docs: void drainOnReadIfNeeded(int bufferIndex, long writeCount) {
          final long pending = (writeCount - readBufferDrainAtWriteCount[bufferIndex].get());
          final boolean delayable = (pending < READ_BUFFER_THRESHOLD);
          final DrainStatus status = drainStatus.get();
          if (status.shouldDrainBuffers(delayable)) {
              tryToDrainBuffers();
          }
      }