Package org.apache.commons.io.input

Class BufferedFileChannelInputStream

java.lang.Object

java.io.InputStream

org.apache.commons.io.input.BufferedFileChannelInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public final class BufferedFileChannelInputStream
extends InputStream

InputStream implementation which uses direct buffer to read a file to avoid extra copy of data between Java and native memory which happens when using BufferedInputStream. Unfortunately, this is not something already available in JDK, sun.nio.ch.ChannelInputStream supports reading a file using NIO, but does not support buffering.

To build an instance, use BufferedFileChannelInputStream.Builder.

This class was ported and adapted from Apache Spark commit 933dc6cb7b3de1d8ccaf73d124d6eb95b947ed19 where it was called NioBufferedFileInputStream.

Since:

2.9.0

See Also:

• BufferedFileChannelInputStream.Builder

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	BufferedFileChannelInputStream.Builder	Builds a new BufferedFileChannelInputStream.

Field Summary

Fields

Modifier and Type	Field	Description
private final ByteBuffer	byteBuffer
private final FileChannel	fileChannel

Constructor Summary

Constructors

Constructor	Description
BufferedFileChannelInputStream(File file)	Deprecated. Use builder(), BufferedFileChannelInputStream.Builder, and BufferedFileChannelInputStream.Builder.get()
BufferedFileChannelInputStream(File file, int bufferSize)	Deprecated. Use builder(), BufferedFileChannelInputStream.Builder, and BufferedFileChannelInputStream.Builder.get()
BufferedFileChannelInputStream(Path path)	Deprecated. Use builder(), BufferedFileChannelInputStream.Builder, and BufferedFileChannelInputStream.Builder.get()
BufferedFileChannelInputStream(Path path, int bufferSize)	Deprecated. Use builder(), BufferedFileChannelInputStream.Builder, and BufferedFileChannelInputStream.Builder.get()

Method Summary

Modifier and Type	Method	Description
int	available()
static BufferedFileChannelInputStream.Builder	builder()	Constructs a new BufferedFileChannelInputStream.Builder.
private void	clean(ByteBuffer buffer)	Attempts to clean up a ByteBuffer if it is direct or memory-mapped.
private void	cleanDirectBuffer(ByteBuffer buffer)	In Java 8, the type of sun.nio.ch.DirectBuffer.cleaner() was sun.misc.Cleaner, and it was possible to access the method sun.misc.Cleaner.clean() to invoke it.
void	close()
int	read()
int	read(byte[] b, int offset, int len)
private boolean	refill()	Checks whether data is left to be read from the input stream.
long	skip(long n)
private long	skipFromFileChannel(long n)

Methods inherited from class java.io.InputStream

mark, markSupported, read, reset

Methods inherited from class java.lang.Object

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

Field Details

byteBuffer

private final ByteBuffer byteBuffer

fileChannel

private final FileChannel fileChannel

Constructor Details

BufferedFileChannelInputStream

@Deprecated
public BufferedFileChannelInputStream(File file)
                               throws IOException

Deprecated.

Use builder(), BufferedFileChannelInputStream.Builder, and BufferedFileChannelInputStream.Builder.get()

Constructs a new instance for the given File.

Parameters:

file - The file to stream.

Throws:

IOException - If an I/O error occurs

BufferedFileChannelInputStream

@Deprecated
public BufferedFileChannelInputStream(File file,
 int bufferSize)
                               throws IOException

Deprecated.

Use builder(), BufferedFileChannelInputStream.Builder, and BufferedFileChannelInputStream.Builder.get()

Constructs a new instance for the given File and buffer size.

Parameters:

file - The file to stream.

bufferSize - buffer size.

Throws:

IOException - If an I/O error occurs

BufferedFileChannelInputStream

@Deprecated
public BufferedFileChannelInputStream(Path path)
                               throws IOException

Deprecated.

Use builder(), BufferedFileChannelInputStream.Builder, and BufferedFileChannelInputStream.Builder.get()

Constructs a new instance for the given Path.

Parameters:

path - The path to stream.

Throws:

IOException - If an I/O error occurs

BufferedFileChannelInputStream

@Deprecated
public BufferedFileChannelInputStream(Path path,
 int bufferSize)
                               throws IOException

Deprecated.

Use builder(), BufferedFileChannelInputStream.Builder, and BufferedFileChannelInputStream.Builder.get()

Constructs a new instance for the given Path and buffer size.

Parameters:

path - The path to stream.

bufferSize - buffer size.

Throws:

IOException - If an I/O error occurs

Method Details

builder

public static BufferedFileChannelInputStream.Builder builder()

Constructs a new BufferedFileChannelInputStream.Builder.

Returns:

a new BufferedFileChannelInputStream.Builder.

Since:

2.12.0

available

public int available()
              throws IOException

Overrides:

available in class InputStream

Throws:

IOException

clean

private void clean(ByteBuffer buffer)

Attempts to clean up a ByteBuffer if it is direct or memory-mapped. This uses an *unsafe* Sun API that will cause errors if one attempts to read from the disposed buffer. However, neither the bytes allocated to direct buffers nor file descriptors opened for memory-mapped buffers put pressure on the garbage collector. Waiting for garbage collection may lead to the depletion of off-heap memory or huge numbers of open files. There's unfortunately no standard API to manually dispose of these kinds of buffers.

Parameters:

buffer - the buffer to clean.

cleanDirectBuffer

private void cleanDirectBuffer(ByteBuffer buffer)

In Java 8, the type of sun.nio.ch.DirectBuffer.cleaner() was sun.misc.Cleaner, and it was possible to access the method sun.misc.Cleaner.clean() to invoke it. The type changed to jdk.internal.ref.Cleaner in later JDKs, and the clean() method is not accessible even with reflection. However sun.misc.Unsafe added an invokeCleaner() method in JDK 9+ and this is still accessible with reflection.

Parameters:

buffer - the buffer to clean. must be a DirectBuffer.

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

read

public int read(byte[] b,
 int offset,
 int len)
         throws IOException

Overrides:

read in class InputStream

Throws:

IOException

refill

private boolean refill()
                throws IOException

Checks whether data is left to be read from the input stream.

Returns:

true if data is left, false otherwise

Throws:

IOException - if an I/O error occurs.

skip

public long skip(long n)
          throws IOException

Overrides:

skip in class InputStream

Throws:

IOException

skipFromFileChannel

private long skipFromFileChannel(long n)
                          throws IOException

Throws:

IOException