presto-memory-context/src/main/java/io/prestosql/memory/context/RootAggregatedMemoryContext.java/RootAggregatedMemoryContext/updateBytes
class RootAggregatedMemoryContext:    @Override
    synchronized ListenableFuture<?> updateBytes(String allocationTag, long bytes)
    {
        checkState(!isClosed(), "RootAggregatedMemoryContext is already closed");
        ListenableFuture<?> future = reservationHandler.reserveMemory(allocationTag, bytes);
        addBytes(bytes);
        // make sure we never block queries below guaranteedMemory
        if (getBytes() < guaranteedMemory) {
            future = NOT_BLOCKED;
        }
        return future;
    }