HWKMETRICS-99: allow Hawkular metrics to start and then wait for a Ca…

…ssandra cluster to become available rather than just failing.

api/metrics-api-jaxrs/src/main/java/org/hawkular/metrics/api/jaxrs/MetricsServiceProducer.java

@@ -28,11 +28,14 @@
 import javax.enterprise.inject.Produces;
 import javax.inject.Inject;
 
+import com.datastax.driver.core.Session;
+import com.google.common.util.concurrent.FutureCallback;
 import org.hawkular.metrics.api.jaxrs.config.Configurable;
 import org.hawkular.metrics.api.jaxrs.config.ConfigurationProperty;
 import org.hawkular.metrics.api.jaxrs.util.Eager;
 import org.hawkular.metrics.core.api.MetricsService;
-import org.hawkular.metrics.core.impl.HawkularMetrics;
+import org.hawkular.metrics.core.impl.cassandra.CassandraSession;
+import org.hawkular.metrics.core.impl.cassandra.MetricsServiceCassandra;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -70,14 +73,28 @@ void init() {
     @Produces
     public MetricsService getMetricsService() {
         if (metricsService == null) {
-            HawkularMetrics.Builder metricsServiceBuilder = new HawkularMetrics.Builder();
+            metricsService = new MetricsServiceCassandra();
             Map<String, String> options = new HashMap<>();
             options.put("cqlport", cqlPort);
             options.put("nodes", nodes);
             options.put("keyspace", keyspace);
 
-            metricsServiceBuilder.withOptions(options);
-            metricsService = metricsServiceBuilder.build();
+            CassandraSession.Builder cassandraSessionBuilder = new CassandraSession.Builder();
+            cassandraSessionBuilder.withOptions(options);
+
+            cassandraSessionBuilder.withInitializationCallback(new FutureCallback<Session>() {
+                @Override
+                public void onSuccess(Session session) {
+                    metricsService.startUp(session);
+                }
+
+                @Override
+                public void onFailure(Throwable t) {
+                    throw new RuntimeException("Error trying to get the Cassandra Session", t);
+                }
+            });
+
+            cassandraSessionBuilder.build();
         }
 
         return metricsService;

api/metrics-api-jaxrs/src/main/java/org/hawkular/metrics/api/jaxrs/filter/CassandraAvailabilityFilter.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2014-2015 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.hawkular.metrics.api.jaxrs.filter;
+
+import org.hawkular.metrics.api.jaxrs.ApiError;
+import org.hawkular.metrics.core.api.MetricsService;
+
+import javax.inject.Inject;
+import javax.ws.rs.container.ContainerRequestContext;
+import javax.ws.rs.container.ContainerRequestFilter;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.ext.Provider;
+import java.io.IOException;
+
+import static javax.ws.rs.core.MediaType.APPLICATION_JSON_TYPE;
+
+/**
+ * Created by mwringe on 20/05/15.
+ */
+@Provider
+public class CassandraAvailabilityFilter implements ContainerRequestFilter {
+
+    private static final String NO_CASSANDRA_SESSION_MSG = "Service unavailable while initializing.";
+
+    @Inject
+    private MetricsService metricsService;
+
+
+    @Override
+    public void filter(ContainerRequestContext containerRequestContext) throws IOException {
+        if (!metricsService.isStarted()) {
+            // Fail since the Cassandra cluster is not yet up yet.
+            Response response = Response.status(Response.Status.SERVICE_UNAVAILABLE)
+                    .type(APPLICATION_JSON_TYPE)
+                    .entity(new ApiError(NO_CASSANDRA_SESSION_MSG))
+                    .build();
+            containerRequestContext.abortWith(response);
+        }
+
+    }
+}

core/metrics-core-api/src/main/java/org/hawkular/metrics/core/api/MetricsService.java

@@ -36,16 +36,14 @@ public interface MetricsService {
     // creating tenants.
     String DEFAULT_TENANT_ID = "test";
 
-    /** called to start the service up if needed
-     * @param params from e.g. servlet context */
-    void startUp(Map<String, String> params);
-
     /**
      * Startup with a given cassandra session
      * @param session
      */
     void startUp(Session session);
 
+    boolean isStarted();
+
     void shutdown();
 
     /**