AbstractInterruptibleChannel

public abstract class AbstractInterruptibleChannel extends Object
implements Channel InterruptibleChannel

Known Direct Subclasses

FileChannel, SelectableChannel

Known Indirect Subclasses

AbstractSelectableChannel, DatagramChannel, Pipe.SinkChannel, Pipe.SourceChannel, ServerSocketChannel, SocketChannel

Base implementation class for interruptible channels.

This class encapsulates the low-level machinery required to implement the asynchronous closing and interruption of channels. A concrete channel class must invoke the begin and end methods before and after, respectively, invoking an I/O operation that might block indefinitely. In order to ensure that the end method is always invoked, these methods should be used within a try ... finally block:

 boolean completed = false;
 try {
     begin();
     completed = ...;    // Perform blocking I/O operation
     return ...;         // Return result
 } finally {
     end(completed);
 }

The completed argument to the end method tells whether or not the I/O operation actually completed, that is, whether it had any effect that would be visible to the invoker. In the case of an operation that reads bytes, for example, this argument should be true if, and only if, some bytes were actually transferred into the invoker's target buffer.

A concrete channel class must also implement the implCloseChannel method in such a way that if it is invoked while another thread is blocked in a native I/O operation upon the channel then that operation will immediately return, either by throwing an exception or by returning normally. If a thread is interrupted or the channel upon which it is blocked is asynchronously closed then the channel's end method will throw the appropriate exception.

This class performs the synchronization required to implement the Channel specification. Implementations of the implCloseChannel method need not synchronize against other threads that might be attempting to close the channel.

Protected Constructor Summary

AbstractInterruptibleChannel()

Initializes a new instance of this class.

Public Method Summary

final void	close() Closes this channel.
final boolean	isOpen() Tells whether or not this channel is open.

Protected Method Summary

final void	begin() Marks the beginning of an I/O operation that might block indefinitely.
final void	end(boolean completed) Marks the end of an I/O operation that might block indefinitely.
abstract void	implCloseChannel() Closes this channel.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of `Class` that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.

From interface java.nio.channels.Channel

abstract void	close() Closes this channel.
abstract boolean	isOpen() Tells whether or not this channel is open.

From interface java.nio.channels.InterruptibleChannel

abstract void

close()

Closes this channel.

From interface java.io.Closeable

abstract void

close()

Closes this stream and releases any system resources associated with it.

From interface java.lang.AutoCloseable

abstract void

close()

Closes this resource, relinquishing any underlying resources.

Protected Constructors

protected AbstractInterruptibleChannel ()

Initializes a new instance of this class.

Public Methods

public final void close ()

Closes this channel.

If the channel has already been closed then this method returns immediately. Otherwise it marks the channel as closed and then invokes the implCloseChannel method in order to complete the close operation.

Throws

IOException	If an I/O error occurs

public final boolean isOpen ()

Tells whether or not this channel is open.

Returns

true if, and only if, this channel is open

Protected Methods

protected final void begin ()

Marks the beginning of an I/O operation that might block indefinitely.

This method should be invoked in tandem with the end method, using a try ... finally block as shown above, in order to implement asynchronous closing and interruption for this channel.

protected final void end (boolean completed)

Marks the end of an I/O operation that might block indefinitely.

This method should be invoked in tandem with the begin method, using a try ... finally block as shown above, in order to implement asynchronous closing and interruption for this channel.

Parameters

completed	`true` if, and only if, the I/O operation completed successfully, that is, had some effect that would be visible to the operation's invoker

Throws

AsynchronousCloseException	If the channel was asynchronously closed
ClosedByInterruptException	If the thread blocked in the I/O operation was interrupted

protected abstract void implCloseChannel ()

Closes this channel.

This method is invoked by the close method in order to perform the actual work of closing the channel. This method is only invoked if the channel has not yet been closed, and it is never invoked more than once.

An implementation of this method must arrange for any other thread that is blocked in an I/O operation upon this channel to return immediately, either by throwing an exception or by returning normally.

Throws

IOException	If an I/O error occurs while closing the channel