntries->freeList;
Assert(INVALID_SESSION_ID == acquired->sessionId &&
acquired->runawayStatus == RunawayStatus_NotRunaway &&
0 == acquired->pinCount &&
CLEANUP_COUNTDOWN_BEFORE_RUNAWAY == acquired->cleanupCountdown &&
0 == acquired->activeProcessCount &&
0 == acquired->sessionVmem &&
0 == acquired->spinLock &&
0 == acquired->sessionVmemRunaway &&
0 == acquired->commandCountRunaway &&
!acquired->isModifiedSessionId);
AllSessionStateEntries->freeList = acquired->next;
acquired->next = AllSessionStateEntries->usedList;
AllSessionStateEntries->usedList = acquired;
AllSessionStateEntries->numSession++;
Assert(AllSessionStateEntries->numSession <= AllSessionStateEntries->maxSession);
acquired->sessionId = sessionId;
acquired->runawayStatus = RunawayStatus_NotRunaway;
acquired->sessionVmemRunaway = 0;
acquired->commandCountRunaway = 0;
acquired->pinCount = 0;
acquired->sessionVmem = 0;
acquired->cleanupCountdown = CLEANUP_COUNTDOWN_BEFORE_RUNAWAY;
acquired->activeProcessCount = 0;
acquired->idle_start = 0;
acquired->resGroupSlot = NULL;
#ifdef USE_ASSERT_CHECKING
acquired->isModifiedSessionId = false;
#endif
/*
* Make sure that the lock is reset to released. Note: this doesn't
* have a matching SpinLockAcquire. We are just resetting the lock
* as part of initialization
*/
SpinLockRelease(&acquired->spinLock);
}
Assert(NULL != acquired);
int pinCount = pg_atomic_add_fetch_u32((pg_atomic_uint32 *) &acquired->pinCount, 1);
ereport(gp_sessionstate_loglevel, (errmsg("SessionState_Acquire: pinCount: %d, activeProcessCount: %d",
pinCount, acquired->activeProcessCount), errprintstack(true)));
LWLockRelease(SessionStateLock);
return acquired;
}
/*
* We have to cut&paste copde of GetNewTransactionId from varsup because we change way of advancing ShmemVariableCache->nextXid
*/
TransactionId
DtmGetNewTransactionId(bool isSubXact)
{
TransactionId xid;
XTM_INFO("%d: GetNewTransactionId\n", getpid());
/*
* Workers synchronize transaction state at the beginning of each parallel
* operation, so we can't account for new XIDs after that point.
*/
if (IsInParallelMode())
elog(ERROR, "cannot assign TransactionIds during a parallel operation");
/*
* During bootstrap initialization, we return the special bootstrap
* transaction id.
*/
if (IsBootstrapProcessingMode())
{
Assert(!isSubXact);
MyPgXact->xid = BootstrapTransactionId;
return BootstrapTransactionId;
}
/* safety check, we should never get this far in a HS slave */
if (RecoveryInProgress())
elog(ERROR, "cannot assign TransactionIds during recovery");
LWLockAcquire(XidGenLock, LW_EXCLUSIVE);
xid = DtmGetNextXid();
/*----------
* Check to see if it's safe to assign another XID. This protects against
* catastrophic data loss due to XID wraparound. The basic rules are:
*
* If we're past xidVacLimit, start trying to force autovacuum cycles.
* If we're past xidWarnLimit, start issuing warnings.
* If we're past xidStopLimit, refuse to execute transactions, unless
* we are running in single-user mode (which gives an escape hatch
* to the DBA who somehow got past the earlier defenses).
*
* Note that this coding also appears in GetNewMultiXactId.
*----------
*/
if (TransactionIdFollowsOrEquals(xid, ShmemVariableCache->xidVacLimit))
{
/*
* For safety's sake, we release XidGenLock while sending signals,
* warnings, etc. This is not so much because we care about
* preserving concurrency in this situation, as to avoid any
* possibility of deadlock while doing get_database_name(). First,
* copy all the shared values we'll need in this path.
*/
TransactionId xidWarnLimit = ShmemVariableCache->xidWarnLimit;
TransactionId xidStopLimit = ShmemVariableCache->xidStopLimit;
TransactionId xidWrapLimit = ShmemVariableCache->xidWrapLimit;
Oid oldest_datoid = ShmemVariableCache->oldestXidDB;
LWLockRelease(XidGenLock);
/*
* To avoid swamping the postmaster with signals, we issue the autovac
* request only once per 64K transaction starts. This still gives
* plenty of chances before we get into real trouble.
*/
if (IsUnderPostmaster && (xid % 65536) == 0)
SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_LAUNCHER);
if (IsUnderPostmaster && TransactionIdFollowsOrEquals(xid, xidStopLimit))
{
char *oldest_datname = get_database_name(oldest_datoid);
/* complain even if that DB has disappeared */
if (oldest_datname)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("database is not accepting commands to avoid wraparound data loss in database \"%s\"",
oldest_datname),
errhint("Stop the postmaster and vacuum that database in single-user mode.\n"
"You might also need to commit or roll back old prepared transactions.")));
else
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("database is not accepting commands to avoid wraparound data loss in database with OID %u",
oldest_datoid),
errhint("Stop the postmaster and vacuum that database in single-user mode.\n"
"You might also need to commit or roll back old prepared transactions.")));
}
else
if (TransactionIdFollowsOrEquals(xid, xidWarnLimit))
{
char *oldest_datname = get_database_name(oldest_datoid);
/* complain even if that DB has disappeared */
if (oldest_datname)
ereport(WARNING,
(errmsg("database \"%s\" must be vacuumed within %u transactions",
oldest_datname,
xidWrapLimit - xid),
errhint("To avoid a database shutdown, execute a database-wide VACUUM in that database.\n"
"You might also need to commit or roll back old prepared transactions.")));
else
ereport(WARNING,
(errmsg("database with OID %u must be vacuumed within %u transactions",
oldest_datoid,
xidWrapLimit - xid),
errhint("To avoid a database shutdown, execute a database-wide VACUUM in that database.\n"
"You might also need to commit or roll back old prepared transactions.")));
}
/* Re-acquire lock and start over */
LWLockAcquire(XidGenLock, LW_EXCLUSIVE);
xid = DtmGetNextXid();
}
/*
* If we are allocating the first XID of a new page of the commit log,
* zero out that commit-log page before returning. We must do this while
* holding XidGenLock, else another xact could acquire and commit a later
* XID before we zero the page. Fortunately, a page of the commit log
* holds 32K or more transactions, so we don't have to do this very often.
*
* Extend pg_subtrans and pg_commit_ts too.
*/
if (TransactionIdFollowsOrEquals(xid, ShmemVariableCache->nextXid))
{
ExtendCLOG(xid);
ExtendCommitTs(xid);
ExtendSUBTRANS(xid);
}
/*
* Now advance the nextXid counter. This must not happen until after we
* have successfully completed ExtendCLOG() --- if that routine fails, we
* want the next incoming transaction to try it again. We cannot assign
* more XIDs until there is CLOG space for them.
*/
if (xid == ShmemVariableCache->nextXid)
TransactionIdAdvance(ShmemVariableCache->nextXid);
else
Assert(TransactionIdPrecedes(xid, ShmemVariableCache->nextXid));
/*
* We must store the new XID into the shared ProcArray before releasing
* XidGenLock. This ensures that every active XID older than
* latestCompletedXid is present in the ProcArray, which is essential for
* correct OldestXmin tracking; see src/backend/access/transam/README.
*
* XXX by storing xid into MyPgXact without acquiring ProcArrayLock, we
* are relying on fetch/store of an xid to be atomic, else other backends
* might see a partially-set xid here. But holding both locks at once
* would be a nasty concurrency hit. So for now, assume atomicity.
*
* Note that readers of PGXACT xid fields should be careful to fetch the
* value only once, rather than assume they can read a value multiple
* times and get the same answer each time.
*
* The same comments apply to the subxact xid count and overflow fields.
*
* A solution to the atomic-store problem would be to give each PGXACT its
* own spinlock used only for fetching/storing that PGXACT's xid and
* related fields.
*
* If there's no room to fit a subtransaction XID into PGPROC, set the
* cache-overflowed flag instead. This forces readers to look in
* pg_subtrans to map subtransaction XIDs up to top-level XIDs. There is a
* race-condition window, in that the new XID will not appear as running
* until its parent link has been placed into pg_subtrans. However, that
* will happen before anyone could possibly have a reason to inquire about
* the status of the XID, so it seems OK. (Snapshots taken during this
* window *will* include the parent XID, so they will deliver the correct
* answer later on when someone does have a reason to inquire.)
*/
{
/*
* Use volatile pointer to prevent code rearrangement; other backends
* could be examining my subxids info concurrently, and we don't want
* them to see an invalid intermediate state, such as incrementing
* nxids before filling the array entry. Note we are assuming that
* TransactionId and int fetch/store are atomic.
*/
volatile PGPROC *myproc = MyProc;
volatile PGXACT *mypgxact = MyPgXact;
if (!isSubXact)
mypgxact->xid = xid;
else
{
int nxids = mypgxact->nxids;
if (nxids < PGPROC_MAX_CACHED_SUBXIDS)
{
myproc->subxids.xids[nxids] = xid;
mypgxact->nxids = nxids + 1;
}
else
mypgxact->overflowed = true;
}
}
LWLockRelease(XidGenLock);
return xid;
}
/*
* shmem_startup hook: allocate or attach to shared memory,
* then load any pre-existing statistics from file.
*/
static void
pgss_shmem_startup(void)
{
bool found;
HASHCTL info;
FILE *file;
uint32 header;
int32 num;
int32 i;
int query_size;
int buffer_size;
char *buffer = NULL;
if (prev_shmem_startup_hook)
prev_shmem_startup_hook();
/* reset in case this is a restart within the postmaster */
pgss = NULL;
pgss_hash = NULL;
/*
* Create or attach to the shared memory state, including hash table
*/
LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE);
pgss = ShmemInitStruct("pg_stat_statements",
sizeof(pgssSharedState),
&found);
if (!found)
{
/* First time through ... */
pgss->lock = LWLockAssign();
pgss->query_size = pgstat_track_activity_query_size;
}
/* Be sure everyone agrees on the hash table entry size */
query_size = pgss->query_size;
memset(&info, 0, sizeof(info));
info.keysize = sizeof(pgssHashKey);
info.entrysize = offsetof(pgssEntry, query) +query_size;
info.hash = pgss_hash_fn;
info.match = pgss_match_fn;
pgss_hash = ShmemInitHash("pg_stat_statements hash",
pgss_max, pgss_max,
&info,
HASH_ELEM | HASH_FUNCTION | HASH_COMPARE);
LWLockRelease(AddinShmemInitLock);
/*
* If we're in the postmaster (or a standalone backend...), set up a shmem
* exit hook to dump the statistics to disk.
*/
if (!IsUnderPostmaster)
on_shmem_exit(pgss_shmem_shutdown, (Datum) 0);
/*
* Attempt to load old statistics from the dump file, if this is the first
* time through and we weren't told not to.
*/
if (found || !pgss_save)
return;
/*
* Note: we don't bother with locks here, because there should be no other
* processes running when this code is reached.
*/
file = AllocateFile(PGSS_DUMP_FILE, PG_BINARY_R);
if (file == NULL)
{
if (errno == ENOENT)
return; /* ignore not-found error */
goto error;
}
buffer_size = query_size;
buffer = (char *) palloc(buffer_size);
if (fread(&header, sizeof(uint32), 1, file) != 1 ||
header != PGSS_FILE_HEADER ||
fread(&num, sizeof(int32), 1, file) != 1)
goto error;
for (i = 0; i < num; i++)
{
pgssEntry temp;
pgssEntry *entry;
if (fread(&temp, offsetof(pgssEntry, mutex), 1, file) != 1)
goto error;
/* Encoding is the only field we can easily sanity-check */
if (!PG_VALID_BE_ENCODING(temp.key.encoding))
goto error;
/* Previous incarnation might have had a larger query_size */
if (temp.key.query_len >= buffer_size)
{
buffer = (char *) repalloc(buffer, temp.key.query_len + 1);
buffer_size = temp.key.query_len + 1;
}
if (fread(buffer, 1, temp.key.query_len, file) != temp.key.query_len)
goto error;
buffer[temp.key.query_len] = '\0';
/* Clip to available length if needed */
if (temp.key.query_len >= query_size)
temp.key.query_len = pg_encoding_mbcliplen(temp.key.encoding,
buffer,
temp.key.query_len,
query_size - 1);
temp.key.query_ptr = buffer;
/* make the hashtable entry (discards old entries if too many) */
entry = entry_alloc(&temp.key);
/* copy in the actual stats */
entry->counters = temp.counters;
}
pfree(buffer);
FreeFile(file);
return;
error:
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not read pg_stat_statement file \"%s\": %m",
PGSS_DUMP_FILE)));
if (buffer)
pfree(buffer);
if (file)
FreeFile(file);
/* If possible, throw away the bogus file; ignore any error */
unlink(PGSS_DUMP_FILE);
}
void
ftsLock(void)
{
LWLockAcquire(ftsControlLock, LW_EXCLUSIVE);
}
/*
* Store some statistics for a statement.
*/
static void
pgss_store(const char *query, double total_time, uint64 rows,
const BufferUsage *bufusage)
{
pgssHashKey key;
double usage;
pgssEntry *entry;
Assert(query != NULL);
/* Safety check... */
if (!pgss || !pgss_hash)
return;
/* Set up key for hashtable search */
key.userid = GetUserId();
key.dbid = MyDatabaseId;
key.encoding = GetDatabaseEncoding();
key.query_len = strlen(query);
if (key.query_len >= pgss->query_size)
key.query_len = pg_encoding_mbcliplen(key.encoding,
query,
key.query_len,
pgss->query_size - 1);
key.query_ptr = query;
usage = USAGE_EXEC(duration);
/* Lookup the hash table entry with shared lock. */
LWLockAcquire(pgss->lock, LW_SHARED);
entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_FIND, NULL);
if (!entry)
{
/* Must acquire exclusive lock to add a new entry. */
LWLockRelease(pgss->lock);
LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
entry = entry_alloc(&key);
}
/* Grab the spinlock while updating the counters. */
{
volatile pgssEntry *e = (volatile pgssEntry *) entry;
SpinLockAcquire(&e->mutex);
e->counters.calls += 1;
e->counters.total_time += total_time;
e->counters.rows += rows;
e->counters.shared_blks_hit += bufusage->shared_blks_hit;
e->counters.shared_blks_read += bufusage->shared_blks_read;
e->counters.shared_blks_written += bufusage->shared_blks_written;
e->counters.local_blks_hit += bufusage->local_blks_hit;
e->counters.local_blks_read += bufusage->local_blks_read;
e->counters.local_blks_written += bufusage->local_blks_written;
e->counters.temp_blks_read += bufusage->temp_blks_read;
e->counters.temp_blks_written += bufusage->temp_blks_written;
e->counters.usage += usage;
SpinLockRelease(&e->mutex);
}
LWLockRelease(pgss->lock);
}
/*
* Permanently drop the currently acquired replication slot which will be
* released by the point this function returns.
*/
static void
ReplicationSlotDropAcquired(void)
{
char path[MAXPGPATH];
char tmppath[MAXPGPATH];
ReplicationSlot *slot = MyReplicationSlot;
Assert(MyReplicationSlot != NULL);
/* slot isn't acquired anymore */
MyReplicationSlot = NULL;
/*
* If some other backend ran this code concurrently with us, we might try
* to delete a slot with a certain name while someone else was trying to
* create a slot with the same name.
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/* Generate pathnames. */
sprintf(path, "pg_replslot/%s", NameStr(slot->data.name));
sprintf(tmppath, "pg_replslot/%s.tmp", NameStr(slot->data.name));
/*
* Rename the slot directory on disk, so that we'll no longer recognize
* this as a valid slot. Note that if this fails, we've got to mark the
* slot inactive before bailing out. If we're dropping an ephemeral slot,
* we better never fail hard as the caller won't expect the slot to
* survive and this might get called during error handling.
*/
if (rename(path, tmppath) == 0)
{
/*
* We need to fsync() the directory we just renamed and its parent to
* make sure that our changes are on disk in a crash-safe fashion. If
* fsync() fails, we can't be sure whether the changes are on disk or
* not. For now, we handle that by panicking;
* StartupReplicationSlots() will try to straighten it out after
* restart.
*/
START_CRIT_SECTION();
fsync_fname(tmppath, true);
fsync_fname("pg_replslot", true);
END_CRIT_SECTION();
}
else
{
volatile ReplicationSlot *vslot = slot;
bool fail_softly = slot->data.persistency == RS_EPHEMERAL;
SpinLockAcquire(&slot->mutex);
vslot->active_pid = 0;
SpinLockRelease(&slot->mutex);
ereport(fail_softly ? WARNING : ERROR,
(errcode_for_file_access(),
errmsg("could not rename file \"%s\" to \"%s\": %m",
path, tmppath)));
}
/*
* The slot is definitely gone. Lock out concurrent scans of the array
* long enough to kill it. It's OK to clear the active flag here without
* grabbing the mutex because nobody else can be scanning the array here,
* and nobody can be attached to this slot and thus access it without
* scanning the array.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_EXCLUSIVE);
slot->active_pid = 0;
slot->in_use = false;
LWLockRelease(ReplicationSlotControlLock);
/*
* Slot is dead and doesn't prevent resource removal anymore, recompute
* limits.
*/
ReplicationSlotsComputeRequiredXmin(false);
ReplicationSlotsComputeRequiredLSN();
/*
* If removing the directory fails, the worst thing that will happen is
* that the user won't be able to create a new___ slot with the same name
* until the next server restart. We warn about it, but that's all.
*/
if (!rmtree(tmppath, true))
ereport(WARNING,
(errcode_for_file_access(),
errmsg("could not remove directory \"%s\"", tmppath)));
/*
* We release this at the very end, so that nobody starts trying to create
* a slot while we're still cleaning up the detritus of the old one.
*/
LWLockRelease(ReplicationSlotAllocationLock);
}
/*
* Retrieve statement statistics.
*/
Datum
pg_stat_statements(PG_FUNCTION_ARGS)
{
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
MemoryContext per_query_ctx;
MemoryContext oldcontext;
Oid userid = GetUserId();
bool is_superuser = superuser();
HASH_SEQ_STATUS hash_seq;
pgssEntry *entry;
if (!pgss || !pgss_hash)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
/* 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);
LWLockAcquire(pgss->lock, LW_SHARED);
hash_seq_init(&hash_seq, pgss_hash);
while ((entry = hash_seq_search(&hash_seq)) != NULL)
{
Datum values[PG_STAT_STATEMENTS_COLS];
bool nulls[PG_STAT_STATEMENTS_COLS];
int i = 0;
Counters tmp;
memset(values, 0, sizeof(values));
memset(nulls, 0, sizeof(nulls));
values[i++] = ObjectIdGetDatum(entry->key.userid);
values[i++] = ObjectIdGetDatum(entry->key.dbid);
if (is_superuser || entry->key.userid == userid)
{
char *qstr;
qstr = (char *)
pg_do_encoding_conversion((unsigned char *) entry->query,
entry->key.query_len,
entry->key.encoding,
GetDatabaseEncoding());
values[i++] = CStringGetTextDatum(qstr);
if (qstr != entry->query)
pfree(qstr);
}
else
values[i++] = CStringGetTextDatum("<insufficient privilege>");
/* copy counters to a local variable to keep locking time short */
{
volatile pgssEntry *e = (volatile pgssEntry *) entry;
SpinLockAcquire(&e->mutex);
tmp = e->counters;
SpinLockRelease(&e->mutex);
}
values[i++] = Int64GetDatumFast(tmp.calls);
values[i++] = Float8GetDatumFast(tmp.total_time);
values[i++] = Int64GetDatumFast(tmp.rows);
values[i++] = Int64GetDatumFast(tmp.shared_blks_hit);
values[i++] = Int64GetDatumFast(tmp.shared_blks_read);
values[i++] = Int64GetDatumFast(tmp.shared_blks_written);
values[i++] = Int64GetDatumFast(tmp.local_blks_hit);
values[i++] = Int64GetDatumFast(tmp.local_blks_read);
values[i++] = Int64GetDatumFast(tmp.local_blks_written);
values[i++] = Int64GetDatumFast(tmp.temp_blks_read);
values[i++] = Int64GetDatumFast(tmp.temp_blks_written);
Assert(i == PG_STAT_STATEMENTS_COLS);
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
}
LWLockRelease(pgss->lock);
/* clean up and return the tuplestore */
tuplestore_donestoring(tupstore);
return (Datum) 0;
}
/*
* Returns activity of walsenders, including pids and xlog locations sent to
* standby servers.
*/
Datum
pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
{
#define PG_STAT_GET_WAL_SENDERS_COLS 8
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
MemoryContext per_query_ctx;
MemoryContext oldcontext;
int *sync_priority;
int priority = 0;
int sync_standby = -1;
int i;
/* 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);
/*
* Get the priorities of sync standbys all in one go, to minimise lock
* acquisitions and to allow us to evaluate who is the current sync
* standby. This code must match the code in SyncRepReleaseWaiters().
*/
sync_priority = palloc(sizeof(int) * max_wal_senders);
LWLockAcquire(SyncRepLock, LW_SHARED);
for (i = 0; i < max_wal_senders; i++)
{
/* use volatile pointer to prevent code rearrangement */
volatile WalSnd *walsnd = &WalSndCtl->walsnds[i];
if (walsnd->pid != 0)
{
sync_priority[i] = walsnd->sync_standby_priority;
if (walsnd->state == WALSNDSTATE_STREAMING &&
walsnd->sync_standby_priority > 0 &&
(priority == 0 ||
priority > walsnd->sync_standby_priority))
{
priority = walsnd->sync_standby_priority;
sync_standby = i;
}
}
}
LWLockRelease(SyncRepLock);
for (i = 0; i < max_wal_senders; i++)
{
/* use volatile pointer to prevent code rearrangement */
volatile WalSnd *walsnd = &WalSndCtl->walsnds[i];
char location[MAXFNAMELEN];
XLogRecPtr sentPtr;
XLogRecPtr write;
XLogRecPtr flush;
XLogRecPtr apply;
WalSndState state;
Datum values[PG_STAT_GET_WAL_SENDERS_COLS];
bool nulls[PG_STAT_GET_WAL_SENDERS_COLS];
if (walsnd->pid == 0)
continue;
SpinLockAcquire(&walsnd->mutex);
sentPtr = walsnd->sentPtr;
state = walsnd->state;
write = walsnd->write;
flush = walsnd->flush;
apply = walsnd->apply;
SpinLockRelease(&walsnd->mutex);
memset(nulls, 0, sizeof(nulls));
values[0] = Int32GetDatum(walsnd->pid);
if (!superuser())
{
/*
* Only superusers can see details. Other users only get the pid
* value to know it's a walsender, but no details.
*/
MemSet(&nulls[1], true, PG_STAT_GET_WAL_SENDERS_COLS - 1);
}
else
{
values[1] = CStringGetTextDatum(WalSndGetStateString(state));
snprintf(location, sizeof(location), "%X/%X",
sentPtr.xlogid, sentPtr.xrecoff);
values[2] = CStringGetTextDatum(location);
if (write.xlogid == 0 && write.xrecoff == 0)
nulls[3] = true;
snprintf(location, sizeof(location), "%X/%X",
write.xlogid, write.xrecoff);
values[3] = CStringGetTextDatum(location);
if (flush.xlogid == 0 && flush.xrecoff == 0)
nulls[4] = true;
snprintf(location, sizeof(location), "%X/%X",
flush.xlogid, flush.xrecoff);
values[4] = CStringGetTextDatum(location);
if (apply.xlogid == 0 && apply.xrecoff == 0)
nulls[5] = true;
snprintf(location, sizeof(location), "%X/%X",
apply.xlogid, apply.xrecoff);
values[5] = CStringGetTextDatum(location);
values[6] = Int32GetDatum(sync_priority[i]);
/*
* More easily understood version of standby state. This is purely
* informational, not different from priority.
*/
if (sync_priority[i] == 0)
values[7] = CStringGetTextDatum("async");
else if (i == sync_standby)
values[7] = CStringGetTextDatum("sync");
else
values[7] = CStringGetTextDatum("potential");
}
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
}
pfree(sync_priority);
/* clean up and return the tuplestore */
tuplestore_donestoring(tupstore);
return (Datum) 0;
}
/*
* CheckPointRelationMap
*
* This is called during a checkpoint. It must ensure that any relation map
* updates that were WAL-logged before the start of the checkpoint are
* securely flushed to disk and will not need to be replayed later. This
* seems unlikely to be a performance-critical issue, so we use a simple
* method: we just take and release the RelationMappingLock. This ensures
* that any already-logged map update is complete, because write_relmap_file
* will fsync the map file before the lock is released.
*/
void
CheckPointRelationMap(void)
{
LWLockAcquire(RelationMappingLock, LW_SHARED);
LWLockRelease(RelationMappingLock);
}
