1: # include   <ingres.h>
   2: # include   <access.h>
   3: # include   <aux.h>
   4: # include   <lock.h>
   5: # include   <sccs.h>
   6: 
   7: SCCSID(@(#)add_ovflo.c	8.2	2/8/85)
   8: 
   9: /*
  10: **	ADD_OVFLO -- Allocates an overflow page which will be
  11: **		attached to current page.  TID must be for current page.
  12: **		TID will be updated to id of new overflow page.
  13: **
  14: **	Parameters:
  15: **		dx - descriptor for relation
  16: **		tid - tid for current page
  17: **
  18: **	Side Effects:
  19: **		tid is updated to id of new overflow page
  20: **
  21: **	Trace Flags:
  22: **		26.3
  23: **
  24: **	Returns:
  25: **		0 - success
  26: **		-1 (NOBUFFER) can't get buffer for overflow page
  27: **		-2 (NOSETUP) can't set up overflow page
  28: **		-3 (NOGETCURRENT) can't get the current page
  29: **		-4 (NORMVMAIN) can't remove main page
  30: **		-5 (NOGETOVFLO) can't get the overflow page
  31: **
  32: */
  33: 
  34: add_ovflo(dx, tid)
  35: DESC    *dx;
  36: TID *tid;
  37: {
  38:     register DESC       *d;
  39:     register struct accbuf  *b;
  40:     extern struct accbuf    *choose_buf();
  41:     register int        lk;
  42:     int         i;
  43:     long            mpage, newpage;
  44:     TID         tidx;
  45: 
  46:     d = dx;
  47: #	ifdef xATR2
  48:     if (tTf(26, 3))
  49:         printf("ADD_OVFLO:\n");
  50: #	endif
  51: 
  52:     /*
  53: 	**	save main page pointer so that it may be used when
  54: 	**	setting up new overflow page.
  55: 	*/
  56:     mpage = Acc_head->mainpg;
  57: 
  58:     if (lk = (Acclock && (d->reldum.relstat & S_CONCUR) && (d->relopn < 0 )))
  59:     {
  60:         setcsl(Acc_head->rel_tupid);
  61:         Acclock = FALSE;
  62:     }
  63: 
  64:     /*
  65: 	**	Determine last page of the relation
  66: 	*/
  67:     last_page(d, &tidx, Acc_head);
  68:     pluck_page(&tidx, &newpage);
  69:     newpage++;
  70: 
  71:     /*
  72: 	**	choose an available buffer as victim for setting up
  73: 	**	overflow page.
  74: 	*/
  75:     if ((b = choose_buf(d, newpage)) == NULL)
  76:     {
  77:         if (lk)
  78:         {
  79:             Acclock = TRUE;
  80:             unlcs(Acc_head->rel_tupid);
  81:         }
  82:         return(NOBUFFER);
  83:     }
  84: 
  85:     /*
  86: 	**	setup overflow page
  87: 	*/
  88: 
  89:     b->mainpg = mpage;
  90:     b->ovflopg = 0;
  91:     b->thispage = newpage;
  92:     b->linetab[0] = (int) b->firstup - (int) b;
  93:     b->nxtlino = 0;
  94:     b->bufstatus |= BUF_DIRTY;
  95:     if (pageflush(b))
  96:         return (NOSETUP);
  97: 
  98:     /*
  99: 	**	now that overflow page has successfully been written,
 100: 	**	get the old current page back and link the new overflow page
 101: 	**	to it.
 102: 	**	If the relation is a heap then don't leave the old main
 103: 	**	page around in the buffers. This is done on the belief
 104: 	**	that it will never be accessed again.
 105: 	*/
 106: 
 107:     if (get_page(d, tid))
 108:         return (NOGETCURRENT);
 109:     Acc_head->ovflopg = newpage;
 110:     Acc_head->bufstatus |= BUF_DIRTY;
 111:     i = pageflush(Acc_head);
 112:     if (lk)
 113:     {
 114:         Acclock = TRUE;
 115:         unlcs(Acc_head->rel_tupid);
 116:     }
 117:     if (i)
 118:         return (NORMVMAIN);
 119:     if (abs(d->reldum.relspec) == M_HEAP)
 120:         resetacc(Acc_head); /* no error is possible */
 121: 
 122:     /*
 123: 	**	now bring the overflow page back and make it current.
 124: 	**	if the overflow page is still in AM cache, then this will not
 125: 	**	cause any disk activity.
 126: 	*/
 127: 
 128:     stuff_page(tid, &newpage);
 129:     if (get_page(d, tid))
 130:         return (NOGETOVFLO);
 131:     return (0);
 132: }

Defined functions

add_ovflo defined in line 7; used 1 times
Last modified: 1986-04-17
Generated: 2016-12-26
Generated by src2html V0.67
page hit count: 831
Valid CSS Valid XHTML 1.0 Strict