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
beginandendmethods before and after, respectively, invoking an I/O operation that might block indefinitely. In order to ensure that theendmethod 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
registermethod that is invoked by a selectable channel'sregistermethod in order to perform the actual work of registering a channel.- Since:
- 1.4
-
-
Constructor Summary
Constructors Modifier Constructor and Description protectedAbstractSelector(SelectorProvider provider)Initializes a new instance of this class.
-
Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method and Description protected voidbegin()Marks the beginning of an I/O operation that might block indefinitely.protected Set<SelectionKey>cancelledKeys()Retrieves this selector's cancelled-key set.voidclose()Closes this selector.protected voidderegister(AbstractSelectionKey key)Removes the given key from its channel's key set.protected voidend()Marks the end of an I/O operation that might block indefinitely.protected abstract voidimplCloseSelector()Closes this selector.booleanisOpen()Tells whether or not this selector is open.SelectorProviderprovider()Returns the provider that created this channel.protected abstract SelectionKeyregister(AbstractSelectableChannel ch, int ops, Object att)Registers the given channel with this selector.
-
-
-
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 IOExceptionCloses 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
implCloseSelectormethod in order to complete the close operation.- Specified by:
-
closein interfaceCloseable - Specified by:
-
closein interfaceAutoCloseable - Specified by:
-
closein classSelector - Throws:
-
IOException- If an I/O error occurs
implCloseSelector
protected abstract void implCloseSelector() throws IOExceptionCloses this selector.This method is invoked by the
closemethod 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
wakeupmethod.- Throws:
-
IOException- If an I/O error occurs while closing the selector
isOpen
public final boolean isOpen()
Description copied from class:SelectorTells whether or not this selector is open.
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
registermethod 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
endmethod, using a try ... finally block as shown above, in order to implement interruption for this selector.Invoking this method arranges for the selector's
wakeupmethod to be invoked if a thread'sinterruptmethod is invoked while the thread is blocked in an I/O operation upon the selector.
end
protected final void end()
-
Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2022, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
