public abstract class AbstractSelector extends Selector
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.
| Modifier | Constructor and Description |
|---|---|
protected |
AbstractSelector(SelectorProvider
Initializes a new instance of this class.
|
| Modifier and Type | Method and Description |
|---|---|
protected void |
begin()
Marks the beginning of an I/O operation that might block indefinitely.
|
protected Set |
cancelledKeys()
Retrieves this selector's cancelled-key set.
|
void |
close()
Closes this selector.
|
protected void |
deregister(AbstractSelectionKey
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.
|
boolean |
isOpen()
Tells whether or not this selector is open.
|
SelectorProvider |
provider()
Returns the provider that created this channel.
|
protected abstract SelectionKey |
register(AbstractSelectableChannel
Registers the given channel with this selector.
|
protected AbstractSelector(SelectorProviderprovider)
provider - The provider that created this selector
public final void close()
throws IOException
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.
close in interface
Closeable
close in interface
AutoCloseable
close in class
Selector
IOException - If an I/O error occurs
protected abstract void implCloseSelector()
throws IOException
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.
IOException - If an I/O error occurs while closing the selector
public final boolean isOpen()
Selector
public final SelectorProviderprovider()
protected final Set<SelectionKey > cancelledKeys()
This set should only be used while synchronized upon it.
protected abstract SelectionKeyregister(AbstractSelectableChannel ch, int ops, Object att)
This method is invoked by a channel's register method in order to perform the actual work of registering the channel with this selector.
ch - The channel to be registered
ops - The initial interest set, which must be valid
att - The initial attachment for the resulting key
protected final void deregister(AbstractSelectionKeykey)
This method must be invoked by the selector for each channel that it deregisters.
key - The selection key to be removed
protected final void begin()
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.
protected final void end()