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/*
* 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.CancelledKeyException;
import java.nio.channels.ClosedSelectorException;
import java.nio.channels.SelectableChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.util.ArrayDeque;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.glassfish.grizzly.Connection;
import org.glassfish.grizzly.Grizzly;
import org.glassfish.grizzly.IOEvent;
import org.glassfish.grizzly.IOStrategy;
import org.glassfish.grizzly.Transport.State;
import org.glassfish.grizzly.localization.LogMessages;
import org.glassfish.grizzly.threadpool.Threads;
import org.glassfish.grizzly.utils.StateHolder;
/**
* Class is responsible for processing certain (single) {@link SelectorHandler}
*
* @author Alexey Stashok
*/
public final class SelectorRunner implements Runnable {
private final static Logger LOGGER = Grizzly.logger(SelectorRunner.class);
private final static String THREAD_MARKER = " SelectorRunner";
private final NIOTransport transport;
private final AtomicReference stateHolder;
private final Queue pendingTasks;
private Queue currentPostponedTasks;
private final Queue evenPostponedTasks;
private final Queue oddPostponedTasks;
private volatile int dumbVolatile = 1;
private Selector selector;
private Thread selectorRunnerThread;
// State fields
private boolean isResume;
private int lastSelectedKeysCount;
private Set readyKeySet;
private Iterator iterator;
private SelectionKey key = null;
private int keyReadyOps;
private final AtomicBoolean selectorWakeupFlag = new AtomicBoolean();
private final AtomicInteger runnerThreadActivityCounter = new AtomicInteger();
public static SelectorRunner create(final NIOTransport transport) throws IOException {
return new SelectorRunner(transport, Selectors.newSelector(transport.getSelectorProvider()));
}
volatile boolean hasPendingTasks;
private SelectorRunner(final NIOTransport transport, final Selector selector) {
this.transport = transport;
this.selector = selector;
stateHolder = new AtomicReference<>(State.STOPPED);
pendingTasks = new ConcurrentLinkedQueue<>();
evenPostponedTasks = new ArrayDeque<>();
oddPostponedTasks = new ArrayDeque<>();
currentPostponedTasks = evenPostponedTasks;
}
void addPendingTask(final SelectorHandlerTask task) {
pendingTasks.offer(task);
hasPendingTasks = true;
wakeupSelector();
}
private void wakeupSelector() {
final Selector localSelector = getSelector();
if (localSelector != null && selectorWakeupFlag.compareAndSet(false, true)) {
try {
localSelector.wakeup();
} catch (Exception e) {
LOGGER.log(Level.FINE, "Error during selector wakeup", e);
}
}
}
public NIOTransport getTransport() {
return transport;
}
public Selector getSelector() {
if (dumbVolatile != 0) {
return selector;
}
return null;
}
/**
* Sets the {@link Selector}, associated with the runner. The method should be called from the runner thread.
*
* @param selector the new {@link Selector} to be associated with this {@link SelectorRunner}.
*/
void setSelector(final Selector selector) {
this.selector = selector;
dumbVolatile++;
}
private void setRunnerThread(final Thread runnerThread) {
this.selectorRunnerThread = runnerThread;
dumbVolatile++;
}
public Thread getRunnerThread() {
if (dumbVolatile != 0) {
return selectorRunnerThread;
}
return null;
}
public State getState() {
return stateHolder.get();
}
public void postpone() {
assert selectorRunnerThread != null;
removeThreadNameMarker(selectorRunnerThread);
Threads.setService(false);
runnerThreadActivityCounter.compareAndSet(1, 0);
selectorRunnerThread = null;
isResume = true;
dumbVolatile++;
}
public synchronized void start() {
if (!stateHolder.compareAndSet(State.STOPPED, State.STARTING)) {
LOGGER.log(Level.WARNING, LogMessages.WARNING_GRIZZLY_SELECTOR_RUNNER_NOT_IN_STOPPED_STATE_EXCEPTION());
return;
}
transport.getKernelThreadPool().execute(this);
}
public synchronized void stop() {
stateHolder.set(State.STOPPING);
wakeupSelector();
// we prefer Selector thread shutdown selector
// but if it's not running - do that ourselves.
if (runnerThreadActivityCounter.compareAndSet(0, -1)) {
// The thread is not running
shutdownSelector();
}
}
private void shutdownSelector() {
final Selector localSelector = getSelector();
if (localSelector != null) {
try {
SelectionKey[] keys = new SelectionKey[0];
while (true) {
try {
keys = localSelector.keys().toArray(keys);
break;
} catch (ConcurrentModificationException ignored) {
}
}
for (final SelectionKey selectionKey : keys) {
final Connection connection = transport.getSelectionKeyHandler().getConnectionForKey(selectionKey);
connection.terminateSilently();
}
} catch (ClosedSelectorException e) {
// If Selector is already closed - OK
} finally {
try {
localSelector.close();
} catch (Exception ignored) {
}
}
}
abortTasksInQueue(pendingTasks);
abortTasksInQueue(evenPostponedTasks);
abortTasksInQueue(oddPostponedTasks);
}
@Override
public void run() {
if (!runnerThreadActivityCounter.compareAndSet(0, 1)) {
return;
}
final Thread currentThread = Thread.currentThread();
try {
if (!isResume) {
if (!stateHolder.compareAndSet(State.STARTING, State.STARTED)) {
return;
}
addThreadNameMarker(currentThread);
}
setRunnerThread(currentThread);
Threads.setService(true);
final StateHolder transportStateHolder = transport.getState();
boolean isSkipping = false;
while (!isSkipping && !isStop()) {
if (transportStateHolder.getState() != State.PAUSED) {
isSkipping = !doSelect();
} else {
try {
transportStateHolder.notifyWhenStateIsNotEqual(State.PAUSED, null).get(5000, TimeUnit.MILLISECONDS);
} catch (Exception ignored) {
}
}
}
} finally {
runnerThreadActivityCounter.compareAndSet(1, 0);
if (isStop()) {
stateHolder.set(State.STOPPED);
setRunnerThread(null);
if (runnerThreadActivityCounter.compareAndSet(0, -1)) {
shutdownSelector();
}
}
removeThreadNameMarker(currentThread);
Threads.setService(false);
}
}
/**
* This method handle the processing of all Selector's interest op (OP_ACCEPT,OP_READ,OP_WRITE,OP_CONNECT) by delegating
* to its Handler. By default, all java.nio.channels.Selector operations are implemented using SelectorHandler. All
* SelectionKey operations are implemented by SelectionKeyHandler. Finally, ProtocolChain creation/re-use are
* implemented by InstanceHandler.
*/
protected boolean doSelect() {
final SelectorHandler selectorHandler = transport.getSelectorHandler();
try {
if (isResume) {
// If resume SelectorRunner - finish postponed keys
isResume = false;
// readyKeySet==null means execution was suspended on preSelect(..)
if (readyKeySet != null) {
if (keyReadyOps != 0) {
if (!iterateKeyEvents()) {
return false;
}
}
if (!iterateKeys()) {
return false;
}
readyKeySet.clear();
}
}
lastSelectedKeysCount = 0;
if (!selectorHandler.preSelect(this)) {
return false;
}
readyKeySet = selectorHandler.select(this);
selectorWakeupFlag.set(false);
if (stateHolder.get() == State.STOPPING) {
return true;
}
lastSelectedKeysCount = readyKeySet.size();
if (lastSelectedKeysCount != 0) {
iterator = readyKeySet.iterator();
if (!iterateKeys()) {
return false;
}
readyKeySet.clear();
}
readyKeySet = null;
iterator = null;
selectorHandler.postSelect(this);
} catch (ClosedSelectorException e) {
if (isRunning()) {
if (selectorHandler.onSelectorClosed(this)) {
return true;
}
}
dropConnectionDueToException(key, "Selector was unexpectedly closed", e, Level.SEVERE, Level.FINE);
} catch (Exception e) {
dropConnectionDueToException(key, "doSelect exception", e, Level.SEVERE, Level.FINE);
} catch (Throwable t) {
LOGGER.log(Level.SEVERE, "doSelect exception", t);
transport.notifyTransportError(t);
}
return true;
}
private boolean iterateKeys() {
final Iterator it = iterator;
while (it.hasNext()) {
try {
key = it.next();
keyReadyOps = key.readyOps();
if (!iterateKeyEvents()) {
return false;
}
} catch (IOException e) {
keyReadyOps = 0;
dropConnectionDueToException(key, "Unexpected IOException. Channel " + key.channel() + " will be closed.", e, Level.WARNING, Level.FINE);
} catch (CancelledKeyException e) {
keyReadyOps = 0;
dropConnectionDueToException(key, "Unexpected CancelledKeyException. Channel " + key.channel() + " will be closed.", e, Level.FINE, Level.FINE);
}
}
return true;
}
private boolean iterateKeyEvents() throws IOException {
final SelectionKey keyLocal = key;
final SelectionKeyHandler selectionKeyHandler = transport.getSelectionKeyHandler();
final IOStrategy ioStrategy = transport.getIOStrategy();
final IOEvent[] ioEvents = selectionKeyHandler.getIOEvents(keyReadyOps);
final NIOConnection connection = selectionKeyHandler.getConnectionForKey(keyLocal);
for (IOEvent ioEvent : ioEvents) {
NIOConnection.notifyIOEventReady(connection, ioEvent);
final int interest = ioEvent.getSelectionKeyInterest();
keyReadyOps &= ~interest;
if (selectionKeyHandler.onProcessInterest(keyLocal, interest)) {
if (!ioStrategy.executeIoEvent(connection, ioEvent)) {
return false;
}
}
}
return true;
}
public Queue getPendingTasks() {
hasPendingTasks = false;
return pendingTasks;
}
public Queue getPostponedTasks() {
return currentPostponedTasks;
}
public Queue obtainPostponedTasks() {
final Queue tasksToReturn = currentPostponedTasks;
currentPostponedTasks = currentPostponedTasks == evenPostponedTasks ? oddPostponedTasks : evenPostponedTasks;
return tasksToReturn;
}
boolean isStop() {
final State state = stateHolder.get();
return state == State.STOPPED || state == State.STOPPING;
}
private boolean isRunning() {
return stateHolder.get() == State.STARTED;
}
/**
* Notify transport about the {@link Exception} happened, log it and cancel the {@link SelectionKey}, if it is not null
*
* @param key {@link SelectionKey}, which was processed, when the {@link Exception} occured
* @param description error description
* @param e {@link Exception} occurred
* @param runLogLevel logger {@link Level} to use, if transport is in running state
* @param stoppedLogLevel logger {@link Level} to use, if transport is not in running state
*/
private void dropConnectionDueToException(final SelectionKey key, final String description, final Exception e, final Level runLogLevel,
final Level stoppedLogLevel) {
if (isRunning()) {
LOGGER.log(runLogLevel, description, e);
if (key != null) {
try {
final Connection connection = transport.getSelectionKeyHandler().getConnectionForKey(key);
if (connection != null) {
connection.closeSilently();
} else {
final SelectableChannel channel = key.channel();
transport.getSelectionKeyHandler().cancel(key);
channel.close();
}
} catch (IOException cancelException) {
LOGGER.log(Level.FINE, "IOException during cancelling key", cancelException);
}
}
transport.notifyTransportError(e);
} else {
LOGGER.log(stoppedLogLevel, description, e);
}
}
/**
* Number of {@link SelectionKey}s, which were selected last time. Operation is not thread-safe.
*
* @return number of {@link SelectionKey}s, which were selected last time.
*/
public int getLastSelectedKeysCount() {
return lastSelectedKeysCount;
}
protected void switchToNewSelector() throws IOException {
final Selector oldSelector = selector;
final Selector newSelector = Selectors.newSelector(transport.getSelectorProvider());
final Set keys = oldSelector.keys();
final SelectionKeyHandler selectionKeyHandler = transport.getSelectionKeyHandler();
for (final SelectionKey selectionKey : keys) {
if (selectionKey.isValid()) {
try {
final NIOConnection nioConnection = selectionKeyHandler.getConnectionForKey(selectionKey);
final SelectionKey newSelectionKey = selectionKey.channel().register(newSelector, selectionKey.interestOps(), selectionKey.attachment());
nioConnection.onSelectionKeyUpdated(newSelectionKey);
} catch (Exception e) {
LOGGER.log(Level.FINE, "Error switching channel to a new selector", e);
}
}
}
setSelector(newSelector);
try {
oldSelector.close();
} catch (Exception ignored) {
}
}
private void abortTasksInQueue(final Queue taskQueue) {
SelectorHandlerTask task;
while ((task = taskQueue.poll()) != null) {
try {
task.cancel();
} catch (Exception ignored) {
}
}
}
/********************** Selector spin discovering *************************/
private long lastSpinTimestamp;
private int emptySpinCounter;
private final Map spinnedSelectorsHistory = new WeakHashMap<>();
void resetSpinCounter() {
emptySpinCounter = 0;
}
/**
* Increments spin counter and returns current spin rate (emptyspins/sec).
*
* @return current spin rate (emptyspins/sec).
*/
int incSpinCounter() {
if (emptySpinCounter++ == 0) {
lastSpinTimestamp = System.nanoTime();
} else if (emptySpinCounter == 1000) {
long deltatime = System.nanoTime() - lastSpinTimestamp;
int contspinspersec = (int) (1000 * 1000000000L / deltatime);
emptySpinCounter = 0;
return contspinspersec;
}
return 0;
}
SelectionKey checkIfSpinnedKey(final SelectionKey key) {
if (!key.isValid() && key.channel().isOpen() && spinnedSelectorsHistory.containsKey(key.selector())) {
final SelectionKey newKey = key.channel().keyFor(getSelector());
newKey.attach(key.attachment());
return newKey;
}
return key;
}
void workaroundSelectorSpin() throws IOException {
if (LOGGER.isLoggable(Level.FINE)) {
LOGGER.log(Level.FINE, "Workaround selector spin. selector={0}", getSelector());
}
spinnedSelectorsHistory.put(getSelector(), System.currentTimeMillis());
switchToNewSelector();
}
void checkSelectorSpin(final boolean hasSelectedKeys, final int spinRateThreshold) throws IOException {
if (hasSelectedKeys) {
resetSpinCounter();
} else {
final long sr = incSpinCounter();
if (sr > spinRateThreshold) {
workaroundSelectorSpin();
}
}
}
private void addThreadNameMarker(final Thread currentThread) {
final String name = currentThread.getName();
if (!name.endsWith(THREAD_MARKER)) {
currentThread.setName(name + THREAD_MARKER);
}
}
private void removeThreadNameMarker(final Thread currentThread) {
final String name = currentThread.getName();
if (name.endsWith(THREAD_MARKER)) {
currentThread.setName(name.substring(0, name.length() - THREAD_MARKER.length()));
}
}
}
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