/*
* 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);
}
/*
* Activate this module whenever necessary.
* This must happen during postmaster or standalong-backend startup,
* or during WAL replay anytime the track_commit_timestamp setting is
* changed in the master.
*
* The reason why this SLRU needs separate activation/deactivation functions is
* that it can be enabled/disabled during start and the activation/deactivation
* on master is propagated to slave via replay. Other SLRUs don't have this
* property and they can be just initialized during normal startup.
*
* This is in charge of creating the currently active segment, if it's not
* already there. The reason for this is that the server might have been
* running with this module disabled for a while and thus might have skipped
* the normal creation point.
*/
static void
ActivateCommitTs(void)
{
TransactionId xid = ShmemVariableCache->nextXid;
int pageno = TransactionIdToCTsPage(xid);
/*
* Re-Initialize our idea of the latest page number.
*/
LWLockAcquire(CommitTsControlLock, LW_EXCLUSIVE);
CommitTsCtl->shared->latest_page_number = pageno;
LWLockRelease(CommitTsControlLock);
/*
* If CommitTs is enabled, but it wasn't in the previous server run, we
* need to set the oldest and newest values to the next Xid; that way, we
* will not try to read data that might not have been set.
*
* XXX does this have a problem if a server is started with commitTs
* enabled, then started with commitTs disabled, then restarted with it
* enabled again? It doesn't look like it does, because there should be a
* checkpoint that sets the value to InvalidTransactionId at end of
* recovery; and so any chance of injecting new transactions without
* CommitTs values would occur after the oldestCommitTs has been set to
* Invalid temporarily.
*/
LWLockAcquire(CommitTsLock, LW_EXCLUSIVE);
if (ShmemVariableCache->oldestCommitTs == InvalidTransactionId)
{
ShmemVariableCache->oldestCommitTs =
ShmemVariableCache->newestCommitTs = ReadNewTransactionId();
}
LWLockRelease(CommitTsLock);
/* Create the current segment file, if necessary */
if (!SimpleLruDoesPhysicalPageExist(CommitTsCtl, pageno))
{
int slotno;
LWLockAcquire(CommitTsControlLock, LW_EXCLUSIVE);
slotno = ZeroCommitTsPage(pageno, false);
SimpleLruWritePage(CommitTsCtl, slotno);
Assert(!CommitTsCtl->shared->page_dirty[slotno]);
LWLockRelease(CommitTsControlLock);
}
/* Change the activation status in shared memory. */
LWLockAcquire(CommitTsLock, LW_EXCLUSIVE);
commitTsShared->commitTsActive = true;
LWLockRelease(CommitTsLock);
}
/*
* CommitTS resource manager's routines
*/
void
commit_ts_redo(XLogReaderState *record)
{
uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
/* Backup blocks are not used in commit_ts records */
Assert(!XLogRecHasAnyBlockRefs(record));
if (info == COMMIT_TS_ZEROPAGE)
{
int pageno;
int slotno;
memcpy(&pageno, XLogRecGetData(record), sizeof(int));
LWLockAcquire(CommitTsControlLock, LW_EXCLUSIVE);
slotno = ZeroCommitTsPage(pageno, false);
SimpleLruWritePage(CommitTsCtl, slotno);
Assert(!CommitTsCtl->shared->page_dirty[slotno]);
LWLockRelease(CommitTsControlLock);
}
else if (info == COMMIT_TS_TRUNCATE)
{
int pageno;
memcpy(&pageno, XLogRecGetData(record), sizeof(int));
/*
* During XLOG replay, latest_page_number isn't set up yet; insert a
* suitable value to bypass the sanity test in SimpleLruTruncate.
*/
CommitTsCtl->shared->latest_page_number = pageno;
SimpleLruTruncate(CommitTsCtl, pageno);
}
else if (info == COMMIT_TS_SETTS)
{
xl_commit_ts_set *setts = (xl_commit_ts_set *) XLogRecGetData(record);
int nsubxids;
TransactionId *subxids;
nsubxids = ((XLogRecGetDataLen(record) - SizeOfCommitTsSet) /
sizeof(TransactionId));
if (nsubxids > 0)
{
subxids = palloc(sizeof(TransactionId) * nsubxids);
memcpy(subxids,
XLogRecGetData(record) + SizeOfCommitTsSet,
sizeof(TransactionId) * nsubxids);
}
else
subxids = NULL;
TransactionTreeSetCommitTsData(setts->mainxid, nsubxids, subxids,
setts->timestamp, setts->nodeid, true);
if (subxids)
pfree(subxids);
}
else
elog(PANIC, "commit_ts_redo: unknown op code %u", info);
}
