presto-main/src/main/java/io/prestosql/operator/exchange/PassthroughExchanger.java/PassthroughExchanger/accept
class PassthroughExchanger:    @Override
    public void accept(Page page)
    {
        long retainedSizeInBytes = page.getRetainedSizeInBytes();
        bufferMemoryManager.updateMemoryUsage(retainedSizeInBytes);
        memoryTracker.accept(retainedSizeInBytes);

        PageReference pageReference = new PageReference(page, 1, () -> {
            bufferMemoryManager.updateMemoryUsage(-retainedSizeInBytes);
            memoryTracker.accept(-retainedSizeInBytes);
        });

        localExchangeSource.addPage(pageReference);
    }