Package org.apache.commons.io.input

# Class ReadAheadInputStream

java.lang.Object
java.io.InputStream
java.io.FilterInputStream
org.apache.commons.io.input.ReadAheadInputStream

All Implemented Interfaces:
  `Closeable`, `AutoCloseable`

public class ReadAheadInputStream extends FilterInputStream
Implements `InputStream` to asynchronously read ahead from an underlying input stream when a specified amount of data has been read from the current buffer. It does so by maintaining two buffers: an active buffer and a read ahead buffer. The active buffer contains data which should be returned when a read() call is issued. The read ahead buffer is used to asynchronously read from the underlying input stream. When the current active buffer is exhausted, we flip the two buffers so that we can start reading from the read ahead buffer without being blocked by disk I/O.

To build an instance, use `ReadAheadInputStream.Builder`.

This class was ported and adapted from Apache Spark commit 933dc6cb7b3de1d8ccaf73d124d6eb95b947ed19.

Since:
  2.9.0
See Also:
  - `ReadAheadInputStream.Builder`

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static class`
  `ReadAheadInputStream.Builder`
  Builds a new `ReadAheadInputStream`.

- ## Field Summary

  ### Fields inherited from class java.io.FilterInputStream

  `in`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ReadAheadInputStream(InputStream inputStream, int bufferSizeInBytes)`
  Deprecated.
  Use `builder()`, `ReadAheadInputStream.Builder`, and `ReadAheadInputStream.Builder.get()`
  `ReadAheadInputStream(InputStream inputStream, int bufferSizeInBytes, ExecutorService executorService)`
  Deprecated.
  Use `builder()`, `ReadAheadInputStream.Builder`, and `ReadAheadInputStream.Builder.get()`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `int`
  `available()`
  `static ReadAheadInputStream.Builder`
  `builder()`
  Constructs a new `ReadAheadInputStream.Builder`.
  `void`
  `close()`
  `int`
  `read()`
  `int`
  `read(byte[] b, int offset, int len)`
  `long`
  `skip(long n)`

  ### Methods inherited from class java.io.FilterInputStream

  `mark, markSupported, read, reset`

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### ReadAheadInputStream

    @Deprecated public ReadAheadInputStream(InputStream inputStream, int bufferSizeInBytes)
    Deprecated.
    Use `builder()`, `ReadAheadInputStream.Builder`, and `ReadAheadInputStream.Builder.get()`
    Constructs an instance with the specified buffer size and read-ahead threshold
    Parameters:
      `inputStream` - The underlying input stream.
      `bufferSizeInBytes` - The buffer size.

  - ### ReadAheadInputStream

    @Deprecated public ReadAheadInputStream(InputStream inputStream, int bufferSizeInBytes, ExecutorService executorService)
    Deprecated.
    Use `builder()`, `ReadAheadInputStream.Builder`, and `ReadAheadInputStream.Builder.get()`
    Constructs an instance with the specified buffer size and read-ahead threshold
    Parameters:
      `inputStream` - The underlying input stream.
      `bufferSizeInBytes` - The buffer size.
      `executorService` - An executor service for the read-ahead thread.

- ## Method Details

  - ### builder

    public static ReadAheadInputStream.Builder builder()
    Constructs a new `ReadAheadInputStream.Builder`.
    Returns:
      a new `ReadAheadInputStream.Builder`.
    Since:
      2.12.0

  - ### available

    public int available() throws IOException
    Overrides:
      `available` in class `FilterInputStream`
    Throws:
      `IOException`

  - ### close

    public void close() throws IOException
    Specified by:
      `close` in interface `AutoCloseable`
    Specified by:
      `close` in interface `Closeable`
    Overrides:
      `close` in class `FilterInputStream`
    Throws:
      `IOException`

  - ### read

    public int read() throws IOException
    Overrides:
      `read` in class `FilterInputStream`
    Throws:
      `IOException`

  - ### read

    public int read(byte[] b, int offset, int len) throws IOException
    Overrides:
      `read` in class `FilterInputStream`
    Throws:
      `IOException`

  - ### skip

    public long skip(long n) throws IOException
    Overrides:
      `skip` in class `FilterInputStream`
    Throws:
      `IOException`