presto-main/src/main/java/io/prestosql/operator/exchange/LocalExchangeSource.java/LocalExchangeSource/getBufferInfo
class LocalExchangeSource:    public LocalExchangeBufferInfo getBufferInfo()
    {
        // This must be lock free to assure task info creation is fast
        // Note: the stats my be internally inconsistent
        return new LocalExchangeBufferInfo(bufferedBytes.get(), buffer.size());
    }