propagate channel buffer parameters to event channel invocations

Author: lhoward

Sources/FlutterSwift/Channel/FlutterChannel.swift

@@ -1,5 +1,5 @@
 //
-// Copyright (c) 2023-2024 PADL Software Pty Ltd
+// Copyright (c) 2023-2025 PADL Software Pty Ltd
 //
 // Licensed under the Apache License, Version 2.0 (the License);
 // you may not use this file except in compliance with the License.
@@ -39,6 +39,9 @@ public protocol FlutterChannel: AnyObject, Hashable, Equatable {
   var binaryMessenger: FlutterBinaryMessenger { get }
   var codec: FlutterMessageCodec { get }
   var priority: TaskPriority? { get }
+
+  func resizeChannelBuffer(_ newSize: Int) async throws
+  func allowChannelBufferOverflow(_ allowed: Bool) async throws
 }
 
 protocol _FlutterBinaryMessengerConnectionRepresentable: FlutterChannel {
@@ -92,25 +95,29 @@ func _allowChannelBufferOverflow(
 }
 
 public extension FlutterChannel {
-  func resizeChannelBuffer(_ newSize: Int) async throws {
+  static func == (lhs: Self, rhs: Self) -> Bool {
+    lhs.name == rhs.name
+  }
+
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(name)
+  }
+}
+
+protocol _FlutterChannelDefaultBufferControl: FlutterChannel {}
+
+extension _FlutterChannelDefaultBufferControl {
+  public func resizeChannelBuffer(_ newSize: Int) async throws {
     try await _resizeChannelBuffer(binaryMessenger: binaryMessenger, on: name, newSize: newSize)
   }
 
-  func allowChannelBufferOverflow(_ allowed: Bool) async throws {
+  public func allowChannelBufferOverflow(_ allowed: Bool) async throws {
     try await _allowChannelBufferOverflow(
       binaryMessenger: binaryMessenger,
       on: name,
       allowed: allowed
     )
   }
-
-  static func == (lhs: Self, rhs: Self) -> Bool {
-    lhs.name == rhs.name
-  }
-
-  func hash(into hasher: inout Hasher) {
-    hasher.combine(name)
-  }
 }
 
 extension _FlutterBinaryMessengerConnectionRepresentable {

Sources/FlutterSwift/Channel/FlutterEventChannel.swift

@@ -1,5 +1,5 @@
 //
-// Copyright (c) 2023-2024 PADL Software Pty Ltd
+// Copyright (c) 2023-2025 PADL Software Pty Ltd
 //
 // Licensed under the Apache License, Version 2.0 (the License);
 // you may not use this file except in compliance with the License.
@@ -32,7 +32,9 @@ public typealias FlutterEventStream<Event: Codable> = AnyAsyncSequence<Event?>
 /**
  * A channel for communicating with the Flutter side using event streams.
  */
-public final class FlutterEventChannel: _FlutterBinaryMessengerConnectionRepresentable, Sendable {
+public final class FlutterEventChannel: _FlutterBinaryMessengerConnectionRepresentable,
+  Sendable
+{
   public let name: String
   public let binaryMessenger: FlutterBinaryMessenger
   public let codec: FlutterMessageCodec
@@ -43,6 +45,10 @@ public final class FlutterEventChannel: _FlutterBinaryMessengerConnectionReprese
   private let _connection: ManagedAtomic<FlutterBinaryMessengerConnection>
   private let tasks: ManagedCriticalState<[String: EventStreamTask]>
 
+  // store these to propagate to separate channel invocations
+  private var channelBufferSize = 1
+  private var allowChannelBufferOverflow = false
+
   var connection: FlutterBinaryMessengerConnection {
     get {
       _connection.load(ordering: .acquiring)
@@ -161,6 +167,19 @@ public final class FlutterEventChannel: _FlutterBinaryMessengerConnectionReprese
 
     switch method.count > 1 ? String(method[0]) : call.method {
     case "listen":
+      if !invocationID.isEmpty {
+        try await _resizeChannelBuffer(
+          binaryMessenger: binaryMessenger,
+          on: name,
+          newSize: channelBufferSize
+        )
+        try await _allowChannelBufferOverflow(
+          binaryMessenger: binaryMessenger,
+          on: name,
+          allowed: allowChannelBufferOverflow
+        )
+      }
+
       let stream = try await onListen(call.arguments)
       let task = EventStreamTask(priority: priority) {
         try? await self._run(for: stream, name: name)
@@ -220,4 +239,18 @@ public final class FlutterEventChannel: _FlutterBinaryMessengerConnectionReprese
   public var tasksCount: Int {
     tasks.withCriticalRegion { $0.count }
   }
+
+  public func resizeChannelBuffer(_ newSize: Int) async throws {
+    try await _resizeChannelBuffer(binaryMessenger: binaryMessenger, on: name, newSize: newSize)
+    channelBufferSize = newSize
+  }
+
+  public func allowChannelBufferOverflow(_ allowed: Bool) async throws {
+    try await _allowChannelBufferOverflow(
+      binaryMessenger: binaryMessenger,
+      on: name,
+      allowed: allowed
+    )
+    allowChannelBufferOverflow = allowed
+  }
 }

Sources/FlutterSwift/Channel/FlutterMethodChannel.swift

@@ -74,7 +74,9 @@ extension FlutterMethodCall: Hashable where Arguments: Codable & Hashable {
  * A channel for communicating with the Flutter side using invocation of
  * asynchronous methods.
  */
-public final class FlutterMethodChannel: _FlutterBinaryMessengerConnectionRepresentable, Sendable {
+public final class FlutterMethodChannel: _FlutterBinaryMessengerConnectionRepresentable,
+  _FlutterChannelDefaultBufferControl, Sendable
+{
   public let name: String
   public let binaryMessenger: FlutterBinaryMessenger
   public let codec: FlutterMessageCodec