Introduce simple container watchdog

This watchdog uses information from the reference count framework in
jdisc_core. Contains no use of System.gc() or WeakReference.

1 files changed, 73 insertions, 0 deletions

diff --git a/jdisc_core/src/test/java/com/yahoo/jdisc/core/ContainerWatchdogTest.java b/jdisc_core/src/test/java/com/yahoo/jdisc/core/ContainerWatchdogTest.java
new file mode 100644
index 00000000000..94e7c3a1d22
--- /dev/null
+++ b/jdisc_core/src/test/java/com/yahoo/jdisc/core/ContainerWatchdogTest.java
@@ -0,0 +1,73 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.jdisc.core;
+
+import com.yahoo.jdisc.Metric;
+import com.yahoo.jdisc.test.TestDriver;
+import com.yahoo.test.ManualClock;
+import org.junit.Test;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Map;
+import java.util.concurrent.ScheduledExecutorService;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
+
+/**
+ * @author bjorncs
+ */
+public class ContainerWatchdogTest {
+
+    @Test
+    public void watchdog_counts_stale_container() {
+        TestDriver driver = TestDriver.newSimpleApplicationInstanceWithoutOsgi();
+        ManualClock clock = new ManualClock(Instant.EPOCH);
+        DummyMetric metric = new DummyMetric();
+        ContainerWatchdog watchdog = new ContainerWatchdog(mock(ScheduledExecutorService.class), clock);
+
+        ActiveContainer containerWithoutRetainedResources = new ActiveContainer(driver.newContainerBuilder());
+
+        watchdog.onContainerActivation(containerWithoutRetainedResources);
+        assertEquals(0, runMonitorStepAndGetStaleContainerCount(watchdog, metric));
+
+        clock.advance(Duration.ofHours(1));
+        watchdog.onContainerActivation(null);
+        assertEquals(0, runMonitorStepAndGetStaleContainerCount(watchdog, metric));
+
+        clock.advance(ContainerWatchdog.GRACE_PERIOD);
+        assertEquals(0, runMonitorStepAndGetStaleContainerCount(watchdog, metric));
+
+        clock.advance(Duration.ofSeconds(1));
+        assertEquals(1, runMonitorStepAndGetStaleContainerCount(watchdog, metric));
+
+        containerWithoutRetainedResources.release();
+        assertEquals(0, runMonitorStepAndGetStaleContainerCount(watchdog, metric));
+    }
+
+    private static int runMonitorStepAndGetStaleContainerCount(ContainerWatchdog watchdog, DummyMetric metric) {
+        watchdog.monitorDeactivatedContainers();
+        watchdog.emitMetrics(metric);
+        return metric.value;
+    }
+
+    private static class DummyMetric implements Metric {
+        int value;
+
+        @Override
+        public void set(String key, Number val, Context ctx) {
+            this.value = val.intValue();
+        }
+
+        @Override
+        public void add(String key, Number val, Context ctx) {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public Context createContext(Map<String, ?> properties) {
+            throw new UnsupportedOperationException();
+        }
+    }
+}
+