Expose the child param configurator as well on the server

Author: gjcairo

Sources/GRPC/ClientConnection.swift

@@ -474,7 +474,7 @@ extension ClientConnection {
     public var debugChannelInitializer: (@Sendable (Channel) -> EventLoopFuture<Void>)?
 
     #if canImport(Network)
-    /// A closure allowing to customise the `NWParameters` used when establising a connection using NIOTransportServices.
+    /// A closure allowing to customise the `NWParameters` used when establishing a connection using `NIOTransportServices`.
     @available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *)
     public var nwParametersConfigurator: (@Sendable (NWParameters) -> Void)? {
       get {

Sources/GRPC/ConnectionPool/GRPCChannelPool.swift

@@ -322,7 +322,7 @@ extension GRPCChannelPool.Configuration {
       return configuration
     }
 
-    /// A closure allowing to customise the `NWParameters` used when establising a connection using NIOTransportServices.
+    /// A closure allowing to customise the `NWParameters` used when establishing a connection using `NIOTransportServices`.
     @available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *)
     public var nwParametersConfigurator: (@Sendable (NWParameters) -> Void)? {
       get {

Sources/GRPC/Server.swift

@@ -129,11 +129,18 @@ public final class Server: @unchecked Sendable {
     }
 
     if #available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *),
-      let configurator = configuration.nwParametersConfigurator,
+      let configurator = configuration.listenerNWParametersConfigurator,
       let transportServicesBootstrap = bootstrap as? NIOTSListenerBootstrap
     {
       _ = transportServicesBootstrap.configureNWParameters(configurator)
     }
+
+    if #available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *),
+       let configurator = configuration.childChannelNWParametersConfigurator,
+       let transportServicesBootstrap = bootstrap as? NIOTSListenerBootstrap
+    {
+      _ = transportServicesBootstrap.configureChildNWParameters(configurator)
+    }
     #endif  // canImport(Network)
 
     return
@@ -392,18 +399,31 @@ extension Server {
     internal var serviceProvidersByName: [Substring: CallHandlerProvider]
 
     #if canImport(Network)
-    /// A closure allowing to customise the `NWParameters` used when establising a connection using NIOTransportServices.
+    /// A closure allowing to customise the listener's `NWParameters` used when establishing a connection using `NIOTransportServices`.
+    @available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *)
+    public var listenerNWParametersConfigurator: (@Sendable (NWParameters) -> Void)? {
+      get {
+        self._listenerNWParametersConfigurator as! (@Sendable (NWParameters) -> Void)?
+      }
+      set {
+        self._listenerNWParametersConfigurator = newValue
+      }
+    }
+
+    private var _listenerNWParametersConfigurator: (any Sendable)?
+
+    /// A closure allowing to customise the child channels' `NWParameters` used when establishing connections using `NIOTransportServices`.
     @available(macOS 10.14, iOS 12.0, watchOS 6.0, tvOS 12.0, *)
-    public var nwParametersConfigurator: (@Sendable (NWParameters) -> Void)? {
+    public var childChannelNWParametersConfigurator: (@Sendable (NWParameters) -> Void)? {
       get {
-        self._nwParametersConfigurator as! (@Sendable (NWParameters) -> Void)?
+        self._childChannelNWParametersConfigurator as! (@Sendable (NWParameters) -> Void)?
       }
       set {
-        self._nwParametersConfigurator = newValue
+        self._childChannelNWParametersConfigurator = newValue
       }
     }
 
-    private var _nwParametersConfigurator: (any Sendable)?
+    private var _childChannelNWParametersConfigurator: (any Sendable)?
     #endif
 
     /// CORS configuration for gRPC-Web support.

Tests/GRPCTests/ServerTests.swift

@@ -18,29 +18,59 @@ import GRPC
 import NIOConcurrencyHelpers
 import NIOTransportServices
 import XCTest
+import EchoModel
+import EchoImplementation
 
 #if canImport(Network)
 import Network
 #endif
 
 class ServerTests: GRPCTestCase {
   #if canImport(Network)
-  func testParametersConfigurator() throws {
-    let counter = NIOLockedValueBox(0)
-    let serverEventLoopGroup = NIOTSEventLoopGroup()
+  func testParametersConfigurators() throws {
+    let listenerCounter = NIOLockedValueBox(0)
+    let childChannelsCounter = NIOLockedValueBox(0)
+    let group = NIOTSEventLoopGroup()
+    defer {
+      try? group.syncShutdownGracefully()
+    }
+
     var serverConfiguration = Server.Configuration.default(
       target: .hostAndPort("localhost", 0),
-      eventLoopGroup: serverEventLoopGroup,
+      eventLoopGroup: group,
       serviceProviders: []
     )
-    serverConfiguration.nwParametersConfigurator = { _ in
-      counter.withLockedValue { $0 += 1 }
+    serverConfiguration.listenerNWParametersConfigurator = { _ in
+      listenerCounter.withLockedValue { $0 += 1 }
+    }
+    serverConfiguration.childChannelNWParametersConfigurator = { _ in
+      childChannelsCounter.withLockedValue { $0 += 1 }
     }
 
     let server = try Server.start(configuration: serverConfiguration).wait()
-    XCTAssertEqual(1, counter.withLockedValue({ $0 }))
+    defer {
+      try? server.close().wait()
+    }
+
+    // The listener channel should be up and running after starting the server
+    XCTAssertEqual(1, listenerCounter.withLockedValue({ $0 }))
+    // However we don't have any child channels set up as there are no active connections
+    XCTAssertEqual(0, childChannelsCounter.withLockedValue({ $0 }))
+
+    // Start a client and execute a request so that a connection is established.
+    let channel = try GRPCChannelPool.with(
+      target: .hostAndPort("localhost", server.channel.localAddress!.port!),
+      transportSecurity: .plaintext,
+      eventLoopGroup: group
+    )
+    defer {
+      try? channel.close().wait()
+    }
+    let echo = Echo_EchoNIOClient(channel: channel)
+    _ = try echo.get(.with { $0.text = "" }).status.wait()
 
-    try? server.close().wait()
+    // Now the configurator should have run.
+    XCTAssertEqual(1, childChannelsCounter.withLockedValue({ $0 }))
   }
   #endif
 }