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* accompanied this code).
*
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package java.nio.channels.spi;
import java.nio.channels.*;
/**
* Base implementation class for selection keys.
*
* <p> This class tracks the validity of the key and implements cancellation.
*
* @author Mark Reinhold
* @author JSR-51 Expert Group
* @since 1.4
*/
public abstract class AbstractSelectionKey
extends SelectionKey
{
/**
* Initializes a new instance of this class. </p>
*/
protected AbstractSelectionKey() { }
private volatile boolean valid = true;
public final boolean isValid() {
return valid;
}
void invalidate() { // package-private
valid = false;
}
/**
* Cancels this key.
*
* <p> If this key has not yet been cancelled then it is added to its
* selector's cancelled-key set while synchronized on that set. </p>
*/
public final void cancel() {
// Synchronizing "this" to prevent this key from getting canceled
// multiple times by different threads, which might cause race
// condition between selector's select() and channel's close().
synchronized (this) {
if (valid) {
valid = false;
((AbstractSelector)selector()).cancel(this);
}
}
}
}