New client pool implementation

http-client-core/src/main/java/io/micronaut/http/client/HttpClientConfiguration.java

@@ -915,7 +915,7 @@ public static class ConnectionPoolConfiguration implements Toggleable {
         private int maxPendingConnections = 4;
 
         private int maxConcurrentRequestsPerHttp2Connection = Integer.MAX_VALUE;
-        private int maxConcurrentHttp1Connections = Integer.MAX_VALUE;
+        private int maxConcurrentHttp1Connections = 1000;
         private int maxConcurrentHttp2Connections = 1;
 
         private int maxPendingAcquires = Integer.MAX_VALUE;
@@ -927,6 +927,9 @@ public static class ConnectionPoolConfiguration implements Toggleable {
         @NonNull
         private HttpClientConfiguration.ConnectionPoolConfiguration.ConnectionLocality connectionLocality = ConnectionLocality.PREFERRED;
 
+        @NonNull
+        private PoolVersion version = PoolVersion.V4_9;
+
         /**
          * Whether connection pooling is enabled.
          * [available in the Netty HTTP client]
@@ -1088,6 +1091,26 @@ public void setConnectionLocality(@NonNull HttpClientConfiguration.ConnectionPoo
             this.connectionLocality = connectionLocality;
         }
 
+        /**
+         * The version of the connection pool implementation. Defaults to {@code V4_9}, can be set
+         * to {@code V4_0} for compatibility.
+         *
+         * @return The pool version
+         */
+        public @NonNull PoolVersion getVersion() {
+            return version;
+        }
+
+        /**
+         * The version of the connection pool implementation. Defaults to {@code V4_9}, can be set
+         * to {@code V4_0} for compatibility.
+         *
+         * @param version The pool version
+         */
+        public void setVersion(@NonNull PoolVersion version) {
+            this.version = version;
+        }
+
         /**
          * Options for {@link #connectionLocality}.
          *
@@ -1120,6 +1143,22 @@ public enum ConnectionLocality {
              */
             ENFORCED_ALWAYS,
         }
+
+        /**
+         * Different pool implementation versions, for compatibility.
+         *
+         * @since 4.9.0
+         */
+        public enum PoolVersion {
+            /**
+             * The connection pool introduced in micronaut-core 4.0.0.
+             */
+            V4_0,
+            /**
+             * The connection pool introduced in micronaut-core 4.9.0.
+             */
+            V4_9
+        }
     }
 
     /**

http-client-core/src/main/java/io/micronaut/http/client/loadbalance/FixedLoadBalancer.java

@@ -15,6 +15,7 @@
  */
 package io.micronaut.http.client.loadbalance;
 
+import io.micronaut.core.annotation.Internal;
 import io.micronaut.core.annotation.Nullable;
 import io.micronaut.core.async.publisher.Publishers;
 import io.micronaut.discovery.ServiceInstance;
@@ -36,6 +37,7 @@
  */
 public class FixedLoadBalancer implements LoadBalancer  {
     private final Publisher<ServiceInstance> publisher;
+    private final ServiceInstance serviceInstance;
     private final URI uri;
 
     /**
@@ -56,7 +58,8 @@ public FixedLoadBalancer(URL url) {
      */
     public FixedLoadBalancer(URI uri) {
         this.uri = uri;
-        this.publisher = Publishers.just(ServiceInstance.of(uri.getHost(), uri));
+        serviceInstance = ServiceInstance.of(uri.getHost(), uri);
+        this.publisher = Publishers.just(serviceInstance);
     }
 
     @Override
@@ -84,6 +87,16 @@ public URI getUri() {
         return uri;
     }
 
+    /**
+     * The fixed {@link ServiceInstance} returned by {@link #select}. Internal use only.
+     *
+     * @return The service instance
+     */
+    @Internal
+    public ServiceInstance getServiceInstance() {
+        return serviceInstance;
+    }
+
     @Override
     public Optional<String> getContextPath() {
         return Optional.ofNullable(getUri().getPath());

http-client/src/main/java/io/micronaut/http/client/netty/BlockHint.java

@@ -19,7 +19,7 @@
 import io.micronaut.core.annotation.NonNull;
 import io.micronaut.core.annotation.Nullable;
 import io.micronaut.http.client.exceptions.HttpClientException;
-import io.netty.channel.EventLoop;
+import io.netty.util.concurrent.EventExecutor;
 
 /**
  * Information about what threads are blocked waiting for a request to complete. This is used to
@@ -64,7 +64,7 @@ static HttpClientException createException() {
                 "https://docs.micronaut.io/latest/guide/index.html#clientConfiguration");
     }
 
-    boolean blocks(EventLoop eventLoop) {
+    boolean blocks(EventExecutor eventLoop) {
         BlockHint bh = this;
         while (bh != null) {
             if (eventLoop.inEventLoop(bh.blockedThread)) {