[#681] Allow a user to access the Selector of an EventLoop
- Make NioEventLoop public so that a user can downcast it - Add NioEventLoop.register() - Add NioTask to let user specify what to do on select()
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Trustin Lee
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63d3210cff
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abd37dacd6
@ -18,6 +18,7 @@ package io.netty.channel.socket.nio;
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import io.netty.channel.Channel;
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import io.netty.channel.ChannelException;
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import io.netty.channel.ChannelTaskScheduler;
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import io.netty.channel.EventLoopException;
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import io.netty.channel.SingleThreadEventLoop;
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import io.netty.channel.socket.nio.AbstractNioChannel.NioUnsafe;
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import io.netty.logging.InternalLogger;
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@ -25,7 +26,6 @@ import io.netty.logging.InternalLoggerFactory;
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import java.io.IOException;
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import java.nio.channels.CancelledKeyException;
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import java.nio.channels.ClosedChannelException;
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import java.nio.channels.SelectableChannel;
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import java.nio.channels.SelectionKey;
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import java.nio.channels.Selector;
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@ -44,7 +44,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
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* {@link Selector} and so does the multi-plexing of these in the event loop.
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*
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*/
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final class NioEventLoop extends SingleThreadEventLoop {
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public final class NioEventLoop extends SingleThreadEventLoop {
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/**
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* Internal Netty logger.
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@ -97,39 +97,76 @@ final class NioEventLoop extends SingleThreadEventLoop {
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return new ConcurrentLinkedQueue<Runnable>();
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}
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/**
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* Registers an arbitrary {@link SelectableChannel}, not necessarily created by Netty, to the {@link Selector}
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* of this event loop. Once the specified {@link SelectableChannel} is registered, the specified {@code task} will
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* be executed by this event loop when the {@link SelectableChannel} is ready.
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*/
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public void register(final SelectableChannel ch, final int interestOps, final NioTask<?> task) {
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if (ch == null) {
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throw new NullPointerException("ch");
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}
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if (interestOps == 0) {
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throw new IllegalArgumentException("interestOps must be non-zero.");
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}
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if ((interestOps & ~ch.validOps()) != 0) {
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throw new IllegalArgumentException(
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"invalid interestOps: " + interestOps + "(validOps: " + ch.validOps() + ")");
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}
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if (task == null) {
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throw new NullPointerException("task");
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}
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if (isShutdown()) {
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throw new IllegalStateException("event loop shut down");
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}
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try {
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ch.register(selector, interestOps, task);
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} catch (Exception e) {
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throw new EventLoopException("failed to register a channel", e);
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}
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}
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// Create a new selector and "transfer" all channels from the old
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// selector to the new one
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private Selector recreateSelector() {
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Selector newSelector = openSelector();
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Selector selector = this.selector;
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this.selector = newSelector;
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final Selector newSelector = openSelector();
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final Selector oldSelector = this.selector;
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// loop over all the keys that are registered with the old Selector
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// and register them with the new one
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for (SelectionKey key: selector.keys()) {
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SelectableChannel ch = key.channel();
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int ops = key.interestOps();
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Object att = key.attachment();
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// cancel the old key
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cancel(key);
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try {
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// register the channel with the new selector now
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ch.register(newSelector, ops, att);
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} catch (ClosedChannelException e) {
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// close channel
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AbstractNioChannel channel = (AbstractNioChannel) att;
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channel.unsafe().close(channel.unsafe().voidFuture());
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// Register all channels to the new Selector.
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boolean success = false;
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try {
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for (SelectionKey key: oldSelector.keys()) {
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key.channel().register(newSelector, key.interestOps(), key.attachment());
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}
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success = true;
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} catch (Exception e) {
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logger.warn("Failed to re-register a Channel to the new Selector.", e);
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} finally {
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if (!success) {
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try {
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newSelector.close();
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} catch (Exception e) {
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logger.warn("Failed to close the new Selector.", e);
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}
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}
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}
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try {
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// time to close the old selector as everything else is registered to the new one
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selector.close();
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} catch (Throwable t) {
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logger.warn("Failed to close a selector.", t);
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if (!success) {
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// Keep using the old Selector on failure.
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return oldSelector;
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}
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logger.warn("Recreated Selector because of possible jdk epoll(..) bug");
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return newSelector;
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// Registration to the new Selector is done. Close the old Selector to cancel all old keys.
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try {
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selector.close();
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} catch (Exception e) {
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logger.warn("Failed to close the old selector.", e);
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}
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logger.info("Selector migration complete.");
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return this.selector = newSelector;
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}
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@Override
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@ -266,25 +303,11 @@ final class NioEventLoop extends SingleThreadEventLoop {
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try {
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for (i = selectedKeys.iterator(); i.hasNext();) {
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final SelectionKey k = i.next();
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final AbstractNioChannel ch = (AbstractNioChannel) k.attachment();
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final NioUnsafe unsafe = ch.unsafe();
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try {
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int readyOps = k.readyOps();
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if ((readyOps & (SelectionKey.OP_READ | SelectionKey.OP_ACCEPT)) != 0 || readyOps == 0) {
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unsafe.read();
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if (!ch.isOpen()) {
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// Connection already closed - no need to handle write.
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continue;
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}
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}
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if ((readyOps & SelectionKey.OP_WRITE) != 0) {
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unsafe.flushNow();
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}
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if ((readyOps & SelectionKey.OP_CONNECT) != 0) {
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unsafe.finishConnect();
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}
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} catch (CancelledKeyException ignored) {
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unsafe.close(unsafe.voidFuture());
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final Object a = k.attachment();
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if (a instanceof AbstractNioChannel) {
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processSelectedKey(k, (AbstractNioChannel) a);
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} else {
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processSelectedKey(k, (NioTask<SelectableChannel>) a);
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}
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if (cleanedCancelledKeys) {
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@ -304,12 +327,58 @@ final class NioEventLoop extends SingleThreadEventLoop {
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}
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}
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private static void processSelectedKey(SelectionKey k, AbstractNioChannel ch) {
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final NioUnsafe unsafe = ch.unsafe();
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try {
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int readyOps = k.readyOps();
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if ((readyOps & (SelectionKey.OP_READ | SelectionKey.OP_ACCEPT)) != 0 || readyOps == 0) {
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unsafe.read();
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if (!ch.isOpen()) {
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// Connection already closed - no need to handle write.
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return;
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}
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}
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if ((readyOps & SelectionKey.OP_WRITE) != 0) {
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unsafe.flushNow();
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}
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if ((readyOps & SelectionKey.OP_CONNECT) != 0) {
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unsafe.finishConnect();
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}
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} catch (CancelledKeyException ignored) {
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unsafe.close(unsafe.voidFuture());
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}
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}
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private static void processSelectedKey(SelectionKey k, NioTask<SelectableChannel> task) {
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boolean success = false;
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try {
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task.channelReady(k.channel(), k);
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success = true;
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} catch (Exception e) {
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logger.warn("Unexpected exception while running NioTask.channelReady() - cancelling the key", e);
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} finally {
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if (!success) {
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k.cancel();
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}
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if (!k.isValid()) { // Either cancelled by channelReady() or by this method.
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invokeChannelUnregistered(task, k);
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}
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}
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}
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private void closeAll() {
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SelectorUtil.cleanupKeys(selector);
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Set<SelectionKey> keys = selector.keys();
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Collection<Channel> channels = new ArrayList<Channel>(keys.size());
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for (SelectionKey k: keys) {
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channels.add((Channel) k.attachment());
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Object a = k.attachment();
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if (a instanceof Channel) {
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channels.add((Channel) a);
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} else {
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k.cancel();
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invokeChannelUnregistered((NioTask<SelectableChannel>) a, k);
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}
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}
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for (Channel ch: channels) {
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@ -317,6 +386,14 @@ final class NioEventLoop extends SingleThreadEventLoop {
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}
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}
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private static void invokeChannelUnregistered(NioTask<SelectableChannel> task, SelectionKey k) {
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try {
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task.channelUnregistered(k.channel());
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} catch (Exception e) {
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logger.warn("Unexpected exception while running NioTask.channelUnregistered()", e);
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}
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}
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@Override
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protected void wakeup(boolean inEventLoop) {
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if (wakenUp.compareAndSet(false, true)) {
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@ -0,0 +1,37 @@
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/*
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* Copyright 2012 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.channel.socket.nio;
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import java.nio.channels.SelectableChannel;
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import java.nio.channels.SelectionKey;
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/**
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* An arbitrary task that can be executed by {@link NioEventLoop} when a {@link SelectableChannel} becomes ready.
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*
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* @see NioEventLoop#register(SelectableChannel, int, NioTask)
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*/
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public interface NioTask<C extends SelectableChannel> {
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/**
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* Invoked when the {@link SelectableChannel} has been selected by the {@link java.nio.channels.Selector}.
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*/
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void channelReady(C ch, SelectionKey key) throws Exception;
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/**
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* Invoked when the {@link SelectionKey} of the specified {@link SelectableChannel} has been cancelled and thus
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* this {@link NioTask} will not be notified anymore.
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*/
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void channelUnregistered(C ch) throws Exception;
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}
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