[NO ISSUE][STO] Log index ref registration and removal

- user model changes: no
- storage format changes: no
- interface changes: no

Change-Id: I95f8565780675798393d7d43c0051c04e2b0a98c
Reviewed-on: https://asterix-gerrit.ics.uci.edu/c/asterixdb/+/15225
Reviewed-by: Ali Alsuliman <ali.al.solaiman@gmail.com>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>

asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetInfo.java

@@ -195,12 +195,14 @@ public synchronized Map<Long, IndexInfo> getIndexes() {
     public synchronized void addIndex(long resourceID, IndexInfo indexInfo) {
         indexes.put(resourceID, indexInfo);
         partitionIndexes.computeIfAbsent(indexInfo.getPartition(), partition -> new HashSet<>()).add(indexInfo);
+        LOGGER.debug("registered reference to index {}", indexInfo);
     }
 
     public synchronized void removeIndex(long resourceID) {
         IndexInfo info = indexes.remove(resourceID);
         if (info != null) {
             partitionIndexes.get(info.getPartition()).remove(info);
+            LOGGER.debug("removed reference to index {}", info);
         }
     }
 

asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/IndexInfo.java

@@ -55,4 +55,10 @@ public int getDatasetId() {
     public LocalResource getLocalResource() {
         return localResource;
     }
+
+    @Override
+    public String toString() {
+        return "IndexInfo{" + "index=" + index + ", datasetId=" + datasetId + ", resourceId=" + resourceId
+                + ", partition=" + partition + ", localResource=" + localResource + '}';
+    }
 }