Address feedbacks

Author: cherylEnkidu

firebase-firestore/src/main/java/com/google/firebase/firestore/FirebaseFirestore.java

@@ -63,7 +63,6 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Executor;
-import java.util.concurrent.atomic.AtomicReference;
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
@@ -106,8 +105,7 @@ public interface InstanceRegistry {
   private volatile FirestoreClient client;
   private final GrpcMetadataProvider metadataProvider;
 
-  private final AtomicReference<PersistentCacheIndexManager> persistentCacheIndexManager =
-      new AtomicReference<>();
+  @Nullable private PersistentCacheIndexManager persistentCacheIndexManager;
 
   @NonNull
   private static FirebaseApp getDefaultFirebaseApp() {
@@ -418,16 +416,14 @@ public Task<Void> setIndexConfiguration(@NonNull String json) {
   /** @hide */
   @RestrictTo(RestrictTo.Scope.LIBRARY)
   @Nullable
-  public PersistentCacheIndexManager getPersistentCacheIndexManager() {
+  public synchronized PersistentCacheIndexManager getPersistentCacheIndexManager() {
     ensureClientConfigured();
-
-    if ((settings.isPersistenceEnabled()
-            || settings.getCacheSettings() instanceof PersistentCacheSettings)
-        && persistentCacheIndexManager.get() == null) {
-      persistentCacheIndexManager.set(new PersistentCacheIndexManager(client));
+    if (persistentCacheIndexManager == null
+        && (settings.isPersistenceEnabled()
+            || settings.getCacheSettings() instanceof PersistentCacheSettings)) {
+      persistentCacheIndexManager = new PersistentCacheIndexManager(client);
     }
-
-    return persistentCacheIndexManager.get();
+    return persistentCacheIndexManager;
   }
 
   /**

firebase-firestore/src/main/java/com/google/firebase/firestore/local/IndexManager.java

@@ -79,7 +79,7 @@ enum IndexType {
   void deleteFieldIndex(FieldIndex index);
 
   /** Creates a full matched field index which serves the given target. */
-  void createTargetIndices(Target target);
+  void createTargetIndexes(Target target);
 
   /**
    * Returns a list of field indexes that correspond to the specified collection group.

firebase-firestore/src/main/java/com/google/firebase/firestore/local/MemoryIndexManager.java

@@ -61,7 +61,7 @@ public void deleteFieldIndex(FieldIndex index) {
   }
 
   @Override
-  public void createTargetIndices(Target target) {}
+  public void createTargetIndexes(Target target) {}
 
   @Override
   @Nullable

firebase-firestore/src/main/java/com/google/firebase/firestore/local/QueryEngine.java

@@ -62,7 +62,7 @@
 public class QueryEngine {
   private static final String LOG_TAG = "QueryEngine";
 
-  private static final int INDEX_AUTO_CREATION_DEFAULT_MIN_COLLECTION_SIZE = 100;
+  private static final int DEFAULT_INDEX_AUTO_CREATION_MIN_COLLECTION_SIZE = 100;
 
   /**
    * This cost represents the evaluation result of (([index, docKey] + [docKey, docContent]) per
@@ -78,7 +78,7 @@ public class QueryEngine {
   private boolean indexAutoCreationEnabled = false;
 
   /** SDK only decides whether it should create index when collection size is larger than this. */
-  private int indexAutoCreationMinCollectionSize = INDEX_AUTO_CREATION_DEFAULT_MIN_COLLECTION_SIZE;
+  private int indexAutoCreationMinCollectionSize = DEFAULT_INDEX_AUTO_CREATION_MIN_COLLECTION_SIZE;
 
   private double relativeIndexReadCostPerDocument = DEFAULT_RELATIVE_INDEX_READ_COST_PER_DOCUMENT;
 
@@ -138,16 +138,18 @@ private void createCacheIndexes(Query query, QueryContext context, int resultSiz
         resultSize);
 
     if (context.getDocumentReadCount() > relativeIndexReadCostPerDocument * resultSize) {
-      indexManager.createTargetIndices(query.toTarget());
+      indexManager.createTargetIndexes(query.toTarget());
       Logger.debug(
           LOG_TAG,
-          "The SDK decides to create cache indexes for this query, as using cache indexes "
-              + "may help improve performance.");
+          "The SDK decides to create cache indexes for query: %s, as using cache indexes "
+              + "may help improve performance.",
+          query.toString());
     } else {
       Logger.debug(
           LOG_TAG,
-          "The SDK decides not to create cache indexes for this query, as using cache indexes "
-              + "may not help improve performance.");
+          "The SDK decides not to create cache indexes for this query: %s, as using cache "
+              + "indexes may not help improve performance.",
+          query.toString());
     }
   }
 

firebase-firestore/src/main/java/com/google/firebase/firestore/local/SQLiteIndexManager.java

@@ -234,7 +234,7 @@ public void deleteFieldIndex(FieldIndex index) {
   }
 
   @Override
-  public void createTargetIndices(Target target) {
+  public void createTargetIndexes(Target target) {
     hardAssert(started, "IndexManager not started");
 
     for (Target subTarget : getSubTargets(target)) {