[camera_avfoundation] fix race condition when starting image stream on iOS

packages/camera/camera_avfoundation/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.9.18+10
+
+* Fix race condition when starting image stream
+
 ## 0.9.18+9
 
 * Backfills unit tests for `CameraPlugin` class.

packages/camera/camera_avfoundation/example/ios/Runner.xcodeproj/project.pbxproj

@@ -37,7 +37,7 @@
 		978D90B42D5F630300CD817E /* StreamingTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 978D90B32D5F630300CD817E /* StreamingTests.swift */; };
 		97922B0D2D6380C300A9B4CF /* SampleBufferTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 97922B0C2D6380C300A9B4CF /* SampleBufferTests.swift */; };
 		979B3DFB2D5B6BC7009BDE1A /* ExceptionCatcher.m in Sources */ = {isa = PBXBuildFile; fileRef = 979B3DFA2D5B6BC7009BDE1A /* ExceptionCatcher.m */; };
-		979B3DFE2D5B985B009BDE1A /* CameraCaptureSessionQueueRaceConditionTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 979B3DFD2D5B985B009BDE1A /* CameraCaptureSessionQueueRaceConditionTests.swift */; };
+		979B3DFE2D5B985B009BDE1A /* CameraInitRaceConditionsTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 979B3DFD2D5B985B009BDE1A /* CameraInitRaceConditionsTests.swift */; };
 		979B3E002D5B9E6C009BDE1A /* CameraMethodChannelTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 979B3DFF2D5B9E6C009BDE1A /* CameraMethodChannelTests.swift */; };
 		979B3E022D5BA48F009BDE1A /* CameraOrientationTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 979B3E012D5BA48F009BDE1A /* CameraOrientationTests.swift */; };
 		97BD4A0E2D5CC5AE00F857D5 /* CameraSettingsTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 97BD4A0D2D5CC5AE00F857D5 /* CameraSettingsTests.swift */; };
@@ -127,7 +127,7 @@
 		979B3DF92D5B6BA2009BDE1A /* ExceptionCatcher.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = ExceptionCatcher.h; sourceTree = "<group>"; };
 		979B3DFA2D5B6BC7009BDE1A /* ExceptionCatcher.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = ExceptionCatcher.m; sourceTree = "<group>"; };
 		979B3DFC2D5B985B009BDE1A /* RunnerTests-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "RunnerTests-Bridging-Header.h"; sourceTree = "<group>"; };
-		979B3DFD2D5B985B009BDE1A /* CameraCaptureSessionQueueRaceConditionTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CameraCaptureSessionQueueRaceConditionTests.swift; sourceTree = "<group>"; };
+		979B3DFD2D5B985B009BDE1A /* CameraInitRaceConditionsTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CameraInitRaceConditionsTests.swift; sourceTree = "<group>"; };
 		979B3DFF2D5B9E6C009BDE1A /* CameraMethodChannelTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CameraMethodChannelTests.swift; sourceTree = "<group>"; };
 		979B3E012D5BA48F009BDE1A /* CameraOrientationTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CameraOrientationTests.swift; sourceTree = "<group>"; };
 		97BD4A0D2D5CC5AE00F857D5 /* CameraSettingsTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CameraSettingsTests.swift; sourceTree = "<group>"; };
@@ -184,7 +184,7 @@
 				979B3DF92D5B6BA2009BDE1A /* ExceptionCatcher.h */,
 				979B3DFA2D5B6BC7009BDE1A /* ExceptionCatcher.m */,
 				979B3DFC2D5B985B009BDE1A /* RunnerTests-Bridging-Header.h */,
-				979B3DFD2D5B985B009BDE1A /* CameraCaptureSessionQueueRaceConditionTests.swift */,
+				979B3DFD2D5B985B009BDE1A /* CameraInitRaceConditionsTests.swift */,
 				979B3DFF2D5B9E6C009BDE1A /* CameraMethodChannelTests.swift */,
 				979B3E012D5BA48F009BDE1A /* CameraOrientationTests.swift */,
 				97BD4A0D2D5CC5AE00F857D5 /* CameraSettingsTests.swift */,
@@ -542,7 +542,8 @@
 				970ADABE2D6740A900EFDCD9 /* MockWritableData.swift in Sources */,
 				7F8FD2292D4BFABF001AF2C1 /* MockGlobalEventApi.m in Sources */,
 				7FD582352D57D97C003B1200 /* MockCaptureDeviceFormat.m in Sources */,
-				979B3DFE2D5B985B009BDE1A /* CameraCaptureSessionQueueRaceConditionTests.swift in Sources */,
+				979B3DFE2D5B985B009BDE1A /* CameraInitRaceConditionsTests.swift in Sources */,
+				7F29EB222D269ED500740257 /* MockEventChannel.m in Sources */,
 				7F8FD22F2D4D0B88001AF2C1 /* MockFlutterBinaryMessenger.m in Sources */,
 				E12C4FF82D68E85500515E70 /* MockFLTCameraPermissionManager.swift in Sources */,
 				97922B0D2D6380C300A9B4CF /* SampleBufferTests.swift in Sources */,

packages/camera/camera_avfoundation/example/ios/RunnerTests/CameraCaptureSessionQueueRaceConditionTests.swift → packages/camera/camera_avfoundation/example/ios/RunnerTests/CameraInitRaceConditionsTests.swift

@@ -6,7 +6,7 @@ import XCTest
 
 @testable import camera_avfoundation
 
-final class CameraCaptureSessionQueueRaceConditionTests: XCTestCase {
+final class CameraInitRaceConditionsTests: XCTestCase {
   private func createCameraPlugin() -> CameraPlugin {
     return CameraPlugin(
       registry: MockFlutterTextureRegistry(),
@@ -52,4 +52,41 @@ final class CameraCaptureSessionQueueRaceConditionTests: XCTestCase {
     XCTAssertNotNil(
       cameraPlugin.captureSessionQueue, "captureSessionQueue must not be nil after create method.")
   }
+
+  func testFlutterChannelInitializedWhenStartingImageStream() {
+    let cameraPlugin = createCameraPlugin()
+    let configuration = FLTCreateTestCameraConfiguration()
+    cameraPlugin.camera = FLTCreateCamWithConfiguration(configuration)
+
+    let createExpectation = expectation(description: "create's result block must be called")
+
+    cameraPlugin.createCameraOnSessionQueue(
+      withName: "acamera",
+      settings: FCPPlatformMediaSettings.make(
+        with: .medium,
+        framesPerSecond: nil,
+        videoBitrate: nil,
+        audioBitrate: nil,
+        enableAudio: true
+      )
+    ) { result, error in
+      createExpectation.fulfill()
+    }
+
+    waitForExpectations(timeout: 30, handler: nil)
+
+    // Start stream and wait for its completion
+    let startStreamExpectation = expectation(
+      description: "startImageStream's result block must be called")
+    cameraPlugin.startImageStream(completion: {
+      _ in
+      startStreamExpectation.fulfill()
+    })
+
+    waitForExpectations(timeout: 30, handler: nil)
+
+    XCTAssertEqual(cameraPlugin.camera?.isStreamingImages, true)
+
+  }
+
 }

packages/camera/camera_avfoundation/example/ios/RunnerTests/StreamingTests.swift

@@ -40,14 +40,28 @@ final class StreamingTests: XCTestCase {
 
   func testExceedMaxStreamingPendingFramesCount() {
     let (camera, sampleBuffer) = createCamera()
+    let handlerMock = MockImageStreamHandler()
+
+    let finishStartStreamExpectation = expectation(
+      description: "Finish startStream")
+
+    let messenger = MockFlutterBinaryMessenger()
+    camera.startImageStream(
+      with: messenger, imageStreamHandler: handlerMock,
+      withCompletion: {
+        _ in
+        finishStartStreamExpectation.fulfill()
+      })
+
+    waitForExpectations(timeout: 30, handler: nil)
+
+    // Setup mocked event sink after the stream starts
     let streamingExpectation = expectation(
       description: "Must not call handler over maxStreamingPendingFramesCount")
-    let handlerMock = MockImageStreamHandler()
+
     handlerMock.eventSinkStub = { event in
       streamingExpectation.fulfill()
     }
-    let messenger = MockFlutterBinaryMessenger()
-    camera.startImageStream(with: messenger, imageStreamHandler: handlerMock)
 
     let expectation = XCTKVOExpectation(
       keyPath: "isStreamingImages", object: camera, expectedValue: true)
@@ -64,14 +78,27 @@ final class StreamingTests: XCTestCase {
 
   func testReceivedImageStreamData() {
     let (camera, sampleBuffer) = createCamera()
+    let handlerMock = MockImageStreamHandler()
+
+    let finishStartStreamExpectation = expectation(
+      description: "Finish startStream")
+
+    let messenger = MockFlutterBinaryMessenger()
+    camera.startImageStream(
+      with: messenger, imageStreamHandler: handlerMock,
+      withCompletion: {
+        _ in
+        finishStartStreamExpectation.fulfill()
+      })
+
+    waitForExpectations(timeout: 30, handler: nil)
+
+    // Setup mocked event sink after the stream starts
     let streamingExpectation = expectation(
       description: "Must be able to call the handler again when receivedImageStreamData is called")
-    let handlerMock = MockImageStreamHandler()
     handlerMock.eventSinkStub = { event in
       streamingExpectation.fulfill()
     }
-    let messenger = MockFlutterBinaryMessenger()
-    camera.startImageStream(with: messenger, imageStreamHandler: handlerMock)
 
     let expectation = XCTKVOExpectation(
       keyPath: "isStreamingImages", object: camera, expectedValue: true)

packages/camera/camera_avfoundation/ios/camera_avfoundation/Sources/camera_avfoundation/CameraPlugin.m

@@ -224,8 +224,7 @@ - (void)initializeCamera:(NSInteger)cameraId
 - (void)startImageStreamWithCompletion:(nonnull void (^)(FlutterError *_Nullable))completion {
   __weak typeof(self) weakSelf = self;
   dispatch_async(self.captureSessionQueue, ^{
-    [weakSelf.camera startImageStreamWithMessenger:weakSelf.messenger];
-    completion(nil);
+    [weakSelf.camera startImageStreamWithMessenger:weakSelf.messenger withCompletion:completion];
   });
 }
 

packages/camera/camera_avfoundation/ios/camera_avfoundation/Sources/camera_avfoundation/FLTCam.m

@@ -842,7 +842,7 @@ - (void)startVideoRecordingWithCompletion:(void (^)(FlutterError *_Nullable))com
                     messengerForStreaming:(nullable NSObject<FlutterBinaryMessenger> *)messenger {
   if (!_isRecording) {
     if (messenger != nil) {
-      [self startImageStreamWithMessenger:messenger];
+      [self startImageStreamWithMessenger:messenger withCompletion:completion];
     }
 
     NSError *error;
@@ -1168,14 +1168,17 @@ - (void)setExposureOffset:(double)offset {
   [_captureDevice unlockForConfiguration];
 }
 
-- (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messenger {
+- (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messenger
+                       withCompletion:(void (^)(FlutterError *))completion {
   [self startImageStreamWithMessenger:messenger
                    imageStreamHandler:[[FLTImageStreamHandler alloc]
-                                          initWithCaptureSessionQueue:_captureSessionQueue]];
+                                          initWithCaptureSessionQueue:_captureSessionQueue]
+                       withCompletion:completion];
 }
 
 - (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messenger
-                   imageStreamHandler:(FLTImageStreamHandler *)imageStreamHandler {
+                   imageStreamHandler:(FLTImageStreamHandler *)imageStreamHandler
+                       withCompletion:(void (^)(FlutterError *))completion {
   if (!_isStreamingImages) {
     id<FLTEventChannel> eventChannel = [FlutterEventChannel
         eventChannelWithName:@"plugins.flutter.io/camera_avfoundation/imageStream"
@@ -1197,6 +1200,7 @@ - (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messen
 
                                       strongSelf.isStreamingImages = YES;
                                       strongSelf.streamingPendingFramesCount = 0;
+                                      completion(nil);
                                     });
                                   }];
   } else {

packages/camera/camera_avfoundation/ios/camera_avfoundation/Sources/camera_avfoundation/include/camera_avfoundation/FLTCam.h

@@ -106,7 +106,8 @@ NS_ASSUME_NONNULL_BEGIN
        withCompletion:(void (^)(FlutterError *_Nullable))completion
     NS_SWIFT_NAME(setFocusPoint(_:completion:));
 - (void)setExposureOffset:(double)offset;
-- (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messenger;
+- (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messenger
+                       withCompletion:(nonnull void (^)(FlutterError *_Nullable))completion;
 - (void)stopImageStream;
 - (void)setZoomLevel:(CGFloat)zoom withCompletion:(void (^)(FlutterError *_Nullable))completion;
 - (void)setUpCaptureSessionForAudioIfNeeded;

packages/camera/camera_avfoundation/ios/camera_avfoundation/Sources/camera_avfoundation/include/camera_avfoundation/FLTCam_Test.h

@@ -47,9 +47,9 @@
 - (void)captureOutput:(AVCaptureOutput *)output
     didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
            fromConnection:(NSObject<FLTCaptureConnection> *)connection;
-
 /// Start streaming images.
 - (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messenger
-                   imageStreamHandler:(FLTImageStreamHandler *)imageStreamHandler;
+                   imageStreamHandler:(FLTImageStreamHandler *)imageStreamHandler
+                       withCompletion:(void (^)(FlutterError *))completion;
 
 @end

packages/camera/camera_avfoundation/pubspec.yaml

@@ -2,7 +2,7 @@ name: camera_avfoundation
 description: iOS implementation of the camera plugin.
 repository: https://github.com/flutter/packages/tree/main/packages/camera/camera_avfoundation
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+camera%22
-version: 0.9.18+9
+version: 0.9.18+10
 
 environment:
   sdk: ^3.4.0