Hi Enrico,
In the new ledger api, we return Iterable<LedgerEntry> instead of
Iterator<LedgerEntry>. In general, it is good to return Iterable, however
it seems to be problematic in following use case:
Iterable<LedgerEntry> entries = rh.read(...);
Iterator<LedgerEntry> iter1 = entries.iterator();
while (iter1.hasNext()) {
LedgerEntry le = iter1.next;
le.getEntryBuffer().release();
}
Iterator<LedgerEntry> iter2 = entries.iterator();
while (iter2.hasNext()) {
LedgerEntry le = iter2.next();
le.getEntryBuffer().release();
}
Using Iterable opens up the chance that people will create multiple
iterators and use them concurrently. I think we should not use
Iterable<LedgerEntry>, which it might actually cause problems.
I am thinking if we can create an interface LedgerEntries to extend
Iterable<LedgerEntry>. so:
- the implementation can create increase right buffer reference when
creating an iterator
- we can make LedgerEntries a recycleable object, and it is returned to the
tool when people called #close()
- on #close(), it releases all the references to release resources
interface LedgerEntries extends Iterable<LedgerEntry>, AutoCloseable {
long getEntry(long entryId);
Iterator<LedgerEntry> iterator();
}
