io.netty.util.concurrent.AbstractScheduledEventExecutor Maven / Gradle / Ivy
/*
* Copyright 2015 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.util.concurrent;
import io.netty.util.internal.DefaultPriorityQueue;
import io.netty.util.internal.ObjectUtil;
import io.netty.util.internal.PriorityQueue;
import java.util.Comparator;
import java.util.Queue;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;
/**
* Abstract base class for {@link EventExecutor}s that want to support scheduling.
*/
public abstract class AbstractScheduledEventExecutor extends AbstractEventExecutor {
private static final Comparator> SCHEDULED_FUTURE_TASK_COMPARATOR =
new Comparator>() {
@Override
public int compare(ScheduledFutureTask o1, ScheduledFutureTask o2) {
return o1.compareTo(o2);
}
};
private static final long START_TIME = System.nanoTime();
static final Runnable WAKEUP_TASK = new Runnable() {
@Override
public void run() { } // Do nothing
};
PriorityQueue> scheduledTaskQueue;
long nextTaskId;
protected AbstractScheduledEventExecutor() {
}
protected AbstractScheduledEventExecutor(EventExecutorGroup parent) {
super(parent);
}
/**
* Get the current time in nanoseconds by this executor's clock. This is not the same as {@link System#nanoTime()}
* for two reasons:
*
*
* - We apply a fixed offset to the {@link System#nanoTime() nanoTime}
* - Implementations (in particular EmbeddedEventLoop) may use their own time source so they can control time
* for testing purposes.
*
*/
protected long getCurrentTimeNanos() {
return defaultCurrentTimeNanos();
}
/**
* @deprecated Use the non-static {@link #getCurrentTimeNanos()} instead.
*/
@Deprecated
protected static long nanoTime() {
return defaultCurrentTimeNanos();
}
static long defaultCurrentTimeNanos() {
return System.nanoTime() - START_TIME;
}
static long deadlineNanos(long nanoTime, long delay) {
long deadlineNanos = nanoTime + delay;
// Guard against overflow
return deadlineNanos < 0 ? Long.MAX_VALUE : deadlineNanos;
}
/**
* Given an arbitrary deadline {@code deadlineNanos}, calculate the number of nano seconds from now
* {@code deadlineNanos} would expire.
* @param deadlineNanos An arbitrary deadline in nano seconds.
* @return the number of nano seconds from now {@code deadlineNanos} would expire.
*/
protected static long deadlineToDelayNanos(long deadlineNanos) {
return ScheduledFutureTask.deadlineToDelayNanos(defaultCurrentTimeNanos(), deadlineNanos);
}
/**
* The initial value used for delay and computations based upon a monatomic time source.
* @return initial value used for delay and computations based upon a monatomic time source.
*/
protected static long initialNanoTime() {
return START_TIME;
}
PriorityQueue> scheduledTaskQueue() {
if (scheduledTaskQueue == null) {
scheduledTaskQueue = new DefaultPriorityQueue>(
SCHEDULED_FUTURE_TASK_COMPARATOR,
// Use same initial capacity as java.util.PriorityQueue
11);
}
return scheduledTaskQueue;
}
private static boolean isNullOrEmpty(Queue> queue) {
return queue == null || queue.isEmpty();
}
/**
* Cancel all scheduled tasks.
*
* This method MUST be called only when {@link #inEventLoop()} is {@code true}.
*/
protected void cancelScheduledTasks() {
assert inEventLoop();
PriorityQueue> scheduledTaskQueue = this.scheduledTaskQueue;
if (isNullOrEmpty(scheduledTaskQueue)) {
return;
}
final ScheduledFutureTask[] scheduledTasks =
scheduledTaskQueue.toArray(new ScheduledFutureTask[0]);
for (ScheduledFutureTask task: scheduledTasks) {
task.cancelWithoutRemove(false);
}
scheduledTaskQueue.clearIgnoringIndexes();
}
/**
* @see #pollScheduledTask(long)
*/
protected final Runnable pollScheduledTask() {
return pollScheduledTask(getCurrentTimeNanos());
}
/**
* Return the {@link Runnable} which is ready to be executed with the given {@code nanoTime}.
* You should use {@link #getCurrentTimeNanos()} to retrieve the correct {@code nanoTime}.
*/
protected final Runnable pollScheduledTask(long nanoTime) {
assert inEventLoop();
ScheduledFutureTask scheduledTask = peekScheduledTask();
if (scheduledTask == null || scheduledTask.deadlineNanos() - nanoTime > 0) {
return null;
}
scheduledTaskQueue.remove();
scheduledTask.setConsumed();
return scheduledTask;
}
/**
* Return the nanoseconds until the next scheduled task is ready to be run or {@code -1} if no task is scheduled.
*/
protected final long nextScheduledTaskNano() {
ScheduledFutureTask scheduledTask = peekScheduledTask();
return scheduledTask != null ? scheduledTask.delayNanos() : -1;
}
/**
* Return the deadline (in nanoseconds) when the next scheduled task is ready to be run or {@code -1}
* if no task is scheduled.
*/
protected final long nextScheduledTaskDeadlineNanos() {
ScheduledFutureTask scheduledTask = peekScheduledTask();
return scheduledTask != null ? scheduledTask.deadlineNanos() : -1;
}
final ScheduledFutureTask peekScheduledTask() {
Queue> scheduledTaskQueue = this.scheduledTaskQueue;
return scheduledTaskQueue != null ? scheduledTaskQueue.peek() : null;
}
/**
* Returns {@code true} if a scheduled task is ready for processing.
*/
protected final boolean hasScheduledTasks() {
ScheduledFutureTask scheduledTask = peekScheduledTask();
return scheduledTask != null && scheduledTask.deadlineNanos() <= getCurrentTimeNanos();
}
@Override
public ScheduledFuture schedule(Runnable command, long delay, TimeUnit unit) {
ObjectUtil.checkNotNull(command, "command");
ObjectUtil.checkNotNull(unit, "unit");
if (delay < 0) {
delay = 0;
}
validateScheduled0(delay, unit);
return schedule(new ScheduledFutureTask(
this,
command,
deadlineNanos(getCurrentTimeNanos(), unit.toNanos(delay))));
}
@Override
public ScheduledFuture schedule(Callable callable, long delay, TimeUnit unit) {
ObjectUtil.checkNotNull(callable, "callable");
ObjectUtil.checkNotNull(unit, "unit");
if (delay < 0) {
delay = 0;
}
validateScheduled0(delay, unit);
return schedule(new ScheduledFutureTask(
this, callable, deadlineNanos(getCurrentTimeNanos(), unit.toNanos(delay))));
}
@Override
public ScheduledFuture scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit) {
ObjectUtil.checkNotNull(command, "command");
ObjectUtil.checkNotNull(unit, "unit");
if (initialDelay < 0) {
throw new IllegalArgumentException(
String.format("initialDelay: %d (expected: >= 0)", initialDelay));
}
if (period <= 0) {
throw new IllegalArgumentException(
String.format("period: %d (expected: > 0)", period));
}
validateScheduled0(initialDelay, unit);
validateScheduled0(period, unit);
return schedule(new ScheduledFutureTask(
this, command, deadlineNanos(getCurrentTimeNanos(), unit.toNanos(initialDelay)), unit.toNanos(period)));
}
@Override
public ScheduledFuture scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit) {
ObjectUtil.checkNotNull(command, "command");
ObjectUtil.checkNotNull(unit, "unit");
if (initialDelay < 0) {
throw new IllegalArgumentException(
String.format("initialDelay: %d (expected: >= 0)", initialDelay));
}
if (delay <= 0) {
throw new IllegalArgumentException(
String.format("delay: %d (expected: > 0)", delay));
}
validateScheduled0(initialDelay, unit);
validateScheduled0(delay, unit);
return schedule(new ScheduledFutureTask(
this, command, deadlineNanos(getCurrentTimeNanos(), unit.toNanos(initialDelay)), -unit.toNanos(delay)));
}
@SuppressWarnings("deprecation")
private void validateScheduled0(long amount, TimeUnit unit) {
validateScheduled(amount, unit);
}
/**
* Sub-classes may override this to restrict the maximal amount of time someone can use to schedule a task.
*
* @deprecated will be removed in the future.
*/
@Deprecated
protected void validateScheduled(long amount, TimeUnit unit) {
// NOOP
}
final void scheduleFromEventLoop(final ScheduledFutureTask task) {
// nextTaskId a long and so there is no chance it will overflow back to 0
scheduledTaskQueue().add(task.setId(++nextTaskId));
}
private ScheduledFuture schedule(final ScheduledFutureTask task) {
if (inEventLoop()) {
scheduleFromEventLoop(task);
} else {
final long deadlineNanos = task.deadlineNanos();
// task will add itself to scheduled task queue when run if not expired
if (beforeScheduledTaskSubmitted(deadlineNanos)) {
execute(task);
} else {
lazyExecute(task);
// Second hook after scheduling to facilitate race-avoidance
if (afterScheduledTaskSubmitted(deadlineNanos)) {
execute(WAKEUP_TASK);
}
}
}
return task;
}
final void removeScheduled(final ScheduledFutureTask task) {
assert task.isCancelled();
if (inEventLoop()) {
scheduledTaskQueue().removeTyped(task);
} else {
// task will remove itself from scheduled task queue when it runs
lazyExecute(task);
}
}
/**
* Called from arbitrary non-{@link EventExecutor} threads prior to scheduled task submission.
* Returns {@code true} if the {@link EventExecutor} thread should be woken immediately to
* process the scheduled task (if not already awake).
*
* If {@code false} is returned, {@link #afterScheduledTaskSubmitted(long)} will be called with
* the same value after the scheduled task is enqueued, providing another opportunity
* to wake the {@link EventExecutor} thread if required.
*
* @param deadlineNanos deadline of the to-be-scheduled task
* relative to {@link AbstractScheduledEventExecutor#getCurrentTimeNanos()}
* @return {@code true} if the {@link EventExecutor} thread should be woken, {@code false} otherwise
*/
protected boolean beforeScheduledTaskSubmitted(long deadlineNanos) {
return true;
}
/**
* See {@link #beforeScheduledTaskSubmitted(long)}. Called only after that method returns false.
*
* @param deadlineNanos relative to {@link AbstractScheduledEventExecutor#getCurrentTimeNanos()}
* @return {@code true} if the {@link EventExecutor} thread should be woken, {@code false} otherwise
*/
protected boolean afterScheduledTaskSubmitted(long deadlineNanos) {
return true;
}
}
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