1: # include   <ingres.h>
   2: # include   <aux.h>
   3: # include   <tree.h>
   4: # include   "globs.h"
   5: # include   <lock.h>
   6: # include   <sccs.h>
   7: 
   8: SCCSID(@(#)lockit.c	8.1	12/31/84)
   9: 
  10: /*
  11: **  LOCKIT -- sets relation locks for integrity locking
  12: **
  13: **	Parameters:
  14: **		root- the root of a query tree;
  15: **		resvar- index of variable to be updated.
  16: **
  17: */
  18: lockit(root, resvar)
  19: QTREE   *root;
  20: int resvar;
  21: {
  22:     register QTREE  *r;
  23:     register int    i, j;
  24:     long        vlist[MAXRANGE];
  25:     int     bmap, cv;
  26:     char        mode;
  27:     int     skvr;
  28:     int     redo;
  29:     DESC        *d, *openr1();
  30:     long        restid;
  31:     int     k;
  32: 
  33:     r = root;
  34:     bmap = r->sym.value.sym_root.lvarm | r->sym.value.sym_root.rvarm;
  35:     if (resvar >= 0)
  36:         bmap |= 01 << resvar;
  37:     else
  38:         restid = -1;
  39:     i = 0;
  40:     /* put relids of relations to be locked into vlist
  41: 	   check for and remove duplicates */
  42:     for (j = 0; j < MAXRANGE; j++)
  43:         if (bmap & (01 << j))
  44:         {
  45:             d = openr1(j);
  46:             if (j == resvar)
  47:                 restid = d->reltid.ltid;
  48:             for (k = 0; k < i; k++)
  49:                 if (vlist[k] == d->reltid.ltid)
  50:                     break;
  51:             if (k == i)
  52:                 vlist[i++] = d->reltid.ltid;
  53:         }
  54:     cv = i;
  55: /*
  56:  *	set the locks: set the first lock with the sleep option
  57:  *			set other locks checking for failure;
  58:  *			if failure, release all locks, sleep on blocking
  59:  *			lock.
  60:  */
  61:     skvr = -1;
  62:     do
  63:     {
  64:         /* skvr is the index of the relation already locked
  65: 		   try to lock the remaining relations */
  66:         redo = FALSE;
  67:         for (i = 0; i < cv; i++)
  68:             if (i != skvr)
  69:             {
  70:                 if (restid == vlist[i])
  71:                     mode = M_EXCL;
  72:                 else
  73:                     mode = M_SHARE;
  74:                 if (setrll(A_RTN, vlist[i], mode) < 0)
  75:                     /* a lock request failed */
  76:                 {
  77:                     unlall();   /* release all locks */
  78:                     setrll(A_SLP, vlist[i], mode);
  79:                             /* wait on problem lock*/
  80:                     skvr = i;
  81:                     redo = TRUE;
  82:                     break;  /* reset the other locks */
  83:                 }
  84:             }
  85:     }
  86:     while (redo);
  87: }

Defined functions

lockit defined in line 8; used 1 times
Last modified: 1986-04-17
Generated: 2016-12-26
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