[pigeon] Allow multi instance support with message channel name suffix (flutter#6224)

Adds the ability to instantiate any api using a suffix string to allow for unique instances. 

partial flutter#66710

Author: tarrinneal

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 18.0.0
+
+* Adds message channel suffix option to all APIs.
+* **Breaking Change** [dart] Changes `FlutterApi` `setup` to `setUp`.
+
 ## 17.3.0
 
 * [swift] Adds `@SwiftClass` annotation to allow choice between `struct` and `class` for data classes.

packages/pigeon/README.md

@@ -75,6 +75,11 @@ When targeting a Flutter version that supports the
 the threading model for handling HostApi methods can be selected with the
 `TaskQueue` annotation.
 
+### Multi-Instance Support
+
+Host and Flutter APIs now support the ability to provide a unique message channel suffix string 
+to the api to allow for multiple instances to be created and operate in parallel. 
+
 ## Usage
 
 1) Add pigeon as a `dev_dependency`.

packages/pigeon/example/README.md

@@ -223,7 +223,7 @@ class _ExampleFlutterApi implements MessageFlutterApi {
   }
 }
 // ···
-  MessageFlutterApi.setup(_ExampleFlutterApi());
+  MessageFlutterApi.setUp(_ExampleFlutterApi());
 ```
 
 ### Swift

packages/pigeon/example/app/android/app/src/main/java/io/flutter/plugins/Messages.java

@@ -268,11 +268,20 @@ public interface ExampleHostApi {
     }
     /** Sets up an instance of `ExampleHostApi` to handle messages through the `binaryMessenger`. */
     static void setUp(@NonNull BinaryMessenger binaryMessenger, @Nullable ExampleHostApi api) {
+      setUp(binaryMessenger, "", api);
+    }
+
+    static void setUp(
+        @NonNull BinaryMessenger binaryMessenger,
+        @NonNull String messageChannelSuffix,
+        @Nullable ExampleHostApi api) {
+      messageChannelSuffix = messageChannelSuffix.isEmpty() ? "" : "." + messageChannelSuffix;
       {
         BasicMessageChannel<Object> channel =
             new BasicMessageChannel<>(
                 binaryMessenger,
-                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.getHostLanguage",
+                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.getHostLanguage"
+                    + messageChannelSuffix,
                 getCodec());
         if (api != null) {
           channel.setMessageHandler(
@@ -295,7 +304,8 @@ static void setUp(@NonNull BinaryMessenger binaryMessenger, @Nullable ExampleHos
         BasicMessageChannel<Object> channel =
             new BasicMessageChannel<>(
                 binaryMessenger,
-                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.add",
+                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.add"
+                    + messageChannelSuffix,
                 getCodec());
         if (api != null) {
           channel.setMessageHandler(
@@ -324,7 +334,8 @@ static void setUp(@NonNull BinaryMessenger binaryMessenger, @Nullable ExampleHos
         BasicMessageChannel<Object> channel =
             new BasicMessageChannel<>(
                 binaryMessenger,
-                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.sendMessage",
+                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.sendMessage"
+                    + messageChannelSuffix,
                 getCodec());
         if (api != null) {
           channel.setMessageHandler(
@@ -356,9 +367,16 @@ public void error(Throwable error) {
   /** Generated class from Pigeon that represents Flutter messages that can be called from Java. */
   public static class MessageFlutterApi {
     private final @NonNull BinaryMessenger binaryMessenger;
+    private final String messageChannelSuffix;
 
     public MessageFlutterApi(@NonNull BinaryMessenger argBinaryMessenger) {
+      this(argBinaryMessenger, "");
+    }
+
+    public MessageFlutterApi(
+        @NonNull BinaryMessenger argBinaryMessenger, @NonNull String messageChannelSuffix) {
       this.binaryMessenger = argBinaryMessenger;
+      this.messageChannelSuffix = messageChannelSuffix.isEmpty() ? "" : "." + messageChannelSuffix;
     }
 
     /** Public interface for sending reply. */
@@ -369,7 +387,8 @@ public MessageFlutterApi(@NonNull BinaryMessenger argBinaryMessenger) {
 
     public void flutterMethod(@Nullable String aStringArg, @NonNull Result<String> result) {
       final String channelName =
-          "dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod";
+          "dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod"
+              + messageChannelSuffix;
       BasicMessageChannel<Object> channel =
           new BasicMessageChannel<>(binaryMessenger, channelName, getCodec());
       channel.send(

packages/pigeon/example/app/android/app/src/main/kotlin/dev/flutter/pigeon_example_app/Messages.g.kt

@@ -119,12 +119,18 @@ interface ExampleHostApi {
     val codec: MessageCodec<Any?> by lazy { ExampleHostApiCodec }
     /** Sets up an instance of `ExampleHostApi` to handle messages through the `binaryMessenger`. */
     @Suppress("UNCHECKED_CAST")
-    fun setUp(binaryMessenger: BinaryMessenger, api: ExampleHostApi?) {
+    fun setUp(
+        binaryMessenger: BinaryMessenger,
+        api: ExampleHostApi?,
+        messageChannelSuffix: String = ""
+    ) {
+      val separatedMessageChannelSuffix =
+          if (messageChannelSuffix.isNotEmpty()) ".$messageChannelSuffix" else ""
       run {
         val channel =
             BasicMessageChannel<Any?>(
                 binaryMessenger,
-                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.getHostLanguage",
+                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.getHostLanguage$separatedMessageChannelSuffix",
                 codec)
         if (api != null) {
           channel.setMessageHandler { _, reply ->
@@ -144,7 +150,7 @@ interface ExampleHostApi {
         val channel =
             BasicMessageChannel<Any?>(
                 binaryMessenger,
-                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.add",
+                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.add$separatedMessageChannelSuffix",
                 codec)
         if (api != null) {
           channel.setMessageHandler { message, reply ->
@@ -167,7 +173,7 @@ interface ExampleHostApi {
         val channel =
             BasicMessageChannel<Any?>(
                 binaryMessenger,
-                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.sendMessage",
+                "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.sendMessage$separatedMessageChannelSuffix",
                 codec)
         if (api != null) {
           channel.setMessageHandler { message, reply ->
@@ -192,14 +198,20 @@ interface ExampleHostApi {
 }
 /** Generated class from Pigeon that represents Flutter messages that can be called from Kotlin. */
 @Suppress("UNCHECKED_CAST")
-class MessageFlutterApi(private val binaryMessenger: BinaryMessenger) {
+class MessageFlutterApi(
+    private val binaryMessenger: BinaryMessenger,
+    private val messageChannelSuffix: String = ""
+) {
   companion object {
     /** The codec used by MessageFlutterApi. */
     val codec: MessageCodec<Any?> by lazy { StandardMessageCodec() }
   }
 
   fun flutterMethod(aStringArg: String?, callback: (Result<String>) -> Unit) {
-    val channelName = "dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod"
+    val separatedMessageChannelSuffix =
+        if (messageChannelSuffix.isNotEmpty()) ".$messageChannelSuffix" else ""
+    val channelName =
+        "dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod$separatedMessageChannelSuffix"
     val channel = BasicMessageChannel<Any?>(binaryMessenger, channelName, codec)
     channel.send(listOf(aStringArg)) {
       if (it is List<*>) {

packages/pigeon/example/app/ios/Runner/Messages.g.swift

@@ -131,9 +131,13 @@ class ExampleHostApiSetup {
   /// The codec used by ExampleHostApi.
   static var codec: FlutterStandardMessageCodec { ExampleHostApiCodec.shared }
   /// Sets up an instance of `ExampleHostApi` to handle messages through the `binaryMessenger`.
-  static func setUp(binaryMessenger: FlutterBinaryMessenger, api: ExampleHostApi?) {
+  static func setUp(
+    binaryMessenger: FlutterBinaryMessenger, api: ExampleHostApi?, messageChannelSuffix: String = ""
+  ) {
+    let channelSuffix = messageChannelSuffix.count > 0 ? ".\(messageChannelSuffix)" : ""
     let getHostLanguageChannel = FlutterBasicMessageChannel(
-      name: "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.getHostLanguage",
+      name:
+        "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.getHostLanguage\(channelSuffix)",
       binaryMessenger: binaryMessenger, codec: codec)
     if let api = api {
       getHostLanguageChannel.setMessageHandler { _, reply in
@@ -148,7 +152,7 @@ class ExampleHostApiSetup {
       getHostLanguageChannel.setMessageHandler(nil)
     }
     let addChannel = FlutterBasicMessageChannel(
-      name: "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.add",
+      name: "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.add\(channelSuffix)",
       binaryMessenger: binaryMessenger, codec: codec)
     if let api = api {
       addChannel.setMessageHandler { message, reply in
@@ -166,7 +170,7 @@ class ExampleHostApiSetup {
       addChannel.setMessageHandler(nil)
     }
     let sendMessageChannel = FlutterBasicMessageChannel(
-      name: "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.sendMessage",
+      name: "dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.sendMessage\(channelSuffix)",
       binaryMessenger: binaryMessenger, codec: codec)
     if let api = api {
       sendMessageChannel.setMessageHandler { message, reply in
@@ -193,14 +197,16 @@ protocol MessageFlutterApiProtocol {
 }
 class MessageFlutterApi: MessageFlutterApiProtocol {
   private let binaryMessenger: FlutterBinaryMessenger
-  init(binaryMessenger: FlutterBinaryMessenger) {
+  private let messageChannelSuffix: String
+  init(binaryMessenger: FlutterBinaryMessenger, messageChannelSuffix: String = "") {
     self.binaryMessenger = binaryMessenger
+    self.messageChannelSuffix = messageChannelSuffix.count > 0 ? ".\(messageChannelSuffix)" : ""
   }
   func flutterMethod(
     aString aStringArg: String?, completion: @escaping (Result<String, FlutterError>) -> Void
   ) {
     let channelName: String =
-      "dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod"
+      "dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(name: channelName, binaryMessenger: binaryMessenger)
     channel.sendMessage([aStringArg] as [Any?]) { response in
       guard let listResponse = response as? [Any?] else {

packages/pigeon/example/app/lib/main.dart

@@ -20,7 +20,7 @@ class _ExampleFlutterApi implements MessageFlutterApi {
 
 void main() {
 // #docregion main-dart-flutter
-  MessageFlutterApi.setup(_ExampleFlutterApi());
+  MessageFlutterApi.setUp(_ExampleFlutterApi());
 // #enddocregion main-dart-flutter
   runApp(const MyApp());
 }

packages/pigeon/example/app/lib/src/messages.g.dart

@@ -97,16 +97,21 @@ class ExampleHostApi {
   /// Constructor for [ExampleHostApi].  The [binaryMessenger] named argument is
   /// available for dependency injection.  If it is left null, the default
   /// BinaryMessenger will be used which routes to the host platform.
-  ExampleHostApi({BinaryMessenger? binaryMessenger})
-      : __pigeon_binaryMessenger = binaryMessenger;
+  ExampleHostApi(
+      {BinaryMessenger? binaryMessenger, String messageChannelSuffix = ''})
+      : __pigeon_binaryMessenger = binaryMessenger,
+        __pigeon_messageChannelSuffix =
+            messageChannelSuffix.isNotEmpty ? '.$messageChannelSuffix' : '';
   final BinaryMessenger? __pigeon_binaryMessenger;
 
   static const MessageCodec<Object?> pigeonChannelCodec =
       _ExampleHostApiCodec();
 
+  final String __pigeon_messageChannelSuffix;
+
   Future<String> getHostLanguage() async {
-    const String __pigeon_channelName =
-        'dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.getHostLanguage';
+    final String __pigeon_channelName =
+        'dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.getHostLanguage$__pigeon_messageChannelSuffix';
     final BasicMessageChannel<Object?> __pigeon_channel =
         BasicMessageChannel<Object?>(
       __pigeon_channelName,
@@ -134,8 +139,8 @@ class ExampleHostApi {
   }
 
   Future<int> add(int a, int b) async {
-    const String __pigeon_channelName =
-        'dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.add';
+    final String __pigeon_channelName =
+        'dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.add$__pigeon_messageChannelSuffix';
     final BasicMessageChannel<Object?> __pigeon_channel =
         BasicMessageChannel<Object?>(
       __pigeon_channelName,
@@ -163,8 +168,8 @@ class ExampleHostApi {
   }
 
   Future<bool> sendMessage(MessageData message) async {
-    const String __pigeon_channelName =
-        'dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.sendMessage';
+    final String __pigeon_channelName =
+        'dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.sendMessage$__pigeon_messageChannelSuffix';
     final BasicMessageChannel<Object?> __pigeon_channel =
         BasicMessageChannel<Object?>(
       __pigeon_channelName,
@@ -198,12 +203,17 @@ abstract class MessageFlutterApi {
 
   String flutterMethod(String? aString);
 
-  static void setup(MessageFlutterApi? api,
-      {BinaryMessenger? binaryMessenger}) {
+  static void setUp(
+    MessageFlutterApi? api, {
+    BinaryMessenger? binaryMessenger,
+    String messageChannelSuffix = '',
+  }) {
+    messageChannelSuffix =
+        messageChannelSuffix.isNotEmpty ? '.$messageChannelSuffix' : '';
     {
       final BasicMessageChannel<Object?> __pigeon_channel = BasicMessageChannel<
               Object?>(
-          'dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod',
+          'dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod$messageChannelSuffix',
           pigeonChannelCodec,
           binaryMessenger: binaryMessenger);
       if (api == null) {

packages/pigeon/example/app/macos/Runner/messages.g.h

@@ -56,11 +56,17 @@ NSObject<FlutterMessageCodec> *PGNExampleHostApiGetCodec(void);
 extern void SetUpPGNExampleHostApi(id<FlutterBinaryMessenger> binaryMessenger,
                                    NSObject<PGNExampleHostApi> *_Nullable api);
 
+extern void SetUpPGNExampleHostApiWithSuffix(id<FlutterBinaryMessenger> binaryMessenger,
+                                             NSObject<PGNExampleHostApi> *_Nullable api,
+                                             NSString *messageChannelSuffix);
+
 /// The codec used by PGNMessageFlutterApi.
 NSObject<FlutterMessageCodec> *PGNMessageFlutterApiGetCodec(void);
 
 @interface PGNMessageFlutterApi : NSObject
 - (instancetype)initWithBinaryMessenger:(id<FlutterBinaryMessenger>)binaryMessenger;
+- (instancetype)initWithBinaryMessenger:(id<FlutterBinaryMessenger>)binaryMessenger
+                   messageChannelSuffix:(nullable NSString *)messageChannelSuffix;
 - (void)flutterMethodAString:(nullable NSString *)aString
                   completion:(void (^)(NSString *_Nullable, FlutterError *_Nullable))completion;
 @end

packages/pigeon/example/app/macos/Runner/messages.g.m

@@ -138,9 +138,21 @@ - (FlutterStandardReader *)readerWithData:(NSData *)data {
 
 void SetUpPGNExampleHostApi(id<FlutterBinaryMessenger> binaryMessenger,
                             NSObject<PGNExampleHostApi> *api) {
+  SetUpPGNExampleHostApiWithSuffix(binaryMessenger, api, @"");
+}
+
+void SetUpPGNExampleHostApiWithSuffix(id<FlutterBinaryMessenger> binaryMessenger,
+                                      NSObject<PGNExampleHostApi> *api,
+                                      NSString *messageChannelSuffix) {
+  messageChannelSuffix = messageChannelSuffix.length > 0
+                             ? [NSString stringWithFormat:@".%@", messageChannelSuffix]
+                             : @"";
   {
     FlutterBasicMessageChannel *channel = [[FlutterBasicMessageChannel alloc]
-           initWithName:@"dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.getHostLanguage"
+           initWithName:[NSString stringWithFormat:@"%@%@",
+                                                   @"dev.flutter.pigeon.pigeon_example_package."
+                                                   @"ExampleHostApi.getHostLanguage",
+                                                   messageChannelSuffix]
         binaryMessenger:binaryMessenger
                   codec:PGNExampleHostApiGetCodec()];
     if (api) {
@@ -159,7 +171,11 @@ void SetUpPGNExampleHostApi(id<FlutterBinaryMessenger> binaryMessenger,
   }
   {
     FlutterBasicMessageChannel *channel = [[FlutterBasicMessageChannel alloc]
-           initWithName:@"dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.add"
+           initWithName:
+               [NSString
+                   stringWithFormat:@"%@%@",
+                                    @"dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.add",
+                                    messageChannelSuffix]
         binaryMessenger:binaryMessenger
                   codec:PGNExampleHostApiGetCodec()];
     if (api) {
@@ -181,7 +197,10 @@ void SetUpPGNExampleHostApi(id<FlutterBinaryMessenger> binaryMessenger,
   }
   {
     FlutterBasicMessageChannel *channel = [[FlutterBasicMessageChannel alloc]
-           initWithName:@"dev.flutter.pigeon.pigeon_example_package.ExampleHostApi.sendMessage"
+           initWithName:[NSString stringWithFormat:@"%@%@",
+                                                   @"dev.flutter.pigeon.pigeon_example_package."
+                                                   @"ExampleHostApi.sendMessage",
+                                                   messageChannelSuffix]
         binaryMessenger:binaryMessenger
                   codec:PGNExampleHostApiGetCodec()];
     if (api) {
@@ -210,21 +229,31 @@ void SetUpPGNExampleHostApi(id<FlutterBinaryMessenger> binaryMessenger,
 
 @interface PGNMessageFlutterApi ()
 @property(nonatomic, strong) NSObject<FlutterBinaryMessenger> *binaryMessenger;
+@property(nonatomic, strong) NSString *messageChannelSuffix;
 @end
 
 @implementation PGNMessageFlutterApi
 
 - (instancetype)initWithBinaryMessenger:(NSObject<FlutterBinaryMessenger> *)binaryMessenger {
-  self = [super init];
+  return [self initWithBinaryMessenger:binaryMessenger messageChannelSuffix:@""];
+}
+- (instancetype)initWithBinaryMessenger:(NSObject<FlutterBinaryMessenger> *)binaryMessenger
+                   messageChannelSuffix:(nullable NSString *)messageChannelSuffix {
+  self = [self init];
   if (self) {
     _binaryMessenger = binaryMessenger;
+    _messageChannelSuffix = [messageChannelSuffix length] == 0
+                                ? @""
+                                : [NSString stringWithFormat:@".%@", messageChannelSuffix];
   }
   return self;
 }
 - (void)flutterMethodAString:(nullable NSString *)arg_aString
                   completion:(void (^)(NSString *_Nullable, FlutterError *_Nullable))completion {
-  NSString *channelName =
-      @"dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod";
+  NSString *channelName = [NSString
+      stringWithFormat:@"%@%@",
+                       @"dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod",
+                       _messageChannelSuffix];
   FlutterBasicMessageChannel *channel =
       [FlutterBasicMessageChannel messageChannelWithName:channelName
                                          binaryMessenger:self.binaryMessenger