Add a method in PoolingHttpClientConnectionManagerBuilder/PoolingAsyncClientConnectionManagerBuilder to configure a listener for connection pool events (onLease/onRelease)

This can be use to implement custom instrumentation (time blocked in http pool for example)

Author: Florian Tavares

httpclient5/src/main/java/org/apache/hc/client5/http/impl/io/PoolingHttpClientConnectionManager.java

@@ -71,6 +71,7 @@
 import org.apache.hc.core5.http.protocol.HttpContext;
 import org.apache.hc.core5.io.CloseMode;
 import org.apache.hc.core5.pool.ConnPoolControl;
+import org.apache.hc.core5.pool.ConnPoolListener;
 import org.apache.hc.core5.pool.DefaultDisposalCallback;
 import org.apache.hc.core5.pool.DisposalCallback;
 import org.apache.hc.core5.pool.LaxConnPool;
@@ -136,6 +137,7 @@ public PoolingHttpClientConnectionManager() {
                 PoolConcurrencyPolicy.STRICT,
                 PoolReusePolicy.LIFO,
                 TimeValue.NEG_ONE_MILLISECOND,
+                null,
                 null);
     }
 
@@ -211,6 +213,7 @@ public PoolingHttpClientConnectionManager(
                 poolConcurrencyPolicy,
                 poolReusePolicy,
                 timeToLive,
+                null,
                 connFactory);
     }
 
@@ -220,8 +223,9 @@ public PoolingHttpClientConnectionManager(
             final PoolConcurrencyPolicy poolConcurrencyPolicy,
             final PoolReusePolicy poolReusePolicy,
             final TimeValue timeToLive,
+            final ConnPoolListener<HttpRoute> connPoolListener,
             final HttpConnectionFactory<ManagedHttpClientConnection> connFactory) {
-        this(httpClientConnectionOperator,poolConcurrencyPolicy,poolReusePolicy,timeToLive,connFactory,false);
+        this(httpClientConnectionOperator,poolConcurrencyPolicy,poolReusePolicy,timeToLive,connPoolListener,connFactory,false);
 
     }
 
@@ -231,6 +235,7 @@ public PoolingHttpClientConnectionManager(
             final PoolConcurrencyPolicy poolConcurrencyPolicy,
             final PoolReusePolicy poolReusePolicy,
             final TimeValue timeToLive,
+            final ConnPoolListener<HttpRoute> connPoolListener,
             final HttpConnectionFactory<ManagedHttpClientConnection> connFactory,
             final boolean offLockDisposalEnabled) {
         super();
@@ -249,7 +254,7 @@ public PoolingHttpClientConnectionManager(
                         timeToLive,
                         poolReusePolicy,
                         callbackForPool,
-                        null) {
+                        connPoolListener) {
 
                     @Override
                     public void closeExpired() {
@@ -264,7 +269,7 @@ public void closeExpired() {
                         timeToLive,
                         poolReusePolicy,
                         callbackForPool,
-                        null) {
+                        connPoolListener) {
 
                     @Override
                     public void closeExpired() {
@@ -280,6 +285,7 @@ public void closeExpired() {
                         timeToLive,
                         poolReusePolicy,
                         new DefaultDisposalCallback<>());
+                // TODO : wire connPoolListener here once `RouteSegmentedConnPool` supports it.
                 break;
             default:
                 throw new IllegalArgumentException("Unexpected PoolConcurrencyPolicy value: " + poolConcurrencyPolicy);

httpclient5/src/main/java/org/apache/hc/client5/http/impl/io/PoolingHttpClientConnectionManagerBuilder.java

@@ -47,6 +47,7 @@
 import org.apache.hc.core5.http.io.HttpConnectionFactory;
 import org.apache.hc.core5.http.io.SocketConfig;
 import org.apache.hc.core5.io.CloseMode;
+import org.apache.hc.core5.pool.ConnPoolListener;
 import org.apache.hc.core5.pool.PoolConcurrencyPolicy;
 import org.apache.hc.core5.pool.PoolReusePolicy;
 import org.apache.hc.core5.util.TimeValue;
@@ -94,6 +95,8 @@ public class PoolingHttpClientConnectionManagerBuilder {
     private int maxConnTotal;
     private int maxConnPerRoute;
 
+    private ConnPoolListener<HttpRoute> connPoolListener;
+
     private boolean offLockDisposalEnabled;
 
     public static PoolingHttpClientConnectionManagerBuilder create() {
@@ -200,6 +203,18 @@ public final PoolingHttpClientConnectionManagerBuilder setMaxConnPerRoute(final
         return this;
     }
 
+    /**
+     * Sets a {@link ConnPoolListener}.
+     * This can be used to subscribe to underlying connection pool events (if it supports it).
+     *
+     * @return this instance.
+     * @since 5.7
+     */
+    public final PoolingHttpClientConnectionManagerBuilder setConnPoolListener(final ConnPoolListener<HttpRoute> connPoolListener) {
+        this.connPoolListener = connPoolListener;
+        return this;
+    }
+
     /**
      * Sets the same {@link SocketConfig} for all routes.
      *
@@ -357,6 +372,7 @@ public PoolingHttpClientConnectionManager build() {
                 poolConcurrencyPolicy,
                 poolReusePolicy,
                 null,
+                connPoolListener,
                 connectionFactory,
                 offLockDisposalEnabled);
         poolingmgr.setSocketConfigResolver(socketConfigResolver);

httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/PoolingAsyncClientConnectionManager.java

@@ -79,6 +79,7 @@
 import org.apache.hc.core5.http2.ssl.ApplicationProtocol;
 import org.apache.hc.core5.io.CloseMode;
 import org.apache.hc.core5.pool.ConnPoolControl;
+import org.apache.hc.core5.pool.ConnPoolListener;
 import org.apache.hc.core5.pool.DefaultDisposalCallback;
 import org.apache.hc.core5.pool.LaxConnPool;
 import org.apache.hc.core5.pool.ManagedConnPool;
@@ -166,7 +167,7 @@ public PoolingAsyncClientConnectionManager(
             final SchemePortResolver schemePortResolver,
             final DnsResolver dnsResolver) {
         this(new DefaultAsyncClientConnectionOperator(tlsStrategyLookup, schemePortResolver, dnsResolver),
-                poolConcurrencyPolicy, poolReusePolicy, timeToLive, false);
+                poolConcurrencyPolicy, poolReusePolicy, timeToLive, null, false);
     }
 
     @Internal
@@ -175,6 +176,7 @@ public PoolingAsyncClientConnectionManager(
             final PoolConcurrencyPolicy poolConcurrencyPolicy,
             final PoolReusePolicy poolReusePolicy,
             final TimeValue timeToLive,
+            final ConnPoolListener<HttpRoute> connPoolListener,
             final boolean messageMultiplexing) {
         this.connectionOperator = Args.notNull(connectionOperator, "Connection operator");
         final ManagedConnPool<HttpRoute, ManagedAsyncClientConnection> managedConnPool;
@@ -186,7 +188,7 @@ public PoolingAsyncClientConnectionManager(
                         timeToLive,
                         poolReusePolicy,
                         new DefaultDisposalCallback<>(),
-                        null) {
+                        connPoolListener) {
 
                     @Override
                     public void closeExpired() {
@@ -200,7 +202,7 @@ public void closeExpired() {
                         DEFAULT_MAX_CONNECTIONS_PER_ROUTE,
                         timeToLive,
                         poolReusePolicy,
-                        null) {
+                        connPoolListener) {
 
                     @Override
                     public void closeExpired() {
@@ -216,6 +218,7 @@ public void closeExpired() {
                         timeToLive,
                         poolReusePolicy,
                         new DefaultDisposalCallback<>());
+                // TODO : wire connPoolListener here once `RouteSegmentedConnPool` supports it.
                 break;
             default:
                 throw new IllegalArgumentException("Unexpected PoolConcurrencyPolicy value: " + poolConcurrencyPolicy);

httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/PoolingAsyncClientConnectionManagerBuilder.java

@@ -42,6 +42,7 @@
 import org.apache.hc.core5.http.URIScheme;
 import org.apache.hc.core5.http.config.RegistryBuilder;
 import org.apache.hc.core5.http.nio.ssl.TlsStrategy;
+import org.apache.hc.core5.pool.ConnPoolListener;
 import org.apache.hc.core5.pool.PoolConcurrencyPolicy;
 import org.apache.hc.core5.pool.PoolReusePolicy;
 import org.apache.hc.core5.util.ReflectionUtils;
@@ -86,6 +87,8 @@ public class PoolingAsyncClientConnectionManagerBuilder {
     private int maxConnTotal;
     private int maxConnPerRoute;
 
+    private ConnPoolListener<HttpRoute> connPoolListener;
+
     private Resolver<HttpRoute, ConnectionConfig> connectionConfigResolver;
     private Resolver<HttpHost, TlsConfig> tlsConfigResolver;
     private boolean messageMultiplexing;
@@ -170,6 +173,18 @@ public final PoolingAsyncClientConnectionManagerBuilder setMaxConnPerRoute(final
         return this;
     }
 
+    /**
+     * Sets a {@link ConnPoolListener}.
+     * This can be used to subscribe to underlying connection pool events (if it supports it).
+     *
+     * @return this instance.
+     * @since 5.7
+     */
+    public final PoolingAsyncClientConnectionManagerBuilder setConnPoolListener(final ConnPoolListener<HttpRoute> connPoolListener) {
+        this.connPoolListener = connPoolListener;
+        return this;
+    }
+
     /**
      * Sets the same {@link ConnectionConfig} for all routes.
      *
@@ -311,6 +326,7 @@ public PoolingAsyncClientConnectionManager build() {
                 poolConcurrencyPolicy,
                 poolReusePolicy,
                 null,
+                connPoolListener,
                 messageMultiplexing);
         poolingmgr.setConnectionConfigResolver(connectionConfigResolver);
         poolingmgr.setTlsConfigResolver(tlsConfigResolver);