Add EvictionConfig.isEvictionThread()

- Use simpler Thread constructor.
- Handy for advanced use and testing.

Author: garydgregory

src/changes/changes.xml

@@ -50,6 +50,7 @@ The <action> type attribute can be add,update,fix,remove.
       <!-- FIX -->
       <!-- ADD -->
       <action type="add" dev="ggregory" due-to="Philip Helger, Gary Gregory" issue="POOL-430">Make AbandonedConfig.DEFAULT_REMOVE_ABANDONED_TIMEOUT_DURATION public.</action>
+      <action type="add" dev="ggregory" due-to="Gary Gregory">Add EvictionConfig.isEvictionThread().</action>
       <!-- UPDATE -->
       <action type="update" dev="ggregory" due-to="Gary Gregory">Bump org.apache.commons:commons-parent from 93 to 95.</action>
     </release>

src/main/java/org/apache/commons/pool2/impl/EvictionConfig.java

@@ -31,8 +31,25 @@
 public class EvictionConfig {
 
     private static final Duration MAX_DURATION = Duration.ofMillis(Long.MAX_VALUE);
+
+    /**
+     * The eviction thread name.
+     */
+    static final String THREAD_NAME = "commons-pool-evictor";
+
+    /**
+     * Tests whether the current thread is the eviction thread.
+     *
+     * @return whether the current thread is the eviction thread.
+     * @since 2.14.0
+     */
+    public static boolean isEvictionThread() {
+        return Thread.currentThread().getName().equals(THREAD_NAME);
+    }
+
     private final Duration idleEvictDuration;
     private final Duration idleSoftEvictDuration;
+
     private final int minIdle;
 
     /**

src/main/java/org/apache/commons/pool2/impl/EvictionTimer.java

@@ -55,13 +55,12 @@ private static final class EvictorThreadFactory implements ThreadFactory {
 
         @Override
         public Thread newThread(final Runnable runnable) {
-            final Thread thread = new Thread(null, runnable, "commons-pool-evictor");
+            final Thread thread = new Thread(runnable, EvictionConfig.THREAD_NAME);
             thread.setDaemon(true); // POOL-363 - Required for applications using Runtime.addShutdownHook().
             AccessController.doPrivileged((PrivilegedAction<Void>) () -> {
                 thread.setContextClassLoader(EvictorThreadFactory.class.getClassLoader());
                 return null;
             });
-
             return thread;
         }
     }
@@ -132,7 +131,7 @@ public void run() {
     /** Executor instance */
     private static ScheduledThreadPoolExecutor executor; //@GuardedBy("EvictionTimer.class")
 
-    /** Keys are weak references to tasks, values are runners managed by executor. */
+    /** Keys are weak references to pools, values are runners managed by executor. */
     private static final HashMap<
         WeakReference<BaseGenericObjectPool<?>.Evictor>,
         WeakRunner<BaseGenericObjectPool<?>.Evictor>> TASK_MAP = new HashMap<>(); // @GuardedBy("EvictionTimer.class")
@@ -175,6 +174,8 @@ static ScheduledThreadPoolExecutor getExecutor() {
     }
 
     /**
+     * Gets the number of eviction tasks under management.
+     *
      * @return the number of eviction tasks under management.
      */
     static synchronized int getNumTasks() {
@@ -191,7 +192,7 @@ static HashMap<WeakReference<BaseGenericObjectPool<?>.Evictor>, WeakRunner<BaseG
     }
 
     /**
-     * Removes evictor from the task set and executor.
+     * Removes an evictor from the task set and executor.
      * Only called when holding the class lock.
      *
      * @param evictor Eviction task to remove
@@ -213,22 +214,20 @@ private static void remove(final BaseGenericObjectPool<?>.Evictor evictor) {
      * to cancel the task to prevent memory and/or thread leaks in application
      * server environments.
      *
-     * @param task      Task to be scheduled.
+     * @param pool      Task to be scheduled.
      * @param delay     Duration before task is executed.
      * @param period    Duration between executions.
      */
-    static synchronized void schedule(
-            final BaseGenericObjectPool<?>.Evictor task, final Duration delay, final Duration period) {
+    static synchronized void schedule(final BaseGenericObjectPool<?>.Evictor pool, final Duration delay, final Duration period) {
         if (null == executor) {
             executor = new ScheduledThreadPoolExecutor(1, new EvictorThreadFactory());
             executor.setRemoveOnCancelPolicy(true);
             executor.scheduleAtFixedRate(new Reaper(), delay.toMillis(), period.toMillis(), TimeUnit.MILLISECONDS);
         }
-        final WeakReference<BaseGenericObjectPool<?>.Evictor> ref = new WeakReference<>(task);
+        final WeakReference<BaseGenericObjectPool<?>.Evictor> ref = new WeakReference<>(pool);
         final WeakRunner<BaseGenericObjectPool<?>.Evictor> runner = new WeakRunner<>(ref);
-        final ScheduledFuture<?> scheduledFuture = executor.scheduleWithFixedDelay(runner, delay.toMillis(),
-                period.toMillis(), TimeUnit.MILLISECONDS);
-        task.setScheduledFuture(scheduledFuture);
+        final ScheduledFuture<?> scheduledFuture = executor.scheduleWithFixedDelay(runner, delay.toMillis(), period.toMillis(), TimeUnit.MILLISECONDS);
+        pool.setScheduledFuture(scheduledFuture);
         TASK_MAP.put(ref, runner);
     }
 
@@ -242,9 +241,7 @@ private EvictionTimer() {
      */
     @Override
     public String toString() {
-        final StringBuilder builder = new StringBuilder();
-        builder.append("EvictionTimer []");
-        return builder.toString();
+        return "EvictionTimer []";
     }
 
 }

src/test/java/org/apache/commons/pool2/impl/TestGenericObjectPool.java

@@ -440,6 +440,7 @@ public static class TestEvictionPolicy<T> implements EvictionPolicy<T> {
 
         @Override
         public boolean evict(final EvictionConfig config, final PooledObject<T> underTest, final int idleCount) {
+            assertTrue(EvictionConfig.isEvictionThread());
             return callCount.incrementAndGet() > 1500;
         }
     }
@@ -1692,6 +1693,7 @@ void testEvictionOrder() throws Exception {
     @Test
     @Timeout(value = 60000, unit = TimeUnit.MILLISECONDS)
     void testEvictionPolicy() throws Exception {
+        assertFalse(EvictionConfig.isEvictionThread());
         genericObjectPool.setMaxIdle(500);
         genericObjectPool.setMaxTotal(500);
         genericObjectPool.setNumTestsPerEvictionRun(500);