Expose channel pool configuration to subclasses.

Motivation:

`SimpleChannelPool` subclasses are likely to override the `connectChannel` method, and are likely to clobber the cloned `Bootstrap` handler in the process. To allow subclasses to properly notify the pool listener of new connections, we should expose (at least) the `handler` property of the pool to subclasses.

Modifications:

Expose `SimpleChannelPool` properties to subclasses via `protected` getters.

Result:

Subclasses can now use the bootstrap, handler, health checker, and health-check-on-release preoperties from their superclass.

transport/src/main/java/io/netty/channel/pool/SimpleChannelPool.java

@@ -82,8 +82,8 @@ public class SimpleChannelPool implements ChannelPool {
      * @param handler            the {@link ChannelPoolHandler} that will be notified for the different pool actions
      * @param healthCheck        the {@link ChannelHealthChecker} that will be used to check if a {@link Channel} is
      *                           still healthy when obtain from the {@link ChannelPool}
-     * @param releaseHealthCheck will offercheck channel health before offering back if this parameter set to
+     * @param releaseHealthCheck will check channel health before offering back if this parameter set to {@code true};
-     *                           {@code true}.
+     *                           otherwise, channel health is only checked at acquisition time
      */
     public SimpleChannelPool(Bootstrap bootstrap, final ChannelPoolHandler handler, ChannelHealthChecker healthCheck,
                              boolean releaseHealthCheck) {
@@ -101,6 +101,43 @@ public class SimpleChannelPool implements ChannelPool {
         });
     }
 
+    /**
+     * Returns the {@link Bootstrap} this pool will use to open new connections.
+     *
+     * @return the {@link Bootstrap} this pool will use to open new connections
+     */
+    protected Bootstrap bootstrap() {
+        return bootstrap;
+    }
+
+    /**
+     * Returns the {@link ChannelPoolHandler} that will be notified for the different pool actions.
+     *
+     * @return the {@link ChannelPoolHandler} that will be notified for the different pool actions
+     */
+    protected ChannelPoolHandler handler() {
+        return handler;
+    }
+
+    /**
+     * Returns the {@link ChannelHealthChecker} that will be used to check if a {@link Channel} is healthy.
+     *
+     * @return the {@link ChannelHealthChecker} that will be used to check if a {@link Channel} is healthy
+     */
+    protected ChannelHealthChecker healthChecker() {
+        return healthCheck;
+    }
+
+    /**
+     * Indicates whether this pool will check the health of channels before offering them back into the pool.
+     *
+     * @return {@code true} if this pool will check the health of channels before offering them back into the pool, or
+     * {@code false} if channel health is only checked at acquisition time
+     */
+    protected boolean releaseHealthCheck() {
+        return releaseHealthCheck;
+    }
+
     @Override
     public final Future<Channel> acquire() {
         return acquire(bootstrap.config().group().next().<Channel>newPromise());

transport/src/test/java/io/netty/channel/pool/SimpleChannelPoolTest.java

@@ -34,12 +34,7 @@ import org.junit.rules.ExpectedException;
 import java.util.Queue;
 import java.util.concurrent.LinkedBlockingQueue;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotSame;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertThat;
-import static org.junit.Assert.fail;
 
 public class SimpleChannelPoolTest {
     private static final String LOCAL_ADDR_ID = "test.id";
@@ -242,4 +237,71 @@ public class SimpleChannelPoolTest {
         channel2.close().syncUninterruptibly();
         group.shutdownGracefully();
     }
+
+    @Test
+    public void testBootstrap() {
+        final SimpleChannelPool pool = new SimpleChannelPool(new Bootstrap(), new CountingChannelPoolHandler());
+
+        try {
+            // Checking for the actual bootstrap object doesn't make sense here, since the pool uses a copy with a
+            // modified channel handler.
+            assertNotNull(pool.bootstrap());
+        } finally {
+            pool.close();
+        }
+    }
+
+    @Test
+    public void testHandler() {
+        final ChannelPoolHandler handler = new CountingChannelPoolHandler();
+        final SimpleChannelPool pool = new SimpleChannelPool(new Bootstrap(), handler);
+
+        try {
+            assertSame(handler, pool.handler());
+        } finally {
+            pool.close();
+        }
+    }
+
+    @Test
+    public void testHealthChecker() {
+        final ChannelHealthChecker healthChecker = ChannelHealthChecker.ACTIVE;
+        final SimpleChannelPool pool = new SimpleChannelPool(
+                new Bootstrap(),
+                new CountingChannelPoolHandler(),
+                healthChecker);
+
+        try {
+            assertSame(healthChecker, pool.healthChecker());
+        } finally {
+            pool.close();
+        }
+    }
+
+    @Test
+    public void testReleaseHealthCheck() {
+        final SimpleChannelPool healthCheckOnReleasePool = new SimpleChannelPool(
+                new Bootstrap(),
+                new CountingChannelPoolHandler(),
+                ChannelHealthChecker.ACTIVE,
+                true);
+
+        try {
+            assertTrue(healthCheckOnReleasePool.releaseHealthCheck());
+        } finally {
+            healthCheckOnReleasePool.close();
+        }
+
+        final SimpleChannelPool noHealthCheckOnReleasePool = new SimpleChannelPool(
+                new Bootstrap(),
+                new CountingChannelPoolHandler(),
+                ChannelHealthChecker.ACTIVE,
+                false);
+
+        try {
+            assertFalse(noHealthCheckOnReleasePool.releaseHealthCheck());
+        } finally {
+            noHealthCheckOnReleasePool.close();
+        }
+    }
 }