Method checkPreload

bolt/exec/TableScan.cpp:485–513

}

void TableScan::checkPreload() {
  auto executor = connector_->executor();
  if (maxSplitPreloadPerDriver_ == 0 || !executor ||
      !connector_->supportsSplitPreload() || !asyncThreadCtx_->allowPreload()) {
    return;
  }
  if (dataSource_->allPrefetchIssued()) {
    maxPreloadedSplits_ = driverCtx_->task->numDrivers(driverCtx_->driver) *
        maxSplitPreloadPerDriver_;
    if (!splitPreloader_) {
      splitPreloader_ =
          [executor, this](std::shared_ptr<connector::ConnectorSplit> split) {
            preload(split);

            int64_t preloadBytes = split->splitSizeBytes();
            executor->add([connectorSplit = split,
                           ctx = asyncThreadCtx_,
                           preloadBytes]() mutable {
              connector::AsyncThreadCtx::Guard guard(ctx.get(), preloadBytes);
              if (!guard) {
                return;
              }
              connectorSplit->dataSource->prepare();
              connectorSplit.reset();
            });
          };
    }
  }
}

bool TableScan::isFinished() {
  return noMoreSplits_;