text: /*-------------------------------------------------------------------------
   *
   * mxactdesc.c
   *	  rmgr descriptor routines for access/transam/multixact.c
   *
   * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/backend/access/rmgrdesc/mxactdesc.c
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include "access/multixact.h"
  
  static void
  out_member(StringInfo buf, MultiXactMember *member)
  {
  	appendStringInfo(buf, "%u ", member->xid);
  	switch (member->status)
  	{
  		case MultiXactStatusForKeyShare:
  			appendStringInfoString(buf, "(keysh) ");
  			break;
  		case MultiXactStatusForShare:
  			appendStringInfoString(buf, "(sh) ");
  			break;
  		case MultiXactStatusForNoKeyUpdate:
  			appendStringInfoString(buf, "(fornokeyupd) ");
  			break;
  		case MultiXactStatusForUpdate:
  			appendStringInfoString(buf, "(forupd) ");
  			break;
  		case MultiXactStatusNoKeyUpdate:
  			appendStringInfoString(buf, "(nokeyupd) ");
  			break;
  		case MultiXactStatusUpdate:
  			appendStringInfoString(buf, "(upd) ");
  			break;
  		default:
  			appendStringInfoString(buf, "(unk) ");
  			break;
  	}
  }
  
  void
  multixact_desc(StringInfo buf, XLogReaderState *record)
  {
  	char	   *rec = XLogRecGetData(record);
  	uint8		info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
  
  	if (info == XLOG_MULTIXACT_ZERO_OFF_PAGE ||
  		info == XLOG_MULTIXACT_ZERO_MEM_PAGE)
  	{
  		int			pageno;
  
  		memcpy(&pageno, rec, sizeof(int));
  		appendStringInfo(buf, "%d", pageno);
  	}
  	else if (info == XLOG_MULTIXACT_CREATE_ID)
  	{
  		xl_multixact_create *xlrec = (xl_multixact_create *) rec;
  		int			i;
  
  		appendStringInfo(buf, "%u offset %u nmembers %d: ", xlrec->mid,
  						 xlrec->moff, xlrec->nmembers);
  		for (i = 0; i < xlrec->nmembers; i++)
  			out_member(buf, &xlrec->members[i]);
  	}
  	else if (info == XLOG_MULTIXACT_TRUNCATE_ID)
  	{
  		xl_multixact_truncate *xlrec = (xl_multixact_truncate *) rec;
  
  		appendStringInfo(buf, "offsets [%u, %u), members [%u, %u)",
  						 xlrec->startTruncOff, xlrec->endTruncOff,
  						 xlrec->startTruncMemb, xlrec->endTruncMemb);
  	}
  }
  
  const char *
  multixact_identify(uint8 info)
  {
  	const char *id = NULL;
  
  	switch (info & ~XLR_INFO_MASK)
  	{
  		case XLOG_MULTIXACT_ZERO_OFF_PAGE:
  			id = "ZERO_OFF_PAGE";
  			break;
  		case XLOG_MULTIXACT_ZERO_MEM_PAGE:
  			id = "ZERO_MEM_PAGE";
  			break;
  		case XLOG_MULTIXACT_CREATE_ID:
  			id = "CREATE_ID";
  			break;
  		case XLOG_MULTIXACT_TRUNCATE_ID:
  			id = "TRUNCATE_ID";
  			break;
  	}
  
  	return id;
  }
  