| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF 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 |
| * |
| * http://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 org.apache.ratis.util; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.util.concurrent.Executors; |
| import java.util.concurrent.ScheduledExecutorService; |
| import java.util.concurrent.ScheduledThreadPoolExecutor; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicReference; |
| import java.util.function.Consumer; |
| import java.util.function.Supplier; |
| |
| public final class TimeoutScheduler { |
| public static final Logger LOG = LoggerFactory.getLogger(TimeoutScheduler.class); |
| |
| private static final TimeDuration DEFAULT_GRACE_PERIOD = TimeDuration.valueOf(1, TimeUnit.MINUTES); |
| |
| public static TimeoutScheduler newInstance(int numThreads) { |
| return new TimeoutScheduler(numThreads); |
| } |
| |
| /** When there is no tasks, the time period to wait before shutting down the scheduler. */ |
| private final AtomicReference<TimeDuration> gracePeriod = new AtomicReference<>(DEFAULT_GRACE_PERIOD); |
| |
| /** The number of scheduled tasks. */ |
| private int numTasks = 0; |
| /** The scheduleID for each task */ |
| private int scheduleID = 0; |
| |
| private final int numThreads; |
| private volatile ScheduledExecutorService scheduler = null; |
| |
| private TimeoutScheduler(int numThreads) { |
| this.numThreads = numThreads; |
| } |
| |
| public int getNumThreads() { |
| final ScheduledExecutorService s = scheduler; |
| return s instanceof ScheduledThreadPoolExecutor? ((ScheduledThreadPoolExecutor)s).getCorePoolSize(): numThreads; |
| } |
| |
| TimeDuration getGracePeriod() { |
| return gracePeriod.get(); |
| } |
| |
| void setGracePeriod(TimeDuration gracePeriod) { |
| this.gracePeriod.set(gracePeriod); |
| } |
| |
| synchronized boolean hasScheduler() { |
| return scheduler != null; |
| } |
| |
| /** |
| * Schedule a timeout task. |
| * |
| * @param timeout the timeout value. |
| * @param task the task to run when timeout. |
| * @param errorHandler to handle the error, if there is any. |
| */ |
| public <THROWABLE extends Throwable> void onTimeout( |
| TimeDuration timeout, CheckedRunnable<THROWABLE> task, Consumer<THROWABLE> errorHandler) { |
| onTimeout(timeout, sid -> { |
| LOG.debug("run a task: sid {}", sid); |
| try { |
| task.run(); |
| } catch(Throwable t) { |
| errorHandler.accept((THROWABLE) t); |
| } finally { |
| onTaskCompleted(); |
| } |
| }); |
| } |
| |
| private synchronized void onTimeout(TimeDuration timeout, Consumer<Integer> toSchedule) { |
| if (scheduler == null) { |
| Preconditions.assertTrue(numTasks == 0); |
| LOG.debug("Initialize scheduler"); |
| scheduler = Executors.newScheduledThreadPool(numThreads); |
| } |
| numTasks++; |
| final int sid = scheduleID++; |
| |
| LOG.debug("schedule a task: timeout {}, sid {}", timeout, sid); |
| schedule(scheduler, () -> toSchedule.accept(sid), () -> "task #" + sid, timeout); |
| } |
| |
| private synchronized void onTaskCompleted() { |
| if (--numTasks == 0) { |
| final int sid = scheduleID; |
| final TimeDuration grace = getGracePeriod(); |
| LOG.debug("Schedule a shutdown task: grace {}, sid {}", grace, sid); |
| schedule(scheduler, () -> tryShutdownScheduler(sid), () -> "shutdown task #" + sid, grace); |
| } |
| } |
| |
| static void schedule(ScheduledExecutorService service, Runnable task, Supplier<String> name, TimeDuration timeDuration) { |
| service.schedule(LogUtils.newRunnable(LOG, task, name), |
| timeDuration.getDuration(), timeDuration.getUnit()); |
| } |
| |
| private synchronized void tryShutdownScheduler(int sid) { |
| if (sid == scheduleID) { |
| // No new tasks submitted, shutdown the scheduler. |
| LOG.debug("shutdown scheduler: sid {}", sid); |
| scheduler.shutdown(); |
| scheduler = null; |
| } else { |
| LOG.debug("shutdown cancelled: scheduleID has changed from {} to {}", sid, scheduleID); |
| } |
| } |
| |
| /** When timeout, run the task. Log the error, if there is any. */ |
| public void onTimeout(TimeDuration timeout, CheckedRunnable<?> task, Logger log, Supplier<String> errorMessage) { |
| onTimeout(timeout, task, t -> log.error(errorMessage.get(), t)); |
| } |
| } |