Improved error messaging when a connection is closed. Fixes #1260.

Author: millems

.changes/next-release/feature-NettyNIOHTTPClient-462de16.json

@@ -0,0 +1,5 @@
+{
+    "category": "Netty NIO HTTP Client", 
+    "type": "feature", 
+    "description": "Improved error messaging when a connection is closed. Fixes [#1260](https://github.com/aws/aws-sdk-java-v2/issues/1260)."
+}

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

@@ -47,6 +47,7 @@
 import java.io.IOException;
 import java.net.URI;
 import java.nio.ByteBuffer;
+import java.nio.channels.ClosedChannelException;
 import java.time.Duration;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
@@ -262,6 +263,8 @@ private Throwable decorateException(Throwable originalCause) {
             return new IOException("Read timed out", originalCause);
         } else if (originalCause instanceof WriteTimeoutException) {
             return new IOException("Write timed out", originalCause);
+        } else if (originalCause instanceof ClosedChannelException) {
+            return new IOException(getMessageForClosedChannel(), originalCause);
         }
 
         return originalCause;
@@ -320,6 +323,12 @@ private String getMessageForTooManyAcquireOperationsError() {
                 + "AWS, or by increasing the number of hosts sending requests.";
     }
 
+    private String getMessageForClosedChannel() {
+        return "The channel was closed. This may have been done by the client (e.g. because the request was aborted), " +
+               "by the service (e.g. because the request took too long or the client tried to write on a read-only socket), " +
+               "or by an intermediary party (e.g. because the channel was idle for too long).";
+    }
+
     /**
      * Close and release the channel back to the pool.
      *