void balblk()
{
BTint val,llink,rlink,cblk;
int nkeys,cnkeys,result,diff;
char tkey[ZKYLEN];
cblk = btact->cntxt->lf.lfblk;
/* get parent block */
btact->cntxt->lf.lfpos = bpull();
btact->cntxt->lf.lfblk = bpull();
nkeys = bgtinf(btact->cntxt->lf.lfblk,ZNKEYS);
cnkeys = bgtinf(cblk,ZNKEYS);
if (btact->cntxt->lf.lfpos < nkeys) {
/* check right sister block */
bsrhbk(btact->cntxt->lf.lfblk,tkey,&btact->cntxt->lf.lfpos,&val,
&llink,&rlink,&result);
if (result != 0) {
bterr("BALBLK",QBALSE,NULL);
goto fin;
}
nkeys = bgtinf(rlink,ZNKEYS);
diff = cnkeys-nkeys;
if (abs(diff) > (int)(ZMXKEY/2)) {
balbk1(cblk,rlink,diff,tkey,val);
goto fin;
}
}
if (btact->cntxt->lf.lfpos > 0) {
/* check left sister block */
btact->cntxt->lf.lfpos--;
bsrhbk(btact->cntxt->lf.lfblk,tkey,&btact->cntxt->lf.lfpos,
&val,&llink,&rlink,&result);
if (result != 0) {
bterr("BALBLK",QBALSE,NULL);
goto fin;
}
nkeys = bgtinf(llink,ZNKEYS);
diff = nkeys-cnkeys;
if (abs(diff) > (int)(ZMXKEY/2)) {
balbk1(llink,cblk,diff,tkey,val);
goto fin;
}
btact->cntxt->lf.lfpos++;
}
/* no balancing possible; restore original environment */
bpush(btact->cntxt->lf.lfblk);
bpush(btact->cntxt->lf.lfpos);
btact->cntxt->lf.lfblk = cblk;
fin:
return;
}
int binsky(BTA *b, char *key,BTint val)
{
BTint lval,dups_allowed;
int status;
KEYENT keyent;
bterr("",0,NULL);
if ((status=bvalap("BINSKY",b)) != 0) return(status);
btact = b;
if (btact->shared) {
if (!block()) {
bterr("BINSKY",QBUSY,NULL);
goto fin;
}
}
if (b->cntxt->super.smode != 0) {
/* read only, can't insert */
bterr("BINSKY",QNOWRT,NULL);
}
else {
dups_allowed = bgtinf(btact->cntxt->super.scroot,ZMISC);
strncpy(keyent.key,key,ZKYLEN);
keyent.key[ZKYLEN-1] = '\0';
keyent.val = val;
keyent.dup = ZNULL;
status = bfndky(b,keyent.key,&lval);
if (status == QNOKEY || (status == 0 && dups_allowed)) {
/* QNOKEY is not an error in this context; remove it */
bterr("",0,NULL);
if (status == 0) {
/* inserting duplicate key */
btdupkey(key,val);
}
else {
bleaf(1);
bputky(btact->cntxt->lf.lfblk,&keyent,ZNULL,ZNULL);
}
}
else {
bterr("BINSKY",QDUP,key);
}
}
fin:
if (btact->shared) bulock();
return(btgerr());
}
/* Checks structure of index file, from current root. Returns number
* of keys found or ZNULL if structure is damaged (either empty blocks
* that are non-root, or inconsistent leaf depth). */
BTint btkeys(BTA* b,int stats)
{
BTint tblks = 0,
tnkeys = 0,
empty_blk = ZNULL,
blkno = ZNULL;
BTint val,link1,link2;
int ioerr,idx,result,loc = 0;
int blk_depth[STKMAX+1];
int leaf_depth = -1,balanced = TRUE;
char key[ZKYLEN];
bterr("",0,NULL);
if ((ioerr=bvalap("BTKEYS",b)) != 0) return(ioerr);
if (btact->shared) {
if (!block()) {
bterr("BTKEYS",QBUSY,NULL);
goto fin;
}
}
btact = b; /* set context pointer */
if (btact->idxunt == NULL) {
bterr("BTKEYS",QNOBTF,NULL);
goto fin;
}
for (idx=0;idx<=STKMAX;idx++) blk_depth[idx] = 0;
tblks = 0; tnkeys = 0; blkno = ZNULL;
do {
int depth,nkeys;
bnxtbk(&blkno);
depth = btstk_depth()/2;
tblks++;
blk_depth[depth]++;
ioerr = brdblk(blkno,&idx);
nkeys = bgtinf(blkno,ZNKEYS);
if (nkeys == 0 && empty_blk == ZNULL) {
if (bgtinf(blkno,ZBTYPE) != ZROOT) empty_blk = blkno;
}
else {
bsrhbk(blkno,key,&loc,&val,&link1,&link2,&result);
if (link1 == ZNULL) {
if (leaf_depth < 0) {
leaf_depth = depth;
}
else if (leaf_depth != depth) {
balanced = FALSE;
if (depth > leaf_depth) leaf_depth = depth;
}
}
nkeys = btcntkeys(blkno);
if (nkeys == ZNULL) return FALSE;
tnkeys += nkeys;
}
} while (blkno != btact->cntxt->super.scroot);
if (stats) {
printf("Block stats:\n");
if (empty_blk != ZNULL) {
printf("At least one non-root block has no keys. "
"First encountered was " ZINTFMT "\n",empty_blk);
}
printf("Index balanced: %s\n",(balanced)?"YES":"NO");
printf("Max leaf depth: %d\n",leaf_depth);
printf("Depth Number of blocks\n");
for (idx=0;idx<=leaf_depth;idx++) {
printf("%5d %18d\n",idx,blk_depth[idx]);
}
}
fin:
return (empty_blk != ZNULL || !balanced)?ZNULL:tnkeys;
}
int bfndky(BTA *b,char *key,BTint *val)
{
BTint cblk, link1, link2, newblk;
int index, result, nkeys, status;
char lkey[ZKYLEN];
bterr("",0,NULL);
status = QNOKEY;
if ((result=bvalap("BFNDKY",b)) != 0) return(result);
btact = b; /* set context pointer */
if (btact->shared) {
if (!block()) {
bterr("BFNDKY",QBUSY,NULL);
goto fin;
}
}
/* take local copy of key, truncating if necessary */
strncpy(lkey,key,ZKYLEN);
lkey[ZKYLEN-1] = '\0';
/* initialise stack etc */
btact->cntxt->lf.lfexct = FALSE;
cblk = btact->cntxt->super.scroot;
bstkin();
btact->cntxt->lf.lfblk = -1;
btact->cntxt->lf.lfpos = -1;
strcpy(btact->cntxt->lf.lfkey,lkey);
while (cblk >= 0) {
#if DEBUG >= 2
fprintf(stderr,"BFNDKY: searching block " ZINTFMT "\n",cblk);
#endif
nkeys = bgtinf(cblk,ZNKEYS);
if (nkeys == ZMXKEY && btact->cntxt->super.smode == 0) {
/* split if block full and updating permitted */
bsptbk(cblk,&newblk);
if (newblk < 0) {
bterr("BFNDKY",QSPLIT,NULL);
break;
}
/* if split occured, then must re-examine parent */
if (cblk != btact->cntxt->super.scroot) {
index = btact->cntxt->lf.lfpos;
cblk = btact->cntxt->lf.lfblk;
btact->cntxt->lf.lfpos = bpull();
btact->cntxt->lf.lfblk = bpull();
}
}
else {
index = -1;
bpush(btact->cntxt->lf.lfblk);
bpush(btact->cntxt->lf.lfpos);
bsrhbk(cblk,lkey,&index,val,&link1,&link2,&result);
btact->cntxt->lf.lfblk = cblk;
btact->cntxt->lf.lfpos = index; /* if block is empty, leave lfpos at -1 */
if (result < 0) {
/* must examine left block */
cblk = link1;
continue;
}
else if (result > 0) {
/* must examine right block */
cblk = link2;
/* increment index to indicate this key "visited" */
btact->cntxt->lf.lfpos++;
continue;
}
else {
status = 0;
btact->cntxt->lf.lfexct = TRUE;
break;
}
}
}
fin:
if (btact->shared) bulock();
/* non-zero status indicates no such key found */
if (status) bterr("BFNDKY",QNOKEY,lkey);
return(btgerr());
}
void bdemte(BTint *cblk)
{
BTint newblk,val,link1,link2,jblk,llink,rlink;
int nkeys,type,result;
int rblke;
char tkey[ZKYLEN];
nkeys = bgtinf(btact->cntxt->lf.lfblk,ZNKEYS);
if (nkeys == 0) {
type = bgtinf(btact->cntxt->lf.lfblk,ZBTYPE);
if (type != ZROOT) {
/* pull parent */
btact->cntxt->lf.lfpos = bpull();
btact->cntxt->lf.lfblk = bpull();
nkeys = bgtinf(btact->cntxt->lf.lfblk,ZNKEYS);
if (btact->cntxt->lf.lfpos != 0) {
/* ensure that empty block is on the right */
rblke = TRUE;
btact->cntxt->lf.lfpos--;
}
else {
/* first block empty, so can't put on right */
rblke = FALSE;
}
bsrhbk(btact->cntxt->lf.lfblk,tkey,&btact->cntxt->lf.lfpos,&val,
&link1,&link2,&result);
if (result != 0) {
bterr("BDEMTE",QDEMSE,NULL);
goto fin;
}
#if DEBUG >= 1
printf("BDEMTE: Demoting key %s from blk: " ZINTFMT "\n",tkey,
btact->cntxt->lf.lfblk);
#endif
/* remove key from original block */
bremky(btact->cntxt->lf.lfblk,btact->cntxt->lf.lfpos);
/* prepare for split check */
if (rblke)
jblk = link1;
else
jblk = link2;
/* if target block for demotion is full, split it */
nkeys = bgtinf(jblk,ZNKEYS);
if (nkeys == ZMXKEY) {
bsptbk(jblk,&newblk);
if (newblk == ZNULL) {
bterr("BDEMTE",QDEMSP,NULL);
goto fin;
}
if (rblke) {
link1 = newblk;
}
}
if (!rblke) {
/* copy keys from right block to empty left block */
nkeys = bgtinf(link2,ZNKEYS);
bsetbs(link1,1);
bcpybk(link1,link2,0,0,nkeys);
bstinf(link1,ZNKEYS,nkeys);
bsetbs(link1,0);
llink = *cblk;
rlink = ZNULL; /* 0 replaced by ZNULL for C */
}
else {
llink = ZNULL; /* 0 replaced by ZNULL for C */
rlink = *cblk;
}
bputky(link1,tkey,val,llink,rlink);
bmkfre(link2);
/* set new potentially dangling block */
*cblk = link1;
}
else {
/* empty block is root; copy keys from child and then free
* the child block */
nkeys = bgtinf(*cblk,ZNKEYS);
bcpybk(btact->cntxt->lf.lfblk,*cblk,0,0,nkeys);
bstinf(btact->cntxt->lf.lfblk,ZNKEYS,nkeys);
bmkfre(*cblk);
*cblk = ZNULL;
}
}
else {
*cblk = ZNULL;
}
fin:
return;
}
int bnxtky(BTA* b,char *key,BTint *val)
{
int idx,nkeys,status;
int found;
bterr("",0,NULL);
if ((status=bvalap("BNXTKY",b)) != 0) return(status);
btact = b; /* set global context pointer */
if (btact->shared) {
if (!block()) {
bterr("BNXTKY",QBUSY,NULL);
goto fin;
}
}
/* handle duplicate positioning */
found = btduppos(ZNEXT,val);
if (found > 0) {
goto fin;
}
else if (found == 0) {
strncpy(key,btact->cntxt->lf.lfkey,ZKYLEN);
key[ZKYLEN-1] = '\0';
goto fin;
}
if (btact->shared && btact->cntxt->lf.lfblk != ZNULL) {
/* position to last found key via bfndky, since context could
* have been invalidated by concurrent updates by other users.
* Note we don't care if the key is found or not, so the error
* status is always cleared. */
status = bfndky(btact,btact->cntxt->lf.lfkey,val);
bterr("",0,NULL);
}
found = FALSE;
while (btact->cntxt->lf.lfblk != ZNULL && !found) {
status = brdblk(btact->cntxt->lf.lfblk,&idx);
if (idx < 0) {
bterr("BNXTKY",QRDBLK,itostr(btact->cntxt->lf.lfblk));
break;
}
nkeys = bgtinf(btact->cntxt->lf.lfblk,ZNKEYS);
#if DEBUG >= 1
printf("BNXTKY: lfblk: " ZINTFMT ", lfpos: %d, nkeys: %d\n",
btact->cntxt->lf.lfblk,btact->cntxt->lf.lfpos,nkeys);
#endif
if (btact->cntxt->lf.lfpos >= nkeys || nkeys == 0) {
/* finished with this block (or no key was found at all),
* get parent from stack */
btact->cntxt->lf.lfpos = bpull();
btact->cntxt->lf.lfblk = bpull();
btact->cntxt->lf.lfexct = FALSE;
continue;
}
if (!btact->cntxt->lf.lfexct) {
btact->cntxt->lf.lfexct = TRUE;
}
else {
btact->cntxt->lf.lfpos++;
/* invalidate existing dup chain */
btact->cntxt->lf.draddr = ZNULL;
idx = bleaf(0);
if (idx < 0) continue;
}
if (btact->cntxt->lf.lfpos < nkeys) {
found = TRUE;
strncpy(key,
((btact->memrec)+idx)->keyblk[btact->cntxt->lf.lfpos].key,
ZKYLEN);
key[ZKYLEN-1] = '\0';
/* remember found key (need for shared mode) */
strncpy(btact->cntxt->lf.lfkey,key,ZKYLEN);
btact->cntxt->lf.lfkey[ZKYLEN-1] = '\0';
*val = ((btact->memrec)+idx)->keyblk[btact->cntxt->lf.lfpos].val;
btduppos(ZNEXT,val);
}
}
if (btact->cntxt->lf.lfblk == ZNULL) {
/* end of index reached */
bclrlf();
bterr("BNXTKY",QNOKEY,NULL);
}
fin:
if (btact->shared) bulock();
return btgerr();
}
