@Override
    public List<KVEntry> bScan(final String startKey, final String endKey, final boolean readOnlySafe,
                               final boolean returnValue) {
        return FutureHelper.get(scan(startKey, endKey, readOnlySafe, returnValue), this.futureTimeoutMillis);
    }
Returns a heap-allocated iterator over the contents of the
database.
<p>
Caller should close the iterator when it is no longer needed.
The returned iterator should be closed before this db is closed.
<p>
<pre>
    KVIterator it = unsafeLocalIterator();
    try {
        // do something
    } finally {
        it.close();
    }
<pre/>
jraft-rheakv/rheakv-core/src/main/java/com/alipay/sofa/jraft/rhea/client/DefaultRheaKVStore.java