Port FSTEventManager to C++ (#3539)

* Initial version of c++ event manager

* Addressing comments - DelayedConstructor

* DelayedConstructor

* formatting

* final fixing

Author: wu-hui

Firestore/Example/Tests/Core/FSTEventManagerTests.mm

@@ -14,8 +14,6 @@
  * limitations under the License.
  */
 
-#import "Firestore/Source/Core/FSTEventManager.h"
-
 #import <OCMock/OCMock.h>
 #import <XCTest/XCTest.h>
 
@@ -27,6 +25,7 @@
 
 #import "Firestore/Example/Tests/Util/FSTHelpers.h"
 
+#include "Firestore/core/src/firebase/firestore/core/event_manager.h"
 #include "Firestore/core/src/firebase/firestore/core/view_snapshot.h"
 #include "Firestore/core/src/firebase/firestore/model/document_key_set.h"
 #include "Firestore/core/src/firebase/firestore/model/document_set.h"
@@ -36,8 +35,10 @@
 #include "Firestore/core/test/firebase/firestore/testutil/xcgmock.h"
 
 using firebase::firestore::core::EventListener;
+using firebase::firestore::core::EventManager;
 using firebase::firestore::core::ListenOptions;
 using firebase::firestore::core::QueryListener;
+using firebase::firestore::core::SyncEngineCallback;
 using firebase::firestore::core::ViewSnapshot;
 using firebase::firestore::model::DocumentKeySet;
 using firebase::firestore::model::DocumentSet;
@@ -63,10 +64,6 @@
 
 }  // namespace
 
-// FSTEventManager implements this delegate privately
-@interface FSTEventManager () <FSTSyncEngineDelegate>
-@end
-
 @interface FSTEventManagerTests : XCTestCase
 @end
 
@@ -79,18 +76,18 @@ - (void)DISABLED_testHandlesManyListenersPerQuery {
   auto listener2 = NoopQueryListener(query);
 
   FSTSyncEngine *syncEngineMock = OCMStrictClassMock([FSTSyncEngine class]);
-  OCMExpect([syncEngineMock setSyncEngineDelegate:[OCMArg any]]);
-  FSTEventManager *eventManager = [FSTEventManager eventManagerWithSyncEngine:syncEngineMock];
+  OCMExpect([syncEngineMock setCallback:static_cast<SyncEngineCallback *>([OCMArg anyPointer])]);
+  EventManager eventManager(syncEngineMock);
 
   OCMExpect([syncEngineMock listenToQuery:query]);
-  [eventManager addListener:listener1];
+  eventManager.AddQueryListener(listener1);
   OCMVerifyAll((id)syncEngineMock);
 
-  [eventManager addListener:listener2];
-  [eventManager removeListener:listener2];
+  eventManager.AddQueryListener(listener2);
+  eventManager.RemoveQueryListener(listener2);
 
   OCMExpect([syncEngineMock stopListeningToQuery:query]);
-  [eventManager removeListener:listener1];
+  eventManager.RemoveQueryListener(listener1);
   OCMVerifyAll((id)syncEngineMock);
 }
 
@@ -99,10 +96,10 @@ - (void)testHandlesUnlistenOnUnknownListenerGracefully {
   auto listener = NoopQueryListener(query);
 
   FSTSyncEngine *syncEngineMock = OCMStrictClassMock([FSTSyncEngine class]);
-  OCMExpect([syncEngineMock setSyncEngineDelegate:[OCMArg any]]);
-  FSTEventManager *eventManager = [FSTEventManager eventManagerWithSyncEngine:syncEngineMock];
+  OCMExpect([syncEngineMock setCallback:static_cast<SyncEngineCallback *>([OCMArg anyPointer])]);
+  EventManager eventManager(syncEngineMock);
 
-  [eventManager removeListener:listener];
+  eventManager.RemoveQueryListener(listener);
   OCMVerifyAll((id)syncEngineMock);
 }
 
@@ -129,17 +126,17 @@ - (void)DISABLED_testNotifiesListenersInTheRightOrder {
       query1, [eventOrder](StatusOr<ViewSnapshot>) { [eventOrder addObject:@"listener3"]; });
 
   FSTSyncEngine *syncEngineMock = OCMClassMock([FSTSyncEngine class]);
-  FSTEventManager *eventManager = [FSTEventManager eventManagerWithSyncEngine:syncEngineMock];
+  EventManager eventManager(syncEngineMock);
 
-  [eventManager addListener:listener1];
-  [eventManager addListener:listener2];
-  [eventManager addListener:listener3];
+  eventManager.AddQueryListener(listener1);
+  eventManager.AddQueryListener(listener2);
+  eventManager.AddQueryListener(listener3);
   OCMVerify([syncEngineMock listenToQuery:query1]);
   OCMVerify([syncEngineMock listenToQuery:query2]);
 
   ViewSnapshot snapshot1 = [self makeEmptyViewSnapshotWithQuery:query1];
   ViewSnapshot snapshot2 = [self makeEmptyViewSnapshotWithQuery:query2];
-  [eventManager handleViewSnapshots:{snapshot1, snapshot2}];
+  eventManager.OnViewSnapshots({snapshot1, snapshot2});
 
   NSArray *expected = @[ @"listener1", @"listener3", @"listener2" ];
   XCTAssertEqualObjects(eventOrder, expected);
@@ -165,14 +162,16 @@ void OnOnlineStateChanged(OnlineState online_state) override {
   auto fake_listener = std::make_shared<FakeQueryListener>(query);
 
   FSTSyncEngine *syncEngineMock = OCMClassMock([FSTSyncEngine class]);
-  OCMExpect([syncEngineMock setSyncEngineDelegate:[OCMArg any]]);
-  FSTEventManager *eventManager = [FSTEventManager eventManagerWithSyncEngine:syncEngineMock];
+  OCMExpect([syncEngineMock setCallback:static_cast<SyncEngineCallback *>([OCMArg anyPointer])]);
+  EventManager eventManager(syncEngineMock);
 
-  [eventManager addListener:fake_listener];
+  eventManager.AddQueryListener(fake_listener);
   XC_ASSERT_THAT(fake_listener->events, ElementsAre(OnlineState::Unknown));
 
-  [eventManager applyChangedOnlineState:OnlineState::Online];
+  eventManager.HandleOnlineStateChange(OnlineState::Online);
   XC_ASSERT_THAT(fake_listener->events, ElementsAre(OnlineState::Unknown, OnlineState::Online));
+
+  OCMVerifyAll((id)syncEngineMock);
 }
 
 @end

Firestore/Example/Tests/SpecTests/FSTSyncEngineTestDriver.mm

@@ -25,7 +25,6 @@
 #include <utility>
 #include <vector>
 
-#import "Firestore/Source/Core/FSTEventManager.h"
 #import "Firestore/Source/Core/FSTSyncEngine.h"
 #import "Firestore/Source/Local/FSTLocalStore.h"
 #import "Firestore/Source/Local/FSTPersistence.h"
@@ -38,11 +37,13 @@
 #include "Firestore/core/src/firebase/firestore/auth/empty_credentials_provider.h"
 #include "Firestore/core/src/firebase/firestore/auth/user.h"
 #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/model/database_id.h"
 #include "Firestore/core/src/firebase/firestore/model/document_key.h"
 #include "Firestore/core/src/firebase/firestore/objc/objc_compatibility.h"
 #include "Firestore/core/src/firebase/firestore/remote/remote_store.h"
 #include "Firestore/core/src/firebase/firestore/util/async_queue.h"
+#include "Firestore/core/src/firebase/firestore/util/delayed_constructor.h"
 #include "Firestore/core/src/firebase/firestore/util/error_apple.h"
 #include "Firestore/core/src/firebase/firestore/util/executor_libdispatch.h"
 #include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
@@ -58,6 +59,7 @@
 using firebase::firestore::auth::HashUser;
 using firebase::firestore::auth::User;
 using firebase::firestore::core::DatabaseInfo;
+using firebase::firestore::core::EventManager;
 using firebase::firestore::core::ListenOptions;
 using firebase::firestore::core::Query;
 using firebase::firestore::core::QueryListener;
@@ -72,13 +74,14 @@
 using firebase::firestore::remote::RemoteStore;
 using firebase::firestore::remote::WatchChange;
 using firebase::firestore::util::AsyncQueue;
-using firebase::firestore::util::TimerId;
+using firebase::firestore::util::DelayedConstructor;
 using firebase::firestore::util::ExecutorLibdispatch;
 using firebase::firestore::util::MakeNSError;
 using firebase::firestore::util::MakeString;
 using firebase::firestore::util::Status;
 using firebase::firestore::util::StatusOr;
 using firebase::firestore::util::StringFormat;
+using firebase::firestore::util::TimerId;
 using firebase::firestore::util::ToString;
 
 NS_ASSUME_NONNULL_BEGIN
@@ -111,7 +114,6 @@ @interface FSTSyncEngineTestDriver ()
 
 #pragma mark - Parts of the Firestore system that the spec tests need to control.
 
-@property(nonatomic, strong, readonly) FSTEventManager *eventManager;
 @property(nonatomic, strong, readonly) FSTLocalStore *localStore;
 @property(nonatomic, strong, readonly) FSTSyncEngine *syncEngine;
 @property(nonatomic, strong, readonly) id<FSTPersistence> persistence;
@@ -137,6 +139,8 @@ @implementation FSTSyncEngineTestDriver {
 
   std::unique_ptr<RemoteStore> _remoteStore;
 
+  DelayedConstructor<EventManager> _eventManager;
+
   std::unordered_map<TargetId, FSTQueryData *> _expectedActiveTargets;
 
   // ivar is declared as mutable.
@@ -183,15 +187,15 @@ - (instancetype)initWithPersistence:(id<FSTPersistence>)persistence
     _remoteStore = absl::make_unique<RemoteStore>(
         _localStore, _datastore, _workerQueue, [self](OnlineState onlineState) {
           [self.syncEngine applyChangedOnlineState:onlineState];
-          [self.eventManager applyChangedOnlineState:onlineState];
+          _eventManager->HandleOnlineStateChange(onlineState);
         });
     ;
 
     _syncEngine = [[FSTSyncEngine alloc] initWithLocalStore:_localStore
                                                 remoteStore:_remoteStore.get()
                                                 initialUser:initialUser];
     _remoteStore->set_sync_engine(_syncEngine);
-    _eventManager = [FSTEventManager eventManagerWithSyncEngine:_syncEngine];
+    _eventManager.Init(_syncEngine);
 
     // Set up internal event tracking for the spec tests.
     NSMutableArray<FSTQueryEvent *> *events = [NSMutableArray array];
@@ -363,7 +367,7 @@ - (TargetId)addUserListenerWithQuery:(Query)query {
       });
   _queryListeners[query] = listener;
   TargetId targetID;
-  _workerQueue->EnqueueBlocking([&] { targetID = [self.eventManager addListener:listener]; });
+  _workerQueue->EnqueueBlocking([&] { targetID = _eventManager->AddQueryListener(listener); });
   return targetID;
 }
 
@@ -373,7 +377,7 @@ - (void)removeUserListenerWithQuery:(const Query &)query {
     std::shared_ptr<QueryListener> listener = found_iter->second;
     _queryListeners.erase(found_iter);
 
-    _workerQueue->EnqueueBlocking([&] { [self.eventManager removeListener:listener]; });
+    _workerQueue->EnqueueBlocking([&] { _eventManager->RemoveQueryListener(listener); });
   }
 }