/sys/src/cmd/ndb/dnresolve.c
% cat >/sys/lib/dist/changes/1176838212.1.txt << EOF
• Add better comments
• Disable code that was good in theory, but not in practice
• Reduce timeout from 60s to 30s
EOF
 [geoff] --rw-rw-r-- M 64 glenda sys 30062 Apr 17 15:19 sys/src/cmd/ndb/dnresolve.c
	/n/sourcesdump/2007/0417/plan9/sys/src/cmd/ndb/dnresolve.c:540,546 - 
	/n/sourcesdump/2007/0418/plan9/sys/src/cmd/ndb/dnresolve.c:540,549
	  		else if (readn(fd, lenbuf, 2) != 2) {
	  			dnslog("readnet: short read of tcp size from %I",
	  				qp->tcpip);
	- 			/* probably a time-out; demote the ns */
	+ 			/*
	+ 			 * probably a time-out; demote the ns.
	+ 			 * actually, the problem may be the query, not the ns.
	+ 			 */
	  			addslug(qp->tcpip);
	  		} else {
	  			len = lenbuf[0]<<8 | lenbuf[1];
	/n/sourcesdump/2007/0417/plan9/sys/src/cmd/ndb/dnresolve.c:1028,1040 - 
	/n/sourcesdump/2007/0418/plan9/sys/src/cmd/ndb/dnresolve.c:1031,1043
	  	}
	  	procsetname("recursive query for %s %s", qp->dp->name,
	  		rrname(qp->type, buf, sizeof buf));
	- 	qunlock(&qp->dp->querylck);
	+ //	qunlock(&qp->dp->querylck);
	  
	  	queryinit(&nquery, qp->dp, qp->type, qp->req);
	  	nquery.nsrp = tp;
	  	rv = netquery(&nquery, depth+1);
	  
	- 	qlock(&qp->dp->querylck);
	+ //	qlock(&qp->dp->querylck);
	  	rrfreelist(tp);
	  	memset(&nquery, 0, sizeof nquery); /* prevent accidents */
	  	return rv;
	/n/sourcesdump/2007/0417/plan9/sys/src/cmd/ndb/dnresolve.c:1246,1253 - 
	/n/sourcesdump/2007/0418/plan9/sys/src/cmd/ndb/dnresolve.c:1249,1256
	  	}
	  	if(fd >= 0) {
	  		qp->req->aborttime = time(nil) + (patient? Maxreqtm: Maxreqtm/2);
	- 		/* tune; was (patient? 15: 10) */
	  		qp->udpfd = fd;
	+ 		/* tune; was (patient? 15: 10) */
	  		rv = netquery1(qp, depth, ibuf, obuf, (patient? 10: 5), inns);
	  		close(fd);
	  	} else
	/n/sourcesdump/2007/0417/plan9/sys/src/cmd/ndb/dnresolve.c:1277,1289 - 
	/n/sourcesdump/2007/0418/plan9/sys/src/cmd/ndb/dnresolve.c:1280,1299
	  	 */
	  
	  	/* don't lock before call to slave so only children can block */
	- 	lock = qp->req->isslave != 0;
	- 	if(lock) {
	+ 	if (0)
	+ 		lock = qp->req->isslave != 0;
	+ 	if(0 && lock) {
	  		procsetname("query lock wait for %s", qp->dp->name);
	- 		/* don't make concurrent queries for this name */
	+ 		/*
	+ 		 * don't make concurrent queries for this name.
	+ 		 *
	+ 		 * this seemed like a good idea, to avoid swamping
	+ 		 * an overloaded ns, but in practice, dns processes
	+ 		 * pile up quickly and dns becomes unresponsive for a while.
	+ 		 */
	  		qlock(&qp->dp->querylck);
	- 		procsetname("netquery: %s", qp->dp->name);
	  	}
	+ 	procsetname("netquery: %s", qp->dp->name);
	  
	  	/* prepare server RR's for incremental lookup */
	  	for(rp = qp->nsrp; rp; rp = rp->next)
	/n/sourcesdump/2007/0417/plan9/sys/src/cmd/ndb/dnresolve.c:1323,1331 - 
	/n/sourcesdump/2007/0418/plan9/sys/src/cmd/ndb/dnresolve.c:1333,1340
	  //	if (rv == 0)		/* could ask /net.alt/dns directly */
	  //		askoutdns(qp->dp, qp->type);
	  
	- 	if(lock) {
	+ 	if(0 && lock)
	  		qunlock(&qp->dp->querylck);
	- 	}
	  	return rv;
	  }
	  
	/n/sourcesdump/2007/0417/plan9/sys/src/cmd/ndb/dnresolve.c:1339,1345 - 
	/n/sourcesdump/2007/0418/plan9/sys/src/cmd/ndb/dnresolve.c:1348,1354
	  
	  	memset(&req, 0, sizeof req);
	  	req.isslave = 1;
	- 	req.aborttime = now + Maxreqtm*2;	/* be patient */
	+ 	req.aborttime = now + Maxreqtm;
	  	queryinit(&query, dnlookup(root, Cin, 1), Tns, &req);
	  	query.nsrp = dblookup(root, Cin, Tns, 0, 0);
	  	rv = netquery(&query, 0);