Given start timestamp and end timestamp, we go through all snapshots between those two until a given block returns true. The block is given a Trx which can then be queried

go_through_snapshots.rb

# BE CAREFUL WITH THE END TIMESTAMP SO THAT YOU DON'T GO TOO FAR INTO THE PAST
# IN CASE THERE'S NO MATCHING SNAPSHOT
def find_snapshot(start_timestamp, end_timestamp = start_timestamp - 1, &block);
    end_timestamp = end_timestamp > 0 ? end_timestamp : 0;
    earlier = nil;
    current_timestamp = start_timestamp;
    while current_timestamp > end_timestamp do;
        current_ss = FastormDb.database.get_snapshot(current_timestamp);
        if block.call(current_ss.begin_trx);
            return {:current => current_timestamp, :earlier => earlier };
        end;
        current_timestamp, earlier = current_ss.parent_timestamp, current_timestamp;
    end;
    return {:current => current_timestamp, :earlier => earlier };
end;