Extract resolveHostname helper, close resolver group before EventLoopGroup, simplify error handling

Agent-Logs-Url: https://github.com/doom369/async-http-client/sessions/b617a76d-89c2-45ca-b160-407a5737bcc7

Co-authored-by: doom369 <1536494+doom369@users.noreply.github.com>

Author: Copilot

client/src/main/java/org/asynchttpclient/netty/channel/ChannelManager.java

@@ -416,12 +416,14 @@ private void doClose() {
         ChannelGroupFuture groupFuture = openChannels.close();
         channelPool.destroy();
         groupFuture.addListener(future -> sslEngineFactory.destroy());
-        if (addressResolverGroup != null) {
-            addressResolverGroup.close();
-        }
     }
 
     public void close() {
+        // Close the resolver group first while the EventLoopGroup is still active,
+        // since Netty DNS resolvers may need a live EventLoop for clean shutdown.
+        if (addressResolverGroup != null) {
+            addressResolverGroup.close();
+        }
         if (allowReleaseEventLoopGroup) {
             final long shutdownQuietPeriod = config.getShutdownQuietPeriod().toMillis();
             final long shutdownTimeout = config.getShutdownTimeout().toMillis();

client/src/main/java/org/asynchttpclient/netty/request/NettyRequestSender.java

@@ -74,7 +74,7 @@
 import org.asynchttpclient.resolver.RequestHostnameResolver;
 import org.asynchttpclient.uri.Uri;
 import org.asynchttpclient.ws.WebSocketUpgradeHandler;
-import org.jetbrains.annotations.Nullable;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -377,11 +377,7 @@ private <T> Future<List<InetSocketAddress>> resolveAddresses(Request request, Pr
             int port = ProxyType.HTTPS.equals(proxy.getProxyType()) || uri.isSecured() ? proxy.getSecuredPort() : proxy.getPort();
             InetSocketAddress unresolvedRemoteAddress = InetSocketAddress.createUnresolved(proxy.getHost(), port);
             scheduleRequestTimeout(future, unresolvedRemoteAddress);
-            AddressResolver<InetSocketAddress> groupResolver = getGroupResolver();
-            if (groupResolver != null) {
-                return RequestHostnameResolver.INSTANCE.resolve(groupResolver, unresolvedRemoteAddress, asyncHandler);
-            }
-            return RequestHostnameResolver.INSTANCE.resolve(request.getNameResolver(), unresolvedRemoteAddress, asyncHandler);
+            return resolveHostname(request, unresolvedRemoteAddress, asyncHandler);
         } else {
             int port = uri.getExplicitPort();
 
@@ -393,18 +389,17 @@ private <T> Future<List<InetSocketAddress>> resolveAddresses(Request request, Pr
                 InetSocketAddress inetSocketAddress = new InetSocketAddress(request.getAddress(), port);
                 return promise.setSuccess(singletonList(inetSocketAddress));
             }
-            AddressResolver<InetSocketAddress> groupResolver = getGroupResolver();
-            if (groupResolver != null) {
-                return RequestHostnameResolver.INSTANCE.resolve(groupResolver, unresolvedRemoteAddress, asyncHandler);
-            } else {
-                return RequestHostnameResolver.INSTANCE.resolve(request.getNameResolver(), unresolvedRemoteAddress, asyncHandler);
-            }
+            return resolveHostname(request, unresolvedRemoteAddress, asyncHandler);
         }
     }
 
-    private @Nullable AddressResolver<InetSocketAddress> getGroupResolver() {
+    private Future<List<InetSocketAddress>> resolveHostname(Request request, InetSocketAddress unresolvedRemoteAddress, AsyncHandler<?> asyncHandler) {
         AddressResolverGroup<InetSocketAddress> group = channelManager.getAddressResolverGroup();
-        return group != null ? group.getResolver(channelManager.getEventLoopGroup().next()) : null;
+        if (group != null) {
+            AddressResolver<InetSocketAddress> resolver = group.getResolver(channelManager.getEventLoopGroup().next());
+            return RequestHostnameResolver.INSTANCE.resolve(resolver, unresolvedRemoteAddress, asyncHandler);
+        }
+        return RequestHostnameResolver.INSTANCE.resolve(request.getNameResolver(), unresolvedRemoteAddress, asyncHandler);
     }
 
     private <T> NettyResponseFuture<T> newNettyResponseFuture(Request request, AsyncHandler<T> asyncHandler, NettyRequest nettyRequest, ProxyServer proxyServer) {

client/src/main/java/org/asynchttpclient/resolver/RequestHostnameResolver.java

@@ -27,7 +27,7 @@
 
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
-import java.net.UnknownHostException;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -126,21 +126,14 @@ protected void onSuccess(List<InetSocketAddress> socketAddresses) {
 
             @Override
             protected void onFailure(Throwable t) {
-                // Wrap non-UnknownHostException DNS errors for backward compatibility.
-                // The JDK resolver always threw UnknownHostException; Netty's async DNS
-                // resolver may throw DnsErrorCauseException for SERVFAIL or other errors.
-                Throwable cause = t instanceof UnknownHostException ? t : new UnknownHostException(hostname);
-                if (!(t instanceof UnknownHostException)) {
-                    cause.initCause(t);
-                }
                 try {
-                    asyncHandler.onHostnameResolutionFailure(hostname, cause);
+                    asyncHandler.onHostnameResolutionFailure(hostname, t);
                 } catch (Exception e) {
                     LOGGER.error("onHostnameResolutionFailure crashed", e);
                     promise.tryFailure(e);
                     return;
                 }
-                promise.tryFailure(cause);
+                promise.tryFailure(t);
             }
         });