/*
* Make sure that SUBTRANS has room for a newly-allocated XID.
*
* NB: this is called while holding XidGenLock. We want it to be very fast
* most of the time; even when it's not so fast, no actual I/O need happen
* unless we're forced to write out a dirty subtrans page to make room
* in shared memory.
*/
void
ExtendSUBTRANS(TransactionId newestXact)
{
int pageno;
/*
* Caller must have already taken mirrored lock shared.
*/
/*
* No work except at first XID of a page. But beware: just after
* wraparound, the first XID of page zero is FirstNormalTransactionId.
*/
if (TransactionIdToEntry(newestXact) != 0 &&
!TransactionIdEquals(newestXact, FirstNormalTransactionId))
return;
pageno = TransactionIdToPage(newestXact);
LWLockAcquire(SubtransControlLock, LW_EXCLUSIVE);
/* Zero the page */
ZeroSUBTRANSPage(pageno);
LWLockRelease(SubtransControlLock);
}
/*
* XactLockTableWait
*
* Wait for the specified transaction to commit or abort.
*/
void
XactLockTableWait(TransactionId xid)
{
LOCKTAG tag;
TransactionId myxid = GetCurrentTransactionId();
Assert(!TransactionIdEquals(xid, myxid));
MemSet(&tag, 0, sizeof(tag));
tag.relId = XactLockTableId;
tag.dbId = InvalidOid;
tag.objId.xid = xid;
if (!LockAcquire(LockTableId, &tag, myxid,
ShareLock, false))
elog(ERROR, "LockAcquire failed");
LockRelease(LockTableId, &tag, myxid, ShareLock);
/*
* Transaction was committed/aborted/crashed - we have to update
* pg_clog if transaction is still marked as running.
*/
if (!TransactionIdDidCommit(xid) && !TransactionIdDidAbort(xid))
TransactionIdAbort(xid);
}
/*
* TransactionIdGetCommitLSN
*
* This function returns an LSN that is late enough to be able
* to guarantee that if we flush up to the LSN returned then we
* will have flushed the transaction's commit record to disk.
*
* The result is not necessarily the exact LSN of the transaction's
* commit record! For example, for long-past transactions (those whose
* clog pages already migrated to disk), we'll return InvalidXLogRecPtr.
* Also, because we group transactions on the same clog page to conserve
* storage, we might return the LSN of a later transaction that falls into
* the same group.
*/
XLogRecPtr
TransactionIdGetCommitLSN(TransactionId xid)
{
XLogRecPtr result;
/*
* Currently, all uses of this function are for xids that were just
* reported to be committed by TransactionLogFetch, so we expect that
* checking TransactionLogFetch's cache will usually succeed and avoid an
* extra trip to shared memory.
*/
if (TransactionIdEquals(xid, cachedFetchXid))
return cachedCommitLSN;
/* Special XIDs are always known committed */
if (!TransactionIdIsNormal(xid))
return InvalidXLogRecPtr;
/*
* Get the transaction status.
*/
(void) TransactionIdGetStatus(xid, &result);
return result;
}
/*
* Make sure that CommitTs has room for a newly-allocated XID.
*
* NB: this is called while holding XidGenLock. We want it to be very fast
* most of the time; even when it's not so fast, no actual I/O need happen
* unless we're forced to write out a dirty CommitTs or xlog page to make room
* in shared memory.
*
* NB: the current implementation relies on track_commit_timestamp being
* PGC_POSTMASTER.
*/
void
ExtendCommitTs(TransactionId newestXact)
{
int pageno;
/*
* Nothing to do if module not enabled. Note we do an unlocked read of
* the flag here, which is okay because this routine is only called from
* GetNewTransactionId, which is never called in a standby.
*/
Assert(!InRecovery);
if (!commitTsShared->commitTsActive)
return;
/*
* No work except at first XID of a page. But beware: just after
* wraparound, the first XID of page zero is FirstNormalTransactionId.
*/
if (TransactionIdToCTsEntry(newestXact) != 0 &&
!TransactionIdEquals(newestXact, FirstNormalTransactionId))
return;
pageno = TransactionIdToCTsPage(newestXact);
LWLockAcquire(CommitTsControlLock, LW_EXCLUSIVE);
/* Zero the page and make an XLOG entry about it */
ZeroCommitTsPage(pageno, !InRecovery);
LWLockRelease(CommitTsControlLock);
}
/*
* TransactionIdIsInProgress -- is given transaction running by some backend
*/
bool
TransactionIdIsInProgress(TransactionId xid)
{
bool result = false;
SISeg *segP = shmInvalBuffer;
ProcState *stateP = segP->procState;
int index;
LWLockAcquire(SInvalLock, LW_SHARED);
for (index = 0; index < segP->lastBackend; index++)
{
SHMEM_OFFSET pOffset = stateP[index].procStruct;
if (pOffset != INVALID_OFFSET)
{
PGPROC *proc = (PGPROC *) MAKE_PTR(pOffset);
/* Fetch xid just once - see GetNewTransactionId */
TransactionId pxid = proc->xid;
if (TransactionIdEquals(pxid, xid))
{
result = true;
break;
}
}
}
LWLockRelease(SInvalLock);
return result;
}
/*
* Make sure that SUBTRANS has room for a newly-allocated XID.
*
* NB: this is called while holding XidGenLock. We want it to be very fast
* most of the time; even when it's not so fast, no actual I/O need happen
* unless we're forced to write out a dirty subtrans page to make room
* in shared memory.
*/
void
ExtendSUBTRANS(TransactionId newestXact)
{
int pageno;
/*
* No work except at first XID of a page. But beware: just after
* wraparound, the first XID of page zero is FirstNormalTransactionId.
*/
#ifdef PGXC /* PGXC_COORD || PGXC_DATANODE */
/*
* In PGXC, it may be that a node is not involved in a transaction,
* and therefore will be skipped, so we need to detect this by using
* the latest_page_number instead of the pg index.
*
* Also, there is a special case of when transactions wrap-around that
* we need to detect.
*/
pageno = TransactionIdToPage(newestXact);
/*
* The first condition makes sure we did not wrap around
* The second checks if we are still using the same page.
* Note that this value can change and we are not holding a lock,
* so we repeat the check below. We do it this way instead of
* grabbing the lock to avoid lock contention.
*/
if (SubTransCtl->shared->latest_page_number - pageno <= SUBTRANS_WRAP_CHECK_DELTA
&& pageno <= SubTransCtl->shared->latest_page_number)
return;
#else
if (TransactionIdToEntry(newestXact) != 0 &&
!TransactionIdEquals(newestXact, FirstNormalTransactionId))
return;
pageno = TransactionIdToPage(newestXact);
#endif
LWLockAcquire(SubtransControlLock, LW_EXCLUSIVE);
#ifdef PGXC
/*
* We repeat the check. Another process may have written
* out the page already and advanced the latest_page_number
* while we were waiting for the lock.
*/
if (SubTransCtl->shared->latest_page_number - pageno <= SUBTRANS_WRAP_CHECK_DELTA
&& pageno <= SubTransCtl->shared->latest_page_number)
{
LWLockRelease(SubtransControlLock);
return;
}
#endif
/* Zero the page */
ZeroSUBTRANSPage(pageno);
LWLockRelease(SubtransControlLock);
}
/*
* xideq - are two xids equal?
*/
Datum
xideq(PG_FUNCTION_ARGS)
{
TransactionId xid1 = PG_GETARG_TRANSACTIONID(0);
TransactionId xid2 = PG_GETARG_TRANSACTIONID(1);
PG_RETURN_BOOL(TransactionIdEquals(xid1, xid2));
}
/*
* TransactionLogFetch --- fetch commit status of specified transaction id
*/
static XidStatus
TransactionLogFetch(TransactionId transactionId)
{
XidStatus xidstatus;
XLogRecPtr xidlsn;
/*
* Before going to the commit log manager, check our single item cache to
* see if we didn't just check the transaction status a moment ago.
*/
if (TransactionIdEquals(transactionId, cachedFetchXid))
return cachedFetchXidStatus;
/*
* Also, check to see if the transaction ID is a permanent one.
*/
if (!TransactionIdIsNormal(transactionId))
{
if (TransactionIdEquals(transactionId, BootstrapTransactionId))
return TRANSACTION_STATUS_COMMITTED;
if (TransactionIdEquals(transactionId, FrozenTransactionId))
return TRANSACTION_STATUS_COMMITTED;
return TRANSACTION_STATUS_ABORTED;
}
/*
* Get the transaction status.
*/
xidstatus = TransactionIdGetStatus(transactionId, &xidlsn);
/*
* Cache it, but DO NOT cache status for unfinished or sub-committed
* transactions! We only cache status that is guaranteed not to change.
*/
if (xidstatus != TRANSACTION_STATUS_IN_PROGRESS &&
xidstatus != TRANSACTION_STATUS_SUB_COMMITTED)
{
cachedFetchXid = transactionId;
cachedFetchXidStatus = xidstatus;
cachedCommitLSN = xidlsn;
}
return xidstatus;
}
/*
* TransactionIdIsKnownCompleted
* True iff transaction associated with the identifier is currently
* known to have either committed or aborted.
*
* This does NOT look into pg_clog but merely probes our local cache
* (and so it's not named TransactionIdDidComplete, which would be the
* appropriate name for a function that worked that way). The intended
* use is just to short-circuit TransactionIdIsInProgress calls when doing
* repeated tqual.c checks for the same XID. If this isn't extremely fast
* then it will be counterproductive.
*
* Note:
* Assumes transaction identifier is valid.
*/
bool
TransactionIdIsKnownCompleted(TransactionId transactionId)
{
if (TransactionIdEquals(transactionId, cachedFetchXid))
{
/* If it's in the cache at all, it must be completed. */
return true;
}
return false;
}
/*
* TransactionIdIsCurrentTransactionId
*
* During bootstrap, we cheat and say "it's not my transaction ID" even though
* it is. Along with transam.c's cheat to say that the bootstrap XID is
* already committed, this causes the tqual.c routines to see previously
* inserted tuples as committed, which is what we need during bootstrap.
*/
bool
TransactionIdIsCurrentTransactionId(TransactionId xid)
{
TransactionState s = CurrentTransactionState;
if (AMI_OVERRIDE)
{
Assert(xid == BootstrapTransactionId);
return false;
}
return TransactionIdEquals(xid, s->transactionIdData);
}
/*
* TransactionIdIsKnownCompleted
* True iff transaction associated with the identifier is currently
* known to have either committed or aborted.
*
* This does NOT look into pg_clog but merely probes our local cache
* (and so it's not named TransactionIdDidComplete, which would be the
* appropriate name for a function that worked that way). The intended
* use is just to short-circuit TransactionIdIsInProgress calls when doing
* repeated tqual.c checks for the same XID. If this isn't extremely fast
* then it will be counterproductive.
*
* Note:
* Assumes transaction identifier is valid.
*/
bool
TransactionIdIsKnownCompleted(TransactionId transactionId)
{
if (TransactionIdEquals(transactionId, cachedFetchXid))
{
#ifdef PGXC
syncGXID_GTM((GlobalTransactionId)transactionId);
#endif
/* If it's in the cache at all, it must be completed. */
return true;
}
return false;
}
/*
* XactLockTableWait
*
* Wait for the specified transaction to commit or abort. If an operation
* is specified, an error context callback is set up. If 'oper' is passed as
* None, no error context callback is set up.
*
* Note that this does the right thing for subtransactions: if we wait on a
* subtransaction, we will exit as soon as it aborts or its top parent commits.
* It takes some extra work to ensure this, because to save on shared memory
* the XID lock of a subtransaction is released when it ends, whether
* successfully or unsuccessfully. So we have to check if it's "still running"
* and if so wait for its parent.
*/
void
XactLockTableWait(TransactionId xid, Relation rel, ItemPointer ctid,
XLTW_Oper oper)
{
LOCKTAG tag;
XactLockTableWaitInfo info;
ErrorContextCallback callback;
/*
* If an operation is specified, set up our verbose error context
* callback.
*/
if (oper != XLTW_None)
{
Assert(RelationIsValid(rel));
Assert(ItemPointerIsValid(ctid));
info.rel = rel;
info.ctid = ctid;
info.oper = oper;
callback.callback = XactLockTableWaitErrorCb;
callback.arg = &info;
callback.previous = error_context_stack;
error_context_stack = &callback;
}
for (;;)
{
Assert(TransactionIdIsValid(xid));
Assert(!TransactionIdEquals(xid, GetTopTransactionIdIfAny()));
SET_LOCKTAG_TRANSACTION(tag, xid);
(void) LockAcquire(&tag, ShareLock, false, false);
LockRelease(&tag, ShareLock, false);
if (!TransactionIdIsInProgress(xid))
break;
xid = SubTransGetParent(xid);
}
if (oper != XLTW_None)
error_context_stack = callback.previous;
}
/*
* Check if specified heap tuple was inserted by given
* xaction/command and return
*
* - -1 if not
* - 0 if there is no tuple at all
* - 1 if yes
*/
int
XLogIsOwnerOfTuple(RelFileNode hnode, ItemPointer iptr,
TransactionId xid, CommandId cid)
{
Relation reln;
Buffer buffer;
Page page;
ItemId lp;
HeapTupleHeader htup;
reln = XLogOpenRelation(false, RM_HEAP_ID, hnode);
if (!RelationIsValid(reln))
return (0);
buffer = ReadBuffer(reln, ItemPointerGetBlockNumber(iptr));
if (!BufferIsValid(buffer))
return (0);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = (Page) BufferGetPage(buffer);
if (PageIsNew((PageHeader) page) ||
ItemPointerGetOffsetNumber(iptr) > PageGetMaxOffsetNumber(page))
{
UnlockAndReleaseBuffer(buffer);
return (0);
}
lp = PageGetItemId(page, ItemPointerGetOffsetNumber(iptr));
if (!ItemIdIsUsed(lp) || ItemIdDeleted(lp))
{
UnlockAndReleaseBuffer(buffer);
return (0);
}
htup = (HeapTupleHeader) PageGetItem(page, lp);
Assert(PageGetSUI(page) == ThisStartUpID);
if (!TransactionIdEquals(HeapTupleHeaderGetXmin(htup), xid) ||
HeapTupleHeaderGetCmin(htup) != cid)
{
UnlockAndReleaseBuffer(buffer);
return (-1);
}
UnlockAndReleaseBuffer(buffer);
return (1);
}
/*
* XactLockTableWait
*
* Wait for the specified transaction to commit or abort.
*
* Note that this does the right thing for subtransactions: if we wait on a
* subtransaction, we will exit as soon as it aborts or its top parent commits.
* It takes some extra work to ensure this, because to save on shared memory
* the XID lock of a subtransaction is released when it ends, whether
* successfully or unsuccessfully. So we have to check if it's "still running"
* and if so wait for its parent.
*/
void
XactLockTableWait(TransactionId xid)
{
LOCKTAG tag;
for (;;)
{
Assert(TransactionIdIsValid(xid));
Assert(!TransactionIdEquals(xid, GetTopTransactionIdIfAny()));
SET_LOCKTAG_TRANSACTION(tag, xid);
(void) LockAcquire(&tag, ShareLock, false, false);
LockRelease(&tag, ShareLock, false);
if (!TransactionIdIsInProgress(xid))
break;
xid = SubTransGetParent(xid);
}
}
/*
* ConditionalXactLockTableWait
*
* As above, but only lock if we can get the lock without blocking.
* Returns TRUE if the lock was acquired.
*/
bool
ConditionalXactLockTableWait(TransactionId xid)
{
LOCKTAG tag;
for (;;)
{
Assert(TransactionIdIsValid(xid));
Assert(!TransactionIdEquals(xid, GetTopTransactionIdIfAny()));
SET_LOCKTAG_TRANSACTION(tag, xid);
if (LockAcquire(&tag, ShareLock, false, true) == LOCKACQUIRE_NOT_AVAIL)
return false;
LockRelease(&tag, ShareLock, false);
if (!TransactionIdIsInProgress(xid))
break;
xid = SubTransGetParent(xid);
}
return true;
}
/*
* Make sure that DistributedLog has room for a newly-allocated XID.
*
* NB: this is called while holding XidGenLock. We want it to be very fast
* most of the time; even when it's not so fast, no actual I/O need happen
* unless we're forced to write out a dirty DistributedLog or xlog page
* to make room in shared memory.
*/
void
DistributedLog_Extend(TransactionId newestXact)
{
MIRRORED_LOCK_DECLARE;
int page;
/*
* No work except at first XID of a page. But beware: just after
* wraparound, the first XID of page zero is FirstNormalTransactionId.
*/
if (TransactionIdToEntry(newestXact) != 0 &&
!TransactionIdEquals(newestXact, FirstNormalTransactionId))
return;
page = TransactionIdToPage(newestXact);
elog((Debug_print_full_dtm ? LOG : DEBUG5),
"DistributedLog_Extend page %d",
page);
MIRRORED_LOCK;
LWLockAcquire(DistributedLogControlLock, LW_EXCLUSIVE);
/* Zero the page and make an XLOG entry about it */
DistributedLog_ZeroPage(page, true);
LWLockRelease(DistributedLogControlLock);
MIRRORED_UNLOCK;
elog((Debug_print_full_dtm ? LOG : DEBUG5),
"DistributedLog_Extend with newest local xid = %d to page = %d",
newestXact, page);
}
/*
* PrescanPreparedTransactions
*
* Scan the pg_twophase directory and determine the range of valid XIDs
* present. This is run during database startup, after we have completed
* reading WAL. ShmemVariableCache->nextXid has been set to one more than
* the highest XID for which evidence exists in WAL.
*
* We throw away any prepared xacts with main XID beyond nextXid --- if any
* are present, it suggests that the DBA has done a PITR recovery to an
* earlier point in time without cleaning out pg_twophase. We dare not
* try to recover such prepared xacts since they likely depend on database
* state that doesn't exist now.
*
* However, we will advance nextXid beyond any subxact XIDs belonging to
* valid prepared xacts. We need to do this since subxact commit doesn't
* write a WAL entry, and so there might be no evidence in WAL of those
* subxact XIDs.
*
* Our other responsibility is to determine and return the oldest valid XID
* among the prepared xacts (if none, return ShmemVariableCache->nextXid).
* This is needed to synchronize pg_subtrans startup properly.
*/
TransactionId
PrescanPreparedTransactions(void)
{
TransactionId origNextXid = ShmemVariableCache->nextXid;
TransactionId result = origNextXid;
DIR *cldir;
struct dirent *clde;
cldir = AllocateDir(TWOPHASE_DIR);
while ((clde = ReadDir(cldir, TWOPHASE_DIR)) != NULL)
{
if (strlen(clde->d_name) == 8 &&
strspn(clde->d_name, "0123456789ABCDEF") == 8)
{
TransactionId xid;
char *buf;
TwoPhaseFileHeader *hdr;
TransactionId *subxids;
int i;
xid = (TransactionId) strtoul(clde->d_name, NULL, 16);
/* Reject XID if too new */
if (TransactionIdFollowsOrEquals(xid, origNextXid))
{
ereport(WARNING,
(errmsg("removing future two-phase state file \"%s\"",
clde->d_name)));
RemoveTwoPhaseFile(xid, true);
continue;
}
/*
* Note: we can't check if already processed because clog
* subsystem isn't up yet.
*/
/* Read and validate file */
buf = ReadTwoPhaseFile(xid);
if (buf == NULL)
{
ereport(WARNING,
(errmsg("removing corrupt two-phase state file \"%s\"",
clde->d_name)));
RemoveTwoPhaseFile(xid, true);
continue;
}
/* Deconstruct header */
hdr = (TwoPhaseFileHeader *) buf;
if (!TransactionIdEquals(hdr->xid, xid))
{
ereport(WARNING,
(errmsg("removing corrupt two-phase state file \"%s\"",
clde->d_name)));
RemoveTwoPhaseFile(xid, true);
pfree(buf);
continue;
}
/*
* OK, we think this file is valid. Incorporate xid into the
* running-minimum result.
*/
if (TransactionIdPrecedes(xid, result))
result = xid;
/*
* Examine subtransaction XIDs ... they should all follow main
* XID, and they may force us to advance nextXid.
*/
subxids = (TransactionId *)
(buf + MAXALIGN(sizeof(TwoPhaseFileHeader)));
for (i = 0; i < hdr->nsubxacts; i++)
{
TransactionId subxid = subxids[i];
Assert(TransactionIdFollows(subxid, xid));
if (TransactionIdFollowsOrEquals(subxid,
ShmemVariableCache->nextXid))
{
ShmemVariableCache->nextXid = subxid;
TransactionIdAdvance(ShmemVariableCache->nextXid);
}
}
pfree(buf);
}
}
FreeDir(cldir);
return result;
}
/*
* StrategyReplaceBuffer
*
* Called by the buffer manager to inform us that he flushed a buffer
* and is now about to replace the content. Prior to this call,
* the cache algorithm still reports the buffer as in the cache. After
* this call we report the new block, even if IO might still need to
* be done to bring in the new content.
*
* cdb_found_index and cdb_replace_index must be the auxiliary values
* returned by previous calls to StrategyBufferLookup and StrategyGetBuffer.
*/
void
StrategyReplaceBuffer(BufferDesc *buf, BufferTag *newTag,
int cdb_found_index, int cdb_replace_index)
{
BufferStrategyCDB *cdb_found;
BufferStrategyCDB *cdb_replace;
if (cdb_found_index >= 0)
{
/* This must have been a ghost buffer cache hit (B1 list) */
cdb_found = &StrategyCDB[cdb_found_index];
/* Assert that the buffer remembered in cdb_found is the one */
/* the buffer manager is currently faulting in */
Assert(BUFFERTAGS_EQUAL(cdb_found->buf_tag, *newTag));
if (cdb_replace_index >= 0)
{
/* We are satisfying it with an evicted T buffer */
cdb_replace = &StrategyCDB[cdb_replace_index];
/* Assert that the buffer remembered in cdb_replace is */
/* the one the buffer manager has just evicted */
Assert(cdb_replace->list == STRAT_LIST_T1 ||
cdb_replace->list == STRAT_LIST_T2);
Assert(cdb_replace->buf_id == buf->buf_id);
Assert(BUFFERTAGS_EQUAL(cdb_replace->buf_tag, buf->tag));
/*
* Under normal circumstances we move evicted T1 list entries
* to the B1 list. However, T1 entries that exist only because
* of VACUUM are just thrown into the unused list instead,
* since it's unlikely they'll be touched again soon. Similarly,
* evicted T2 entries are thrown away; the LRU T2 entry cannot
* have been touched recently.
*/
if (cdb_replace->t1_vacuum || cdb_replace->list == STRAT_LIST_T2)
{
BufTableDelete(&(cdb_replace->buf_tag));
STRAT_LIST_REMOVE(cdb_replace);
cdb_replace->next = StrategyControl->listUnusedCDB;
StrategyControl->listUnusedCDB = cdb_replace_index;
}
else
{
STRAT_LIST_REMOVE(cdb_replace);
STRAT_MRU_INSERT(cdb_replace, STRAT_LIST_B1);
}
/* And clear its block reference */
cdb_replace->buf_id = -1;
}
else
{
/* We are satisfying it with an unused buffer */
}
/* Now the found B1 CDB gets the buffer and is moved to T2 */
cdb_found->buf_id = buf->buf_id;
STRAT_LIST_REMOVE(cdb_found);
STRAT_MRU_INSERT(cdb_found, STRAT_LIST_T2);
}
else
{
/*
* This was a complete cache miss, so we need to create a new CDB.
* We use a free one if available, else reclaim the tail end of B1.
*/
if (StrategyControl->listUnusedCDB >= 0)
{
cdb_found = &StrategyCDB[StrategyControl->listUnusedCDB];
StrategyControl->listUnusedCDB = cdb_found->next;
}
else
{
/* Can't fail because we have more CDBs than buffers... */
if (B1_LENGTH == 0)
elog(PANIC, "StrategyReplaceBuffer: out of CDBs");
cdb_found = &StrategyCDB[StrategyControl->listHead[STRAT_LIST_B1]];
BufTableDelete(&(cdb_found->buf_tag));
STRAT_LIST_REMOVE(cdb_found);
}
/* Set the CDB's buf_tag and insert it into the hash table */
cdb_found->buf_tag = *newTag;
BufTableInsert(&(cdb_found->buf_tag), (cdb_found - StrategyCDB));
if (cdb_replace_index >= 0)
{
/*
* The buffer was formerly in a T list, move its CDB to the
* appropriate list: B1 if T1, else discard it, as above
*/
cdb_replace = &StrategyCDB[cdb_replace_index];
Assert(cdb_replace->list == STRAT_LIST_T1 ||
cdb_replace->list == STRAT_LIST_T2);
Assert(cdb_replace->buf_id == buf->buf_id);
Assert(BUFFERTAGS_EQUAL(cdb_replace->buf_tag, buf->tag));
if (cdb_replace->list == STRAT_LIST_T1)
{
STRAT_LIST_REMOVE(cdb_replace);
STRAT_MRU_INSERT(cdb_replace, STRAT_LIST_B1);
}
else
{
BufTableDelete(&(cdb_replace->buf_tag));
STRAT_LIST_REMOVE(cdb_replace);
cdb_replace->next = StrategyControl->listUnusedCDB;
StrategyControl->listUnusedCDB = cdb_replace_index;
}
/* And clear its block reference */
cdb_replace->buf_id = -1;
}
else
{
/* We are satisfying it with an unused buffer */
}
/* Assign the buffer id to the new CDB */
cdb_found->buf_id = buf->buf_id;
/*
* Specialized VACUUM optimization. If this complete cache miss
* happened because vacuum needed the page, we place it at the LRU
* position of T1; normally it goes at the MRU position.
*/
if (strategy_hint_vacuum)
{
if (TransactionIdEquals(strategy_vacuum_xid,
GetTopTransactionId()))
STRAT_LRU_INSERT(cdb_found, STRAT_LIST_T1);
else
{
/* VACUUM must have been aborted by error, reset flag */
strategy_hint_vacuum = false;
STRAT_MRU_INSERT(cdb_found, STRAT_LIST_T1);
}
}
else
STRAT_MRU_INSERT(cdb_found, STRAT_LIST_T1);
/*
* Remember the Xid when this buffer went onto T1 to avoid a
* single UPDATE promoting a newcomer straight into T2. Also
* remember if it was loaded for VACUUM.
*/
cdb_found->t1_xid = GetTopTransactionId();
cdb_found->t1_vacuum = strategy_hint_vacuum;
}
}
/*
* For all items in this page, find their respective root line pointers.
* If item k is part of a HOT-chain with root at item j, then we set
* root_offsets[k - 1] = j.
*
* The passed-in root_offsets array must have MaxHeapTuplesPerPage entries.
* We zero out all unused entries.
*
* The function must be called with at least share lock on the buffer, to
* prevent concurrent prune operations.
*
* Note: The information collected here is valid only as long as the caller
* holds a pin on the buffer. Once pin is released, a tuple might be pruned
* and reused by a completely unrelated tuple.
*/
void
heap_get_root_tuples(Page page, OffsetNumber *root_offsets)
{
OffsetNumber offnum,
maxoff;
MemSet(root_offsets, 0, MaxHeapTuplesPerPage * sizeof(OffsetNumber));
maxoff = PageGetMaxOffsetNumber(page);
for (offnum = FirstOffsetNumber; offnum <= maxoff; offnum = OffsetNumberNext(offnum))
{
ItemId lp = PageGetItemId(page, offnum);
HeapTupleHeader htup;
OffsetNumber nextoffnum;
TransactionId priorXmax;
/* skip unused and dead items */
if (!ItemIdIsUsed(lp) || ItemIdIsDead(lp))
continue;
if (ItemIdIsNormal(lp))
{
htup = (HeapTupleHeader) PageGetItem(page, lp);
/*
* Check if this tuple is part of a HOT-chain rooted at some other
* tuple. If so, skip it for now; we'll process it when we find
* its root.
*/
if (HeapTupleHeaderIsHeapOnly(htup))
continue;
/*
* This is either a plain tuple or the root of a HOT-chain.
* Remember it in the mapping.
*/
root_offsets[offnum - 1] = offnum;
/* If it's not the start of a HOT-chain, we're done with it */
if (!HeapTupleHeaderIsHotUpdated(htup))
continue;
/* Set up to scan the HOT-chain */
nextoffnum = ItemPointerGetOffsetNumber(&htup->t_ctid);
priorXmax = HeapTupleHeaderGetXmax(htup);
}
else
{
/* Must be a redirect item. We do not set its root_offsets entry */
Assert(ItemIdIsRedirected(lp));
/* Set up to scan the HOT-chain */
nextoffnum = ItemIdGetRedirect(lp);
priorXmax = InvalidTransactionId;
}
/*
* Now follow the HOT-chain and collect other tuples in the chain.
*
* Note: Even though this is a nested loop, the complexity of the
* function is O(N) because a tuple in the page should be visited not
* more than twice, once in the outer loop and once in HOT-chain
* chases.
*/
for (;;)
{
lp = PageGetItemId(page, nextoffnum);
/* Check for broken chains */
if (!ItemIdIsNormal(lp))
break;
htup = (HeapTupleHeader) PageGetItem(page, lp);
if (TransactionIdIsValid(priorXmax) &&
!TransactionIdEquals(priorXmax, HeapTupleHeaderGetXmin(htup)))
break;
/* Remember the root line pointer for this item */
root_offsets[nextoffnum - 1] = offnum;
/* Advance to next chain member, if any */
if (!HeapTupleHeaderIsHotUpdated(htup))
break;
nextoffnum = ItemPointerGetOffsetNumber(&htup->t_ctid);
priorXmax = HeapTupleHeaderGetXmax(htup);
}
}
}
/*
* XidInMVCCSnapshot
* Is the given XID still-in-progress according to the snapshot?
*
* Note: GetSnapshotData never stores either top xid or subxids of our own
* backend into a snapshot, so these xids will not be reported as "running"
* by this function. This is OK for current uses, because we actually only
* apply this for known-committed XIDs.
*/
static bool
XidInMVCCSnapshot(TransactionId xid, Snapshot snapshot)
{
uint32 i;
/*
* Make a quick range check to eliminate most XIDs without looking at the
* xip arrays. Note that this is OK even if we convert a subxact XID to
* its parent below, because a subxact with XID < xmin has surely also got
* a parent with XID < xmin, while one with XID >= xmax must belong to a
* parent that was not yet committed at the time of this snapshot.
*/
/* Any xid < xmin is not in-progress */
if (TransactionIdPrecedes(xid, snapshot->xmin))
return false;
/* Any xid >= xmax is in-progress */
if (TransactionIdFollowsOrEquals(xid, snapshot->xmax))
return true;
/*
* Snapshot information is stored slightly differently in snapshots taken
* during recovery.
*/
if (!snapshot->takenDuringRecovery)
{
/*
* If the snapshot contains full subxact data, the fastest way to
* check things is just to compare the given XID against both subxact
* XIDs and top-level XIDs. If the snapshot overflowed, we have to
* use pg_subtrans to convert a subxact XID to its parent XID, but
* then we need only look at top-level XIDs not subxacts.
*/
if (!snapshot->suboverflowed)
{
/* full data, so search subxip */
int32 j;
for (j = 0; j < snapshot->subxcnt; j++)
{
if (TransactionIdEquals(xid, snapshot->subxip[j]))
return true;
}
/* not there, fall through to search xip[] */
}
else
{
/* overflowed, so convert xid to top-level */
xid = SubTransGetTopmostTransaction(xid);
/*
* If xid was indeed a subxact, we might now have an xid < xmin,
* so recheck to avoid an array scan. No point in rechecking
* xmax.
*/
if (TransactionIdPrecedes(xid, snapshot->xmin))
return false;
}
for (i = 0; i < snapshot->xcnt; i++)
{
if (TransactionIdEquals(xid, snapshot->xip[i]))
return true;
}
}
else
{
int32 j;
/*
* In recovery we store all xids in the subxact array because it is by
* far the bigger array, and we mostly don't know which xids are
* top-level and which are subxacts. The xip array is empty.
*
* We start by searching subtrans, if we overflowed.
*/
if (snapshot->suboverflowed)
{
/* overflowed, so convert xid to top-level */
xid = SubTransGetTopmostTransaction(xid);
/*
* If xid was indeed a subxact, we might now have an xid < xmin,
* so recheck to avoid an array scan. No point in rechecking
* xmax.
*/
if (TransactionIdPrecedes(xid, snapshot->xmin))
return false;
}
/*
* We now have either a top-level xid higher than xmin or an
* indeterminate xid. We don't know whether it's top level or subxact
* but it doesn't matter. If it's present, the xid is visible.
*/
for (j = 0; j < snapshot->subxcnt; j++)
{
if (TransactionIdEquals(xid, snapshot->subxip[j]))
return true;
}
}
return false;
}
Datum
_Slony_I_createEvent(PG_FUNCTION_ARGS)
{
TransactionId newXid = GetTopTransactionId();
Slony_I_ClusterStatus *cs;
char *ev_type_c;
Datum argv[9];
char nulls[10];
char *buf;
size_t buf_size;
int rc;
int i;
int64 retval;
bool isnull;
#ifdef HAVE_GETACTIVESNAPSHOT
if (GetActiveSnapshot() == NULL)
elog(ERROR, "Slony-I: ActiveSnapshot is NULL in createEvent()");
#else
if (SerializableSnapshot == NULL)
elog(ERROR, "Slony-I: SerializableSnapshot is NULL in createEvent()");
#endif
if ((rc = SPI_connect()) < 0)
elog(ERROR, "Slony-I: SPI_connect() failed in createEvent()");
/*
* Get or create the cluster status information and make sure it has the
* SPI plans that we need here.
*/
cs = getClusterStatus(PG_GETARG_NAME(0),
PLAN_INSERT_EVENT);
buf_size = 8192;
buf = palloc(buf_size);
/*
* Do the following only once per transaction.
*/
if (!TransactionIdEquals(cs->currentXid, newXid))
{
cs->currentXid = newXid;
}
/*
* Call the saved INSERT plan
*/
for (i = 1; i < 10; i++)
{
if (i >= PG_NARGS() || PG_ARGISNULL(i))
{
argv[i - 1] = (Datum) 0;
nulls[i - 1] = 'n';
}
else
{
argv[i - 1] = PG_GETARG_DATUM(i);
nulls[i - 1] = ' ';
}
}
nulls[9] = '\0';
if ((rc = SPI_execp(cs->plan_insert_event, argv, nulls, 0)) < 0)
elog(ERROR, "Slony-I: SPI_execp() failed for \"INSERT INTO sl_event ...\"");
/*
* The INSERT plan also contains a SELECT currval('sl_event_seq'), use the
* new sequence number as return value.
*/
if (SPI_processed != 1)
elog(ERROR, "Slony-I: INSERT plan did not return 1 result row");
retval = DatumGetInt64(SPI_getbinval(SPI_tuptable->vals[0],
SPI_tuptable->tupdesc, 1, &isnull));
/*
* For SYNC and ENABLE_SUBSCRIPTION events, we also remember all current
* sequence values.
*/
if (PG_NARGS() > 1 && !PG_ARGISNULL(1))
{
ev_type_c = DatumGetPointer(DirectFunctionCall1(
textout, PG_GETARG_DATUM(1)));
if (strcmp(ev_type_c, "SYNC") == 0 ||
strcmp(ev_type_c, "ENABLE_SUBSCRIPTION") == 0)
{
/*@-nullpass@*/
if ((rc = SPI_execp(cs->plan_record_sequences, NULL, NULL, 0)) < 0)
elog(ERROR, "Slony-I: SPI_execp() failed for \"INSERT INTO sl_seqlog ...\"");
/*@+nullpass@*/
}
}
(void) SPI_finish();
/*@-mustfreefresh@*/
PG_RETURN_INT64(retval);
}
Datum
_Slony_I_logTrigger(PG_FUNCTION_ARGS)
{
TransactionId newXid = GetTopTransactionId();
Slony_I_ClusterStatus *cs;
TriggerData *tg;
Datum argv[4];
text *cmdtype = NULL;
int rc;
Name cluster_name;
int32 tab_id;
char *attkind;
int attkind_idx;
int cmddata_need;
/*
* Don't do any logging if the current session role isn't Origin.
*/
if (SessionReplicationRole != SESSION_REPLICATION_ROLE_ORIGIN)
return PointerGetDatum(NULL);
/*
* Get the trigger call context
*/
if (!CALLED_AS_TRIGGER(fcinfo))
elog(ERROR, "Slony-I: logTrigger() not called as trigger");
tg = (TriggerData *) (fcinfo->context);
/*
* Check all logTrigger() calling conventions
*/
if (!TRIGGER_FIRED_AFTER(tg->tg_event))
elog(ERROR, "Slony-I: logTrigger() must be fired AFTER");
if (!TRIGGER_FIRED_FOR_ROW(tg->tg_event))
elog(ERROR, "Slony-I: logTrigger() must be fired FOR EACH ROW");
if (tg->tg_trigger->tgnargs != 3)
elog(ERROR, "Slony-I: logTrigger() must be defined with 3 args");
/*
* Connect to the SPI manager
*/
if ((rc = SPI_connect()) < 0)
elog(ERROR, "Slony-I: SPI_connect() failed in createEvent()");
/*
* Get all the trigger arguments
*/
cluster_name = DatumGetName(DirectFunctionCall1(namein,
CStringGetDatum(tg->tg_trigger->tgargs[0])));
tab_id = strtol(tg->tg_trigger->tgargs[1], NULL, 10);
attkind = tg->tg_trigger->tgargs[2];
/*
* Get or create the cluster status information and make sure it has the
* SPI plans that we need here.
*/
cs = getClusterStatus(cluster_name, PLAN_INSERT_LOG);
/*
* Do the following only once per transaction.
*/
if (!TransactionIdEquals(cs->currentXid, newXid))
{
int32 log_status;
bool isnull;
/*
* Determine the currently active log table
*/
if (SPI_execp(cs->plan_get_logstatus, NULL, NULL, 0) < 0)
elog(ERROR, "Slony-I: cannot determine log status");
if (SPI_processed != 1)
elog(ERROR, "Slony-I: cannot determine log status");
log_status = DatumGetInt32(SPI_getbinval(SPI_tuptable->vals[0],
SPI_tuptable->tupdesc, 1, &isnull));
SPI_freetuptable(SPI_tuptable);
switch (log_status)
{
case 0:
case 2:
cs->plan_active_log = cs->plan_insert_log_1;
break;
case 1:
case 3:
cs->plan_active_log = cs->plan_insert_log_2;
break;
default:
elog(ERROR, "Slony-I: illegal log status %d", log_status);
break;
}
cs->currentXid = newXid;
}
/*
* Determine cmdtype and cmddata depending on the command type
*/
if (TRIGGER_FIRED_BY_INSERT(tg->tg_event))
{
HeapTuple new_row = tg->tg_trigtuple;
TupleDesc tupdesc = tg->tg_relation->rd_att;
char *col_ident;
char *col_value;
int len_ident;
int len_value;
int i;
int need_comma = false;
char *OldDateStyle;
char *cp = VARDATA(cs->cmddata_buf);
/*
* INSERT
*
* cmdtype = 'I' cmddata = ("col" [, ...]) values ('value' [, ...])
*/
cmdtype = cs->cmdtype_I;
/*
* Specify all the columns
*/
*cp++ = '(';
for (i = 0; i < tg->tg_relation->rd_att->natts; i++)
{
/*
* Skip dropped columns
*/
if (tupdesc->attrs[i]->attisdropped)
continue;
col_ident = (char *) slon_quote_identifier(SPI_fname(tupdesc, i + 1));
cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
(len_ident = strlen(col_ident));
if (cs->cmddata_size < cmddata_need)
{
int have = (cp - (char *) (cs->cmddata_buf));
while (cs->cmddata_size < cmddata_need)
cs->cmddata_size *= 2;
cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
cp = (char *) (cs->cmddata_buf) + have;
}
if (need_comma)
*cp++ = ',';
else
need_comma = true;
memcpy(cp, col_ident, len_ident);
cp += len_ident;
}
/*
* Append the string ") values ("
*/
*cp++ = ')';
*cp++ = ' ';
*cp++ = 'v';
*cp++ = 'a';
*cp++ = 'l';
*cp++ = 'u';
*cp++ = 'e';
*cp++ = 's';
*cp++ = ' ';
*cp++ = '(';
/*
* Append the values
*/
need_comma = false;
OldDateStyle = GetConfigOptionByName("DateStyle", NULL);
if (!strstr(OldDateStyle, "ISO"))
set_config_option("DateStyle", "ISO", PGC_USERSET, PGC_S_SESSION, true, true);
for (i = 0; i < tg->tg_relation->rd_att->natts; i++)
{
/*
* Skip dropped columns
*/
if (tupdesc->attrs[i]->attisdropped)
continue;
if ((col_value = SPI_getvalue(new_row, tupdesc, i + 1)) == NULL)
{
col_value = "NULL";
}
else
{
col_value = slon_quote_literal(col_value);
}
cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
(len_value = strlen(col_value));
if (cs->cmddata_size < cmddata_need)
{
int have = (cp - (char *) (cs->cmddata_buf));
while (cs->cmddata_size < cmddata_need)
cs->cmddata_size *= 2;
cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
cp = (char *) (cs->cmddata_buf) + have;
}
if (need_comma)
*cp++ = ',';
else
need_comma = true;
memcpy(cp, col_value, len_value);
cp += len_value;
}
if (!strstr(OldDateStyle, "ISO"))
set_config_option("DateStyle", OldDateStyle, PGC_USERSET, PGC_S_SESSION, true, true);
/*
* Terminate and done
*/
*cp++ = ')';
*cp = '\0';
SET_VARSIZE(cs->cmddata_buf,
VARHDRSZ + (cp - VARDATA(cs->cmddata_buf)));
}
else if (TRIGGER_FIRED_BY_UPDATE(tg->tg_event))
{
HeapTuple old_row = tg->tg_trigtuple;
HeapTuple new_row = tg->tg_newtuple;
TupleDesc tupdesc = tg->tg_relation->rd_att;
Datum old_value;
Datum new_value;
bool old_isnull;
bool new_isnull;
char *col_ident;
char *col_value;
int len_ident;
int len_value;
int i;
int need_comma = false;
int need_and = false;
char *OldDateStyle;
char *cp = VARDATA(cs->cmddata_buf);
/*
* UPDATE
*
* cmdtype = 'U' cmddata = "col_ident"='value' [, ...] where
* "pk_ident" = 'value' [ and ...]
*/
cmdtype = cs->cmdtype_U;
for (i = 0; i < tg->tg_relation->rd_att->natts; i++)
{
/*
* Ignore dropped columns
*/
if (tupdesc->attrs[i]->attisdropped)
continue;
old_value = SPI_getbinval(old_row, tupdesc, i + 1, &old_isnull);
new_value = SPI_getbinval(new_row, tupdesc, i + 1, &new_isnull);
/*
* If old and new value are NULL, the column is unchanged
*/
if (old_isnull && new_isnull)
continue;
/*
* If both are NOT NULL, we need to compare the values and skip
* setting the column if equal
*/
if (!old_isnull && !new_isnull)
{
Oid opr_oid;
FmgrInfo *opr_finfo_p;
/*
* Lookup the equal operators function call info using the
* typecache if available
*/
#ifdef HAVE_TYPCACHE
TypeCacheEntry *type_cache;
type_cache = lookup_type_cache(
SPI_gettypeid(tupdesc, i + 1),
TYPECACHE_EQ_OPR | TYPECACHE_EQ_OPR_FINFO);
opr_oid = type_cache->eq_opr;
if (opr_oid == ARRAY_EQ_OP)
opr_oid = InvalidOid;
else
opr_finfo_p = &(type_cache->eq_opr_finfo);
#else
FmgrInfo opr_finfo;
opr_oid = compatible_oper_funcid(makeList1(makeString("=")),
SPI_gettypeid(tupdesc, i + 1),
SPI_gettypeid(tupdesc, i + 1), true);
if (OidIsValid(opr_oid))
{
fmgr_info(opr_oid, &opr_finfo);
opr_finfo_p = &opr_finfo;
}
#endif
/*
* If we have an equal operator, use that to do binary
* comparision. Else get the string representation of both
* attributes and do string comparision.
*/
if (OidIsValid(opr_oid))
{
if (DatumGetBool(FunctionCall2(opr_finfo_p,
old_value, new_value)))
continue;
}
else
{
char *old_strval = SPI_getvalue(old_row, tupdesc, i + 1);
char *new_strval = SPI_getvalue(new_row, tupdesc, i + 1);
if (strcmp(old_strval, new_strval) == 0)
continue;
}
}
if (need_comma)
*cp++ = ',';
else
need_comma = true;
col_ident = (char *) slon_quote_identifier(SPI_fname(tupdesc, i + 1));
if (new_isnull)
col_value = "NULL";
else
{
OldDateStyle = GetConfigOptionByName("DateStyle", NULL);
if (!strstr(OldDateStyle, "ISO"))
set_config_option("DateStyle", "ISO", PGC_USERSET, PGC_S_SESSION, true, true);
col_value = slon_quote_literal(SPI_getvalue(new_row, tupdesc, i + 1));
if (!strstr(OldDateStyle, "ISO"))
set_config_option("DateStyle", OldDateStyle, PGC_USERSET, PGC_S_SESSION, true, true);
}
cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
(len_ident = strlen(col_ident)) +
(len_value = strlen(col_value));
if (cs->cmddata_size < cmddata_need)
{
int have = (cp - (char *) (cs->cmddata_buf));
while (cs->cmddata_size < cmddata_need)
cs->cmddata_size *= 2;
cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
cp = (char *) (cs->cmddata_buf) + have;
}
memcpy(cp, col_ident, len_ident);
cp += len_ident;
*cp++ = '=';
memcpy(cp, col_value, len_value);
cp += len_value;
}
/*
* It can happen that the only UPDATE an application does is to set a
* column to the same value again. In that case, we'd end up here with
* no columns in the SET clause yet. We add the first key column here
* with it's old value to simulate the same for the replication
* engine.
*/
if (!need_comma)
{
for (i = 0, attkind_idx = -1; i < tg->tg_relation->rd_att->natts; i++)
{
if (tupdesc->attrs[i]->attisdropped)
continue;
attkind_idx++;
if (!attkind[attkind_idx])
elog(ERROR, "Slony-I: no key columns found in logTrigger() attkind parameter");
if (attkind[attkind_idx] == 'k')
break;
}
col_ident = (char *) slon_quote_identifier(SPI_fname(tupdesc, i + 1));
col_value = slon_quote_literal(SPI_getvalue(old_row, tupdesc, i + 1));
cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
(len_ident = strlen(col_ident)) +
(len_value = strlen(col_value));
if (cs->cmddata_size < cmddata_need)
{
int have = (cp - (char *) (cs->cmddata_buf));
while (cs->cmddata_size < cmddata_need)
cs->cmddata_size *= 2;
cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
cp = (char *) (cs->cmddata_buf) + have;
}
memcpy(cp, col_ident, len_ident);
cp += len_ident;
*cp++ = '=';
memcpy(cp, col_value, len_value);
cp += len_value;
}
*cp++ = ' ';
*cp++ = 'w';
*cp++ = 'h';
*cp++ = 'e';
*cp++ = 'r';
*cp++ = 'e';
*cp++ = ' ';
for (i = 0, attkind_idx = -1; i < tg->tg_relation->rd_att->natts; i++)
{
/*
* Ignore dropped columns
*/
if (tupdesc->attrs[i]->attisdropped)
continue;
attkind_idx++;
if (!attkind[attkind_idx])
break;
if (attkind[attkind_idx] != 'k')
continue;
col_ident = (char *) slon_quote_identifier(SPI_fname(tupdesc, i + 1));
col_value = slon_quote_literal(SPI_getvalue(old_row, tupdesc, i + 1));
if (col_value == NULL)
elog(ERROR, "Slony-I: old key column %s.%s IS NULL on UPDATE",
NameStr(tg->tg_relation->rd_rel->relname), col_ident);
cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
(len_ident = strlen(col_ident)) +
(len_value = strlen(col_value));
if (cs->cmddata_size < cmddata_need)
{
int have = (cp - (char *) (cs->cmddata_buf));
while (cs->cmddata_size < cmddata_need)
cs->cmddata_size *= 2;
cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
cp = (char *) (cs->cmddata_buf) + have;
}
if (need_and)
{
*cp++ = ' ';
*cp++ = 'a';
*cp++ = 'n';
*cp++ = 'd';
*cp++ = ' ';
}
else
need_and = true;
memcpy(cp, col_ident, len_ident);
cp += len_ident;
*cp++ = '=';
memcpy(cp, col_value, len_value);
cp += len_value;
}
*cp = '\0';
SET_VARSIZE(cs->cmddata_buf,
VARHDRSZ + (cp - VARDATA(cs->cmddata_buf)));
}
else if (TRIGGER_FIRED_BY_DELETE(tg->tg_event))
{
HeapTuple old_row = tg->tg_trigtuple;
TupleDesc tupdesc = tg->tg_relation->rd_att;
char *col_ident;
char *col_value;
int len_ident;
int len_value;
int i;
int need_and = false;
char *cp = VARDATA(cs->cmddata_buf);
/*
* DELETE
*
* cmdtype = 'D' cmddata = "pk_ident"='value' [and ...]
*/
cmdtype = cs->cmdtype_D;
for (i = 0, attkind_idx = -1; i < tg->tg_relation->rd_att->natts; i++)
{
if (tupdesc->attrs[i]->attisdropped)
continue;
attkind_idx++;
if (!attkind[attkind_idx])
break;
if (attkind[attkind_idx] != 'k')
continue;
col_ident = (char *) slon_quote_identifier(SPI_fname(tupdesc, i + 1));
col_value = slon_quote_literal(SPI_getvalue(old_row, tupdesc, i + 1));
if (col_value == NULL)
elog(ERROR, "Slony-I: old key column %s.%s IS NULL on DELETE",
NameStr(tg->tg_relation->rd_rel->relname), col_ident);
cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
(len_ident = strlen(col_ident)) +
(len_value = strlen(col_value));
if (cs->cmddata_size < cmddata_need)
{
int have = (cp - (char *) (cs->cmddata_buf));
while (cs->cmddata_size < cmddata_need)
cs->cmddata_size *= 2;
cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
cp = (char *) (cs->cmddata_buf) + have;
}
if (need_and)
{
*cp++ = ' ';
*cp++ = 'a';
*cp++ = 'n';
*cp++ = 'd';
*cp++ = ' ';
}
else
need_and = true;
memcpy(cp, col_ident, len_ident);
cp += len_ident;
*cp++ = '=';
memcpy(cp, col_value, len_value);
cp += len_value;
}
*cp = '\0';
SET_VARSIZE(cs->cmddata_buf,
VARHDRSZ + (cp - VARDATA(cs->cmddata_buf)));
}
else
elog(ERROR, "Slony-I: logTrigger() fired for unhandled event");
/*
* Construct the parameter array and insert the log row.
*/
argv[0] = Int32GetDatum(tab_id);
argv[1] = PointerGetDatum(cmdtype);
argv[2] = PointerGetDatum(cs->cmddata_buf);
SPI_execp(cs->plan_active_log, argv, NULL, 0);
SPI_finish();
return PointerGetDatum(NULL);
}
/* ----------------
* index_getnext - get the next heap tuple from a scan
*
* The result is the next heap tuple satisfying the scan keys and the
* snapshot, or NULL if no more matching tuples exist. On success,
* the buffer containing the heap tuple is pinned (the pin will be dropped
* at the next index_getnext or index_endscan).
*
* Note: caller must check scan->xs_recheck, and perform rechecking of the
* scan keys if required. We do not do that here because we don't have
* enough information to do it efficiently in the general case.
* ----------------
*/
HeapTuple
index_getnext(IndexScanDesc scan, ScanDirection direction)
{
HeapTuple heapTuple = &scan->xs_ctup;
ItemPointer tid = &heapTuple->t_self;
FmgrInfo *procedure;
SCAN_CHECKS;
GET_SCAN_PROCEDURE(amgettuple);
Assert(TransactionIdIsValid(RecentGlobalXmin));
/*
* We always reset xs_hot_dead; if we are here then either we are just
* starting the scan, or we previously returned a visible tuple, and in
* either case it's inappropriate to kill the prior index entry.
*/
scan->xs_hot_dead = false;
for (;;)
{
OffsetNumber offnum;
bool at_chain_start;
Page dp;
if (scan->xs_next_hot != InvalidOffsetNumber)
{
/*
* We are resuming scan of a HOT chain after having returned an
* earlier member. Must still hold pin on current heap page.
*/
Assert(BufferIsValid(scan->xs_cbuf));
Assert(ItemPointerGetBlockNumber(tid) ==
BufferGetBlockNumber(scan->xs_cbuf));
Assert(TransactionIdIsValid(scan->xs_prev_xmax));
offnum = scan->xs_next_hot;
at_chain_start = false;
scan->xs_next_hot = InvalidOffsetNumber;
}
else
{
bool found;
Buffer prev_buf;
/*
* If we scanned a whole HOT chain and found only dead tuples,
* tell index AM to kill its entry for that TID. We do not do this
* when in recovery because it may violate MVCC to do so. see
* comments in RelationGetIndexScan().
*/
if (!scan->xactStartedInRecovery)
scan->kill_prior_tuple = scan->xs_hot_dead;
/*
* The AM's gettuple proc finds the next index entry matching the
* scan keys, and puts the TID in xs_ctup.t_self (ie, *tid). It
* should also set scan->xs_recheck, though we pay no attention to
* that here.
*/
found = DatumGetBool(FunctionCall2(procedure,
PointerGetDatum(scan),
Int32GetDatum(direction)));
/* Reset kill flag immediately for safety */
scan->kill_prior_tuple = false;
/* If we're out of index entries, break out of outer loop */
if (!found)
break;
pgstat_count_index_tuples(scan->indexRelation, 1);
/* Switch to correct buffer if we don't have it already */
prev_buf = scan->xs_cbuf;
scan->xs_cbuf = ReleaseAndReadBuffer(scan->xs_cbuf,
scan->heapRelation,
ItemPointerGetBlockNumber(tid));
/*
* Prune page, but only if we weren't already on this page
*/
if (prev_buf != scan->xs_cbuf)
heap_page_prune_opt(scan->heapRelation, scan->xs_cbuf,
RecentGlobalXmin);
/* Prepare to scan HOT chain starting at index-referenced offnum */
offnum = ItemPointerGetOffsetNumber(tid);
at_chain_start = true;
/* We don't know what the first tuple's xmin should be */
scan->xs_prev_xmax = InvalidTransactionId;
/* Initialize flag to detect if all entries are dead */
scan->xs_hot_dead = true;
}
/* Obtain share-lock on the buffer so we can examine visibility */
LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
dp = (Page) BufferGetPage(scan->xs_cbuf);
/* Scan through possible multiple members of HOT-chain */
for (;;)
{
ItemId lp;
ItemPointer ctid;
bool valid;
/* check for bogus TID */
if (offnum < FirstOffsetNumber ||
offnum > PageGetMaxOffsetNumber(dp))
break;
lp = PageGetItemId(dp, offnum);
/* check for unused, dead, or redirected items */
if (!ItemIdIsNormal(lp))
{
/* We should only see a redirect at start of chain */
if (ItemIdIsRedirected(lp) && at_chain_start)
{
/* Follow the redirect */
offnum = ItemIdGetRedirect(lp);
at_chain_start = false;
continue;
}
/* else must be end of chain */
break;
}
/*
* We must initialize all of *heapTuple (ie, scan->xs_ctup) since
* it is returned to the executor on success.
*/
heapTuple->t_data = (HeapTupleHeader) PageGetItem(dp, lp);
heapTuple->t_len = ItemIdGetLength(lp);
ItemPointerSetOffsetNumber(tid, offnum);
heapTuple->t_tableOid = RelationGetRelid(scan->heapRelation);
ctid = &heapTuple->t_data->t_ctid;
/*
* Shouldn't see a HEAP_ONLY tuple at chain start. (This test
* should be unnecessary, since the chain root can't be removed
* while we have pin on the index entry, but let's make it
* anyway.)
*/
if (at_chain_start && HeapTupleIsHeapOnly(heapTuple))
break;
/*
* The xmin should match the previous xmax value, else chain is
* broken. (Note: this test is not optional because it protects
* us against the case where the prior chain member's xmax aborted
* since we looked at it.)
*/
if (TransactionIdIsValid(scan->xs_prev_xmax) &&
!TransactionIdEquals(scan->xs_prev_xmax,
HeapTupleHeaderGetXmin(heapTuple->t_data)))
break;
/* If it's visible per the snapshot, we must return it */
valid = HeapTupleSatisfiesVisibility(heapTuple, scan->xs_snapshot,
scan->xs_cbuf);
CheckForSerializableConflictOut(valid, scan->heapRelation,
heapTuple, scan->xs_cbuf);
if (valid)
{
/*
* If the snapshot is MVCC, we know that it could accept at
* most one member of the HOT chain, so we can skip examining
* any more members. Otherwise, check for continuation of the
* HOT-chain, and set state for next time.
*/
if (IsMVCCSnapshot(scan->xs_snapshot)
&& !IsolationIsSerializable())
scan->xs_next_hot = InvalidOffsetNumber;
else if (HeapTupleIsHotUpdated(heapTuple))
{
Assert(ItemPointerGetBlockNumber(ctid) ==
ItemPointerGetBlockNumber(tid));
scan->xs_next_hot = ItemPointerGetOffsetNumber(ctid);
scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
}
else
scan->xs_next_hot = InvalidOffsetNumber;
PredicateLockTuple(scan->heapRelation, heapTuple);
LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
pgstat_count_heap_fetch(scan->indexRelation);
return heapTuple;
}
/*
* If we can't see it, maybe no one else can either. Check to see
* if the tuple is dead to all transactions. If we find that all
* the tuples in the HOT chain are dead, we'll signal the index AM
* to not return that TID on future indexscans.
*/
if (scan->xs_hot_dead &&
HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin,
scan->xs_cbuf) != HEAPTUPLE_DEAD)
scan->xs_hot_dead = false;
/*
* Check to see if HOT chain continues past this tuple; if so
* fetch the next offnum (we don't bother storing it into
* xs_next_hot, but must store xs_prev_xmax), and loop around.
*/
if (HeapTupleIsHotUpdated(heapTuple))
{
Assert(ItemPointerGetBlockNumber(ctid) ==
ItemPointerGetBlockNumber(tid));
offnum = ItemPointerGetOffsetNumber(ctid);
at_chain_start = false;
scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
}
else
break; /* end of chain */
} /* loop over a single HOT chain */
LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
/* Loop around to ask index AM for another TID */
scan->xs_next_hot = InvalidOffsetNumber;
}
/* Release any held pin on a heap page */
if (BufferIsValid(scan->xs_cbuf))
{
ReleaseBuffer(scan->xs_cbuf);
scan->xs_cbuf = InvalidBuffer;
}
return NULL; /* failure exit */
}
/*
* Prune specified item pointer or a HOT chain originating at that item.
*
* If the item is an index-referenced tuple (i.e. not a heap-only tuple),
* the HOT chain is pruned by removing all DEAD tuples at the start of the HOT
* chain. We also prune any RECENTLY_DEAD tuples preceding a DEAD tuple.
* This is OK because a RECENTLY_DEAD tuple preceding a DEAD tuple is really
* DEAD, the OldestXmin test is just too coarse to detect it.
*
* The root line pointer is redirected to the tuple immediately after the
* latest DEAD tuple. If all tuples in the chain are DEAD, the root line
* pointer is marked LP_DEAD. (This includes the case of a DEAD simple
* tuple, which we treat as a chain of length 1.)
*
* OldestXmin is the cutoff XID used to identify dead tuples.
*
* We don't actually change the page here, except perhaps for hint-bit updates
* caused by HeapTupleSatisfiesVacuum. We just add entries to the arrays in
* prstate showing the changes to be made. Items to be redirected are added
* to the redirected[] array (two entries per redirection); items to be set to
* LP_DEAD state are added to nowdead[]; and items to be set to LP_UNUSED
* state are added to nowunused[].
*
* If redirect_move is true, we intend to get rid of redirecting line pointers,
* not just make redirection entries.
*
* Returns the number of tuples (to be) deleted from the page.
*/
static int
heap_prune_chain(Relation relation, Buffer buffer, OffsetNumber rootoffnum,
TransactionId OldestXmin,
PruneState *prstate,
bool redirect_move)
{
int ndeleted = 0;
Page dp = (Page) BufferGetPage(buffer);
TransactionId priorXmax = InvalidTransactionId;
ItemId rootlp;
HeapTupleHeader htup;
OffsetNumber latestdead = InvalidOffsetNumber,
redirect_target = InvalidOffsetNumber,
maxoff = PageGetMaxOffsetNumber(dp),
offnum;
OffsetNumber chainitems[MaxHeapTuplesPerPage];
int nchain = 0,
i;
rootlp = PageGetItemId(dp, rootoffnum);
/*
* If it's a heap-only tuple, then it is not the start of a HOT chain.
*/
if (ItemIdIsNormal(rootlp))
{
htup = (HeapTupleHeader) PageGetItem(dp, rootlp);
if (HeapTupleHeaderIsHeapOnly(htup))
{
/*
* If the tuple is DEAD and doesn't chain to anything else, mark
* it unused immediately. (If it does chain, we can only remove
* it as part of pruning its chain.)
*
* We need this primarily to handle aborted HOT updates, that is,
* XMIN_INVALID heap-only tuples. Those might not be linked to by
* any chain, since the parent tuple might be re-updated before
* any pruning occurs. So we have to be able to reap them
* separately from chain-pruning. (Note that
* HeapTupleHeaderIsHotUpdated will never return true for an
* XMIN_INVALID tuple, so this code will work even when there were
* sequential updates within the aborted transaction.)
*
* Note that we might first arrive at a dead heap-only tuple
* either here or while following a chain below. Whichever path
* gets there first will mark the tuple unused.
*/
if (HeapTupleSatisfiesVacuum(relation, htup, OldestXmin, buffer)
== HEAPTUPLE_DEAD && !HeapTupleHeaderIsHotUpdated(htup))
{
heap_prune_record_unused(prstate, rootoffnum);
ndeleted++;
}
/* Nothing more to do */
return ndeleted;
}
}
/* Start from the root tuple */
offnum = rootoffnum;
/* while not end of the chain */
for (;;)
{
ItemId lp;
bool tupdead,
recent_dead;
/* Some sanity checks */
if (offnum < FirstOffsetNumber || offnum > maxoff)
break;
/* If item is already processed, stop --- it must not be same chain */
if (prstate->marked[offnum])
break;
lp = PageGetItemId(dp, offnum);
/* Unused item obviously isn't part of the chain */
if (!ItemIdIsUsed(lp))
break;
/*
* If we are looking at the redirected root line pointer, jump to the
* first normal tuple in the chain. If we find a redirect somewhere
* else, stop --- it must not be same chain.
*/
if (ItemIdIsRedirected(lp))
{
if (nchain > 0)
break; /* not at start of chain */
chainitems[nchain++] = offnum;
offnum = ItemIdGetRedirect(rootlp);
continue;
}
/*
* Likewise, a dead item pointer can't be part of the chain. (We
* already eliminated the case of dead root tuple outside this
* function.)
*/
if (ItemIdIsDead(lp))
break;
Assert(ItemIdIsNormal(lp));
htup = (HeapTupleHeader) PageGetItem(dp, lp);
/*
* Check the tuple XMIN against prior XMAX, if any
*/
if (TransactionIdIsValid(priorXmax) &&
!TransactionIdEquals(HeapTupleHeaderGetXmin(htup), priorXmax))
break;
/*
* OK, this tuple is indeed a member of the chain.
*/
chainitems[nchain++] = offnum;
/*
* Check tuple's visibility status.
*/
tupdead = recent_dead = false;
switch (HeapTupleSatisfiesVacuum(relation, htup, OldestXmin, buffer))
{
case HEAPTUPLE_DEAD:
tupdead = true;
break;
case HEAPTUPLE_RECENTLY_DEAD:
recent_dead = true;
/*
* This tuple may soon become DEAD. Update the hint field so
* that the page is reconsidered for pruning in future.
*/
heap_prune_record_prunable(prstate,
HeapTupleHeaderGetXmax(htup));
break;
case HEAPTUPLE_DELETE_IN_PROGRESS:
/*
* This tuple may soon become DEAD. Update the hint field so
* that the page is reconsidered for pruning in future.
*/
heap_prune_record_prunable(prstate,
HeapTupleHeaderGetXmax(htup));
break;
case HEAPTUPLE_LIVE:
case HEAPTUPLE_INSERT_IN_PROGRESS:
/*
* If we wanted to optimize for aborts, we might consider
* marking the page prunable when we see INSERT_IN_PROGRESS.
* But we don't. See related decisions about when to mark the
* page prunable in heapam.c.
*/
break;
default:
elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
break;
}
/*
* Remember the last DEAD tuple seen. We will advance past
* RECENTLY_DEAD tuples just in case there's a DEAD one after them;
* but we can't advance past anything else. (XXX is it really worth
* continuing to scan beyond RECENTLY_DEAD? The case where we will
* find another DEAD tuple is a fairly unusual corner case.)
*/
if (tupdead)
latestdead = offnum;
else if (!recent_dead)
break;
/*
* If the tuple is not HOT-updated, then we are at the end of this
* HOT-update chain.
*/
if (!HeapTupleHeaderIsHotUpdated(htup))
break;
/*
* Advance to next chain member.
*/
Assert(ItemPointerGetBlockNumber(&htup->t_ctid) ==
BufferGetBlockNumber(buffer));
offnum = ItemPointerGetOffsetNumber(&htup->t_ctid);
priorXmax = HeapTupleHeaderGetXmax(htup);
}
/*
* If we found a DEAD tuple in the chain, adjust the HOT chain so that all
* the DEAD tuples at the start of the chain are removed and the root line
* pointer is appropriately redirected.
*/
if (OffsetNumberIsValid(latestdead))
{
/*
* Mark as unused each intermediate item that we are able to remove
* from the chain.
*
* When the previous item is the last dead tuple seen, we are at the
* right candidate for redirection.
*/
for (i = 1; (i < nchain) && (chainitems[i - 1] != latestdead); i++)
{
heap_prune_record_unused(prstate, chainitems[i]);
ndeleted++;
}
/*
* If the root entry had been a normal tuple, we are deleting it, so
* count it in the result. But changing a redirect (even to DEAD
* state) doesn't count.
*/
if (ItemIdIsNormal(rootlp))
ndeleted++;
/*
* If the DEAD tuple is at the end of the chain, the entire chain is
* dead and the root line pointer can be marked dead. Otherwise just
* redirect the root to the correct chain member.
*/
if (i >= nchain)
heap_prune_record_dead(prstate, rootoffnum);
else
{
heap_prune_record_redirect(prstate, rootoffnum, chainitems[i]);
/* If the redirection will be a move, need more processing */
if (redirect_move)
redirect_target = chainitems[i];
}
}
else if (nchain < 2 && ItemIdIsRedirected(rootlp))
{
/*
* We found a redirect item that doesn't point to a valid follow-on
* item. This can happen if the loop in heap_page_prune caused us to
* visit the dead successor of a redirect item before visiting the
* redirect item. We can clean up by setting the redirect item to
* DEAD state.
*/
heap_prune_record_dead(prstate, rootoffnum);
}
else if (redirect_move && ItemIdIsRedirected(rootlp))
{
/*
* If we desire to eliminate LP_REDIRECT items by moving tuples, make
* a redirection entry for each redirected root item; this will cause
* heap_page_prune_execute to actually do the move. (We get here only
* when there are no DEAD tuples in the chain; otherwise the
* redirection entry was made above.)
*/
heap_prune_record_redirect(prstate, rootoffnum, chainitems[1]);
redirect_target = chainitems[1];
}
/*
* If we are going to implement a redirect by moving tuples, we have to
* issue a cache invalidation against the redirection target tuple,
* because its CTID will be effectively changed by the move. Note that
* CacheInvalidateHeapTuple only queues the request, it doesn't send it;
* if we fail before reaching EndNonTransactionalInvalidation, nothing
* happens and no harm is done.
*/
if (OffsetNumberIsValid(redirect_target))
{
ItemId firstlp = PageGetItemId(dp, redirect_target);
HeapTupleData firsttup;
Assert(ItemIdIsNormal(firstlp));
/* Set up firsttup to reference the tuple at its existing CTID */
firsttup.t_data = (HeapTupleHeader) PageGetItem(dp, firstlp);
firsttup.t_len = ItemIdGetLength(firstlp);
ItemPointerSet(&firsttup.t_self,
BufferGetBlockNumber(buffer),
redirect_target);
CacheInvalidateHeapTuple(relation, &firsttup);
}
return ndeleted;
}
/*
* FinishPreparedTransaction: execute COMMIT PREPARED or ROLLBACK PREPARED
*/
void
FinishPreparedTransaction(const char *gid, bool isCommit)
{
GlobalTransaction gxact;
TransactionId xid;
char *buf;
char *bufptr;
TwoPhaseFileHeader *hdr;
TransactionId latestXid;
TransactionId *children;
RelFileNode *commitrels;
RelFileNode *abortrels;
RelFileNode *delrels;
int ndelrels;
int i;
/*
* Validate the GID, and lock the GXACT to ensure that two backends do not
* try to commit the same GID at once.
*/
gxact = LockGXact(gid, GetUserId());
xid = gxact->proc.xid;
/*
* Read and validate the state file
*/
buf = ReadTwoPhaseFile(xid);
if (buf == NULL)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("two-phase state file for transaction %u is corrupt",
xid)));
/*
* Disassemble the header area
*/
hdr = (TwoPhaseFileHeader *) buf;
Assert(TransactionIdEquals(hdr->xid, xid));
bufptr = buf + MAXALIGN(sizeof(TwoPhaseFileHeader));
children = (TransactionId *) bufptr;
bufptr += MAXALIGN(hdr->nsubxacts * sizeof(TransactionId));
commitrels = (RelFileNode *) bufptr;
bufptr += MAXALIGN(hdr->ncommitrels * sizeof(RelFileNode));
abortrels = (RelFileNode *) bufptr;
bufptr += MAXALIGN(hdr->nabortrels * sizeof(RelFileNode));
/* compute latestXid among all children */
latestXid = TransactionIdLatest(xid, hdr->nsubxacts, children);
/*
* The order of operations here is critical: make the XLOG entry for
* commit or abort, then mark the transaction committed or aborted in
* pg_clog, then remove its PGPROC from the global ProcArray (which means
* TransactionIdIsInProgress will stop saying the prepared xact is in
* progress), then run the post-commit or post-abort callbacks. The
* callbacks will release the locks the transaction held.
*/
if (isCommit)
RecordTransactionCommitPrepared(xid,
hdr->nsubxacts, children,
hdr->ncommitrels, commitrels);
else
RecordTransactionAbortPrepared(xid,
hdr->nsubxacts, children,
hdr->nabortrels, abortrels);
ProcArrayRemove(&gxact->proc, latestXid);
/*
* In case we fail while running the callbacks, mark the gxact invalid so
* no one else will try to commit/rollback, and so it can be recycled
* properly later. It is still locked by our XID so it won't go away yet.
*
* (We assume it's safe to do this without taking TwoPhaseStateLock.)
*/
gxact->valid = false;
/*
* We have to remove any files that were supposed to be dropped. For
* consistency with the regular xact.c code paths, must do this before
* releasing locks, so do it before running the callbacks.
*
* NB: this code knows that we couldn't be dropping any temp rels ...
*/
if (isCommit)
{
delrels = commitrels;
ndelrels = hdr->ncommitrels;
}
else
{
delrels = abortrels;
ndelrels = hdr->nabortrels;
}
for (i = 0; i < ndelrels; i++)
{
SMgrRelation srel = smgropen(delrels[i]);
ForkNumber fork;
for (fork = 0; fork <= MAX_FORKNUM; fork++)
{
if (smgrexists(srel, fork))
smgrdounlink(srel, fork, false, false);
}
smgrclose(srel);
}
/* And now do the callbacks */
if (isCommit)
ProcessRecords(bufptr, xid, twophase_postcommit_callbacks);
else
ProcessRecords(bufptr, xid, twophase_postabort_callbacks);
/* Count the prepared xact as committed or aborted */
AtEOXact_PgStat(isCommit);
/*
* And now we can clean up our mess.
*/
RemoveTwoPhaseFile(xid, true);
RemoveGXact(gxact);
pfree(buf);
}
/*
* XidInMVCCSnapshot
* Is the given XID still-in-progress according to the snapshot?
*
* Note: GetSnapshotData never stores either top xid or subxids of our own
* backend into a snapshot, so these xids will not be reported as "running"
* by this function. This is OK for current uses, because we actually only
* apply this for known-committed XIDs.
*/
static bool
XidInMVCCSnapshot(TransactionId xid, Snapshot snapshot)
{
uint32 i;
/*
* Make a quick range check to eliminate most XIDs without looking at the
* xip arrays. Note that this is OK even if we convert a subxact XID to
* its parent below, because a subxact with XID < xmin has surely also got
* a parent with XID < xmin, while one with XID >= xmax must belong to a
* parent that was not yet committed at the time of this snapshot.
*/
/* Any xid < xmin is not in-progress */
if (TransactionIdPrecedes(xid, snapshot->xmin))
return false;
/* Any xid >= xmax is in-progress */
if (TransactionIdFollowsOrEquals(xid, snapshot->xmax))
return true;
/*
* If the snapshot contains full subxact data, the fastest way to check
* things is just to compare the given XID against both subxact XIDs and
* top-level XIDs. If the snapshot overflowed, we have to use pg_subtrans
* to convert a subxact XID to its parent XID, but then we need only look
* at top-level XIDs not subxacts.
*/
if (snapshot->subxcnt >= 0)
{
/* full data, so search subxip */
int32 j;
for (j = 0; j < snapshot->subxcnt; j++)
{
if (TransactionIdEquals(xid, snapshot->subxip[j]))
return true;
}
/* not there, fall through to search xip[] */
}
else
{
/* overflowed, so convert xid to top-level */
xid = SubTransGetTopmostTransaction(xid);
/*
* If xid was indeed a subxact, we might now have an xid < xmin, so
* recheck to avoid an array scan. No point in rechecking xmax.
*/
if (TransactionIdPrecedes(xid, snapshot->xmin))
return false;
}
for (i = 0; i < snapshot->xcnt; i++)
{
if (TransactionIdEquals(xid, snapshot->xip[i]))
return true;
}
return false;
}
/*
* HeapTupleSatisfiesVacuum
*
* Determine the status of tuples for VACUUM purposes. Here, what
* we mainly want to know is if a tuple is potentially visible to *any*
* running transaction. If so, it can't be removed yet by VACUUM.
*
* OldestXmin is a cutoff XID (obtained from GetOldestXmin()). Tuples
* deleted by XIDs >= OldestXmin are deemed "recently dead"; they might
* still be visible to some open transaction, so we can't remove them,
* even if we see that the deleting transaction has committed.
*/
HTSV_Result
HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin,
Buffer buffer)
{
/*
* Has inserting transaction committed?
*
* If the inserting transaction aborted, then the tuple was never visible
* to any other transaction, so we can delete it immediately.
*/
if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
{
if (tuple->t_infomask & HEAP_XMIN_INVALID)
return HEAPTUPLE_DEAD;
else if (tuple->t_infomask & HEAP_MOVED_OFF)
{
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
if (TransactionIdIsCurrentTransactionId(xvac))
return HEAPTUPLE_DELETE_IN_PROGRESS;
if (TransactionIdIsInProgress(xvac))
return HEAPTUPLE_DELETE_IN_PROGRESS;
if (TransactionIdDidCommit(xvac))
{
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
InvalidTransactionId);
return HEAPTUPLE_DEAD;
}
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
InvalidTransactionId);
}
else if (tuple->t_infomask & HEAP_MOVED_IN)
{
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
if (TransactionIdIsCurrentTransactionId(xvac))
return HEAPTUPLE_INSERT_IN_PROGRESS;
if (TransactionIdIsInProgress(xvac))
return HEAPTUPLE_INSERT_IN_PROGRESS;
if (TransactionIdDidCommit(xvac))
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
InvalidTransactionId);
else
{
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
InvalidTransactionId);
return HEAPTUPLE_DEAD;
}
}
else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
{
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
return HEAPTUPLE_INSERT_IN_PROGRESS;
if (tuple->t_infomask & HEAP_IS_LOCKED)
return HEAPTUPLE_INSERT_IN_PROGRESS;
/* inserted and then deleted by same xact */
return HEAPTUPLE_DELETE_IN_PROGRESS;
}
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
HeapTupleHeaderGetXmin(tuple));
else
{
/*
* Not in Progress, Not Committed, so either Aborted or crashed
*/
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
InvalidTransactionId);
return HEAPTUPLE_DEAD;
}
/*
* At this point the xmin is known committed, but we might not have
* been able to set the hint bit yet; so we can no longer Assert that
* it's set.
*/
}
/*
* Okay, the inserter committed, so it was good at some point. Now what
* about the deleting transaction?
*/
if (tuple->t_infomask & HEAP_XMAX_INVALID)
return HEAPTUPLE_LIVE;
if (tuple->t_infomask & HEAP_IS_LOCKED)
{
/*
* "Deleting" xact really only locked it, so the tuple is live in any
* case. However, we should make sure that either XMAX_COMMITTED or
* XMAX_INVALID gets set once the xact is gone, to reduce the costs of
* examining the tuple for future xacts. Also, marking dead
* MultiXacts as invalid here provides defense against MultiXactId
* wraparound (see also comments in heap_freeze_tuple()).
*/
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
{
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
{
if (MultiXactIdIsRunning(HeapTupleHeaderGetXmax(tuple)))
return HEAPTUPLE_LIVE;
}
else
{
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
return HEAPTUPLE_LIVE;
}
/*
* We don't really care whether xmax did commit, abort or crash.
* We know that xmax did lock the tuple, but it did not and will
* never actually update it.
*/
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
InvalidTransactionId);
}
return HEAPTUPLE_LIVE;
}
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
{
/* MultiXacts are currently only allowed to lock tuples */
Assert(tuple->t_infomask & HEAP_IS_LOCKED);
return HEAPTUPLE_LIVE;
}
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
{
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
return HEAPTUPLE_DELETE_IN_PROGRESS;
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
SetHintBits(tuple, buffer, HEAP_XMAX_COMMITTED,
HeapTupleHeaderGetXmax(tuple));
else
{
/*
* Not in Progress, Not Committed, so either Aborted or crashed
*/
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
InvalidTransactionId);
return HEAPTUPLE_LIVE;
}
/*
* At this point the xmax is known committed, but we might not have
* been able to set the hint bit yet; so we can no longer Assert that
* it's set.
*/
}
/*
* Deleter committed, but check special cases.
*/
if (TransactionIdEquals(HeapTupleHeaderGetXmin(tuple),
HeapTupleHeaderGetXmax(tuple)))
{
/*
* Inserter also deleted it, so it was never visible to anyone else.
* However, we can only remove it early if it's not an updated tuple;
* else its parent tuple is linking to it via t_ctid, and this tuple
* mustn't go away before the parent does.
*/
if (!(tuple->t_infomask & HEAP_UPDATED))
return HEAPTUPLE_DEAD;
}
if (!TransactionIdPrecedes(HeapTupleHeaderGetXmax(tuple), OldestXmin))
{
/* deleting xact is too recent, tuple could still be visible */
return HEAPTUPLE_RECENTLY_DEAD;
}
/* Otherwise, it's dead and removable */
return HEAPTUPLE_DEAD;
}
/*
* HeapTupleSatisfiesSnapshot
* True iff heap tuple is valid for the given snapshot.
*
* Here, we consider the effects of:
* all transactions committed as of the time of the given snapshot
* previous commands of this transaction
*
* Does _not_ include:
* transactions shown as in-progress by the snapshot
* transactions started after the snapshot was taken
* changes made by the current command
*
* This is the same as HeapTupleSatisfiesNow, except that transactions that
* were in progress or as yet unstarted when the snapshot was taken will
* be treated as uncommitted, even if they have committed by now.
*
* (Notice, however, that the tuple status hint bits will be updated on the
* basis of the true state of the transaction, even if we then pretend we
* can't see it.)
*/
bool
HeapTupleSatisfiesSnapshot(HeapTupleHeader tuple, Snapshot snapshot)
{
if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
{
if (tuple->t_infomask & HEAP_XMIN_INVALID)
return false;
if (tuple->t_infomask & HEAP_MOVED_OFF)
{
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
if (TransactionIdIsCurrentTransactionId(xvac))
return false;
if (!TransactionIdIsInProgress(xvac))
{
if (TransactionIdDidCommit(xvac))
{
tuple->t_infomask |= HEAP_XMIN_INVALID;
return false;
}
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
}
}
else if (tuple->t_infomask & HEAP_MOVED_IN)
{
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
if (!TransactionIdIsCurrentTransactionId(xvac))
{
if (TransactionIdIsInProgress(xvac))
return false;
if (TransactionIdDidCommit(xvac))
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
else
{
tuple->t_infomask |= HEAP_XMIN_INVALID;
return false;
}
}
}
else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple)))
{
if (HeapTupleHeaderGetCmin(tuple) >= snapshot->curcid)
return false; /* inserted after scan started */
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
return true;
Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)));
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
return true;
if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
return true; /* deleted after scan started */
else
return false; /* deleted before scan started */
}
else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
return false;
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
else
{
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMIN_INVALID;
return false;
}
}
/*
* By here, the inserting transaction has committed - have to check
* when...
*/
if (TransactionIdFollowsOrEquals(HeapTupleHeaderGetXmin(tuple),
snapshot->xmin))
{
uint32 i;
if (TransactionIdFollowsOrEquals(HeapTupleHeaderGetXmin(tuple),
snapshot->xmax))
return false;
for (i = 0; i < snapshot->xcnt; i++)
{
if (TransactionIdEquals(HeapTupleHeaderGetXmin(tuple),
snapshot->xip[i]))
return false;
}
}
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid or aborted */
return true;
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
return true;
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
{
if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
{
if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
return true; /* deleted after scan started */
else
return false; /* deleted before scan started */
}
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
return true;
if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
{
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMAX_INVALID;
return true;
}
/* xmax transaction committed */
tuple->t_infomask |= HEAP_XMAX_COMMITTED;
}
/*
* OK, the deleting transaction committed too ... but when?
*/
if (TransactionIdFollowsOrEquals(HeapTupleHeaderGetXmax(tuple), snapshot->xmin))
{
uint32 i;
if (TransactionIdFollowsOrEquals(HeapTupleHeaderGetXmax(tuple),
snapshot->xmax))
return true;
for (i = 0; i < snapshot->xcnt; i++)
{
if (TransactionIdEquals(HeapTupleHeaderGetXmax(tuple), snapshot->xip[i]))
return true;
}
}
return false;
}
/*
* RecoverPreparedTransactions
*
* Scan the pg_twophase directory and reload shared-memory state for each
* prepared transaction (reacquire locks, etc). This is run during database
* startup.
*/
void
RecoverPreparedTransactions(void)
{
char dir[MAXPGPATH];
DIR *cldir;
struct dirent *clde;
snprintf(dir, MAXPGPATH, "%s", TWOPHASE_DIR);
cldir = AllocateDir(dir);
while ((clde = ReadDir(cldir, dir)) != NULL)
{
if (strlen(clde->d_name) == 8 &&
strspn(clde->d_name, "0123456789ABCDEF") == 8)
{
TransactionId xid;
char *buf;
char *bufptr;
TwoPhaseFileHeader *hdr;
TransactionId *subxids;
GlobalTransaction gxact;
int i;
xid = (TransactionId) strtoul(clde->d_name, NULL, 16);
/* Already processed? */
if (TransactionIdDidCommit(xid) || TransactionIdDidAbort(xid))
{
ereport(WARNING,
(errmsg("removing stale two-phase state file \"%s\"",
clde->d_name)));
RemoveTwoPhaseFile(xid, true);
continue;
}
/* Read and validate file */
buf = ReadTwoPhaseFile(xid);
if (buf == NULL)
{
ereport(WARNING,
(errmsg("removing corrupt two-phase state file \"%s\"",
clde->d_name)));
RemoveTwoPhaseFile(xid, true);
continue;
}
ereport(LOG,
(errmsg("recovering prepared transaction %u", xid)));
/* Deconstruct header */
hdr = (TwoPhaseFileHeader *) buf;
Assert(TransactionIdEquals(hdr->xid, xid));
bufptr = buf + MAXALIGN(sizeof(TwoPhaseFileHeader));
subxids = (TransactionId *) bufptr;
bufptr += MAXALIGN(hdr->nsubxacts * sizeof(TransactionId));
bufptr += MAXALIGN(hdr->ncommitrels * sizeof(RelFileNode));
bufptr += MAXALIGN(hdr->nabortrels * sizeof(RelFileNode));
/*
* Reconstruct subtrans state for the transaction --- needed
* because pg_subtrans is not preserved over a restart. Note that
* we are linking all the subtransactions directly to the
* top-level XID; there may originally have been a more complex
* hierarchy, but there's no need to restore that exactly.
*/
for (i = 0; i < hdr->nsubxacts; i++)
SubTransSetParent(subxids[i], xid);
/*
* Recreate its GXACT and dummy PGPROC
*
* Note: since we don't have the PREPARE record's WAL location at
* hand, we leave prepare_lsn zeroes. This means the GXACT will
* be fsync'd on every future checkpoint. We assume this
* situation is infrequent enough that the performance cost is
* negligible (especially since we know the state file has already
* been fsynced).
*/
gxact = MarkAsPreparing(xid, hdr->gid,
hdr->prepared_at,
hdr->owner, hdr->database);
GXactLoadSubxactData(gxact, hdr->nsubxacts, subxids);
MarkAsPrepared(gxact);
/*
* Recover other state (notably locks) using resource managers
*/
ProcessRecords(bufptr, xid, twophase_recover_callbacks);
pfree(buf);
}
}
FreeDir(cldir);
}
/*
* HeapTupleSatisfiesVacuum
*
* Determine the status of tuples for VACUUM purposes. Here, what
* we mainly want to know is if a tuple is potentially visible to *any*
* running transaction. If so, it can't be removed yet by VACUUM.
*
* OldestXmin is a cutoff XID (obtained from GetOldestXmin()). Tuples
* deleted by XIDs >= OldestXmin are deemed "recently dead"; they might
* still be visible to some open transaction, so we can't remove them,
* even if we see that the deleting transaction has committed.
*/
HTSV_Result
HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin)
{
/*
* Has inserting transaction committed?
*
* If the inserting transaction aborted, then the tuple was never visible
* to any other transaction, so we can delete it immediately.
*/
if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
{
if (tuple->t_infomask & HEAP_XMIN_INVALID)
return HEAPTUPLE_DEAD;
else if (tuple->t_infomask & HEAP_MOVED_OFF)
{
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
if (TransactionIdIsCurrentTransactionId(xvac))
return HEAPTUPLE_DELETE_IN_PROGRESS;
if (TransactionIdIsInProgress(xvac))
return HEAPTUPLE_DELETE_IN_PROGRESS;
if (TransactionIdDidCommit(xvac))
{
tuple->t_infomask |= HEAP_XMIN_INVALID;
return HEAPTUPLE_DEAD;
}
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
}
else if (tuple->t_infomask & HEAP_MOVED_IN)
{
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
if (TransactionIdIsCurrentTransactionId(xvac))
return HEAPTUPLE_INSERT_IN_PROGRESS;
if (TransactionIdIsInProgress(xvac))
return HEAPTUPLE_INSERT_IN_PROGRESS;
if (TransactionIdDidCommit(xvac))
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
else
{
tuple->t_infomask |= HEAP_XMIN_INVALID;
return HEAPTUPLE_DEAD;
}
}
else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
{
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
return HEAPTUPLE_INSERT_IN_PROGRESS;
Assert(HeapTupleHeaderGetXmin(tuple) ==
HeapTupleHeaderGetXmax(tuple));
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
return HEAPTUPLE_INSERT_IN_PROGRESS;
/* inserted and then deleted by same xact */
return HEAPTUPLE_DELETE_IN_PROGRESS;
}
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
else
{
/*
* Not in Progress, Not Committed, so either Aborted or
* crashed
*/
tuple->t_infomask |= HEAP_XMIN_INVALID;
return HEAPTUPLE_DEAD;
}
/* Should only get here if we set XMIN_COMMITTED */
Assert(tuple->t_infomask & HEAP_XMIN_COMMITTED);
}
/*
* Okay, the inserter committed, so it was good at some point. Now
* what about the deleting transaction?
*/
if (tuple->t_infomask & HEAP_XMAX_INVALID)
return HEAPTUPLE_LIVE;
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
{
/*
* "Deleting" xact really only marked it for update, so the tuple
* is live in any case. However, we must make sure that either
* XMAX_COMMITTED or XMAX_INVALID gets set once the xact is gone;
* otherwise it is unsafe to recycle CLOG status after vacuuming.
*/
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
{
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
return HEAPTUPLE_LIVE;
/*
* We don't really care whether xmax did commit, abort or
* crash. We know that xmax did mark the tuple for update, but
* it did not and will never actually update it.
*/
tuple->t_infomask |= HEAP_XMAX_INVALID;
}
return HEAPTUPLE_LIVE;
}
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
{
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
return HEAPTUPLE_DELETE_IN_PROGRESS;
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
tuple->t_infomask |= HEAP_XMAX_COMMITTED;
else
{
/*
* Not in Progress, Not Committed, so either Aborted or
* crashed
*/
tuple->t_infomask |= HEAP_XMAX_INVALID;
return HEAPTUPLE_LIVE;
}
/* Should only get here if we set XMAX_COMMITTED */
Assert(tuple->t_infomask & HEAP_XMAX_COMMITTED);
}
/*
* Deleter committed, but check special cases.
*/
if (TransactionIdEquals(HeapTupleHeaderGetXmin(tuple),
HeapTupleHeaderGetXmax(tuple)))
{
/*
* Inserter also deleted it, so it was never visible to anyone
* else. However, we can only remove it early if it's not an
* updated tuple; else its parent tuple is linking to it via t_ctid,
* and this tuple mustn't go away before the parent does.
*/
if (!(tuple->t_infomask & HEAP_UPDATED))
return HEAPTUPLE_DEAD;
}
if (!TransactionIdPrecedes(HeapTupleHeaderGetXmax(tuple), OldestXmin))
{
/* deleting xact is too recent, tuple could still be visible */
return HEAPTUPLE_RECENTLY_DEAD;
}
/* Otherwise, it's dead and removable */
return HEAPTUPLE_DEAD;
}
