WAL XLOG读取 写入 起始/开始 LSN位置 相关全局变量 函数

	ReadRecPtr = xlogreader->ReadRecPtr;
	EndRecPtr  = xlogreader->EndRecPtr;


Insert->PrevBytePos = XLogRecPtrToBytePos(LastRec);
Insert->CurrBytePos = XLogRecPtrToBytePos(EndOfLog);

XLogWrite

搜索 INSERT @ 可知道在执行 XLogInsertRecord

checkPoint.redo = XLogSegSize + SizeOfXLogLongPHD;

XLogInsert XLogInsertRecord ReserveXLogInsertLocation
{

startbytepos = Insert->CurrBytePos;
endbytepos = startbytepos + size;
prevbytepos = Insert->PrevBytePos;
Insert->CurrBytePos = endbytepos;
Insert->PrevBytePos = startbytepos;

SpinLockRelease(&Insert->insertpos_lck);

*StartPos = XLogBytePosToRecPtr(startbytepos);
*EndPos   = XLogBytePosToEndRecPtr(endbytepos);
*PrevPtr  = XLogBytePosToRecPtr(prevbytepos);

}

获取XLOG缓冲区
GetXLogBuffer

LogwrtResult.Write = LogwrtResult.Flush = EndOfLog;

XLogCtl->LogwrtRqst.Write = EndOfLog;
XLogCtl->LogwrtRqst.Flush = EndOfLog;

XLogWrite

XLogCtl->pages