Enable Index-Free queries (#4618)

Author: schmidt-sebastian

Firestore/CHANGELOG.md

@@ -1,4 +1,9 @@
-# Unreleased
+# Unreleased (v1.10.0)
+- [changed] Improved the performance of repeatedly executed queries when
+  persistence is enabled. Recently executed queries should see dramatic
+  improvements. This benefit is reduced if changes accumulate while the query
+  is inactive. Queries that use the `limit()` API may not always benefit,
+  depending on the accumulated changes.
 
 # v1.9.0
 - [feature] Added a `limit(toLast:)` query operator, which returns the last

Firestore/Example/Tests/SpecTests/FSTSyncEngineTestDriver.mm

@@ -33,9 +33,9 @@
 #include "Firestore/core/src/firebase/firestore/core/database_info.h"
 #include "Firestore/core/src/firebase/firestore/core/event_manager.h"
 #include "Firestore/core/src/firebase/firestore/core/sync_engine.h"
+#include "Firestore/core/src/firebase/firestore/local/index_free_query_engine.h"
 #include "Firestore/core/src/firebase/firestore/local/local_store.h"
 #include "Firestore/core/src/firebase/firestore/local/persistence.h"
-#include "Firestore/core/src/firebase/firestore/local/simple_query_engine.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
 #include "Firestore/core/src/firebase/firestore/model/document_key.h"
 #include "Firestore/core/src/firebase/firestore/remote/remote_store.h"
@@ -66,10 +66,10 @@
 using firebase::firestore::core::QueryListener;
 using firebase::firestore::core::SyncEngine;
 using firebase::firestore::core::ViewSnapshot;
+using firebase::firestore::local::IndexFreeQueryEngine;
 using firebase::firestore::local::LocalStore;
 using firebase::firestore::local::Persistence;
 using firebase::firestore::local::QueryData;
-using firebase::firestore::local::SimpleQueryEngine;
 using firebase::firestore::model::DatabaseId;
 using firebase::firestore::model::DocumentKey;
 using firebase::firestore::model::DocumentKeySet;
@@ -181,8 +181,7 @@ @implementation FSTSyncEngineTestDriver {
   std::vector<std::shared_ptr<EventListener<Empty>>> _snapshotsInSyncListeners;
   std::shared_ptr<MockDatastore> _datastore;
 
-  // TODO(index-free): Use IndexFreeQueryEngine
-  SimpleQueryEngine _queryEngine;
+  IndexFreeQueryEngine _queryEngine;
 
   int _snapshotsInSyncEvents;
 }

Firestore/core/src/firebase/firestore/core/firestore_client.cc

@@ -25,11 +25,11 @@
 #include "Firestore/core/src/firebase/firestore/core/database_info.h"
 #include "Firestore/core/src/firebase/firestore/core/event_manager.h"
 #include "Firestore/core/src/firebase/firestore/core/view.h"
+#include "Firestore/core/src/firebase/firestore/local/index_free_query_engine.h"
 #include "Firestore/core/src/firebase/firestore/local/leveldb_persistence.h"
 #include "Firestore/core/src/firebase/firestore/local/local_serializer.h"
 #include "Firestore/core/src/firebase/firestore/local/memory_persistence.h"
 #include "Firestore/core/src/firebase/firestore/local/query_result.h"
-#include "Firestore/core/src/firebase/firestore/local/simple_query_engine.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
 #include "Firestore/core/src/firebase/firestore/model/document_set.h"
 #include "Firestore/core/src/firebase/firestore/model/mutation.h"
@@ -59,13 +59,13 @@ using api::SnapshotMetadata;
 using auth::CredentialsProvider;
 using auth::User;
 using firestore::Error;
+using local::IndexFreeQueryEngine;
 using local::LevelDbPersistence;
 using local::LocalSerializer;
 using local::LocalStore;
 using local::LruParams;
 using local::MemoryPersistence;
 using local::QueryResult;
-using local::SimpleQueryEngine;
 using model::DatabaseId;
 using model::Document;
 using model::DocumentKeySet;
@@ -185,8 +185,7 @@ void FirestoreClient::Initialize(const User& user, const Settings& settings) {
     persistence_ = MemoryPersistence::WithEagerGarbageCollector();
   }
 
-  // TODO(index-free): Use IndexFreeQueryEngine
-  query_engine_ = absl::make_unique<SimpleQueryEngine>();
+  query_engine_ = absl::make_unique<IndexFreeQueryEngine>();
   local_store_ = absl::make_unique<LocalStore>(persistence_.get(),
                                                query_engine_.get(), user);