org.michailov.async.io

Class EOFInputStream

java.lang.Object

java.io.InputStream

org.michailov.async.io.EOFInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class EOFInputStream
extends java.io.InputStream

An InputStream that can explicitly report EOF.

The built-in InputStream imposes a problem for clients that don't want to block. A client doesn't know what to do when available == 0 - does it mean "fetching more data" or "EOF". It is possible for an InputStream to support this scenario - the InputStream can "lie" and report 1 available byte and when the client comes to read it, it will get -1 right away. However, neither FileInputStream nor the InputStream from Process.getInputStream() do that.

This class enables clients to use their own information on whether EOF of the InputStream has been reached.

Optionally, clients may modify the available behavior.

This class offers static factory methods for creating EOFInputStream instances from File and from Process.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	EOFInputStream() Implicit constructor for derived classes.
	EOFInputStream(java.io.InputStream inputStream, java.util.function.Predicate<AsyncByteStreamReader> eof) Constructs a new EOFInputStream.
	EOFInputStream(java.io.InputStream inputStream, java.util.function.Predicate<AsyncByteStreamReader> eof, java.util.function.ToIntFunction<AsyncByteStreamReader> available) Constructs a new EOFInputStream.

Method Summary

Modifier and Type	Method and Description
int	available()
boolean	eof() Used by the consuming AsyncByteStreamReader to check whether EOF has been reached.
static EOFInputStream	fromFile(java.io.File file) Factory method for Process.getInputStream().
static EOFInputStream	fromProcess(java.lang.Process process) Factory method for Process.getInputStream().
int	read()
int	read(byte[] b, int off, int len)

Methods inherited from class java.io.InputStream

close, mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

EOFInputStream

public EOFInputStream(java.io.InputStream inputStream,
                      java.util.function.Predicate<AsyncByteStreamReader> eof)

Constructs a new EOFInputStream.

Parameters:

inputStream - InputStream to override.

eof - EOF predicate. Takes a AsyncByteStreamReader as a parameter. It could be used to get hold of the related ByteRingBuffer to get the total count of read bytes or to obtain other related objects.

EOFInputStream

public EOFInputStream(java.io.InputStream inputStream,
                      java.util.function.Predicate<AsyncByteStreamReader> eof,
                      java.util.function.ToIntFunction<AsyncByteStreamReader> available)

Constructs a new EOFInputStream.

Parameters:

inputStream - InputStream to override.

eof - EOF predicate. Takes a AsyncByteStreamReader as a parameter. It could be used to get hold of the related ByteRingBuffer to get the total count of read bytes or to obtain other related objects.

available - available function. Takes a AsyncByteStreamReader as a parameter. It could be used to get hold of the related ByteRingBuffer to get the total count of read bytes or to obtain other related objects.

EOFInputStream

protected EOFInputStream()

Implicit constructor for derived classes.

Method Detail

eof

public boolean eof()

Used by the consuming AsyncByteStreamReader to check whether EOF has been reached. Invokes the eof() predicate passing the consuming AsyncByteStreamReader.

Returns:

The value of the eof() predicate which should be true iff EOF has been reached.

available

public int available()
              throws java.io.IOException

Overrides:

available in class java.io.InputStream

Throws:

java.io.IOException

See Also:

InputStream

read

public int read()
         throws java.io.IOException

Specified by:

read in class java.io.InputStream

Throws:

java.io.IOException

See Also:

InputStream

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Overrides:

read in class java.io.InputStream

Throws:

java.io.IOException

See Also:

InputStream

fromProcess

public static EOFInputStream fromProcess(java.lang.Process process)

Factory method for Process.getInputStream().

eof() returns true iff Process.isAlive() returns false.

Parameters:

process - The Process whose InputStream will be read.

Returns:

A new EOFInputStream instance.

fromFile

public static EOFInputStream fromFile(java.io.File file)
                               throws java.io.FileNotFoundException

Factory method for Process.getInputStream().

eof() returns true iff File.length bytes have been read by the consuming AsyncByteStreamReader.

Parameters:

file - The File whose FileInputStream will be read.

Returns:

A new EOFInputStream instance.

Throws:

java.io.FileNotFoundException - @see FileInputStream.