HDDS-13513. Ozone Event Notification

hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/OzoneConsts.java

@@ -539,6 +539,11 @@ public final class OzoneConsts {
   public static final String COMPACTION_LOG_TABLE =
       "compactionLogTable";
 
+  /**
+   * DB completed request info table name. Referenced in RDBStore.
+   */
+  public static final String COMPLETED_REQUEST_INFO_TABLE = "completedRequestInfoTable";
+
   /**
    * S3G multipart upload request's ETag header key.
    */

hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/eventlistener/NotificationCheckpointStrategy.java

@@ -0,0 +1,15 @@
+package org.apache.hadoop.ozone.om.eventlistener;
+
+import java.io.IOException;
+
+/**
+ * Interface for implementations which load/save the current checkpoint
+ * position representing the last known notification sent by an event
+ * notification plugin.
+ */
+public interface NotificationCheckpointStrategy {
+
+  String load() throws IOException;
+
+  void save(String val) throws IOException;
+}

hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/eventlistener/OMEventListener.java

@@ -0,0 +1,12 @@
+package org.apache.hadoop.ozone.om.eventlistener;
+
+import org.apache.hadoop.hdds.conf.OzoneConfiguration;
+
+public interface OMEventListener {
+
+  void initialize(OzoneConfiguration conf, OMEventListenerPluginContext pluginContext);
+
+  void start();
+
+  void shutdown();
+}

hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/eventlistener/OMEventListenerPluginContext.java

@@ -0,0 +1,24 @@
+package org.apache.hadoop.ozone.om.eventlistener;
+
+import java.io.IOException;
+import java.util.List;
+import org.apache.hadoop.ozone.om.helpers.OmCompletedRequestInfo;
+
+/**
+ * A narrow set of functionality we are ok with exposing to plugin
+ * implementations
+ */
+public interface OMEventListenerPluginContext {
+
+  boolean isLeaderReady();
+
+  // TODO: should we allow plugins to pass in maxResults or just limit
+  // them to some predefined value for safety?  e.g. 10K
+  List<OmCompletedRequestInfo> listCompletedRequestInfo(String startKey, int maxResults) throws IOException;
+
+  // XXX: this probably doesn't belong here
+  String getThreadNamePrefix();
+
+  NotificationCheckpointStrategy getOzoneNotificationCheckpointStrategy();
+
+}