SingleThreadEventLoop 基于单线程的EventLoop抽象类，将Channel注册到EventLoop上
public abstract class SingleThreadEventLoop extends SingleThreadEventExecutor implements EventLoop {
//默认任务队列最大数量**加粗样式**
protected static final int DEFAULT_MAX_PENDING_TASKS = Math.max(16,
SystemPropertyUtil.getInt("io.netty.eventLoop.maxPendingTasks", Integer.MAX_VALUE));
//尾部任务队列
private final Queue<Runnable> tailTasks;
protected SingleThreadEventLoop(EventLoopGroup parent, ThreadFactory threadFactory, boolean addTaskWakesUp) {
this(parent, threadFactory, addTaskWakesUp, DEFAULT_MAX_PENDING_TASKS, RejectedExecutionHandlers.reject());
}
protected SingleThreadEventLoop(EventLoopGroup parent, Executor executor, boolean addTaskWakesUp) {
this(parent, executor, addTaskWakesUp, DEFAULT_MAX_PENDING_TASKS, RejectedExecutionHandlers.reject());
}
protected SingleThreadEventLoop(EventLoopGroup parent, ThreadFactory threadFactory,
boolean addTaskWakesUp, int maxPendingTasks,
RejectedExecutionHandler rejectedExecutionHandler) {
super(parent, threadFactory, addTaskWakesUp, maxPendingTasks, rejectedExecutionHandler);
tailTasks = newTaskQueue(maxPendingTasks);
}
protected SingleThreadEventLoop(EventLoopGroup parent, Executor executor,
boolean addTaskWakesUp, int maxPendingTasks,
RejectedExecutionHandler rejectedExecutionHandler) {
super(parent, executor, addTaskWakesUp, maxPendingTasks, rejectedExecutionHandler);
tailTasks = newTaskQueue(maxPendingTasks);
}
protected SingleThreadEventLoop(EventLoopGroup parent, Executor executor,
boolean addTaskWakesUp, Queue<Runnable> taskQueue, Queue<Runnable> tailTaskQueue,
RejectedExecutionHandler rejectedExecutionHandler) {
super(parent, executor, addTaskWakesUp, taskQueue, rejectedExecutionHandler);
tailTasks = ObjectUtil.checkNotNull(tailTaskQueue, "tailTaskQueue");
}
//获取所属的EventLoopGroup
@Override
public EventLoopGroup parent() {
return (EventLoopGroup) super.parent();
}
//获取自己
@Override
public EventLoop next() {
return (EventLoop) super.next();
}
//注册Channel到EventLoop上
@Override
public ChannelFuture register(Channel channel) {
return register(new DefaultChannelPromise(channel, this));
}
@Override
public ChannelFuture register(final ChannelPromise promise) {
ObjectUtil.checkNotNull(promise, "promise");
//注册Channel到EventLoop上
promise.channel().unsafe().register(this, promise);
//返回ChannelPromise对象
return promise;
}
@Deprecated
@Override
public ChannelFuture register(final Channel channel, final ChannelPromise promise) {
ObjectUtil.checkNotNull(promise, "promise");
ObjectUtil.checkNotNull(channel, "channel");
channel.unsafe().register(this, promise);
return promise;
}
@UnstableApi
public final void executeAfterEventLoopIteration(Runnable task) {
ObjectUtil.checkNotNull(task, "task");
//关闭时，拒绝任务
if (isShutdown()) {
reject();
}
//添加到任务队列
if (!tailTasks.offer(task)) {
//添加失败则拒绝任务
reject(task);
}
if (!(task instanceof LazyRunnable) && wakesUpForTask(task)) {
//唤醒线程
wakeup(inEventLoop());
}
}
//移除指定任务
@UnstableApi
final boolean removeAfterEventLoopIterationTask(Runnable task) {
return tailTasks.remove(ObjectUtil.checkNotNull(task, "task"));
}
//运行完所有任务后，执行tailTasks队列中的任务
@Override
protected void afterRunningAllTasks() {
runAllTasksFrom(tailTasks);
}
//队列中是否有任务
@Override
protected boolean hasTasks() {
return super.hasTasks() || !tailTasks.isEmpty();
}
//获得队列中的任务数
@Override
public int pendingTasks() {
return super.pendingTasks() + tailTasks.size();
}
@UnstableApi
public int registeredChannels() {
return -1;
}
}
NioEventLoop 继承SingleThreadEventLoop抽象类，NIOEventLoop实现类
public final class NioEventLoop extends SingleThreadEventLoop {
private static final InternalLogger logger = InternalLoggerFactory.getInstance(NioEventLoop.class);
//清理间隙
private static final int CLEANUP_INTERVAL = 256;
//是否禁用SelectionKey的优化，默认开启
private static final boolean DISABLE_KEY_SET_OPTIMIZATION =
SystemPropertyUtil.getBoolean("io.netty.noKeySetOptimization", false);
//少于该N值，不开启空轮询重建新的Selector对象的功能
private static final int MIN_PREMATURE_SELECTOR_RETURNS = 3;
//空轮询了N次后，重建新的Selector对象
private static final int SELECTOR_AUTO_REBUILD_THRESHOLD;
private final IntSupplier selectNowSupplier = new IntSupplier() {
@Override
public int get() throws Exception {
return selectNow();
}
};
//静态代码块
static {
//得到bugLevel
final String key = "sun.nio.ch.bugLevel";
final String bugLevel = SystemPropertyUtil.get(key);
if (bugLevel == null) {
try {
AccessController.doPrivileged(new PrivilegedAction<Void>() {
@Override
public Void run() {
System.setProperty(key, "");
return null;
}
});
} catch (final SecurityException e) {
logger.debug("Unable to get/set System Property: " + key, e);
}
}
//初始化
int selectorAutoRebuildThreshold = SystemPropertyUtil.getInt("io.netty.selectorAutoRebuildThreshold", 512);
if (selectorAutoRebuildThreshold < MIN_PREMATURE_SELECTOR_RETURNS) {
selectorAutoRebuildThreshold = 0;
}
SELECTOR_AUTO_REBUILD_THRESHOLD = selectorAutoRebuildThreshold;
if (logger.isDebugEnabled()) {
logger.debug("-Dio.netty.noKeySetOptimization: {}", DISABLE_KEY_SET_OPTIMIZATION);
logger.debug("-Dio.netty.selectorAutoRebuildThreshold: {}", SELECTOR_AUTO_REBUILD_THRESHOLD);
}
}
//包装的Selector对象，经过优化
private Selector selector;
//未包装的Selector对象
private Selector unwrappedSelector;
//注册的SelectionKey集合
private SelectedSelectionKeySet selectedKeys;
//SelectionProvider对象，用于创建Selector对象
private final SelectorProvider provider;
private static final long AWAKE = -1L;
private static final long NONE = Long.MAX_VALUE;
//唤醒标记
private final AtomicLong nextWakeupNanos = new AtomicLong(AWAKE);
//Select策略
private final SelectStrategy selectStrategy;
//处理Channel的就绪的IO事件，占处理任务的总时间的比例
private volatile int ioRatio = 50;
//取消SelectionKey的数量
private int cancelledKeys;
//是否需要再次select Selector对象
private boolean needsToSelectAgain;
NioEventLoop(NioEventLoopGroup parent, Executor executor, SelectorProvider selectorProvider,
SelectStrategy strategy, RejectedExecutionHandler rejectedExecutionHandler,
EventLoopTaskQueueFactory queueFactory) {
super(parent, executor, false, newTaskQueue(queueFactory), newTaskQueue(queueFactory),
rejectedExecutionHandler);
this.provider = ObjectUtil.checkNotNull(selectorProvider, "selectorProvider");
this.selectStrategy = ObjectUtil.checkNotNull(strategy, "selectStrategy");
//创建Selector对象
final SelectorTuple selectorTuple = openSelector();
this.selector = selectorTuple.selector;
this.unwrappedSelector = selectorTuple.unwrappedSelector;
}
private static Queue<Runnable> newTaskQueue(
EventLoopTaskQueueFactory queueFactory) {
if (queueFactory == null) {
return newTaskQueue0(DEFAULT_MAX_PENDING_TASKS);
}
return queueFactory.newTaskQueue(DEFAULT_MAX_PENDING_TASKS);
}
//内嵌在NioEventLoop，Selector元组
private static final class SelectorTuple {
//未包装的Selector对象
final Selector unwrappedSelector;
//Selector对象
final Selector selector;
SelectorTuple(Selector unwrappedSelector) {
this.unwrappedSelector = unwrappedSelector;
this.selector = unwrappedSelector;
}
SelectorTuple(Selector unwrappedSelector, Selector selector) {
this.unwrappedSelector = unwrappedSelector;
this.selector = selector;
}
}
//创建NIO Selector对象
private SelectorTuple openSelector() {
//创建Selector对象，作为unwrappedSelector
final Selector unwrappedSelector;
try {
unwrappedSelector = provider.openSelector();
} catch (IOException e) {
throw new ChannelException("failed to open a new selector", e);
}
//禁用Selectionkey的优化，则直接返回SelectorTuple对象
if (DISABLE_KEY_SET_OPTIMIZATION) {
return new SelectorTuple(unwrappedSelector);
}
//获得SelectorImpl类
Object maybeSelectorImplClass = AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
try {
//成功则返回该类
return Class.forName(
"sun.nio.ch.SelectorImpl",
false,
PlatformDependent.getSystemClassLoader());
} catch (Throwable cause) {
//失败则返回该异常
return cause;
}
}
});
// 获得 SelectorImpl 类失败，则直接返回 SelectorTuple 对象
if (!(maybeSelectorImplClass instanceof Class) ||
!((Class<?>) maybeSelectorImplClass).isAssignableFrom(unwrappedSelector.getClass())) {
if (maybeSelectorImplClass instanceof Throwable) {
Throwable t = (Throwable) maybeSelectorImplClass;
logger.trace("failed to instrument a special java.util.Set into: {}", unwrappedSelector, t);
}
return new SelectorTuple(unwrappedSelector);
}
final Class<?> selectorImplClass = (Class<?>) maybeSelectorImplClass;
//创建SelectedSelectionKeySet对象
final SelectedSelectionKeySet selectedKeySet = new SelectedSelectionKeySet();
//设置SelectedSelectionKeySet对象到unwrappedSelector
Object maybeException = AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
try {
//获得selectedKeys和publicSelectedKeys的Field
Field selectedKeysField = selectorImplClass.getDeclaredField("selectedKeys");
Field publicSelectedKeysField = selectorImplClass.getDeclaredField("publicSelectedKeys");
if (PlatformDependent.javaVersion() >= 9 && PlatformDependent.hasUnsafe()) {
long selectedKeysFieldOffset = PlatformDependent.objectFieldOffset(selectedKeysField);
long publicSelectedKeysFieldOffset =
PlatformDependent.objectFieldOffset(publicSelectedKeysField);
if (selectedKeysFieldOffset != -1 && publicSelectedKeysFieldOffset != -1) {
PlatformDependent.putObject(
unwrappedSelector, selectedKeysFieldOffset, selectedKeySet);
PlatformDependent.putObject(
unwrappedSelector, publicSelectedKeysFieldOffset, selectedKeySet);
return null;
}
}
//设置Field可访问
Throwable cause = ReflectionUtil.trySetAccessible(selectedKeysField, true);
if (cause != null) {
return cause;
}
cause = ReflectionUtil.trySetAccessible(publicSelectedKeysField, true);
if (cause != null) {
return cause;
}
//设置SelectedSelectionKeySet对象到unwrappedSelector的Field中
selectedKeysField.set(unwrappedSelector, selectedKeySet);
publicSelectedKeysField.set(unwrappedSelector, selectedKeySet);
return null;
} catch (NoSuchFieldException e) {
return e;
} catch (IllegalAccessException e) {
return e;
}
}
});
//设置SelectedSelectionKeySet对象到unwrappedSelector中失败，则直接返回Selector
if (maybeException instanceof Exception) {
selectedKeys = null;
Exception e = (Exception) maybeException;
logger.trace("failed to instrument a special java.util.Set into: {}", unwrappedSelector, e);
return new SelectorTuple(unwrappedSelector);
}
// 设置 SelectedSelectionKeySet 对象到 selectedKeys 中
selectedKeys = selectedKeySet;
logger.trace("instrumented a special java.util.Set into: {}", unwrappedSelector);
// 创建 SelectedSelectionKeySetSelector 对象
return new SelectorTuple(unwrappedSelector,
new SelectedSelectionKeySetSelector(unwrappedSelector, selectedKeySet));
}
public SelectorProvider selectorProvider() {
return provider;
}
//创建任务队列
@Override
protected Queue<Runnable> newTaskQueue(int maxPendingTasks) {
return newTaskQueue0(maxPendingTasks);
}
private static Queue<Runnable> newTaskQueue0(int maxPendingTasks) {
return maxPendingTasks == Integer.MAX_VALUE ? PlatformDependent.<Runnable>newMpscQueue()
: PlatformDependent.<Runnable>newMpscQueue(maxPendingTasks);
}
//注册NIO Channel到Selector上
public void register(final SelectableChannel ch, final int interestOps, final NioTask<?> task) {
ObjectUtil.checkNotNull(ch, "ch");
if (interestOps == 0) {
throw new IllegalArgumentException("interestOps must be non-zero.");
}
if ((interestOps & ~ch.validOps()) != 0) {
throw new IllegalArgumentException(
"invalid interestOps: " + interestOps + "(validOps: " + ch.validOps() + ')');
}
ObjectUtil.checkNotNull(task, "task");
if (isShutdown()) {
throw new IllegalStateException("event loop shut down");
}
if (inEventLoop()) {
register0(ch, interestOps, task);
} else {
try {
submit(new Runnable() {
@Override
public void run() {
register0(ch, interestOps, task);
}
}).sync();
} catch (InterruptedException ignore) {
// Even if interrupted we did schedule it so just mark the Thread as interrupted.
Thread.currentThread().interrupt();
}
}
}
private void register0(SelectableChannel ch, int interestOps, NioTask<?> task) {
try {
ch.register(unwrappedSelector, interestOps, task);
} catch (Exception e) {
throw new EventLoopException("failed to register a channel", e);
}
}
public int getIoRatio() {
return ioRatio;
}
//设置ioRatio属性
public void setIoRatio(int ioRatio) {
if (ioRatio <= 0 || ioRatio > 100) {
throw new IllegalArgumentException("ioRatio: " + ioRatio + " (expected: 0 < ioRatio <= 100)");
}
this.ioRatio = ioRatio;
}
//重建NIO Selector对象
public void rebuildSelector() {
//只允许在EventLoop的线程中执行
if (!inEventLoop()) {
execute(new Runnable() {
@Override
public void run() {
rebuildSelector0();
}
});
return;
}
rebuildSelector0();
}
@Override
public int registeredChannels() {
return selector.keys().size() - cancelledKeys;
}
//重建Selector对象
private void rebuildSelector0() {
//原来的Selector
final Selector oldSelector = selector;
final SelectorTuple newSelectorTuple;
if (oldSelector == null) {
return;
}
//创建新的Selector对象
try {
newSelectorTuple = openSelector();
} catch (Exception e) {
logger.warn("Failed to create a new Selector.", e);
return;
}
//将注册到NioEventLoop上的所有Channel，注册到新创建Selector对象上
//计算重新注册成功的Channel数量
int nChannels = 0;
for (SelectionKey key: oldSelector.keys()) {
Object a = key.attachment();
try {
if (!key.isValid() || key.channel().keyFor(newSelectorTuple.unwrappedSelector) != null) {
continue;
}
int interestOps = key.interestOps();
//取消老的SelectionKey
key.cancel();
//将Channel注册到新的Selector对象上
SelectionKey newKey = key.channel().register(newSelectorTuple.unwrappedSelector, interestOps, a);
//修改Channel的selectionKey指向新的SelectionKey上
if (a instanceof AbstractNioChannel) {
((AbstractNioChannel) a).selectionKey = newKey;
}
//计数++
nChannels ++;
} catch (Exception e) {
logger.warn("Failed to re-register a Channel to the new Selector.", e);
//关闭发生异常的Channel
if (a instanceof AbstractNioChannel) {
AbstractNioChannel ch = (AbstractNioChannel) a;
ch.unsafe().close(ch.unsafe().voidPromise());
//调用NioTask的取消注册事件
} else {
@SuppressWarnings("unchecked")
NioTask<SelectableChannel> task = (NioTask<SelectableChannel>) a;
invokeChannelUnregistered(task, key, e);
}
}
}
//修改selector和unwrappedSelector指向新的Selector对象
selector = newSelectorTuple.selector;
unwrappedSelector = newSelectorTuple.unwrappedSelector;
//关闭老的Selector对象
try {
oldSelector.close();
} catch (Throwable t) {
if (logger.isWarnEnabled()) {
logger.warn("Failed to close the old Selector.", t);
}
}
if (logger.isInfoEnabled()) {
logger.info("Migrated " + nChannels + " channel(s) to the new Selector.");
}
}
//NioEventLoop运行，处理任务。
@Override
protected void run() {
int selectCnt = 0;
for (;;) {
try {
int strategy;
try {
//选择策略
strategy = selectStrategy.calculateStrategy(selectNowSupplier, hasTasks());
switch (strategy) {
//默认实现下，不存在这个情况
case SelectStrategy.CONTINUE:
continue;
//NIO不支持
case SelectStrategy.BUSY_WAIT:
//选择策略
case SelectStrategy.SELECT:
long curDeadlineNanos = nextScheduledTaskDeadlineNanos();
if (curDeadlineNanos == -1L) {
curDeadlineNanos = NONE;
}
nextWakeupNanos.set(curDeadlineNanos);
try {
if (!hasTasks()) {
strategy = select(curDeadlineNanos);
}
} finally {
nextWakeupNanos.lazySet(AWAKE);
}
default:
}
} catch (IOException e) {
rebuildSelector0();
selectCnt = 0;
handleLoopException(e);
continue;
}
selectCnt++;
cancelledKeys = 0;
needsToSelectAgain = false;
final int ioRatio = this.ioRatio;
boolean ranTasks;
if (ioRatio == 100) {
try {
if (strategy > 0) {
//处理Channel感兴趣的就绪IO事件
processSelectedKeys();
}
} finally {
//运行所有普通任务和定时任务，不限制时间
ranTasks = runAllTasks();
}
} else if (strategy > 0) {
//得到开始时间
final long ioStartTime = System.nanoTime();
try {
processSelectedKeys();
} finally {
//运行所有普通任务和定时任务，限制时间
final long ioTime = System.nanoTime() - ioStartTime;
ranTasks = runAllTasks(ioTime * (100 - ioRatio) / ioRatio);
}
} else {
ranTasks = runAllTasks(0); // This will run the minimum number of tasks
}
if (ranTasks || strategy > 0) {
if (selectCnt > MIN_PREMATURE_SELECTOR_RETURNS && logger.isDebugEnabled()) {
logger.debug("Selector.select() returned prematurely {} times in a row for Selector {}.",
selectCnt - 1, selector);
}
selectCnt = 0;
} else if (unexpectedSelectorWakeup(selectCnt)) { // Unexpected wakeup (unusual case)
selectCnt = 0;
}
} catch (CancelledKeyException e) {
// Harmless exception - log anyway
if (logger.isDebugEnabled()) {
logger.debug(CancelledKeyException.class.getSimpleName() + " raised by a Selector {} - JDK bug?",
selector, e);
}
} catch (Throwable t) {
handleLoopException(t);
}
//EventLoop优雅关闭
try {
if (isShuttingDown()) {
closeAll();
if (confirmShutdown()) {
return;
}
}
} catch (Throwable t) {
handleLoopException(t);
}
}
}
private boolean unexpectedSelectorWakeup(int selectCnt) {
if (Thread.interrupted()) {
if (logger.isDebugEnabled()) {
logger.debug("Selector.select() returned prematurely because " +
"Thread.currentThread().interrupt() was called. Use " +
"NioEventLoop.shutdownGracefully() to shutdown the NioEventLoop.");
}
return true;
}
if (SELECTOR_AUTO_REBUILD_THRESHOLD > 0 &&
selectCnt >= SELECTOR_AUTO_REBUILD_THRESHOLD) {
// The selector returned prematurely many times in a row.
// Rebuild the selector to work around the problem.
logger.warn("Selector.select() returned prematurely {} times in a row; rebuilding Selector {}.",
selectCnt, selector);
rebuildSelector();
return true;
}
return false;
}
//处理异常
private static void handleLoopException(Throwable t) {
logger.warn("Unexpected exception in the selector loop.", t);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
}
}
//处理Channel新增就绪的IO事件
private void processSelectedKeys() {
if (selectedKeys != null) {
//处理Channel新增就绪的IO事件
processSelectedKeysOptimized();
} else {
processSelectedKeysPlain(selector.selectedKeys());
}
}
@Override
protected void cleanup() {
try {
selector.close();
} catch (IOException e) {
logger.warn("Failed to close a selector.", e);
}
}
void cancel(SelectionKey key) {
key.cancel();
cancelledKeys ++;
if (cancelledKeys >= CLEANUP_INTERVAL) {
cancelledKeys = 0;
needsToSelectAgain = true;
}
}
//处理Channel新增就绪的IO事件
private void processSelectedKeysPlain(Set<SelectionKey> selectedKeys) {
if (selectedKeys.isEmpty()) {
return;
}
//遍历SelectionKey迭代器
Iterator<SelectionKey> i = selectedKeys.iterator();
for (;;) {
//获得SelectionKey对象
final SelectionKey k = i.next();
final Object a = k.attachment();
//从迭代器中移除
i.remove();
//处理一个Channel就绪的IO事件
if (a instanceof AbstractNioChannel) {
processSelectedKey(k, (AbstractNioChannel) a);
//使用NioTask处理一个Channel就绪的IO事件
} else {
@SuppressWarnings("unchecked")
NioTask<SelectableChannel> task = (NioTask<SelectableChannel>) a;
processSelectedKey(k, task);
}
//没有下一个节点就结束
if (!i.hasNext()) {
break;
}
//是否需要再次筛选
if (needsToSelectAgain) {
selectAgain();
selectedKeys = selector.selectedKeys();
if (selectedKeys.isEmpty()) {
break;
} else {
i = selectedKeys.iterator();
}
}
}
}
private void processSelectedKeysOptimized() {
//遍历数组
for (int i = 0; i < selectedKeys.size; ++i) {
final SelectionKey k = selectedKeys.keys[i];
selectedKeys.keys[i] = null;
final Object a = k.attachment();
//处理一个Channel就绪IO事件
if (a instanceof AbstractNioChannel) {
processSelectedKey(k, (AbstractNioChannel) a);
} else {
@SuppressWarnings("unchecked")
NioTask<SelectableChannel> task = (NioTask<SelectableChannel>) a;
processSelectedKey(k, task);
}
if (needsToSelectAgain) {
selectedKeys.reset(i + 1);
selectAgain();
i = -1;
}
}
}
//处理一个Channel就绪的IO事件
private void processSelectedKey(SelectionKey k, AbstractNioChannel ch) {
final AbstractNioChannel.NioUnsafe unsafe = ch.unsafe();
//如果SelectionKey是不合法的则关闭Channel
if (!k.isValid()) {
final EventLoop eventLoop;
try {
eventLoop = ch.eventLoop();
} catch (Throwable ignored) {
return;
}
if (eventLoop == this) {
unsafe.close(unsafe.voidPromise());
}
return;
}
try {
//获得就绪的IO事件的ops
int readyOps = k.readyOps();
if ((readyOps & SelectionKey.OP_CONNECT) != 0) {
//移除对OP_CONNECT感兴趣
int ops = k.interestOps();
ops &= ~SelectionKey.OP_CONNECT;
k.interestOps(ops);
//完成连接
unsafe.finishConnect();
}
if ((readyOps & SelectionKey.OP_WRITE) != 0) {
//向Channel写入数据
ch.unsafe().forceFlush();
}
if ((readyOps & (SelectionKey.OP_READ | SelectionKey.OP_ACCEPT)) != 0 || readyOps == 0) {
unsafe.read();
}
} catch (CancelledKeyException ignored) {
//发生异常关闭Channel
unsafe.close(unsafe.voidPromise());
}
}
//自定义实现Channel处理ChannelIO就绪事件
private static void processSelectedKey(SelectionKey k, NioTask<SelectableChannel> task) {
int state = 0;
try {
//调用NIOTask的Chanel就绪事件
task.channelReady(k.channel(), k);
state = 1;
} catch (Exception e) {
//SelectionKey取消
k.cancel();
//执行Channel取消注册
invokeChannelUnregistered(task, k, e);
state = 2;
} finally {
switch (state) {
case 0:
k.cancel();
invokeChannelUnregistered(task, k, null);
break;
case 1:
//SelelctionKey不合法，则执行Channel取消注册
if (!k.isValid()) { // Cancelled by channelReady()
invokeChannelUnregistered(task, k, null);
}
break;
}
}
}
private void closeAll() {
selectAgain();
Set<SelectionKey> keys = selector.keys();
Collection<AbstractNioChannel> channels = new ArrayList<AbstractNioChannel>(keys.size());
for (SelectionKey k: keys) {
Object a = k.attachment();
if (a instanceof AbstractNioChannel) {
channels.add((AbstractNioChannel) a);
} else {
k.cancel();
@SuppressWarnings("unchecked")
NioTask<SelectableChannel> task = (NioTask<SelectableChannel>) a;
invokeChannelUnregistered(task, k, null);
}
}
for (AbstractNioChannel ch: channels) {
ch.unsafe().close(ch.unsafe().voidPromise());
}
}
//执行Channel取消注册
private static void invokeChannelUnregistered(NioTask<SelectableChannel> task, SelectionKey k, Throwable cause) {
try {
task.channelUnregistered(k.channel(), cause);
} catch (Exception e) {
logger.warn("Unexpected exception while running NioTask.channelUnregistered()", e);
}
}
//唤醒线程
@Override
protected void wakeup(boolean inEventLoop) {
if (!inEventLoop && nextWakeupNanos.getAndSet(AWAKE) != AWAKE) {
selector.wakeup();
}
}
@Override
protected boolean beforeScheduledTaskSubmitted(long deadlineNanos) {
return deadlineNanos < nextWakeupNanos.get();
}
@Override
protected boolean afterScheduledTaskSubmitted(long deadlineNanos) {
// Note this is also correct for the nextWakeupNanos == -1 (AWAKE) case
return deadlineNanos < nextWakeupNanos.get();
}
Selector unwrappedSelector() {
return unwrappedSelector;
}
//立刻选择
int selectNow() throws IOException {
return selector.selectNow();
}
//选择查询任务
private int select(long deadlineNanos) throws IOException {
if (deadlineNanos == NONE) {
return selector.select();
}
//计算本次select的超时时间
long timeoutMillis = deadlineToDelayNanos(deadlineNanos + 995000L) / 1000000L;
//如果超时时间为负，就立刻选择
return timeoutMillis <= 0 ? selector.selectNow() : selector.select(timeoutMillis);
}
private void selectAgain() {
needsToSelectAgain = false;
try {
selector.selectNow();
} catch (Throwable t) {
logger.warn("Failed to update SelectionKeys.", t);
}
}
}
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