Optimize and refactor EventPublisher class in VES

* Remove need for having sendEvent synchronized by means of using
  Guava LoadingCache. The only thing that made it synchronized was the
  creation of new entries in the map but the synchronization was made
  on each incoming event.
* Split the class to smaller classes which conform to SRP. This makes us
  able to...
* ... write unit tests for affected classes
* TODO: upgrade to Java8 so lambdas will simplify the code even more

Change-Id: I14cf4cfab0570ce5aecc9a5e5dc9f541c499f9d7
Issue-ID: DCAEGEN2-440
Signed-off-by: Piotr Jaszczyk <piotr.jaszczyk@nokia.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/src/main/java/org/onap/dcae/commonFunction/DmaapPublishers.java b/src/main/java/org/onap/dcae/commonFunction/DmaapPublishers.java
new file mode 100644
index 00000000..c86a3742
--- /dev/null
+++ b/src/main/java/org/onap/dcae/commonFunction/DmaapPublishers.java
@@ -0,0 +1,96 @@
+/*-
+ * ============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;
+
+import com.att.nsa.cambria.client.CambriaBatchingPublisher;
+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 java.io.IOException;
+import java.net.MalformedURLException;
+import java.security.GeneralSecurityException;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+class DmaapPublishers {
+
+    private static Logger log = LoggerFactory.getLogger(DmaapPublishers.class);
+    private final LoadingCache<String, CambriaBatchingPublisher> publishers;
+
+    private DmaapPublishers(
+            LoadingCache<String, CambriaBatchingPublisher> publishers) {
+        this.publishers = publishers;
+    }
+
+    static DmaapPublishers create() {
+        return create(new CambriaPublisherFactory());
+    }
+
+    static DmaapPublishers create(final CambriaPublisherFactory publisherFactory) {
+        final LoadingCache<String, CambriaBatchingPublisher> cache = CacheBuilder.<String, CambriaBatchingPublisher>newBuilder()
+//            .expireAfterAccess(10, TimeUnit.MINUTES)
+                .removalListener(new RemovalListener<String, CambriaBatchingPublisher>() {
+                    @Override
+                    public void onRemoval(RemovalNotification<String, CambriaBatchingPublisher> notification) {
+                        if (notification.getValue() != null) {
+                            onCacheItemInvalidated(notification.getValue());
+                        }
+                    }
+                })
+                .build(new CacheLoader<String, CambriaBatchingPublisher>() {
+                    @Override
+                    public CambriaBatchingPublisher load(String streamId)
+                            throws MalformedURLException, GeneralSecurityException {
+                        try {
+                            return publisherFactory.createCambriaPublisher(streamId);
+                        } catch (MalformedURLException | GeneralSecurityException e) {
+                            log.error("CambriaClientBuilders connection reader exception : streamID - " + streamId + " "
+                                    + e.getMessage());
+                            throw e;
+                        }
+                    }
+                });
+        return new DmaapPublishers(cache);
+    }
+
+    public CambriaBatchingPublisher getByStreamId(String streamId) {
+        return publishers.getUnchecked(streamId);
+    }
+
+    public void closeByStreamId(String streamId) {
+        publishers.invalidate(streamId);
+    }
+
+    private static void onCacheItemInvalidated(CambriaBatchingPublisher pub) {
+        try {
+            final List<?> stuck = pub.close(20, TimeUnit.SECONDS);
+            if (!stuck.isEmpty()) {
+                log.error(stuck.size() + " messages unsent");
+            }
+        } catch (InterruptedException | IOException e) {
+            log.error("Caught Exception on Close event: {}", e);
+        }
+    }
+}