/*
* Insert an XLOG record having the specified RMID and info bytes, with the
* body of the record being the data and buffer references registered earlier
* with XLogRegister* calls.
*
* Returns XLOG pointer to end of record (beginning of next record).
* This can be used as LSN for data pages affected by the logged action.
* (LSN is the XLOG point up to which the XLOG must be flushed to disk
* before the data page can be written out. This implements the basic
* WAL rule "write the log before the data".)
*/
XLogRecPtr
XLogInsert(RmgrId rmid, uint8 info)
{
XLogRecPtr EndPos;
/* XLogBeginInsert() must have been called. */
if (!begininsert_called)
elog(ERROR, "XLogBeginInsert was not called");
/*
* The caller can set rmgr bits, XLR_SPECIAL_REL_UPDATE and
* XLR_CHECK_CONSISTENCY; the rest are reserved for use by me.
*/
if ((info & ~(XLR_RMGR_INFO_MASK |
XLR_SPECIAL_REL_UPDATE |
XLR_CHECK_CONSISTENCY)) != 0)
elog(PANIC, "invalid xlog info mask %02X", info);
TRACE_POSTGRESQL_WAL_INSERT(rmid, info);
/*
* In bootstrap mode, we don't actually log anything but XLOG resources;
* return a phony record pointer.
*/
if (IsBootstrapProcessingMode() && rmid != RM_XLOG_ID)
{
XLogResetInsertion();
EndPos = SizeOfXLogLongPHD; /* start of 1st chkpt record */
return EndPos;
}
do
{
XLogRecPtr RedoRecPtr;
bool doPageWrites;
XLogRecPtr fpw_lsn;
XLogRecData *rdt;
/*
* Get values needed to decide whether to do full-page writes. Since
* we don't yet have an insertion lock, these could change under us,
* but XLogInsertRecord will recheck them once it has a lock.
*/
GetFullPageWriteInfo(&RedoRecPtr, &doPageWrites);
rdt = XLogRecordAssemble(rmid, info, RedoRecPtr, doPageWrites,
&fpw_lsn);
EndPos = XLogInsertRecord(rdt, fpw_lsn, curinsert_flags);
} while (EndPos == InvalidXLogRecPtr);
XLogResetInsertion();
return EndPos;
}
/*
* Determine whether the buffer referenced has to be backed up.
*
* Since we don't yet have the insert lock, fullPageWrites and forcePageWrites
* could change later, so the result should be used for optimization purposes
* only.
*/
bool
XLogCheckBufferNeedsBackup(Buffer buffer)
{
XLogRecPtr RedoRecPtr;
bool doPageWrites;
Page page;
GetFullPageWriteInfo(&RedoRecPtr, &doPageWrites);
page = BufferGetPage(buffer);
if (doPageWrites && PageGetLSN(page) <= RedoRecPtr)
return true; /* buffer requires backup */
return false; /* buffer does not need to be backed up */
}