topping a scheduled task does not stop other tasks with the same exec…

…ution time. (#44)

.github/workflows/build.yaml

@@ -20,10 +20,9 @@ jobs:
       max-parallel: 100
       matrix:
         spring_boot_version:
-          - 3.1.2
-          - 3.0.7
-          - 2.7.13
-          - 2.6.15
+          - 3.1.6
+          - 3.0.13
+          - 2.7.18
     env:
       SPRING_BOOT_VERSION: ${{ matrix.spring_boot_version }}
     steps:

CHANGELOG.md

@@ -5,6 +5,18 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.12.2] - 2024-01-05
+
+### Fixed
+
+* Stopping a scheduled task does not stop other tasks with the same execution time.
+
+## [1.12.1] - 2023-10-29
+
+### Added
+
+* UuidUtils.add method.
+
 ## [1.12.1] - 2023-10-29
 
 ### Added

build.libraries.gradle

@@ -1,17 +1,17 @@
 ext {
-    springBootVersion = "${System.getenv("SPRING_BOOT_VERSION") ?: "2.6.15"}"
+    springBootVersion = "${System.getenv("SPRING_BOOT_VERSION") ?: "2.7.18"}"
 
     libraries = [
             // version defined
             awaitility            : "org.awaitility:awaitility:4.2.0",
+            guava                 : 'com.google.guava:guava:33.0.0-jre',
             jakartaValidationApi  : 'jakarta.validation:jakarta.validation-api:3.0.2',
             javaxValidationApi    : "javax.validation:validation-api:2.0.1.Final",
             spockCore             : "org.spockframework:spock-core:2.3-groovy-4.0",
             springBootDependencies: "org.springframework.boot:spring-boot-dependencies:${springBootVersion}",
 
             // versions managed by spring-boot-dependencies platform
             commonsLang3          : "org.apache.commons:commons-lang3",
-            guava                 : 'com.google.guava:guava:31.1-jre',
             junitJupiter          : "org.junit.jupiter:junit-jupiter",
             logbackClassic        : "ch.qos.logback:logback-classic",
             lombok                : "org.projectlombok:lombok",

gradle.properties

@@ -1 +1 @@
-version=1.12.1
+version=1.12.2

tw-base-utils/build.gradle

@@ -16,6 +16,7 @@ dependencies {
     implementation libraries.jacksonDatabind
     implementation libraries.jacksonJsr310
     implementation libraries.jacksonJdk8
+    implementation libraries.guava
 
     testImplementation libraries.awaitility
     testImplementation libraries.guava

tw-base-utils/src/main/java/com/transferwise/common/baseutils/concurrency/DefaultExecutorServicesProvider.java

@@ -22,7 +22,7 @@ public void afterPropertiesSet() {
     try {
       if (!initialized) {
         executorService = Executors.newCachedThreadPool(new CountingThreadFactory("tw-base"));
-        scheduledTaskExecutor = new SimpleScheduledTaskExecutor(null, executorService);
+        scheduledTaskExecutor = new SimpleScheduledTaskExecutor("gste", executorService);
         scheduledTaskExecutor.start();
         initialized = true;
       }

tw-base-utils/src/main/java/com/transferwise/common/baseutils/concurrency/SimpleScheduledTaskExecutor.java

@@ -1,8 +1,10 @@
 package com.transferwise.common.baseutils.concurrency;
 
+import com.google.common.util.concurrent.RateLimiter;
 import com.transferwise.common.baseutils.ExceptionUtils;
 import java.time.Clock;
 import java.time.Duration;
+import java.time.Instant;
 import java.util.concurrent.DelayQueue;
 import java.util.concurrent.Delayed;
 import java.util.concurrent.ExecutorService;
@@ -16,14 +18,15 @@
 @Slf4j
 public class SimpleScheduledTaskExecutor implements ScheduledTaskExecutor {
 
-  private ExecutorService executorService;
-  private DelayQueue<ScheduledTask> taskQueue;
+  private final ExecutorService executorService;
+  private final DelayQueue<ScheduledTask> taskQueue;
   @SuppressWarnings("checkstyle:MagicNumber")
   private Duration tick = Duration.ofMillis(50);
   private Clock clock;
-  private Lock stateLock;
-  private Condition stateCondition;
-  private AtomicInteger workingTasksCount;
+  private final Lock stateLock;
+  private final Condition stateCondition;
+  private final AtomicInteger workingTasksCount;
+  private final RateLimiter nextTaskLoggingRateLimiter = RateLimiter.create(1);
 
   private volatile boolean started;
   private volatile boolean stopRequested;
@@ -77,6 +80,14 @@ public void start() {
     executorService.submit(() -> {
       while (!stopRequested) {
         ScheduledTask scheduledTask = ExceptionUtils.doUnchecked(() -> taskQueue.poll(tick.toMillis(), TimeUnit.MILLISECONDS));
+        if (log.isDebugEnabled() && scheduledTask == null) {
+          if (nextTaskLoggingRateLimiter.tryAcquire()) {
+            var nextScheduledTask = taskQueue.peek();
+            if (nextScheduledTask != null) {
+              log.debug("Next scheduled task is executed at '{}'.", Instant.ofEpochMilli(nextScheduledTask.nextExecutionTime));
+            }
+          }
+        }
         if (scheduledTask != null && !stopRequested) {
           executorService.submit(scheduledTask::execute);
         }
@@ -130,14 +141,14 @@ private long currentTimeMillis() {
 
   private static class ScheduledTask implements Delayed {
 
-    private Runnable runnable;
-    private TaskHandle taskHandle;
-    private Duration period;
+    private final Runnable runnable;
+    private final TaskHandle taskHandle;
+    private final Duration period;
     private long nextExecutionTime;
-    private SimpleScheduledTaskExecutor taskExecutor;
+    private final SimpleScheduledTaskExecutor taskExecutor;
 
-    private Lock stateLock;
-    private Condition stateCondition;
+    private final Lock stateLock;
+    private final Condition stateCondition;
 
     private volatile boolean stopRequested;
     private volatile boolean working;
@@ -148,45 +159,7 @@ private ScheduledTask(SimpleScheduledTaskExecutor taskExecutor, Runnable task, D
       this.stateLock = new ReentrantLock();
       this.stateCondition = stateLock.newCondition();
       this.taskExecutor = taskExecutor;
-
-      createTaskHandler();
-    }
-
-    private void createTaskHandler() {
-      this.taskHandle = new TaskHandle() {
-        @Override
-        public void stop() {
-          LockUtils.withLock(stateLock, () -> {
-            stopRequested = true;
-            taskExecutor.taskQueue.remove(ScheduledTask.this);
-            stateCondition.signalAll();
-          });
-        }
-
-        @Override
-        public boolean hasStopped() {
-          return LockUtils.withLock(stateLock, () -> stopRequested() && !working);
-        }
-
-        @Override
-        public boolean waitUntilStopped(Duration waitTime) {
-          long start = taskExecutor.currentTimeMillis();
-          while (taskExecutor.currentTimeMillis() >= start + waitTime.toMillis()) {
-            if (hasStopped()) {
-              return true;
-            }
-            LockUtils.withLock(stateLock, () -> ExceptionUtils.doUnchecked(() -> {
-              boolean ignored = stateCondition.await(start - taskExecutor.currentTimeMillis() + waitTime.toMillis(), TimeUnit.MILLISECONDS);
-            }));
-          }
-          return hasStopped();
-        }
-
-        @Override
-        public boolean isWorking() {
-          return working;
-        }
-      };
+      this.taskHandle = new DefaultTaskHandle();
     }
 
     private void execute() {
@@ -236,10 +209,7 @@ public int compareTo(Delayed o) {
 
     @Override
     public boolean equals(Object o) {
-      if (o instanceof Delayed) {
-        return compareTo((Delayed) o) == 0;
-      }
-      return false;
+      return this == o;
     }
 
     @Override
@@ -250,5 +220,44 @@ public int hashCode() {
     protected boolean stopRequested() {
       return stopRequested || taskExecutor.stopRequested;
     }
+
+    class DefaultTaskHandle implements TaskHandle {
+
+      @Override
+      public void stop() {
+        LockUtils.withLock(stateLock, () -> {
+          stopRequested = true;
+          // This is O(n)
+          // TODO: Think if we should just leave the things into the queue.
+          taskExecutor.taskQueue.remove(ScheduledTask.this);
+          stateCondition.signalAll();
+        });
+      }
+
+      @Override
+      public boolean hasStopped() {
+        return LockUtils.withLock(stateLock, () -> stopRequested() && !working);
+      }
+
+      @Override
+      public boolean waitUntilStopped(Duration waitTime) {
+        long start = taskExecutor.currentTimeMillis();
+        while (taskExecutor.currentTimeMillis() >= start + waitTime.toMillis()) {
+          if (hasStopped()) {
+            return true;
+          }
+          LockUtils.withLock(stateLock, () -> ExceptionUtils.doUnchecked(() -> {
+            boolean ignored = stateCondition.await(start - taskExecutor.currentTimeMillis() + waitTime.toMillis(), TimeUnit.MILLISECONDS);
+          }));
+        }
+        return hasStopped();
+      }
+
+      @Override
+      public boolean isWorking() {
+        return working;
+      }
+
+    }
   }
 }

tw-base-utils/src/test/java/com/transferwise/common/baseutils/concurrency/SimpleScheduledTaskExecutorTest.java

@@ -3,19 +3,23 @@
 import static org.awaitility.Awaitility.await;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import com.transferwise.common.baseutils.BaseTest;
 import com.transferwise.common.baseutils.clock.TestClock;
+import com.transferwise.common.baseutils.concurrency.ScheduledTaskExecutor.TaskHandle;
 import java.time.Duration;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Map;
-import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
 import lombok.SneakyThrows;
 import lombok.extern.slf4j.Slf4j;
 import org.junit.jupiter.api.Disabled;
@@ -211,4 +215,46 @@ public void testIfSchedulingOnceWorks() {
 
     scheduledTaskExecutor.stop();
   }
+
+  /*
+    Covers a bug, where ScheduledTask's equals method was considering tasks with the same execution time as equals.
+
+    Stopping one task, stopped all other tasks with the same execution time as well.
+   */
+  @Test
+  public void testIfStoppingTasksWorksCorrectly() {
+    var testClock = new TestClock();
+    Map<Long, Boolean> results = new ConcurrentHashMap<>();
+
+    var executorService = Executors.newCachedThreadPool();
+    var scheduledTaskExecutor = new SimpleScheduledTaskExecutor("test", executorService).setTick(Duration.ofMillis(5))
+        .setClock(testClock);
+    scheduledTaskExecutor.start();
+
+    List<TaskHandle> taskHandleList = new ArrayList<>();
+    var finishedCount = new AtomicInteger();
+    for (int i = 0; i < 100; i++) {
+      long finalI = i;
+      taskHandleList.add(scheduledTaskExecutor.scheduleOnce(
+          () -> {
+            results.put(finalI, Boolean.TRUE);
+            finishedCount.incrementAndGet();
+          }, Duration.ofSeconds(1))
+      );
+    }
+
+    taskHandleList.get(50).stop();
+    testClock.tick(Duration.ofMillis(1001));
+
+    await().until(() -> finishedCount.get() == 99);
+
+    assertNull(results.get(50L));
+    for (long i = 0; i < 100; i++) {
+      if (i != 50) {
+        assertNotNull(results.get(i));
+      }
+    }
+
+    scheduledTaskExecutor.stop();
+  }
 }