Class AbstractInterruptibleChannel
- java.lang.Object
-
- java.nio.channels.spi.AbstractInterruptibleChannel
- All Implemented Interfaces:
-
Closeable
,AutoCloseable
,Channel
,InterruptibleChannel
- Direct Known Subclasses:
-
FileChannel
,SelectableChannel
public abstract class AbstractInterruptibleChannel extends Object implements Channel, InterruptibleChannel
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.
- Since:
- 1.4
Constructor Summary
Modifier | Constructor | Description |
---|---|---|
protected | AbstractInterruptibleChannel() | Initializes a new instance of this class. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
protected void | begin() | Marks the beginning of an I/O operation that might block indefinitely. |
void | close() | Closes this channel. |
protected void | end(boolean completed) | Marks the end of an I/O operation that might block indefinitely. |
protected abstract void | implCloseChannel() | Closes this channel. |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods declared in interface java.nio.channels.Channel
isOpen
Constructor Detail
AbstractInterruptibleChannel
protected AbstractInterruptibleChannel()
Initializes a new instance of this class.
Method Detail
close
public final void close() throws IOException
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.
- Specified by:
-
close
in interfaceAutoCloseable
- Specified by:
-
close
in interfaceChannel
- Specified by:
-
close
in interfaceCloseable
- Specified by:
-
close
in interfaceInterruptibleChannel
- Throws:
-
IOException
- If an I/O error occurs
implCloseChannel
protected abstract void implCloseChannel() throws IOException
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
begin
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.
end
protected final void end(boolean completed) throws AsynchronousCloseException
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