类似这种
boolean writeToTxnLog = !snapshotNeeded;
outerLoop:
while (self.isRunning()) {
readPacket(qp);
switch(qp.getType()) {
case Leader.PROPOSAL:
........
break;
case Leader.COMMIT:
.......
break;
case Leader.INFORM:
......
break;
case Leader.UPTODATE:
.......
break outerLoop;
java 中 outerLoop 的作用是什么?