Reintroduce enforced destruction of ActiveContainer (#2712)

Reintroduce enforced destruction of ActiveContainer - without using finalizer

1 files changed, 54 insertions, 0 deletions

diff --git a/jdisc_core/src/test/java/com/yahoo/jdisc/core/ActiveContainerDeactivationWatchdogTest.java b/jdisc_core/src/test/java/com/yahoo/jdisc/core/ActiveContainerDeactivationWatchdogTest.java
index 1a776f59e29..09ca2f93ff1 100644
--- a/jdisc_core/src/test/java/com/yahoo/jdisc/core/ActiveContainerDeactivationWatchdogTest.java
+++ b/jdisc_core/src/test/java/com/yahoo/jdisc/core/ActiveContainerDeactivationWatchdogTest.java
@@ -7,12 +7,20 @@ import com.yahoo.jdisc.test.TestDriver;
 import com.yahoo.test.ManualClock;
 import org.junit.Test;
 
+import java.lang.ref.WeakReference;
+import java.time.Clock;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Map;
 import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
 
 /**
  * @author bjorncs
@@ -59,6 +67,31 @@ public class ActiveContainerDeactivationWatchdogTest {
 
     }
 
+    @Test
+    public void deactivated_container_destructed_if_its_reference_counter_is_nonzero() {
+        ExecutorMock executor = new ExecutorMock();
+        ActiveContainerDeactivationWatchdog watchdog =
+                new ActiveContainerDeactivationWatchdog(Clock.systemUTC(), executor);
+        ActiveContainer container =
+                new ActiveContainer(TestDriver.newSimpleApplicationInstanceWithoutOsgi().newContainerBuilder());
+        AtomicBoolean destructed = new AtomicBoolean(false);
+        container.shutdown().notifyTermination(() -> destructed.set(true));
+
+        container.refer(); // increase reference counter to simluate a leaking resource
+        watchdog.onContainerActivation(container);
+        container.release(); // release resource
+        watchdog.onContainerActivation(null); // deactive container
+
+        WeakReference<ActiveContainer> containerWeakReference = new WeakReference<>(container);
+        container = null; // make container instance collectable by GC
+        System.gc();
+
+        assertNull("Container is not GCed - probably because the watchdog has a concrete reference to it",
+                   containerWeakReference.get());
+        executor.containerDestructorCommand.run();
+        assertTrue("Destructor is not called on deactivated container", destructed.get());
+    }
+
     private static class MockMetric implements Metric {
         public int totalCount;
         public int withRetainedReferencesCount;
@@ -88,4 +121,25 @@ public class ActiveContainerDeactivationWatchdogTest {
         }
     }
 
+    private static class ExecutorMock extends ScheduledThreadPoolExecutor {
+
+        public Runnable containerDestructorCommand;
+        private int registrationCounter = 0;
+
+        public ExecutorMock() {
+            super(1);
+        }
+
+        @Override
+        public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit) {
+            if (registrationCounter == 2) {
+                containerDestructorCommand = command;
+            } else if (registrationCounter > 2){
+                throw new IllegalStateException("Unexpected registration");
+            }
+            ++registrationCounter;
+            return null;
+        }
+    }
+
 }