[Rollup] Register FeatureSetUsage with xpack, add tests (elastic/x-pack-elasticsearch#4040)

We had a Usage class before, but weren't registering it with XPack.
Would be nice to add more usage info in the future (like the running
jobs on each node), but unclear the best way to do it since we'd need
to filter through the list of allocated tasks.

Original commit: elastic/x-pack-elasticsearch@5207d2758b

plugin/core/src/main/java/org/elasticsearch/xpack/core/XPackClientPlugin.java

@@ -92,6 +92,7 @@ import org.elasticsearch.persistent.PersistentTasksNodeService;
 import org.elasticsearch.persistent.RemovePersistentTaskAction;
 import org.elasticsearch.persistent.StartPersistentTaskAction;
 import org.elasticsearch.persistent.UpdatePersistentTaskStatusAction;
+import org.elasticsearch.xpack.core.rollup.RollupFeatureSetUsage;
 import org.elasticsearch.xpack.core.rollup.RollupField;
 import org.elasticsearch.xpack.core.rollup.action.DeleteRollupJobAction;
 import org.elasticsearch.xpack.core.rollup.action.GetRollupCapsAction;
@@ -344,6 +345,7 @@ public class XPackClientPlugin extends Plugin implements ActionPlugin, NetworkPl
                 new NamedWriteableRegistry.Entry(MetaData.Custom.class, LicensesMetaData.TYPE, LicensesMetaData::new),
                 new NamedWriteableRegistry.Entry(NamedDiff.class, LicensesMetaData.TYPE, LicensesMetaData::readDiffFrom),
                 //rollup
+                new NamedWriteableRegistry.Entry(XPackFeatureSet.Usage.class, XPackField.ROLLUP, RollupFeatureSetUsage::new),
                 new NamedWriteableRegistry.Entry(PersistentTaskParams.class, RollupJob.NAME, RollupJob::new),
                 new NamedWriteableRegistry.Entry(Task.Status.class, RollupJobStatus.NAME, RollupJobStatus::new)
         );

plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/RollupFeatureSetUsage.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.core.rollup;
+
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.xpack.core.XPackFeatureSet;
+import org.elasticsearch.xpack.core.XPackField;
+
+import java.io.IOException;
+
+public class RollupFeatureSetUsage extends XPackFeatureSet.Usage {
+
+    public RollupFeatureSetUsage(StreamInput input) throws IOException {
+        super(input);
+    }
+
+    public RollupFeatureSetUsage(boolean available, boolean enabled) {
+        super(XPackField.ROLLUP, available, enabled);
+    }
+}

plugin/rollup/src/main/java/org/elasticsearch/xpack/rollup/RollupFeatureSet.java

@@ -8,14 +8,13 @@ package org.elasticsearch.xpack.rollup;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.inject.Inject;
-import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.license.XPackLicenseState;
 import org.elasticsearch.xpack.core.XPackFeatureSet;
 import org.elasticsearch.xpack.core.XPackField;
 import org.elasticsearch.xpack.core.XPackSettings;
+import org.elasticsearch.xpack.core.rollup.RollupFeatureSetUsage;
 
-import java.io.IOException;
 import java.util.Map;
 
 public class RollupFeatureSet implements XPackFeatureSet {
@@ -56,17 +55,7 @@ public class RollupFeatureSet implements XPackFeatureSet {
 
     @Override
     public void usage(ActionListener<XPackFeatureSet.Usage> listener) {
-        listener.onResponse(new RollupFeatureSet.Usage(available(), enabled()));
+        // TODO expose the currently running rollup tasks on this node?  Unclear the best way to do that
-    }
+        listener.onResponse(new RollupFeatureSetUsage(available(), enabled()));
-
-    public static class Usage extends XPackFeatureSet.Usage {
-
-        public Usage(StreamInput input) throws IOException {
-            super(input);
-        }
-
-        public Usage(boolean available, boolean enabled) {
-            super(XPackField.ROLLUP, available, enabled);
-        }
     }
 }

plugin/rollup/src/test/java/org/elasticsearch/xpack/rollup/RollupFeatureSetTests.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.rollup;
+
+import org.elasticsearch.action.support.PlainActionFuture;
+import org.elasticsearch.common.io.stream.BytesStreamOutput;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.license.XPackLicenseState;
+import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.xpack.core.XPackFeatureSet;
+import org.elasticsearch.xpack.core.rollup.RollupFeatureSetUsage;
+import org.junit.Before;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.concurrent.ExecutionException;
+
+import static org.hamcrest.core.Is.is;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class RollupFeatureSetTests extends ESTestCase {
+    private XPackLicenseState licenseState;
+
+    @Before
+    public void init() {
+        licenseState = mock(XPackLicenseState.class);
+    }
+
+    public void testAvailable() {
+        RollupFeatureSet featureSet = new RollupFeatureSet(Settings.EMPTY, licenseState);
+        boolean available = randomBoolean();
+        when(licenseState.isRollupAllowed()).thenReturn(available);
+        assertThat(featureSet.available(), is(available));
+    }
+
+    public void testEnabledSetting() {
+        boolean enabled = randomBoolean();
+        Settings.Builder settings = Settings.builder();
+        settings.put("xpack.rollup.enabled", enabled);
+        RollupFeatureSet featureSet = new RollupFeatureSet(settings.build(), licenseState);
+        assertThat(featureSet.enabled(), is(enabled));
+    }
+
+    public void testEnabledDefault() {
+        RollupFeatureSet featureSet = new RollupFeatureSet(Settings.EMPTY, licenseState);
+        assertThat(featureSet.enabled(), is(true));
+    }
+
+    public void testUsage() throws ExecutionException, InterruptedException, IOException {
+        RollupFeatureSet featureSet = new RollupFeatureSet(Settings.EMPTY, licenseState);
+        PlainActionFuture<XPackFeatureSet.Usage> future = new PlainActionFuture<>();
+        featureSet.usage(future);
+        XPackFeatureSet.Usage rollupUsage = future.get();
+        BytesStreamOutput out = new BytesStreamOutput();
+        rollupUsage.writeTo(out);
+        XPackFeatureSet.Usage serializedUsage = new RollupFeatureSetUsage(out.bytes().streamInput());
+        for (XPackFeatureSet.Usage usage : Arrays.asList(rollupUsage, serializedUsage)) {
+            assertThat(usage.name(), is(featureSet.name()));
+            assertThat(usage.enabled(), is(featureSet.enabled()));
+        }
+    }
+
+}