Merge branch '836-jmx-collision' into 2.x

Author: nebhale

cloudfoundry-client-reactor/src/main/java/org/cloudfoundry/reactor/_DefaultConnectionContext.java

@@ -38,6 +38,7 @@
 import javax.annotation.PostConstruct;
 import javax.annotation.PreDestroy;
 import javax.management.JMException;
+import javax.management.MalformedObjectNameException;
 import javax.management.ObjectName;
 import java.lang.management.ManagementFactory;
 import java.time.Duration;
@@ -57,6 +58,8 @@
 @Value.Immutable
 abstract class _DefaultConnectionContext implements ConnectionContext {
 
+    private static final int DEFAULT_PORT = 443;
+
     private static final int RECEIVE_BUFFER_SIZE = 10 * 1024 * 1024;
 
     private static final int SEND_BUFFER_SIZE = 10 * 1024 * 1024;
@@ -70,6 +73,16 @@ abstract class _DefaultConnectionContext implements ConnectionContext {
     public final void dispose() {
         getConnectionPool().ifPresent(PoolResources::dispose);
         getThreadPool().dispose();
+
+        try {
+            ObjectName name = getByteBufAllocatorObjectName();
+
+            if (ManagementFactory.getPlatformMBeanServer().isRegistered(name)) {
+                ManagementFactory.getPlatformMBeanServer().unregisterMBean(name);
+            }
+        } catch (JMException e) {
+            this.logger.error("Unable to register ByteBufAllocator MBean", e);
+        }
     }
 
     /**
@@ -146,7 +159,6 @@ public Mono<Void> trust(String host, int port) {
     /**
      * The hostname of the API root.  Typically something like {@code api.run.pivotal.io}.
      */
-    @Nullable
     abstract String getApiHost();
 
     /**
@@ -222,11 +234,21 @@ LoopResources getThreadPool() {
     @PostConstruct
     void monitorByteBufAllocator() {
         try {
-            ManagementFactory.getPlatformMBeanServer()
-                .registerMBean(new ByteBufAllocatorMetricProviderWrapper(PooledByteBufAllocator.DEFAULT), ObjectName.getInstance("org.cloudfoundry.reactor:type=ByteBufAllocator"));
+            ObjectName name = getByteBufAllocatorObjectName();
+
+            if (ManagementFactory.getPlatformMBeanServer().isRegistered(name)) {
+                this.logger.warn("MBean '{}' is already registered and will be removed. You should only have a single DefaultConnectionContext per endpoint.", name);
+                ManagementFactory.getPlatformMBeanServer().unregisterMBean(name);
+            }
+
+            ManagementFactory.getPlatformMBeanServer().registerMBean(new ByteBufAllocatorMetricProviderWrapper(PooledByteBufAllocator.DEFAULT), name);
         } catch (JMException e) {
             this.logger.error("Unable to register ByteBufAllocator MBean", e);
         }
     }
 
+    private ObjectName getByteBufAllocatorObjectName() throws MalformedObjectNameException {
+        return ObjectName.getInstance(String.format("org.cloudfoundry.reactor:type=ByteBufAllocator,endpoint=%s/%d", getApiHost(), getPort().orElse(DEFAULT_PORT)));
+    }
+
 }

cloudfoundry-client-reactor/src/test/java/org/cloudfoundry/reactor/DefaultConnectionContextTest.java

@@ -68,4 +68,21 @@ public void getInfo() throws Exception {
             .verify(Duration.ofSeconds(5));
     }
 
+    @Test
+    public void multipleInstances() {
+        DefaultConnectionContext first = DefaultConnectionContext.builder()
+            .apiHost("test-host")
+            .build();
+
+        DefaultConnectionContext second = DefaultConnectionContext.builder()
+            .apiHost("test-host")
+            .build();
+
+        first.monitorByteBufAllocator();
+        second.monitorByteBufAllocator();
+
+        first.dispose();
+        second.dispose();
+    }
+
 }