public
abstract
class
AbstractSelector
extends Selector
java.lang.Object | ||
↳ | java.nio.channels.Selector | |
↳ | java.nio.channels.spi.AbstractSelector |
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 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 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();
}
register
method that is invoked by a
selectable channel's register
method in order to perform the actual work of registering a channel.
Protected constructors | |
---|---|
AbstractSelector(SelectorProvider provider)
Initializes a new instance of this class. |
Public methods | |
---|---|
final
void
|
close()
Closes this selector. |
final
boolean
|
isOpen()
Tells whether or not this selector is open. |
final
SelectorProvider
|
provider()
Returns the provider that created this channel. |
Protected methods | |
---|---|
final
void
|
begin()
Marks the beginning of an I/O operation that might block indefinitely. |
final
Set<SelectionKey>
|
cancelledKeys()
Retrieves this selector's cancelled-key set. |
final
void
|
deregister(AbstractSelectionKey key)
Removes the given key from its channel's key set. |
final
void
|
end()
Marks the end of an I/O operation that might block indefinitely. |
abstract
void
|
implCloseSelector()
Closes this selector. |
abstract
SelectionKey
|
register(AbstractSelectableChannel ch, int ops, Object att)
Registers the given channel with this selector. |
Inherited methods | |
---|---|
From
class
java.nio.channels.Selector
| |
From
class
java.lang.Object
| |
From
interface
java.io.Closeable
| |
From
interface
java.lang.AutoCloseable
|
AbstractSelector (SelectorProvider provider)
Initializes a new instance of this class.
Parameters | |
---|---|
provider |
SelectorProvider
|
void close ()
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.
Throws | |
---|---|
IOException |
If an I/O error occurs |
boolean isOpen ()
Tells whether or not this selector is open.
Returns | |
---|---|
boolean |
true if, and only if, this selector is open |
SelectorProvider provider ()
Returns the provider that created this channel.
Returns | |
---|---|
SelectorProvider |
The provider that created this channel |
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.
Set<SelectionKey> cancelledKeys ()
Retrieves this selector's cancelled-key set.
This set should only be used while synchronized upon it.
Returns | |
---|---|
Set<SelectionKey> |
The cancelled-key set |
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 |
AbstractSelectionKey :
The selection key to be removed
|
void end ()
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 interruption for
this selector.
void implCloseSelector ()
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 |
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 |
AbstractSelectableChannel :
The channel to be registered |
ops |
int :
The initial interest set, which must be valid |
att |
Object :
The initial attachment for the resulting key |
Returns | |
---|---|
SelectionKey |
A new key representing the registration of the given channel with this selector |