Make UnusedChannelExceptionHandler sharable

Author: dagnir

http-clients/netty-nio-client/src/main/java/software/amazon/awssdk/http/nio/netty/internal/ChannelPipelineInitializer.java

@@ -83,7 +83,7 @@ public void channelCreated(Channel ch) {
         }
 
         pipeline.addLast(FutureCancelHandler.getInstance());
-        pipeline.addLast(new UnusedChannelExceptionHandler());
+        pipeline.addLast(UnusedChannelExceptionHandler.getInstance());
         pipeline.addLast(new LoggingHandler(LogLevel.DEBUG));
     }
 

http-clients/netty-nio-client/src/main/java/software/amazon/awssdk/http/nio/netty/internal/UnusedChannelExceptionHandler.java

@@ -15,6 +15,7 @@
 
 package software.amazon.awssdk.http.nio.netty.internal;
 
+import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerAdapter;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.util.Attribute;
@@ -33,9 +34,15 @@
  * This prevents spamming customer logs when errors (eg. connection resets) occur on an unused channel.
  */
 @SdkInternalApi
-public class UnusedChannelExceptionHandler extends ChannelHandlerAdapter {
+@ChannelHandler.Sharable
+public final class UnusedChannelExceptionHandler extends ChannelHandlerAdapter {
+    public static final UnusedChannelExceptionHandler INSTANCE = new UnusedChannelExceptionHandler();
+
     private static final Logger log = Logger.loggerFor(UnusedChannelExceptionHandler.class);
 
+    private UnusedChannelExceptionHandler() {
+    }
+
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
         boolean channelInUse = getAttribute(ctx, ChannelAttributeKey.IN_USE).orElse(false);
@@ -65,6 +72,10 @@ public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
         }
     }
 
+    public static UnusedChannelExceptionHandler getInstance() {
+        return INSTANCE;
+    }
+
     private <T> Optional<T> getAttribute(ChannelHandlerContext ctx, AttributeKey<T> key) {
         return Optional.ofNullable(ctx.channel().attr(key))
                        .map(Attribute::get);

http-clients/netty-nio-client/src/test/java/software/amazon/awssdk/http/nio/netty/internal/UnusedChannelExceptionHandlerTest.java

@@ -39,7 +39,7 @@ public void setUp() {
     public void inUseDoesNothing() {
         Mockito.when(inUseAttribute.get()).thenReturn(true);
 
-        new UnusedChannelExceptionHandler().exceptionCaught(ctx, exception);
+        UnusedChannelExceptionHandler.getInstance().exceptionCaught(ctx, exception);
 
         Mockito.verify(ctx).fireExceptionCaught(exception);
         Mockito.verify(ctx, new Times(0)).close();
@@ -59,7 +59,7 @@ private void notInUseCloses(Throwable exception) {
         Mockito.when(inUseAttribute.get()).thenReturn(false);
         Mockito.when(futureAttribute.get()).thenReturn(CompletableFuture.completedFuture(null));
 
-        new UnusedChannelExceptionHandler().exceptionCaught(ctx, exception);
+        UnusedChannelExceptionHandler.getInstance().exceptionCaught(ctx, exception);
 
         Mockito.verify(ctx).close();
     }
@@ -71,7 +71,7 @@ public void notInUseFutureCompletes() {
         Mockito.when(inUseAttribute.get()).thenReturn(false);
         Mockito.when(futureAttribute.get()).thenReturn(incompleteFuture);
 
-        new UnusedChannelExceptionHandler().exceptionCaught(ctx, exception);
+        UnusedChannelExceptionHandler.getInstance().exceptionCaught(ctx, exception);
 
         Mockito.verify(ctx).close();
         assertThat(incompleteFuture.isDone()).isTrue();