resolve comments, simplify some abstractions

Author: Brian Chen

firebase-firestore/src/main/java/com/google/firebase/firestore/core/ComponentProvider.java

@@ -20,7 +20,7 @@
 import com.google.firebase.firestore.auth.User;
 import com.google.firebase.firestore.local.LocalStore;
 import com.google.firebase.firestore.local.Persistence;
-import com.google.firebase.firestore.local.StartStopScheduler;
+import com.google.firebase.firestore.local.Scheduler;
 import com.google.firebase.firestore.remote.ConnectivityMonitor;
 import com.google.firebase.firestore.remote.Datastore;
 import com.google.firebase.firestore.remote.RemoteStore;
@@ -39,8 +39,8 @@ public abstract class ComponentProvider {
   private RemoteStore remoteStore;
   private EventManager eventManager;
   private ConnectivityMonitor connectivityMonitor;
-  @Nullable private StartStopScheduler garbageCollectionScheduler;
-  @Nullable private StartStopScheduler indexBackfillScheduler;
+  @Nullable private Scheduler garbageCollectionScheduler;
+  @Nullable private Scheduler indexBackfillScheduler;
 
   /** Configuration options for the component provider. */
   public static class Configuration {
@@ -104,12 +104,12 @@ public Persistence getPersistence() {
   }
 
   @Nullable
-  public StartStopScheduler getGarbageCollectionScheduler() {
+  public Scheduler getGarbageCollectionScheduler() {
     return garbageCollectionScheduler;
   }
 
   @Nullable
-  public StartStopScheduler getIndexBackfillScheduler() {
+  public Scheduler getIndexBackfillScheduler() {
     return indexBackfillScheduler;
   }
 
@@ -147,10 +147,9 @@ public void initialize(Configuration configuration) {
     indexBackfillScheduler = createIndexBackfillScheduler(configuration);
   }
 
-  protected abstract StartStopScheduler createGarbageCollectionScheduler(
-      Configuration configuration);
+  protected abstract Scheduler createGarbageCollectionScheduler(Configuration configuration);
 
-  protected abstract StartStopScheduler createIndexBackfillScheduler(Configuration configuration);
+  protected abstract Scheduler createIndexBackfillScheduler(Configuration configuration);
 
   protected abstract EventManager createEventManager(Configuration configuration);
 

firebase-firestore/src/main/java/com/google/firebase/firestore/core/FirestoreClient.java

@@ -35,7 +35,7 @@
 import com.google.firebase.firestore.local.LocalStore;
 import com.google.firebase.firestore.local.Persistence;
 import com.google.firebase.firestore.local.QueryResult;
-import com.google.firebase.firestore.local.StartStopScheduler;
+import com.google.firebase.firestore.local.Scheduler;
 import com.google.firebase.firestore.model.Document;
 import com.google.firebase.firestore.model.DocumentKey;
 import com.google.firebase.firestore.model.FieldIndex;
@@ -74,9 +74,9 @@ public final class FirestoreClient {
   private EventManager eventManager;
 
   // LRU-related
-  @Nullable private StartStopScheduler gcScheduler;
+  @Nullable private Scheduler gcScheduler;
 
-  @Nullable private StartStopScheduler indexScheduler;
+  @Nullable private Scheduler indexScheduler;
 
   public FirestoreClient(
       final Context context,
@@ -146,7 +146,7 @@ public Task<Void> terminate() {
             gcScheduler.stop();
           }
 
-          if (indexScheduler != null) {
+          if (indexScheduler != null && Persistence.INDEXING_SUPPORT_ENABLED) {
             indexScheduler.stop();
           }
         });
@@ -272,7 +272,7 @@ private void initialize(Context context, User user, FirebaseFirestoreSettings se
       gcScheduler.start();
     }
 
-    if (indexScheduler != null) {
+    if (indexScheduler != null && Persistence.INDEXING_SUPPORT_ENABLED) {
       indexScheduler.start();
     }
   }

firebase-firestore/src/main/java/com/google/firebase/firestore/core/MemoryComponentProvider.java

@@ -20,7 +20,7 @@
 import com.google.firebase.firestore.local.LocalStore;
 import com.google.firebase.firestore.local.MemoryPersistence;
 import com.google.firebase.firestore.local.Persistence;
-import com.google.firebase.firestore.local.StartStopScheduler;
+import com.google.firebase.firestore.local.Scheduler;
 import com.google.firebase.firestore.model.DocumentKey;
 import com.google.firebase.firestore.model.mutation.MutationBatchResult;
 import com.google.firebase.firestore.remote.AndroidConnectivityMonitor;
@@ -36,13 +36,13 @@ public class MemoryComponentProvider extends ComponentProvider {
 
   @Override
   @Nullable
-  protected StartStopScheduler createGarbageCollectionScheduler(Configuration configuration) {
+  protected Scheduler createGarbageCollectionScheduler(Configuration configuration) {
     return null;
   }
 
   @Override
   @Nullable
-  protected StartStopScheduler createIndexBackfillScheduler(Configuration configuration) {
+  protected Scheduler createIndexBackfillScheduler(Configuration configuration) {
     return null;
   }
 

firebase-firestore/src/main/java/com/google/firebase/firestore/core/SQLiteComponentProvider.java

@@ -19,26 +19,23 @@
 import com.google.firebase.firestore.local.LruDelegate;
 import com.google.firebase.firestore.local.LruGarbageCollector;
 import com.google.firebase.firestore.local.Persistence;
-import com.google.firebase.firestore.local.SQLiteIndexBackfillerDelegate;
 import com.google.firebase.firestore.local.SQLitePersistence;
-import com.google.firebase.firestore.local.StartStopScheduler;
+import com.google.firebase.firestore.local.Scheduler;
 import com.google.firebase.firestore.remote.RemoteSerializer;
 
 /** Provides all components needed for Firestore with SQLite persistence. */
 public class SQLiteComponentProvider extends MemoryComponentProvider {
 
   @Override
-  protected StartStopScheduler createGarbageCollectionScheduler(Configuration configuration) {
+  protected Scheduler createGarbageCollectionScheduler(Configuration configuration) {
     LruDelegate lruDelegate = ((SQLitePersistence) getPersistence()).getReferenceDelegate();
     LruGarbageCollector gc = lruDelegate.getGarbageCollector();
     return gc.newScheduler(configuration.getAsyncQueue(), getLocalStore());
   }
 
   @Override
-  protected StartStopScheduler createIndexBackfillScheduler(Configuration configuration) {
-    SQLiteIndexBackfillerDelegate indexBackfillDelegate =
-        ((SQLitePersistence) getPersistence()).getIndexBackfillDelegate();
-    IndexBackfiller indexBackfiller = indexBackfillDelegate.getIndexBackfiller();
+  protected Scheduler createIndexBackfillScheduler(Configuration configuration) {
+    IndexBackfiller indexBackfiller = ((SQLitePersistence) getPersistence()).getIndexBackfiller();
     return indexBackfiller.newScheduler(configuration.getAsyncQueue(), getLocalStore());
   }
 

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

@@ -15,14 +15,25 @@
 package com.google.firebase.firestore.local;
 
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+import com.google.firebase.firestore.index.IndexEntry;
 import com.google.firebase.firestore.util.AsyncQueue;
 import java.util.concurrent.TimeUnit;
 
+/**
+ * Implements the steps for backfilling indexes.
+ */
 public class IndexBackfiller {
-  /** How long we wait to try running LRU GC after SDK initialization. */
-  private static final long INITIAL_GC_DELAY_MS = TimeUnit.MINUTES.toMillis(1);
-  /** Minimum amount of time between GC checks, after the first one. */
-  private static final long REGULAR_GC_DELAY_MS = TimeUnit.MINUTES.toMillis(5);
+  /** How long we wait to try running index backfill after SDK initialization. */
+  private static final long INITIAL_BACKFILL_DELAY_MS = TimeUnit.SECONDS.toMillis(15);
+  /** Minimum amount of time between backfill checks, after the first one. */
+  private static final long REGULAR_BACKFILL_DELAY_MS = TimeUnit.MINUTES.toMillis(1);
+
+  private final SQLitePersistence persistence;
+
+  public IndexBackfiller(SQLitePersistence sqLitePersistence) {
+    this.persistence = sqLitePersistence;
+  }
 
   public static class Results {
     private final boolean hasRun;
@@ -53,13 +64,13 @@ public int getEntriesRemoved() {
     }
   }
 
-  public class Scheduler implements StartStopScheduler {
+  public class BackfillScheduler implements Scheduler {
     private final AsyncQueue asyncQueue;
     private final LocalStore localStore;
     private boolean hasRun = false;
-    @Nullable private AsyncQueue.DelayedTask gcTask;
+    @Nullable private AsyncQueue.DelayedTask backfillTask;
 
-    public Scheduler(AsyncQueue asyncQueue, LocalStore localStore) {
+    public BackfillScheduler(AsyncQueue asyncQueue, LocalStore localStore) {
       this.asyncQueue = asyncQueue;
       this.localStore = localStore;
     }
@@ -71,16 +82,16 @@ public void start() {
 
     @Override
     public void stop() {
-      if (gcTask != null) {
-        gcTask.cancel();
+      if (backfillTask != null) {
+        backfillTask.cancel();
       }
     }
 
     private void scheduleBackfill() {
-      long delay = hasRun ? REGULAR_GC_DELAY_MS : INITIAL_GC_DELAY_MS;
-      gcTask =
+      long delay = hasRun ? REGULAR_BACKFILL_DELAY_MS : INITIAL_BACKFILL_DELAY_MS;
+      backfillTask =
           asyncQueue.enqueueAfterDelay(
-              AsyncQueue.TimerId.GARBAGE_COLLECTION,
+              AsyncQueue.TimerId.INDEX_BACKFILL,
               delay,
               () -> {
                 localStore.backfillIndexes(IndexBackfiller.this);
@@ -90,21 +101,52 @@ private void scheduleBackfill() {
     }
   }
 
-  private final IndexBackfillerDelegate delegate;
-
-  IndexBackfiller(IndexBackfillerDelegate delegate) {
-    this.delegate = delegate;
-  }
-
-  public Scheduler newScheduler(AsyncQueue asyncQueue, LocalStore localStore) {
-    return new Scheduler(asyncQueue, localStore);
+  public BackfillScheduler newScheduler(AsyncQueue asyncQueue, LocalStore localStore) {
+    return new BackfillScheduler(asyncQueue, localStore);
   }
 
   // TODO: Figure out which index entries to backfill.
-  Results backfill() {
+  public Results backfill() {
     int numIndexesWritten = 0;
     int numIndexesRemoved = 0;
-    delegate.addIndexEntry();
     return new Results(/* hasRun= */ true, numIndexesWritten, numIndexesRemoved);
   }
+
+  public void addIndexEntry(IndexEntry entry) {
+    persistence.execute(
+        "INSERT OR IGNORE INTO index_entries ("
+            + "index_id, "
+            + "index_value, "
+            + "uid, "
+            + "document_id) VALUES(?, ?, ?, ?)",
+        entry.getIndexId(),
+        entry.getIndexValue(),
+        entry.getUid(),
+        entry.getDocumentId());
+  }
+
+  public void removeIndexEntry(int indexId, String uid, String documentId) {
+    persistence.execute(
+        "DELETE FROM index_entries "
+            + "WHERE index_id = ? "
+            + "AND uid = ?"
+            + "AND document_id = ?",
+        indexId,
+        uid,
+        documentId);
+    ;
+  }
+
+  @Nullable
+  @VisibleForTesting
+  public IndexEntry getIndexEntry(int indexId) {
+    return persistence
+        .query("SELECT index_value, uid, document_id FROM index_entries WHERE index_id = ?")
+        .binding(indexId)
+        .firstValue(
+            row ->
+                row == null
+                    ? null
+                    : new IndexEntry(indexId, row.getBlob(0), row.getString(1), row.getString(2)));
+  }
 }

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

@@ -111,13 +111,13 @@ public int getDocumentsRemoved() {
    * This class is responsible for the scheduling of LRU garbage collection. It handles checking
    * whether or not GC is enabled, as well as which delay to use before the next run.
    */
-  public class Scheduler implements StartStopScheduler {
+  public class GCScheduler implements Scheduler {
     private final AsyncQueue asyncQueue;
     private final LocalStore localStore;
     private boolean hasRun = false;
     @Nullable private AsyncQueue.DelayedTask gcTask;
 
-    public Scheduler(AsyncQueue asyncQueue, LocalStore localStore) {
+    public GCScheduler(AsyncQueue asyncQueue, LocalStore localStore) {
       this.asyncQueue = asyncQueue;
       this.localStore = localStore;
     }
@@ -159,8 +159,8 @@ private void scheduleGC() {
   }
 
   /** A helper method to create a new scheduler. */
-  public Scheduler newScheduler(AsyncQueue asyncQueue, LocalStore localStore) {
-    return new Scheduler(asyncQueue, localStore);
+  public GCScheduler newScheduler(AsyncQueue asyncQueue, LocalStore localStore) {
+    return new GCScheduler(asyncQueue, localStore);
   }
 
   /** Given a percentile of target to collect, returns the number of targets to collect. */