Class Hardwood

java.lang.Object
dev.hardwood.Hardwood
All Implemented Interfaces:
AutoCloseable
public class Hardwood extends Object implements AutoCloseable

Entry point for reading Parquet files with a shared thread pool.

Use this when reading multiple files to share the executor across readers:

try (Hardwood hardwood = Hardwood.create()) {
    ParquetFileReader file1 = hardwood.open(InputFile.of(path1));
    ParquetFileReader file2 = hardwood.open(InputFile.of(path2));
    // ...
}

To control the decode parallelism, or to reuse one context (and its thread pool) across many reads and standalone ParquetFileReaders, create the HardwoodContext yourself and pass it in:

try (HardwoodContext context = HardwoodContext.create(4)) {
    try (Hardwood hardwood = Hardwood.create(context)) {
        // ...
    }
    // context is still open here for further use
}

For single-file usage, ParquetFileReader.open(InputFile) is simpler.

  • Method Details

    • create

      public static Hardwood create()
      Create a new Hardwood instance with a thread pool sized to available processors. The context is owned by this instance and closed when it is closed.

    • create

      public static Hardwood create(HardwoodContext context)

      Create a new Hardwood instance backed by the given context, e.g. one created via HardwoodContext.create(int) to size the decode thread pool.

      The caller retains ownership of the context: it is not closed when this instance is closed, so the same context — and its thread pool — can be reused for later reads and shared with standalone ParquetFileReaders opened via ParquetFileReader.open(InputFile, HardwoodContext).

    • open

      public ParquetFileReader open(InputFile inputFile) throws IOException
      Open a single Parquet file. The file is opened immediately and closed when the returned reader is closed.
      Throws:
      IOException

    • openAll

      public ParquetFileReader openAll(List<? extends InputFile> inputFiles) throws IOException
      Open multiple Parquet files for reading with cross-file prefetching. The schema is read from the first file. Files are opened on demand by the iterator and closed when the returned reader is closed.
      Parameters:
      inputFiles - the input files to read (must not be empty)
      Throws:
      IOException - if the first file cannot be opened or read
      IllegalArgumentException - if the list is empty

    • close

      public void close()
      Specified by:
      close in interface AutoCloseable