/*
 * Copyright (c) 2008, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.grizzly.nio;

import java.io.IOException;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.SelectableChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.glassfish.grizzly.CompletionHandler;
import org.glassfish.grizzly.Grizzly;
import org.glassfish.grizzly.impl.FutureImpl;
import org.glassfish.grizzly.impl.SafeFutureImpl;
import org.glassfish.grizzly.utils.Futures;

Default implementation of NIO SelectorHandler
Author:Alexey Stashok
/** * Default implementation of NIO <code>SelectorHandler</code> * * @author Alexey Stashok */
public class DefaultSelectorHandler implements SelectorHandler { private static final long DEFAULT_SELECT_TIMEOUT_MILLIS = 30000; private static final Logger logger = Grizzly.logger(DefaultSelectorHandler.class); public static final boolean IS_WORKAROUND_SELECTOR_SPIN = Boolean.getBoolean(DefaultSelectorHandler.class.getName() + ".force-selector-spin-detection") || System.getProperty("os.name").equalsIgnoreCase("linux"); protected final long selectTimeout; // Selector spin workaround artifacts
The threshold for detecting selector.select spin on linux, used for enabling workaround to prevent server from hanging.
/** * The threshold for detecting selector.select spin on linux, used for enabling workaround to prevent server from * hanging. */
private static final int SPIN_RATE_THRESHOLD = 2000; // ---------------- public DefaultSelectorHandler() { this(DEFAULT_SELECT_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS); } public DefaultSelectorHandler(final long selectTimeout, final TimeUnit timeunit) { this.selectTimeout = TimeUnit.MILLISECONDS.convert(selectTimeout, timeunit); } @Override public long getSelectTimeout() { return selectTimeout; } @Override public boolean preSelect(final SelectorRunner selectorRunner) throws IOException { return processPendingTasks(selectorRunner); } @Override public Set<SelectionKey> select(final SelectorRunner selectorRunner) throws IOException { final Selector selector = selectorRunner.getSelector(); final boolean hasPostponedTasks = !selectorRunner.getPostponedTasks().isEmpty(); // The selector.select(...) returns the *new* SelectionKey count, // so it may return 0 even in the case, when there are unprocessed, but // ready SelectionKeys in the Selector's selected key set. if (!hasPostponedTasks) { selector.select(selectTimeout); } else { selector.selectNow(); } final Set<SelectionKey> selectedKeys = selector.selectedKeys(); if (IS_WORKAROUND_SELECTOR_SPIN) { selectorRunner.checkSelectorSpin(!selectedKeys.isEmpty() || hasPostponedTasks, SPIN_RATE_THRESHOLD); } return selectedKeys; } @Override public void postSelect(final SelectorRunner selectorRunner) throws IOException { } @Override public void registerKeyInterest(final SelectorRunner selectorRunner, final SelectionKey key, final int interest) throws IOException { if (isSelectorRunnerThread(selectorRunner)) { registerKey0(key, interest); } else { selectorRunner.addPendingTask(new RegisterKeyTask(key, interest)); } } private static void registerKey0(final SelectionKey selectionKey, final int interest) { if (selectionKey.isValid()) { final int currentOps = selectionKey.interestOps(); if ((currentOps & interest) != interest) { selectionKey.interestOps(currentOps | interest); } } }
{@inheritDoc}
/** * {@inheritDoc} */
@Override public void deregisterKeyInterest(final SelectorRunner selectorRunner, final SelectionKey key, final int interest) throws IOException { if (key.isValid()) { final int currentOps = key.interestOps(); if ((currentOps & interest) != 0) { key.interestOps(currentOps & ~interest); } } } @Override public void registerChannel(final SelectorRunner selectorRunner, final SelectableChannel channel, final int interest, final Object attachment) throws IOException { final FutureImpl<RegisterChannelResult> future = SafeFutureImpl.create(); registerChannelAsync(selectorRunner, channel, interest, attachment, Futures.toCompletionHandler(future)); try { future.get(selectTimeout, TimeUnit.MILLISECONDS); } catch (Exception e) { throw new IOException(e.getMessage()); } } @Override public void registerChannelAsync(SelectorRunner selectorRunner, SelectableChannel channel, int interest, Object attachment, CompletionHandler<RegisterChannelResult> completionHandler) { if (isSelectorRunnerThread(selectorRunner)) { registerChannel0(selectorRunner, channel, interest, attachment, completionHandler); } else { addPendingTask(selectorRunner, new RegisterChannelOperation(channel, interest, attachment, completionHandler)); } } @Override public void deregisterChannel(final SelectorRunner selectorRunner, final SelectableChannel channel) throws IOException { final FutureImpl<RegisterChannelResult> future = SafeFutureImpl.create(); deregisterChannelAsync(selectorRunner, channel, Futures.toCompletionHandler(future)); try { future.get(selectTimeout, TimeUnit.MILLISECONDS); } catch (Exception e) { throw new IOException(e.getMessage()); } } @Override public void deregisterChannelAsync(final SelectorRunner selectorRunner, final SelectableChannel channel, final CompletionHandler<RegisterChannelResult> completionHandler) { if (isSelectorRunnerThread(selectorRunner)) { deregisterChannel0(selectorRunner, channel, completionHandler); } else { addPendingTask(selectorRunner, new DeregisterChannelOperation(channel, completionHandler)); } } @Override public void execute(final SelectorRunner selectorRunner, final Task task, final CompletionHandler<Task> completionHandler) { if (isSelectorRunnerThread(selectorRunner)) { try { task.run(); if (completionHandler != null) { completionHandler.completed(task); } } catch (Exception e) { if (completionHandler != null) { completionHandler.failed(e); } } } else { addPendingTask(selectorRunner, new RunnableTask(task, completionHandler)); } } @Override public void enque(final SelectorRunner selectorRunner, final Task task, final CompletionHandler<Task> completionHandler) { if (isSelectorRunnerThread(selectorRunner)) { // If this is Selector thread - put the task to postponed queue // it's faster than using pending task queue, which is thread-safe final Queue<SelectorHandlerTask> postponedTasks = selectorRunner.getPostponedTasks(); postponedTasks.offer(new RunnableTask(task, completionHandler)); } else { addPendingTask(selectorRunner, new RunnableTask(task, completionHandler)); } } private void addPendingTask(final SelectorRunner selectorRunner, final SelectorHandlerTask task) { if (selectorRunner == null) { task.cancel(); return; } selectorRunner.addPendingTask(task); if (selectorRunner.isStop() && selectorRunner.getPendingTasks().remove(task)) { task.cancel(); } } private boolean processPendingTasks(final SelectorRunner selectorRunner) throws IOException { return processPendingTaskQueue(selectorRunner, selectorRunner.obtainPostponedTasks()) && (!selectorRunner.hasPendingTasks || processPendingTaskQueue(selectorRunner, selectorRunner.getPendingTasks())); } private boolean processPendingTaskQueue(final SelectorRunner selectorRunner, final Queue<SelectorHandlerTask> selectorHandlerTasks) throws IOException { SelectorHandlerTask selectorHandlerTask; while ((selectorHandlerTask = selectorHandlerTasks.poll()) != null) { if (!selectorHandlerTask.run(selectorRunner)) { return false; } } return true; } private static void registerChannel0(final SelectorRunner selectorRunner, final SelectableChannel channel, final int interest, final Object attachment, final CompletionHandler<RegisterChannelResult> completionHandler) { try { if (channel.isOpen()) { final Selector selector = selectorRunner.getSelector(); final SelectionKey key = channel.keyFor(selector); // Check whether the channel has been registered on a selector if (key == null || key.isValid()) { // If channel is not registered or key is valid final SelectionKey registeredSelectionKey = channel.register(selector, interest, attachment); selectorRunner.getTransport().getSelectionKeyHandler().onKeyRegistered(registeredSelectionKey); final RegisterChannelResult result = new RegisterChannelResult(selectorRunner, registeredSelectionKey, channel); if (completionHandler != null) { completionHandler.completed(result); } } else { // Channel has been registered already, // but the key is not valid final Queue<SelectorHandlerTask> postponedTasks = selectorRunner.getPostponedTasks(); final RegisterChannelOperation operation = new RegisterChannelOperation(channel, interest, attachment, completionHandler); postponedTasks.add(operation); } } else { failChannelRegistration(completionHandler, new ClosedChannelException()); } } catch (IOException e) { failChannelRegistration(completionHandler, e); } } private static void failChannelRegistration(final CompletionHandler<RegisterChannelResult> completionHandler, final Throwable error) { if (completionHandler != null) { completionHandler.failed(error); } } private static void deregisterChannel0(final SelectorRunner selectorRunner, final SelectableChannel channel, final CompletionHandler<RegisterChannelResult> completionHandler) { final Throwable error; try { if (channel.isOpen()) { final Selector selector = selectorRunner.getSelector(); final SelectionKey key = channel.keyFor(selector); // Check whether the channel has been registered on a selector if (key != null) { // If channel is registered selectorRunner.getTransport().getSelectionKeyHandler().cancel(key); selectorRunner.getTransport().getSelectionKeyHandler().onKeyDeregistered(key); final RegisterChannelResult result = new RegisterChannelResult(selectorRunner, key, channel); if (completionHandler != null) { completionHandler.completed(result); } return; } error = new IllegalStateException("Channel is not registered"); } else { error = new ClosedChannelException(); } Futures.notifyFailure(null, completionHandler, error); } catch (IOException e) { Futures.notifyFailure(null, completionHandler, e); } } @Override public boolean onSelectorClosed(final SelectorRunner selectorRunner) { try { selectorRunner.workaroundSelectorSpin(); return true; } catch (Exception e) { return false; } } private static boolean isSelectorRunnerThread(final SelectorRunner selectorRunner) { return selectorRunner != null && Thread.currentThread() == selectorRunner.getRunnerThread(); } protected static final class RegisterKeyTask implements SelectorHandlerTask { private final SelectionKey selectionKey; private final int interest; public RegisterKeyTask(final SelectionKey selectionKey, final int interest) { this.selectionKey = selectionKey; this.interest = interest; } @Override public boolean run(final SelectorRunner selectorRunner) throws IOException { SelectionKey localSelectionKey = selectionKey; if (IS_WORKAROUND_SELECTOR_SPIN) { localSelectionKey = selectorRunner.checkIfSpinnedKey(selectionKey); } registerKey0(localSelectionKey, interest); return true; } @Override public void cancel() { } } protected static final class RegisterChannelOperation implements SelectorHandlerTask { private final SelectableChannel channel; private final int interest; private final Object attachment; private final CompletionHandler<RegisterChannelResult> completionHandler; private RegisterChannelOperation(final SelectableChannel channel, final int interest, final Object attachment, final CompletionHandler<RegisterChannelResult> completionHandler) { this.channel = channel; this.interest = interest; this.attachment = attachment; this.completionHandler = completionHandler; } @Override public boolean run(final SelectorRunner selectorRunner) throws IOException { registerChannel0(selectorRunner, channel, interest, attachment, completionHandler); return true; } @Override public void cancel() { if (completionHandler != null) { completionHandler.failed(new IOException("Selector is closed")); } } } protected static final class RunnableTask implements SelectorHandlerTask { private final Task task; private final CompletionHandler<Task> completionHandler; private RunnableTask(final Task task, final CompletionHandler<Task> completionHandler) { this.task = task; this.completionHandler = completionHandler; } @Override public boolean run(final SelectorRunner selectorRunner) throws IOException { boolean continueExecution = true; try { continueExecution = task.run(); if (completionHandler != null) { completionHandler.completed(task); } } catch (Throwable t) { logger.log(Level.FINEST, "doExecutePendiongIO failed.", t); if (completionHandler != null) { completionHandler.failed(t); } } return continueExecution; } @Override public void cancel() { if (completionHandler != null) { completionHandler.failed(new IOException("Selector is closed")); } } } protected static final class DeregisterChannelOperation implements SelectorHandlerTask { private final SelectableChannel channel; private final CompletionHandler<RegisterChannelResult> completionHandler; private DeregisterChannelOperation(final SelectableChannel channel, final CompletionHandler<RegisterChannelResult> completionHandler) { this.channel = channel; this.completionHandler = completionHandler; } @Override public boolean run(final SelectorRunner selectorRunner) throws IOException { deregisterChannel0(selectorRunner, channel, completionHandler); return true; } @Override public void cancel() { if (completionHandler != null) { completionHandler.failed(new IOException("Selector is closed")); } } } }