Expose APIs to customise NWParameters when using NIOTS

Sources/GRPC/ClientConnection.swift

@@ -469,6 +469,24 @@ extension ClientConnection {
     @preconcurrency
     public var debugChannelInitializer: (@Sendable (Channel) -> EventLoopFuture<Void>)?
 
+    #if canImport(Network)
+    @available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *)
+    public var clientBootstrapNWParametersConfigurator: (
+      @Sendable (NIOTSConnectionBootstrap) -> Void
+    )? {
+      get {
+        return self._clientBootstrapNWParametersConfigurator as! (
+          @Sendable (NIOTSConnectionBootstrap) -> Void
+        )?
+      }
+      set {
+        self._clientBootstrapNWParametersConfigurator = newValue
+      }
+    }
+
+    private var _clientBootstrapNWParametersConfigurator: (any Sendable)?
+    #endif
+
     #if canImport(NIOSSL)
     /// Create a `Configuration` with some pre-defined defaults. Prefer using
     /// `ClientConnection.secure(group:)` to build a connection secured with TLS or

Sources/GRPC/ConnectionManagerChannelProvider.swift

@@ -72,6 +72,56 @@ internal struct DefaultChannelProvider: ConnectionManagerChannelProvider {
   @usableFromInline
   internal var debugChannelInitializer: Optional<(Channel) -> EventLoopFuture<Void>>
 
+  #if canImport(Network)
+  @available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *)
+  @usableFromInline
+  internal var clientBootstrapNWParametersConfigurator: (
+    @Sendable (NIOTSConnectionBootstrap) -> Void
+  )? {
+    get {
+      return self._clientBootstrapNWParametersConfigurator as! (
+        @Sendable (NIOTSConnectionBootstrap) -> Void
+      )?
+    }
+    set {
+      self._clientBootstrapNWParametersConfigurator = newValue
+    }
+  }
+
+  private var _clientBootstrapNWParametersConfigurator: (any Sendable)?
+  #endif
+
+  #if canImport(Network)
+  @inlinable
+  @available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *)
+  internal init(
+    connectionTarget: ConnectionTarget,
+    connectionKeepalive: ClientConnectionKeepalive,
+    connectionIdleTimeout: TimeAmount,
+    tlsMode: TLSMode,
+    tlsConfiguration: GRPCTLSConfiguration?,
+    httpTargetWindowSize: Int,
+    httpMaxFrameSize: Int,
+    errorDelegate: ClientErrorDelegate?,
+    debugChannelInitializer: ((Channel) -> EventLoopFuture<Void>)?,
+    clientBootstrapNWParametersConfigurator: (@Sendable (NIOTSConnectionBootstrap) -> Void)?
+  ) {
+    self.init(
+      connectionTarget: connectionTarget,
+      connectionKeepalive: connectionKeepalive,
+      connectionIdleTimeout: connectionIdleTimeout,
+      tlsMode: tlsMode,
+      tlsConfiguration: tlsConfiguration,
+      httpTargetWindowSize: httpTargetWindowSize,
+      httpMaxFrameSize: httpMaxFrameSize,
+      errorDelegate: errorDelegate,
+      debugChannelInitializer: debugChannelInitializer
+    )
+
+    self.clientBootstrapNWParametersConfigurator = clientBootstrapNWParametersConfigurator
+  }
+  #endif
+
   @inlinable
   internal init(
     connectionTarget: ConnectionTarget,
@@ -133,6 +183,12 @@ internal struct DefaultChannelProvider: ConnectionManagerChannelProvider {
       errorDelegate: configuration.errorDelegate,
       debugChannelInitializer: configuration.debugChannelInitializer
     )
+
+    #if canImport(Network)
+    if #available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *) {
+      self.clientBootstrapNWParametersConfigurator = configuration.clientBootstrapNWParametersConfigurator
+    }
+    #endif
   }
 
   private var serverHostname: String? {
@@ -210,6 +266,14 @@ internal struct DefaultChannelProvider: ConnectionManagerChannelProvider {
           return channel.eventLoop.makeFailedFuture(error)
         }
 
+        #if canImport(Network)
+        if #available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *),
+           let configurator = self.clientBootstrapNWParametersConfigurator,
+           let niotsBootstrap = bootstrap as? NIOTSConnectionBootstrap {
+          configurator(niotsBootstrap)
+        }
+        #endif
+
         // Run the debug initializer, if there is one.
         if let debugInitializer = self.debugChannelInitializer {
           return debugInitializer(channel)

Sources/GRPC/ConnectionPool/GRPCChannelPool.swift

@@ -17,6 +17,10 @@ import Logging
 import NIOCore
 import NIOPosix
 
+#if canImport(Network)
+import NIOTransportServices
+#endif
+
 import struct Foundation.UUID
 
 public enum GRPCChannelPool {
@@ -191,6 +195,8 @@ extension GRPCChannelPool {
         return SwiftLogNoOpLogHandler()
       }
     )
+
+    public var transportServices: TransportServices = .defaults
   }
 }
 
@@ -299,6 +305,39 @@ extension GRPCChannelPool.Configuration {
   }
 }
 
+#if canImport(Network)
+extension GRPCChannelPool.Configuration {
+  public struct TransportServices: Sendable {
+    /// Default transport services configuration.
+    public static let defaults = Self()
+
+    @inlinable
+    public static func with(_ configure: (inout Self) -> Void) -> Self {
+      var configuration = Self.defaults
+      configure(&configuration)
+      return configuration
+    }
+
+    // TODO: write docs
+    @available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *)
+    public var clientBootstrapNWParametersConfigurator: (
+      @Sendable (NIOTSConnectionBootstrap) -> Void
+    )? {
+      get {
+        return self._clientBootstrapNWParametersConfigurator as! (
+          @Sendable (NIOTSConnectionBootstrap) -> Void
+        )?
+      }
+      set {
+        self._clientBootstrapNWParametersConfigurator = newValue
+      }
+    }
+
+    private var _clientBootstrapNWParametersConfigurator: (any Sendable)?
+  }
+}
+#endif // canImport(Network)
+
 /// The ID of a connection in the connection pool.
 public struct GRPCConnectionID: Hashable, Sendable, CustomStringConvertible {
   private enum Value: Sendable, Hashable {

Sources/GRPC/ConnectionPool/PooledChannel.swift

@@ -79,7 +79,36 @@ internal final class PooledChannel: GRPCChannel {
 
     self._scheme = scheme
 
-    let provider = DefaultChannelProvider(
+    let provider: DefaultChannelProvider
+    #if canImport(Network)
+    if #available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *) {
+      provider = DefaultChannelProvider(
+        connectionTarget: configuration.target,
+        connectionKeepalive: configuration.keepalive,
+        connectionIdleTimeout: configuration.idleTimeout,
+        tlsMode: tlsMode,
+        tlsConfiguration: configuration.transportSecurity.tlsConfiguration,
+        httpTargetWindowSize: configuration.http2.targetWindowSize,
+        httpMaxFrameSize: configuration.http2.maxFrameSize,
+        errorDelegate: configuration.errorDelegate,
+        debugChannelInitializer: configuration.debugChannelInitializer,
+        clientBootstrapNWParametersConfigurator: configuration.transportServices.clientBootstrapNWParametersConfigurator
+      )
+    } else {
+      provider = DefaultChannelProvider(
+        connectionTarget: configuration.target,
+        connectionKeepalive: configuration.keepalive,
+        connectionIdleTimeout: configuration.idleTimeout,
+        tlsMode: tlsMode,
+        tlsConfiguration: configuration.transportSecurity.tlsConfiguration,
+        httpTargetWindowSize: configuration.http2.targetWindowSize,
+        httpMaxFrameSize: configuration.http2.maxFrameSize,
+        errorDelegate: configuration.errorDelegate,
+        debugChannelInitializer: configuration.debugChannelInitializer
+      )
+    }
+    #else
+    provider = DefaultChannelProvider(
       connectionTarget: configuration.target,
       connectionKeepalive: configuration.keepalive,
       connectionIdleTimeout: configuration.idleTimeout,
@@ -90,6 +119,7 @@ internal final class PooledChannel: GRPCChannel {
       errorDelegate: configuration.errorDelegate,
       debugChannelInitializer: configuration.debugChannelInitializer
     )
+    #endif
 
     self._pool = PoolManager.makeInitializedPoolManager(
       using: configuration.eventLoopGroup,

Sources/GRPC/Server.swift

@@ -127,6 +127,12 @@ public final class Server: @unchecked Sendable {
         _ = transportServicesBootstrap.tlsOptions(from: tlsConfiguration)
       }
     }
+
+    if #available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *),
+       let nwParametersConfigurator = configuration.serverBootstrapNWParametersConfigurator,
+       let transportServicesBootstrap = bootstrap as? NIOTSListenerBootstrap {
+        nwParametersConfigurator(transportServicesBootstrap)
+    }
     #endif  // canImport(Network)
 
     return
@@ -384,6 +390,24 @@ extension Server {
     /// the need to recalculate this dictionary each time we receive an rpc.
     internal var serviceProvidersByName: [Substring: CallHandlerProvider]
 
+    #if canImport(Network)
+    @available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *)
+    public var serverBootstrapNWParametersConfigurator: (
+      @Sendable (NIOTSListenerBootstrap) -> Void
+    )? {
+      get {
+        return self._serverBootstrapNWParametersConfigurator as! (
+          @Sendable (NIOTSListenerBootstrap) -> Void
+        )?
+      }
+      set {
+        self._serverBootstrapNWParametersConfigurator = newValue
+      }
+    }
+
+    private var _serverBootstrapNWParametersConfigurator: (any Sendable)?
+    #endif
+
     /// CORS configuration for gRPC-Web support.
     public var webCORS = Configuration.CORS()
 

Tests/GRPCTests/ConnectionManagerTests.swift

@@ -20,6 +20,12 @@ import NIOEmbedded
 import NIOHTTP2
 import XCTest
 
+#if canImport(Network)
+import NIOConcurrencyHelpers
+import NIOTransportServices
+import Network
+#endif
+
 @testable import GRPC
 
 class ConnectionManagerTests: GRPCTestCase {
@@ -1412,6 +1418,54 @@ extension ConnectionManagerTests {
       XCTAssert(error is DoomedChannelError)
     }
   }
+
+  #if canImport(Network)
+  func testDefaultChannelProvider_NWParametersConfigurator() throws {
+    let counter = NIOLockedValueBox(0)
+    let group = NIOTSEventLoopGroup(loopCount: 1)
+    var configuration = ClientConnection.Configuration.default(
+      target: .unixDomainSocket("/ignored"),
+      eventLoopGroup: group
+    )
+    configuration.clientBootstrapNWParametersConfigurator = { _ in
+      counter.withLockedValue { $0 += 1 }
+    }
+
+    // We need to trigger the connection to apply the parameters configurator.
+    // However, we don't actually care about establishing the connection: only triggering it.
+    // In other tests, we used mocked channel providers to simply return completed futures when "creating"
+    // the channels. However, in this test we want to make sure that the `DefaultChannelProvider`,
+    // which is the one we actually use, correctly sets and executes the configurator.
+    // For this reason, we can wait on a promise that is succeeded after the configurator has been called,
+    // in the debug channel initializer. This promise will always succeed regardless of the actual
+    // connection being established. And because this closure is executed after the parameters configurator,
+    // we know the counter should be updated by the time the promise has been completed.
+    let promise = group.next().makePromise(of: Void.self)
+    configuration.debugChannelInitializer = { channel in
+      promise.succeed()
+      return promise.futureResult
+    }
+
+    let manager = ConnectionManager(
+      configuration: configuration,
+      connectivityDelegate: self.monitor,
+      idleBehavior: .closeWhenIdleTimeout,
+      logger: self.logger
+    )
+
+    // Start connecting. We don't care about the actual result of the connection.
+    _ = manager.getHTTP2Multiplexer()
+
+    // Wait until the configurator has been called.
+    try promise.futureResult.wait()
+
+    XCTAssertEqual(1, counter.withLockedValue({ $0 }))
+
+    try group.syncShutdownGracefully()
+  }
+  #endif
+
+  // TODO: add test using the default channel provider that uses the parameter configurator and make sure it gets called
 }
 
 internal struct Change: Hashable, CustomStringConvertible {

Tests/GRPCTests/ConnectionPool/GRPCChannelPoolTests.swift

@@ -24,8 +24,13 @@ import NIOPosix
 import NIOSSL
 import XCTest
 
+#if canImport(Network)
+import Network
+import NIOTransportServices
+#endif
+
 final class GRPCChannelPoolTests: GRPCTestCase {
-  private var group: MultiThreadedEventLoopGroup!
+  private var group: (any EventLoopGroup)!
   private var server: Server?
   private var channel: GRPCChannel?
 
@@ -618,5 +623,24 @@ final class GRPCChannelPoolTests: GRPCTestCase {
 
     XCTAssertGreaterThan(statsEvents.count, 0)
   }
+
+  #if canImport(Network)
+  func testNWParametersConfigurator() {
+    let counter = NIOLockedValueBox(0)
+    self.group = NIOTSEventLoopGroup()
+    self.startServer(withTLS: false)
+    self.startChannel(withTLS: false) { configuration in
+      configuration.transportServices.clientBootstrapNWParametersConfigurator = { _ in
+        counter.withLockedValue { $0 += 1 }
+      }
+    }
+
+    // Execute an RPC to make sure a channel gets created/activated and the parameters configurator run.
+    let rpc = self.echo.get(.with { $0.text = "" })
+    XCTAssertNoThrow(try rpc.status.wait())
+
+    XCTAssertEqual(1, counter.withLockedValue({ $0 }))
+  }
+  #endif // canImport(Network)
 }
 #endif  // canImport(NIOSSL)