Prepare codebase for dynamic DMaaP configuration

From now on, there is only one single place
where we can create whole app core concerning sending events
and it has a single entry point, based on DMaaP configuration.
It can be used to rebuild part of app that is responsible
for sending events dynamically.
Changes are in scope for the dynamic DMaaP config feature.
+ bumped up code coverage a bit

Change-Id: Iecc8c4e534ae9b781f47e3616409271ba83169c8
Signed-off-by: PawelSzalapski <pawel.szalapski@nokia.com>
Issue-ID: DCAEGEN2-517

1 files changed, 124 insertions, 0 deletions

diff --git a/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPPublishersCache.java b/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPPublishersCache.java
new file mode 100644
index 00000000..102d2774
--- /dev/null
+++ b/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPPublishersCache.java
@@ -0,0 +1,124 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * org.onap.dcaegen2.collectors.ves
+ * ================================================================================
+ * Copyright (C) 2017-2018 AT&T Intellectual Property. All rights reserved.
+ * Copyright (C) 2018 Nokia. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcae.commonFunction.event.publishing;
+
+import static io.vavr.API.Option;
+import static org.onap.dcae.commonFunction.event.publishing.VavrUtils.f;
+
+import com.att.nsa.cambria.client.CambriaBatchingPublisher;
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.common.cache.RemovalListener;
+import com.google.common.cache.RemovalNotification;
+import io.vavr.collection.Map;
+import io.vavr.control.Option;
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import javax.annotation.Nonnull;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * @author Pawel Szalapski (pawel.szalapski@nokia.com)
+ */
+class DMaaPPublishersCache {
+
+    private static final Logger log = LoggerFactory.getLogger(DMaaPPublishersCache.class);
+    private final LoadingCache<String, CambriaBatchingPublisher> publishersCache;
+    private AtomicReference<Map<String, PublisherConfig>> dMaaPConfiguration;
+
+    DMaaPPublishersCache(Map<String, PublisherConfig> dMaaPConfiguration) {
+        this.dMaaPConfiguration = new AtomicReference<>(dMaaPConfiguration);
+        this.publishersCache = CacheBuilder.newBuilder()
+            .removalListener(new OnPublisherRemovalListener())
+            .build(new CambriaPublishersCacheLoader());
+    }
+
+    DMaaPPublishersCache(CambriaPublishersCacheLoader dMaaPPublishersCacheLoader,
+                         OnPublisherRemovalListener onPublisherRemovalListener,
+                         Map<String, PublisherConfig> dMaaPConfiguration) {
+        this.dMaaPConfiguration = new AtomicReference<>(dMaaPConfiguration);
+        this.publishersCache = CacheBuilder.newBuilder()
+            .removalListener(onPublisherRemovalListener)
+            .build(dMaaPPublishersCacheLoader);
+    }
+
+    Option<CambriaBatchingPublisher> getPublisher(String streamID) {
+        try {
+            return Option(publishersCache.getUnchecked(streamID));
+        } catch (Exception e) {
+            log.warn("Could not create / load Cambria Publisher for streamID", e);
+            return Option.none();
+        }
+    }
+
+    void closePublisherFor(String streamId) {
+        publishersCache.invalidate(streamId);
+    }
+
+    synchronized void reconfigure(Map<String, PublisherConfig> newConfig) {
+        Map<String, PublisherConfig> currentConfig = dMaaPConfiguration.get();
+        Map<String, PublisherConfig> removedConfigurations = currentConfig
+            .filterKeys(domain -> !newConfig.containsKey(domain));
+        Map<String, PublisherConfig> changedConfigurations = newConfig
+            .filterKeys(e -> currentConfig.containsKey(e) && !currentConfig.get(e).equals(newConfig.get(e)));
+        dMaaPConfiguration.set(newConfig);
+        removedConfigurations.merge(changedConfigurations).forEach(e -> publishersCache.invalidate(e._1));
+    }
+
+    static class OnPublisherRemovalListener implements RemovalListener<String, CambriaBatchingPublisher> {
+
+        @Override
+        public void onRemoval(@Nonnull RemovalNotification<String, CambriaBatchingPublisher> notification) {
+            CambriaBatchingPublisher publisher = notification.getValue();
+            if (publisher != null) { // The value might get Garbage Collected at this moment, regardless of @Nonnull
+                try {
+                    int timeout = 20;
+                    TimeUnit unit = TimeUnit.SECONDS;
+                    java.util.List<?> stuck = publisher.close(timeout, unit);
+                    if (!stuck.isEmpty()) {
+                        log.error(f("Publisher got stuck and did not manage to close in '%s' '%s', "
+                            + "%s messages were dropped", stuck.size(), timeout, unit));
+                    }
+                } catch (InterruptedException | IOException e) {
+                    log.error("Could not close Cambria publisher, some messages might have been dropped", e);
+                }
+            }
+        }
+    }
+
+    class CambriaPublishersCacheLoader extends CacheLoader<String, CambriaBatchingPublisher> {
+
+        @Override
+        public CambriaBatchingPublisher load(@Nonnull String domain) {
+            return dMaaPConfiguration.get()
+                .get(domain)
+                .toTry(() -> new RuntimeException(
+                    f("DMaaP configuration contains no configuration for domain: '%s'", domain)))
+                .flatMap(DMaaPPublishersBuilder::buildPublisher)
+                .get();
+        }
+    }
+
+}