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8231603: (se) Selector implementations do not need to use cancelledKeys

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Reviewed-by: chegar, bpb
This commit is contained in:
Alan Bateman 2019-10-02 09:16:18 +01:00
parent 8200eb4d45
commit 38bdacafbc
3 changed files with 84 additions and 44 deletions
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39
src/java.base/share/classes/java/nio/channels/spi/AbstractSelectionKey.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -25,8 +25,13 @@
package java.nio.channels.spi;
import java.nio.channels.*;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.VarHandle;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import sun.nio.ch.SelectionKeyImpl;
import sun.nio.ch.SelectorImpl;
/**
* Base implementation class for selection keys.
@ -41,20 +46,29 @@ import java.nio.channels.*;
public abstract class AbstractSelectionKey
extends SelectionKey
{
private static final VarHandle INVALID;
static {
try {
MethodHandles.Lookup l = MethodHandles.lookup();
INVALID = l.findVarHandle(AbstractSelectionKey.class, "invalid", boolean.class);
} catch (Exception e) {
throw new InternalError(e);
}
}
/**
* Initializes a new instance of this class.
*/
protected AbstractSelectionKey() { }
private volatile boolean valid = true;
private volatile boolean invalid;
public final boolean isValid() {
return valid;
return !invalid;
}
void invalidate() { // package-private
valid = false;
invalid = true;
}
/**
@ -64,13 +78,14 @@ public abstract class AbstractSelectionKey
* 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);
boolean changed = (boolean) INVALID.compareAndSet(this, false, true);
if (changed) {
Selector sel = selector();
if (sel instanceof SelectorImpl) {
// queue cancelled key directly
((SelectorImpl) sel).cancel((SelectionKeyImpl) this);
} else {
((AbstractSelector) sel).cancel(this);
}
}
}