Class AbstractSelector
- java.lang.Object
-
- java.nio.channels.Selector
-
- java.nio.channels.spi.AbstractSelector
- All Implemented Interfaces:
-
Closeable
,AutoCloseable
public abstract class AbstractSelector extends Selector
Base implementation class for selectors.
This class encapsulates the low-level machinery required to implement the interruption of selection operations. A concrete selector 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:
try { begin(); // Perform blocking I/O operation here ... } finally { end(); }
This class also defines methods for maintaining a selector's cancelled-key set and for removing a key from its channel's key set, and declares the abstract register
method that is invoked by a selectable channel's register
method in order to perform the actual work of registering a channel.
- Since:
- 1.4
Constructor Summary
Modifier | Constructor | Description |
---|---|---|
protected | AbstractSelector(SelectorProvider provider) | 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. |
protected Set<SelectionKey> | cancelledKeys() | Retrieves this selector's cancelled-key set. |
void | close() | Closes this selector. |
protected void | deregister(AbstractSelectionKey key) | Removes the given key from its channel's key set. |
protected void | end() | Marks the end of an I/O operation that might block indefinitely. |
protected abstract void | implCloseSelector() | Closes this selector. |
SelectorProvider | provider() | Returns the provider that created this channel. |
protected abstract SelectionKey | register(AbstractSelectableChannel ch,
int ops,
Object att) | Registers the given channel with this selector. |
Methods declared in class java.nio.channels.Selector
isOpen, keys, open, select, select, select, select, selectedKeys, selectNow, selectNow, wakeup
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Constructor Detail
AbstractSelector
protected AbstractSelector(SelectorProvider provider)
Initializes a new instance of this class.
- Parameters:
-
provider
- The provider that created this selector
Method Detail
close
public final void close() throws IOException
Closes this selector.
If the selector has already been closed then this method returns immediately. Otherwise it marks the selector as closed and then invokes the implCloseSelector
method in order to complete the close operation.
- Specified by:
-
close
in interfaceAutoCloseable
- Specified by:
-
close
in interfaceCloseable
- Specified by:
-
close
in classSelector
- Throws:
-
IOException
- If an I/O error occurs
implCloseSelector
protected abstract void implCloseSelector() throws IOException
Closes this selector.
This method is invoked by the close
method in order to perform the actual work of closing the selector. This method is only invoked if the selector 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 a selection operation upon this selector to return immediately as if by invoking the wakeup
method.
- Throws:
-
IOException
- If an I/O error occurs while closing the selector
provider
public final SelectorProvider provider()
Returns the provider that created this channel.
cancelledKeys
protected final Set<SelectionKey> cancelledKeys()
Retrieves this selector's cancelled-key set.
This set should only be used while synchronized upon it.
- Returns:
- The cancelled-key set
register
protected abstract SelectionKey register(AbstractSelectableChannel ch, int ops, Object att)
Registers the given channel with this selector.
This method is invoked by a channel's register
method in order to perform the actual work of registering the channel with this selector.
- Parameters:
-
ch
- The channel to be registered -
ops
- The initial interest set, which must be valid -
att
- The initial attachment for the resulting key - Returns:
- A new key representing the registration of the given channel with this selector
deregister
protected final void deregister(AbstractSelectionKey key)
Removes the given key from its channel's key set.
This method must be invoked by the selector for each channel that it deregisters.
- Parameters:
-
key
- The selection key to be removed
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 interruption for this selector.
Invoking this method arranges for the selector's wakeup
method to be invoked if a thread's interrupt
method is invoked while the thread is blocked in an I/O operation upon the selector.
end
protected final void end()