public boolean removeRegion(final long regionId) {
        final StampedLock stampedLock = this.stampedLock;
        final long stamp = stampedLock.writeLock();
        try {
            final Region region = this.regionTable.remove(regionId);
            if (region != null) {
                final byte[] startKey = BytesUtil.nullToEmpty(region.getStartKey());
                return this.rangeTable.remove(startKey) != null;
            }
        } finally {
            stampedLock.unlockWrite(stamp);
        }
        return false;
    }
Returns the region to which the key belongs.
jraft-rheakv/rheakv-core/src/main/java/com/alipay/sofa/jraft/rhea/client/RegionRouteTable.java