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NioEventLoop#rebuildSelector0 throws ClassCastException

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Motivation:
Commit 795f318 simplified some code related to the special case Set for the selected keys and introduced a Selector wrapper to make sure this set was properly reset. However the JDK makes assumptions about the type of Selector and this type is not extensible. This means whenever we call into the JDK we must provide the unwrapped version of the Selector or we get a ClassCastException. We missed a case of unwrapping in NioEventLoop#rebuildSelector0.

Modificaitons:
- NioEventLoop#openSelector should return a tuple so we can atomically set the wrapped and unwrapped Selector
- NioEventLoop#rebuildSelector0 should use the unwrapped version of the selector

Result:
Fixes https://github.com/netty/netty/issues/6607.
This commit is contained in:
Scott Mitchell 2017-04-05 10:28:59 -07:00
parent 077a1988b9
commit c37267d682
1 changed files with 31 additions and 11 deletions
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42
transport/src/main/java/io/netty/channel/nio/NioEventLoop.java
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@ -146,11 +146,29 @@ public final class NioEventLoop extends SingleThreadEventLoop {
throw new NullPointerException("selectStrategy"); throw new NullPointerException("selectStrategy");
} }
provider = selectorProvider; provider = selectorProvider;
selector = openSelector(); final SelectorTuple selectorTuple = openSelector();
selector = selectorTuple.selector;
unwrappedSelector = selectorTuple.unwrappedSelector;
selectStrategy = strategy; selectStrategy = strategy;
} }
private Selector openSelector() { private static final class SelectorTuple {
final Selector unwrappedSelector;
final Selector selector;
SelectorTuple(Selector unwrappedSelector) {
this.unwrappedSelector = unwrappedSelector;
this.selector = unwrappedSelector;
}
SelectorTuple(Selector unwrappedSelector, Selector selector) {
this.unwrappedSelector = unwrappedSelector;
this.selector = selector;
}
}
private SelectorTuple openSelector() {
final Selector unwrappedSelector;
try { try {
unwrappedSelector = provider.openSelector(); unwrappedSelector = provider.openSelector();
} catch (IOException e) { } catch (IOException e) {
@ -158,7 +176,7 @@ public final class NioEventLoop extends SingleThreadEventLoop {
} }
if (DISABLE_KEYSET_OPTIMIZATION) { if (DISABLE_KEYSET_OPTIMIZATION) {
return unwrappedSelector; return new SelectorTuple(unwrappedSelector);
} }
final SelectedSelectionKeySet selectedKeySet = new SelectedSelectionKeySet(); final SelectedSelectionKeySet selectedKeySet = new SelectedSelectionKeySet();
@ -184,7 +202,7 @@ public final class NioEventLoop extends SingleThreadEventLoop {
Throwable t = (Throwable) maybeSelectorImplClass; Throwable t = (Throwable) maybeSelectorImplClass;
logger.trace("failed to instrument a special java.util.Set into: {}", unwrappedSelector, t); logger.trace("failed to instrument a special java.util.Set into: {}", unwrappedSelector, t);
} }
return unwrappedSelector; return new SelectorTuple(unwrappedSelector);
} }
final Class<?> selectorImplClass = (Class<?>) maybeSelectorImplClass; final Class<?> selectorImplClass = (Class<?>) maybeSelectorImplClass;
@ -220,11 +238,12 @@ public final class NioEventLoop extends SingleThreadEventLoop {
selectedKeys = null; selectedKeys = null;
Exception e = (Exception) maybeException; Exception e = (Exception) maybeException;
logger.trace("failed to instrument a special java.util.Set into: {}", unwrappedSelector, e); logger.trace("failed to instrument a special java.util.Set into: {}", unwrappedSelector, e);
return unwrappedSelector; return new SelectorTuple(unwrappedSelector);
} }
selectedKeys = selectedKeySet; selectedKeys = selectedKeySet;
logger.trace("instrumented a special java.util.Set into: {}", unwrappedSelector); logger.trace("instrumented a special java.util.Set into: {}", unwrappedSelector);
return new SelectedSelectionKeySetSelector(unwrappedSelector, selectedKeySet); return new SelectorTuple(unwrappedSelector,
new SelectedSelectionKeySetSelector(unwrappedSelector, selectedKeySet));
} }
/** /**
@ -320,14 +339,14 @@ public final class NioEventLoop extends SingleThreadEventLoop {
private void rebuildSelector0() { private void rebuildSelector0() {
final Selector oldSelector = selector; final Selector oldSelector = selector;
final Selector newSelector; final SelectorTuple newSelectorTuple;
if (oldSelector == null) { if (oldSelector == null) {
return; return;
} }
try { try {
newSelector = openSelector(); newSelectorTuple = openSelector();
} catch (Exception e) { } catch (Exception e) {
logger.warn("Failed to create a new Selector.", e); logger.warn("Failed to create a new Selector.", e);
return; return;
@ -338,13 +357,13 @@ public final class NioEventLoop extends SingleThreadEventLoop {
for (SelectionKey key: oldSelector.keys()) { for (SelectionKey key: oldSelector.keys()) {
Object a = key.attachment(); Object a = key.attachment();
try { try {
if (!key.isValid() || key.channel().keyFor(newSelector) != null) { if (!key.isValid() || key.channel().keyFor(newSelectorTuple.unwrappedSelector) != null) {
continue; continue;
} }
int interestOps = key.interestOps(); int interestOps = key.interestOps();
key.cancel(); key.cancel();
SelectionKey newKey = key.channel().register(newSelector, interestOps, a); SelectionKey newKey = key.channel().register(newSelectorTuple.unwrappedSelector, interestOps, a);
if (a instanceof AbstractNioChannel) { if (a instanceof AbstractNioChannel) {
// Update SelectionKey // Update SelectionKey
((AbstractNioChannel) a).selectionKey = newKey; ((AbstractNioChannel) a).selectionKey = newKey;
@ -363,7 +382,8 @@ public final class NioEventLoop extends SingleThreadEventLoop {
} }
} }
selector = newSelector; selector = newSelectorTuple.selector;
unwrappedSelector = newSelectorTuple.unwrappedSelector;
try { try {
// time to close the old selector as everything else is registered to the new one // time to close the old selector as everything else is registered to the new one