APIdia Launch Partner
Top Description Fields Constructors Methods
java.nio.channels.spi

public abstract Class AbstractSelectableChannel

extends SelectableChannel
Class Inheritance
Known Direct Subclasses
java.nio.channels.DatagramChannel, java.nio.channels.Pipe.SourceChannel, java.nio.channels.Pipe.SinkChannel, java.nio.channels.ServerSocketChannel, java.nio.channels.SocketChannel
Imports
java.io.IOException, java.nio.channels.CancelledKeyException, .ClosedChannelException, .ClosedSelectorException, .IllegalBlockingModeException, .IllegalSelectorException, .SelectableChannel, .SelectionKey, .Selector, java.util.Arrays, java.util.function.Consumer
Base implementation class for selectable channels.

This class defines methods that handle the mechanics of channel registration, deregistration, and closing. It maintains the current blocking mode of this channel as well as its current set of selection keys. It performs all of the synchronization required to implement the java.nio.channels.SelectableChannel specification. Implementations of the protected abstract methods defined in this class need not synchronize against other threads that might be engaged in the same operations.

Authors
Mark Reinhold, Mike McCloskey, JSR-51 Expert Group
Since
1.4

Field Summary

Modifier and TypeField and Description
private int
keyCount

private final Object
keyLock

private SelectionKey[]
keys

private volatile boolean
nonBlocking

private final SelectorProvider
provider

private final Object
regLock

Constructor Summary

AccessConstructor and Description
protected
AbstractSelectableChannel(SelectorProvider
The provider that created this channel
provider)

Initializes a new instance of this class.

Method Summary

Modifier and TypeMethod and Description
private void
addKey(SelectionKey k)

public final Object
blockingLock()

Implements abstract java.nio.channels.SelectableChannel.blockingLock.

Retrieves the object upon which the configureBlocking and register methods synchronize.

public final SelectableChannel
configureBlocking(boolean block)

Implements abstract java.nio.channels.SelectableChannel.configureBlocking.

Adjusts this channel's blocking mode.

private SelectionKey
findKey(Selector sel)

private void
forEach(Consumer<SelectionKey> action)

Invokes an action for each key.

private boolean
haveValidKeys()

protected final void
implCloseChannel()

Implements abstract java.nio.channels.spi.AbstractInterruptibleChannel.implCloseChannel.

Closes this channel.

protected abstract void
implCloseSelectableChannel()

Closes this selectable channel.

protected abstract void
implConfigureBlocking(boolean
If true then this channel will be placed in blocking mode; if false then it will be placed non-blocking mode
block)

Adjusts this channel's blocking mode.

public final boolean
isBlocking()

Implements abstract java.nio.channels.SelectableChannel.isBlocking.

Tells whether or not every I/O operation on this channel will block until it completes.

public final boolean
isRegistered()

Implements abstract java.nio.channels.SelectableChannel.isRegistered.

Tells whether or not this channel is currently registered with any selectors.

public final SelectionKey
keyFor(Selector sel)

Implements abstract java.nio.channels.SelectableChannel.keyFor.

Retrieves the key representing the channel's registration with the given selector.

public final SelectorProvider

Returns:

The provider that created this channel
provider()

Implements abstract java.nio.channels.SelectableChannel.provider.

Returns the provider that created this channel.

public final SelectionKey
register(Selector sel, int ops, Object att)

Implements abstract java.nio.channels.SelectableChannel.register.

Registers this channel with the given selector, returning a selection key.

pack-priv void
removeKey(SelectionKey k)

Inherited from java.nio.channels.SelectableChannel:
registervalidOps

Field Detail

keyCountback to summary
private int keyCount
keyLockback to summary
private final Object keyLock
keysback to summary
private SelectionKey[] keys
nonBlockingback to summary
private volatile boolean nonBlocking
providerback to summary
private final SelectorProvider provider
regLockback to summary
private final Object regLock

Constructor Detail

AbstractSelectableChannelback to summary
protected AbstractSelectableChannel(SelectorProvider provider)

Initializes a new instance of this class.

Parameters
provider:SelectorProvider

The provider that created this channel

Method Detail

addKeyback to summary
private void addKey(SelectionKey k)
blockingLockback to summary
public final Object blockingLock()

Implements abstract java.nio.channels.SelectableChannel.blockingLock.

Doc from java.nio.channels.SelectableChannel.blockingLock.

Retrieves the object upon which the configureBlocking and register methods synchronize. This is often useful in the implementation of adaptors that require a specific blocking mode to be maintained for a short period of time.

configureBlockingback to summary
public final SelectableChannel configureBlocking(boolean block) throws IOException

Implements abstract java.nio.channels.SelectableChannel.configureBlocking.

Adjusts this channel's blocking mode.

If the given blocking mode is different from the current blocking mode then this method invokes the implConfigureBlocking method, while holding the appropriate locks, in order to change the mode.

Exceptions
IOException:

Doc from java.nio.channels.SelectableChannel.configureBlocking.

If an I/O error occurs

ClosedChannelException:
If this channel is closed
findKeyback to summary
private SelectionKey findKey(Selector sel)
forEachback to summary
private void forEach(Consumer<SelectionKey> action)

Invokes an action for each key. This method is invoked by DatagramChannelImpl::disconnect.

haveValidKeysback to summary
private boolean haveValidKeys()
implCloseChannelback to summary
protected final void implCloseChannel() throws IOException

Implements abstract java.nio.channels.spi.AbstractInterruptibleChannel.implCloseChannel.

Closes this channel.

This method, which is specified in the AbstractInterruptibleChannel class and is invoked by the close method, in turn invokes the implCloseSelectableChannel method in order to perform the actual work of closing this channel. It then cancels all of this channel's keys.

Exceptions
IOException:

Doc from java.nio.channels.spi.AbstractInterruptibleChannel.implCloseChannel.

If an I/O error occurs while closing the channel

implCloseSelectableChannelback to summary
protected abstract void implCloseSelectableChannel() throws IOException

Closes this selectable 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.

Exceptions
IOException:
If an I/O error occurs
implConfigureBlockingback to summary
protected abstract void implConfigureBlocking(boolean block) throws IOException

Adjusts this channel's blocking mode.

This method is invoked by the configureBlocking method in order to perform the actual work of changing the blocking mode. This method is only invoked if the new mode is different from the current mode.

Parameters
block:boolean

If true then this channel will be placed in blocking mode; if false then it will be placed non-blocking mode

Exceptions
IOException:
If an I/O error occurs
isBlockingback to summary
public final boolean isBlocking()

Implements abstract java.nio.channels.SelectableChannel.isBlocking.

Doc from java.nio.channels.SelectableChannel.isBlocking.

Tells whether or not every I/O operation on this channel will block until it completes. A newly-created channel is always in blocking mode.

If this channel is closed then the value returned by this method is not specified.

isRegisteredback to summary
public final boolean isRegistered()

Implements abstract java.nio.channels.SelectableChannel.isRegistered.

Doc from java.nio.channels.SelectableChannel.isRegistered.

Tells whether or not this channel is currently registered with any selectors. A newly-created channel is not registered.

Due to the inherent delay between key cancellation and channel deregistration, a channel may remain registered for some time after all of its keys have been cancelled. A channel may also remain registered for some time after it is closed.

keyForback to summary
public final SelectionKey keyFor(Selector sel)

Implements abstract java.nio.channels.SelectableChannel.keyFor.

Doc from java.nio.channels.SelectableChannel.keyFor.

Retrieves the key representing the channel's registration with the given selector.

providerback to summary
public final SelectorProvider provider()

Implements abstract java.nio.channels.SelectableChannel.provider.

Returns the provider that created this channel.

Returns:SelectorProvider

The provider that created this channel

registerback to summary
public final SelectionKey register(Selector sel, int ops, Object att) throws ClosedChannelException

Implements abstract java.nio.channels.SelectableChannel.register.

Registers this channel with the given selector, returning a selection key.

This method first verifies that this channel is open and that the given initial interest set is valid.

If this channel is already registered with the given selector then the selection key representing that registration is returned after setting its interest set to the given value.

Otherwise this channel has not yet been registered with the given selector, so the register method of the selector is invoked while holding the appropriate locks. The resulting key is added to this channel's key set before being returned.

Exceptions
ClosedChannelException:

Doc from java.nio.channels.SelectableChannel.register.

If this channel is closed

ClosedSelectorException:
If the selector is closed
IllegalBlockingModeException:
If this channel is in blocking mode
IllegalSelectorException:
If this channel was not created by the same provider as the given selector
CancelledKeyException:
If this channel is currently registered with the given selector but the corresponding key has already been cancelled
IllegalArgumentException:
If a bit in the ops set does not correspond to an operation that is supported by this channel, that is, if set & ~validOps() != 0
removeKeyback to summary
pack-priv void removeKey(SelectionKey k)