Don't leak orphaned docs when deleting (#32)

Don't leak orphaned docs when deleting in memory lru reference delegate

Author: Greg Soltis

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

@@ -18,6 +18,7 @@
 
 import com.google.firebase.firestore.core.ListenSequence;
 import com.google.firebase.firestore.model.DocumentKey;
+import com.google.firebase.firestore.model.MaybeDocument;
 import com.google.firebase.firestore.util.Consumer;
 import java.util.HashMap;
 import java.util.Map;
@@ -99,7 +100,17 @@ public int removeTargets(long upperBound, Set<Integer> activeTargetIds) {
 
   @Override
   public int removeOrphanedDocuments(long upperBound) {
-    return persistence.getRemoteDocumentCache().removeOrphanedDocuments(this, upperBound);
+    int count = 0;
+    MemoryRemoteDocumentCache cache = persistence.getRemoteDocumentCache();
+    for (Map.Entry<DocumentKey, MaybeDocument> entry : cache.getDocuments()) {
+      DocumentKey key = entry.getKey();
+      if (!isPinned(key, upperBound)) {
+        cache.remove(key);
+        orphanedSequenceNumbers.remove(key);
+        count++;
+      }
+    }
+    return count;
   }
 
   @Override
@@ -139,7 +150,11 @@ private boolean mutationQueuesContainsKey(DocumentKey key) {
     return false;
   }
 
-  public boolean isPinned(DocumentKey key, long upperBound) {
+  /**
+   * @return true if there is anything that would keep the given document alive or if the document's
+   *     sequence number is greater than the provided upper bound.
+   */
+  private boolean isPinned(DocumentKey key, long upperBound) {
     if (mutationQueuesContainsKey(key)) {
       return true;
     }

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

@@ -83,17 +83,7 @@ public ImmutableSortedMap<DocumentKey, Document> getAllDocumentsMatchingQuery(Qu
     return result;
   }
 
-  /** Remove any documents that the delegate reports as not pinned at the given upper bound. */
-  int removeOrphanedDocuments(MemoryLruReferenceDelegate delegate, long upperBound) {
-    int count = 0;
-    ImmutableSortedMap<DocumentKey, MaybeDocument> updated = docs;
-    for (Map.Entry<DocumentKey, MaybeDocument> entry : docs) {
-      if (!delegate.isPinned(entry.getKey(), upperBound)) {
-        updated = updated.remove(entry.getKey());
-        count++;
-      }
-    }
-    docs = updated;
-    return count;
+  ImmutableSortedMap<DocumentKey, MaybeDocument> getDocuments() {
+    return docs;
   }
 }