关于动态定时任务的解决方案。

之前做定时任务都是用 Scheduled注解来实现，如果需要动态的配置，则不能满足这种需求。查询资料知道这种可以用时间轮算法来实现。大概就是模拟时间表盘来做任务。

 具体java实现：

  1 package com.education.task.provider;
  2 
  3 import org.slf4j.Logger;
  4 import org.slf4j.LoggerFactory;
  5 
  6 import java.util.HashSet;
  7 import java.util.Map;
  8 import java.util.Set;
  9 import java.util.concurrent.ConcurrentHashMap;
 10 import java.util.concurrent.ExecutorService;
 11 import java.util.concurrent.TimeUnit;
 12 import java.util.concurrent.atomic.AtomicBoolean;
 13 import java.util.concurrent.atomic.AtomicInteger;
 14 import java.util.concurrent.locks.Condition;
 15 import java.util.concurrent.locks.Lock;
 16 import java.util.concurrent.locks.ReentrantLock;
 17 
 18 /**
 19  * @author pengbenlei
 20  * @company leenleda
 21  * @date 2020/12/21 9:53
 22  * @description 时间轮算法调度任务
 23  */
 24 public class RingBufferWheel {
 25 
 26     private Logger logger = LoggerFactory.getLogger(RingBufferWheel.class);
 27     /**
 28      * default ring buffer size
 29      */
 30     private static final int STATIC_RING_SIZE = 60;
 31 
 32     private Object[] ringBuffer;
 33 
 34     private int bufferSize;
 35 
 36     /**
 37      * business thread pool
 38      */
 39     private ExecutorService executorService;
 40 
 41     private volatile int size = 0;
 42 
 43     /***
 44      * task stop sign
 45      */
 46     private volatile boolean stop = false;
 47 
 48     /**
 49      * task start sign
 50      */
 51     private volatile AtomicBoolean start = new AtomicBoolean(false);
 52 
 53     /**
 54      * total tick times
 55      */
 56     private AtomicInteger tick = new AtomicInteger();
 57 
 58     private Lock lock = new ReentrantLock();
 59     private Condition condition = lock.newCondition();
 60 
 61     private AtomicInteger taskId = new AtomicInteger();
 62     private Map taskMap = new ConcurrentHashMap<>(16);
 63 
 64     /**
 65      * Create a new delay task ring buffer by default size
 66      *
 67      * @param executorService the business thread pool
 68      */
 69     public RingBufferWheel(ExecutorService executorService) {
 70         this.executorService = executorService;
 71         this.bufferSize = STATIC_RING_SIZE;
 72         this.ringBuffer = new Object[bufferSize];
 73     }
 74 
 75 
 76     /**
 77      * Create a new delay task ring buffer by custom buffer size
 78      *
 79      * @param executorService the business thread pool
 80      * @param bufferSize      custom buffer size
 81      */
 82     public RingBufferWheel(ExecutorService executorService, int bufferSize) {
 83         this(executorService);
 84 
 85         if (!powerOf2(bufferSize)) {
 86             throw new RuntimeException("bufferSize=[" + bufferSize + "] must be a power of 2");
 87         }
 88         this.bufferSize = bufferSize;
 89         this.ringBuffer = new Object[bufferSize];
 90     }
 91 
 92     /**
 93      * Add a task into the ring buffer(thread safe)
 94      *
 95      * @param task business task extends {@link BusinessTask}
 96      */
 97     public int addTask(BusinessTask task) {
 98         int key = task.getKey();
 99         int id;
100 
101         try {
102             lock.lock();
103             int index = mod(key, bufferSize);
104             task.setIndex(index);
105             Set tasks = get(index);
106 
107             int cycleNum = cycleNum(key, bufferSize);
108             if (tasks != null) {
109                 task.setCycleNum(cycleNum);
110                 tasks.add(task);
111             } else {
112                 task.setIndex(index);
113                 task.setCycleNum(cycleNum);
114                 Set sets = new HashSet<>();
115                 sets.add(task);
116                 put(key, sets);
117             }
118             id = taskId.incrementAndGet();
119             task.setTaskId(id);
120             taskMap.put(id, task);
121             size++;
122         } finally {
123             lock.unlock();
124         }
125 
126         start();
127 
128         return id;
129     }
130 
131 
132     /**
133      * Cancel task by taskId
134      *
135      * @param id unique id through {@link #addTask(BusinessTask)}
136      * @return
137      */
138     public boolean cancel(int id) {
139 
140         boolean flag = false;
141         Set tempTask = new HashSet<>();
142 
143         try {
144             lock.lock();
145             BusinessTask task = taskMap.get(id);
146             if (task == null) {
147                 return false;
148             }
149 
150             Set tasks = get(task.getIndex());
151             for (BusinessTask tk : tasks) {
152                 if (tk.getKey() == task.getKey() && tk.getCycleNum() == task.getCycleNum()) {
153                     size--;
154                     flag = true;
155                     taskMap.remove(id);
156                 } else {
157                     tempTask.add(tk);
158                 }
159 
160             }
161             //update origin data
162             ringBuffer[task.getIndex()] = tempTask;
163         } finally {
164             lock.unlock();
165         }
166 
167         return flag;
168     }
169 
170     /**
171      * Thread safe
172      *
173      * @return the size of ring buffer
174      */
175     public int taskSize() {
176         return size;
177     }
178 
179     /**
180      * Same with method {@link #taskSize}
181      *
182      * @return
183      */
184     public int taskMapSize() {
185         return taskMap.size();
186     }
187 
188     /**
189      * Start background thread to consumer wheel timer, it will always run until you call method {@link #stop}
190      */
191     public void start() {
192         if (!start.get()) {
193 
194             if (start.compareAndSet(start.get(), true)) {
195                 logger.info("Delay task is starting");
196                 Thread job = new Thread(new TriggerJob());
197                 job.setName("consumer RingBuffer thread");
198                 job.start();
199                 start.set(true);
200             }
201 
202         }
203     }
204 
205     /**
206      * Stop consumer ring buffer thread
207      *
208      * @param force True will force close consumer thread and discard all pending tasks
209      *              otherwise the consumer thread waits for all tasks to completes before closing.
210      */
211     public void stop(boolean force) {
212         if (force) {
213             logger.info("Delay task is forced stop");
214             stop = true;
215             executorService.shutdownNow();
216         } else {
217             logger.info("Delay task is stopping");
218             if (taskSize() > 0) {
219                 try {
220                     lock.lock();
221                     condition.await();
222                     stop = true;
223                 } catch (InterruptedException e) {
224                     logger.error("InterruptedException", e);
225                 } finally {
226                     lock.unlock();
227                 }
228             }
229             executorService.shutdown();
230         }
231 
232 
233     }
234 
235 
236     private Set get(int index) {
237         return (Set) ringBuffer[index];
238     }
239 
240     private void put(int key, Set tasks) {
241         int index = mod(key, bufferSize);
242         ringBuffer[index] = tasks;
243     }
244 
245     /**
246      * Remove and get task list.
247      *
248      * @param key
249      * @return task list
250      */
251     private Set remove(int key) {
252         Set tempTask = new HashSet<>();
253         Set result = new HashSet<>();
254 
255         Set tasks = (Set) ringBuffer[key];
256         if (tasks == null) {
257             return result;
258         }
259 
260         for (BusinessTask task : tasks) {
261             if (task.getCycleNum() == 0) {
262                 result.add(task);
263 
264                 size2Notify();
265             } else {
266                 // decrement 1 cycle number and update origin data
267                 task.setCycleNum(task.getCycleNum() - 1);
268                 tempTask.add(task);
269             }
270             // remove task, and free the memory.
271             taskMap.remove(task.getTaskId());
272         }
273 
274         //update origin data
275         ringBuffer[key] = tempTask;
276 
277         return result;
278     }
279 
280     private void size2Notify() {
281         try {
282             lock.lock();
283             size--;
284             if (size == 0) {
285                 condition.signal();
286             }
287         } finally {
288             lock.unlock();
289         }
290     }
291 
292     private boolean powerOf2(int target) {
293         if (target < 0) {
294             return false;
295         }
296         int value = target & (target - 1);
297         if (value != 0) {
298             return false;
299         }
300 
301         return true;
302     }
303 
304     private int mod(int target, int mod) {
305         // equals target % mod
306         target = target + tick.get();
307         return target & (mod - 1);
308     }
309 
310     private int cycleNum(int target, int mod) {
311         //equals target/mod
312         return target >> Integer.bitCount(mod - 1);
313     }
314 
315 
316 
317     private class TriggerJob implements Runnable {
318 
319         @Override
320         public void run() {
321             int index = 0;
322             while (!stop) {
323                 try {
324                     System.out.println(index);
325                     Set tasks = remove(index);
326                     for (BusinessTask task : tasks) {
327                         executorService.submit(task);
328                     }
329 
330                     if (++index > bufferSize - 1) {
331                         index = 0;
332                     }
333 
334                     //Total tick number of records
335                     tick.incrementAndGet();
336                     TimeUnit.SECONDS.sleep(1);
337 
338                 } catch (Exception e) {
339                     logger.error("Exception", e);
340                 }
341 
342             }
343 
344             logger.info("Delay task has stopped");
345         }
346     }
347 }

 1 package com.education.task.provider;
 2 
 3 import lombok.Getter;
 4 import lombok.Setter;
 5 
 6 /**
 7  * @author pengbenlei
 8  * @company leenleda
 9  * @date 2020/12/21 10:49
10  * @description
11  */
12 @Getter
13 @Setter
14 public abstract class BusinessTask extends Thread {
15 
16     /**
17      * 所在位置
18      */
19     private int index;
20 
21     /**
22      * cycleNum 轮盘上的圈数
23      */
24     private int cycleNum;
25 
26     /**
27      * 轮盘的刻度
28      */
29     private int key;
30 
31     /**
32      * The unique ID of the task
33      */
34     private int taskId;
35 
36     @Override
37     public void run() {
38     }
39 
40 }

测试调用：

1     public static class Job extends BusinessTask{
2         @Override
3         public void run() {
4             System.out.println("12346");
5         }
6     }

1 SpringApplication.run(TaskProviderApplication.class, args);
2         RingBufferWheel ringBufferWheel = new RingBufferWheel( Executors.newFixedThreadPool(2));
3         for (int i = 0; i < 2; i++) {
4             BusinessTask job = new Job();
5             job.setKey(10);
6             job.setCycleNum(i);
7             ringBufferWheel.addTask(job);
8         }

后续，后来听朋友说有个开源项目 xxl-job ： https://github.com/xuxueli/xxl-job，真香。功能比较全。