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gnodet pushed a commit to branch camel-4.22.x
in repository https://gitbox.apache.org/repos/asf/camel.git
The following commit(s) were added to refs/heads/camel-4.22.x by this push:
new e2a069f0cd12 [backport camel-4.22.x] Fix NPE in BacklogTracer when
transform is the last route step (#26599)
e2a069f0cd12 is described below
commit e2a069f0cd12946fc912b5fb85ebc393562f50a6
Author: Guillaume Nodet <[email protected]>
AuthorDate: Sat Sep 19 18:21:18 2026 +0200
[backport camel-4.22.x] Fix NPE in BacklogTracer when transform is the last
route step (#26599)
---
.../TransformLastStepBacklogTracerNpeTest.java | 99 ++++++++++++++++++++++
.../org/apache/camel/util/ExchangeHelperTest.java | 50 +++++++++++
.../org/apache/camel/support/ExchangeHelper.java | 7 +-
3 files changed, 154 insertions(+), 2 deletions(-)
diff --git
a/core/camel-core/src/test/java/org/apache/camel/processor/TransformLastStepBacklogTracerNpeTest.java
b/core/camel-core/src/test/java/org/apache/camel/processor/TransformLastStepBacklogTracerNpeTest.java
new file mode 100644
index 000000000000..fe2a2a814c1f
--- /dev/null
+++
b/core/camel-core/src/test/java/org/apache/camel/processor/TransformLastStepBacklogTracerNpeTest.java
@@ -0,0 +1,99 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.processor;
+
+import org.apache.camel.CamelContext;
+import org.apache.camel.ContextTestSupport;
+import org.apache.camel.Exchange;
+import org.apache.camel.builder.RouteBuilder;
+import org.apache.camel.support.DefaultExchange;
+import org.apache.camel.support.DefaultMessage;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * A specialized (subclass of {@link DefaultMessage}) IN message, such as the
one platform-http or http create, must
+ * stay attached to the exchange when a {@code transform} EIP is the last step
of a route and the backlog tracer is
+ * active (or in standby mode with message history enabled, as camel-debug
sets it up). Otherwise
+ * BacklogTracerRouteAdvice#after fails with a NullPointerException while
dumping the IN message.
+ */
+class TransformLastStepBacklogTracerNpeTest extends ContextTestSupport {
+
+ @Test
+ void transformAsLastStepWithSpecializedMessage() {
+ Exchange out = sendSpecializedMessage("direct:transformLast", "Hello");
+
+ assertThat(out.getException()).as("route must not fail").isNull();
+ assertThat(out.getMessage().getBody(String.class)).isEqualTo("Hello
World");
+ }
+
+ @Test
+ void transformAsLastStepWithPlainDefaultMessage() {
+ Exchange exchange = new DefaultExchange(context);
+ exchange.getIn().setBody("Hello");
+
+ Exchange out = template.send("direct:transformLast", exchange);
+
+ assertThat(out.getException()).as("route must not fail").isNull();
+ assertThat(out.getMessage().getBody(String.class)).isEqualTo("Hello
World");
+ }
+
+ @Test
+ void transformFollowedByAnotherStepWithSpecializedMessage() {
+ Exchange out = sendSpecializedMessage("direct:transformFollowed",
"Hello");
+
+ assertThat(out.getException()).as("route must not fail").isNull();
+ assertThat(out.getMessage().getBody(String.class)).isEqualTo("Hello
World");
+ }
+
+ private Exchange sendSpecializedMessage(String uri, String body) {
+ Exchange exchange = new DefaultExchange(context);
+ exchange.setIn(new SpecializedMessage(context));
+ exchange.getIn().setBody(body);
+ return template.send(uri, exchange);
+ }
+
+ @Override
+ protected RouteBuilder createRouteBuilder() {
+ return new RouteBuilder() {
+ @Override
+ public void configure() {
+ context.setUseBreadcrumb(false);
+ context.setBacklogTracingStandby(true);
+ context.setMessageHistory(true);
+
+ from("direct:transformLast")
+ .transform(simple("${body} World"));
+
+ from("direct:transformFollowed")
+ .transform(simple("${body} World"))
+ .removeHeader("X-Does-Not-Exist");
+ }
+ };
+ }
+
+ /**
+ * Mimics HttpMessage (platform-http, http, etc.): a specialized message
that is not exactly a
+ * {@link DefaultMessage}, forcing TransformProcessor to copy it into a
new DefaultMessage.
+ */
+ private static class SpecializedMessage extends DefaultMessage {
+ SpecializedMessage(CamelContext camelContext) {
+ super(camelContext);
+ }
+ }
+}
diff --git
a/core/camel-core/src/test/java/org/apache/camel/util/ExchangeHelperTest.java
b/core/camel-core/src/test/java/org/apache/camel/util/ExchangeHelperTest.java
index 564049ac9249..c2c03180efd1 100644
---
a/core/camel-core/src/test/java/org/apache/camel/util/ExchangeHelperTest.java
+++
b/core/camel-core/src/test/java/org/apache/camel/util/ExchangeHelperTest.java
@@ -23,12 +23,14 @@ import java.util.Map;
import org.apache.camel.ContextTestSupport;
import org.apache.camel.Exchange;
import org.apache.camel.ExchangePattern;
+import org.apache.camel.Message;
import org.apache.camel.NoSuchBeanException;
import org.apache.camel.NoSuchHeaderException;
import org.apache.camel.NoSuchPropertyException;
import org.apache.camel.converter.stream.InputStreamCache;
import org.apache.camel.impl.DefaultCamelContext;
import org.apache.camel.support.DefaultExchange;
+import org.apache.camel.support.DefaultMessage;
import org.apache.camel.support.ExchangeHelper;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
@@ -249,6 +251,54 @@ public class ExchangeHelperTest extends ContextTestSupport
{
assertNull(third);
}
+ @Test
+ public void testReplaceMessageOutOnlyWithNoExistingOutKeepsInAttached() {
+ // simulates what TransformProcessor does when transform is the last
step of a route:
+ // replace the message as OUT, even though there is no OUT message
yet, so the current
+ // IN message is what exchange.getMessage() (aliased here as "old")
actually returns
+ assertFalse(exchange.hasOut());
+ Message in = exchange.getIn();
+
+ Message replacement = new DefaultMessage(exchange.getContext());
+ ExchangeHelper.replaceMessage(exchange, replacement, true);
+
+ assertSame(replacement, exchange.getOut());
+ assertSame(in, exchange.getIn());
+ // the IN message must remain attached to the exchange, otherwise
anything that calls
+ // exchange.getIn().getExchange() afterwards (e.g. the backlog tracer)
hits an NPE
+ assertNotNull(exchange.getIn().getExchange());
+ }
+
+ @Test
+ public void testReplaceMessageOutOnlyWithExistingOutDetachesOldOut() {
+ Message firstOut = new DefaultMessage(exchange.getContext());
+ exchange.setOut(firstOut);
+
+ Message replacement = new DefaultMessage(exchange.getContext());
+ ExchangeHelper.replaceMessage(exchange, replacement, true);
+
+ assertSame(replacement, exchange.getOut());
+ assertNull(firstOut.getExchange());
+ }
+
+ @Test
+ public void testReplaceMessageInOnlyWithNoExistingOutDoesNotCreateOut() {
+ // simulates what SetBodyProcessor and ConvertBodyProcessor do:
replace the IN message in place
+ assertFalse(exchange.hasOut());
+ Message in = exchange.getIn();
+
+ Message replacement = new DefaultMessage(exchange.getContext());
+ replacement.setBody("new");
+ ExchangeHelper.replaceMessage(exchange, replacement, false);
+
+ assertSame(replacement, exchange.getIn());
+ // must not lazily create an OUT message, otherwise
exchange.getMessage() would return an empty OUT
+ assertFalse(exchange.hasOut());
+ assertEquals("new", exchange.getMessage().getBody(String.class));
+ // the old IN message is no longer referenced by the exchange and must
be detached
+ assertNull(in.getExchange());
+ }
+
@Override
@BeforeEach
public void setUp() throws Exception {
diff --git
a/core/camel-support/src/main/java/org/apache/camel/support/ExchangeHelper.java
b/core/camel-support/src/main/java/org/apache/camel/support/ExchangeHelper.java
index 1f4e32d81067..64f83528f874 100644
---
a/core/camel-support/src/main/java/org/apache/camel/support/ExchangeHelper.java
+++
b/core/camel-support/src/main/java/org/apache/camel/support/ExchangeHelper.java
@@ -878,8 +878,11 @@ public final class ExchangeHelper {
exchange.setIn(newMessage);
}
- // need to de-reference old from the exchange so it can be GC
- if (old instanceof MessageSupport messageSupport) {
+ // need to de-reference old from the exchange so it can be GC, but
only if the exchange no longer
+ // references it: with outOnly and no OUT message yet, old is the
(untouched) IN message and detaching it
+ // would leave IN without an exchange reference. Use hasOut() before
getOut() as getOut() lazily creates OUT.
+ if (old != exchange.getIn() && !(exchange.hasOut() && old ==
exchange.getOut())
+ && old instanceof MessageSupport messageSupport) {
messageSupport.setExchange(null);
}
}
