Denovo1998 opened a new pull request, #26180:
URL: https://github.com/apache/pulsar/pull/26180
### Motivation
PR #26030 replaced `PendingAcksMap` object values with packed primitive
values and removed the public `PendingAcksMap#get(long, long)` method. However,
this method was included in previous Pulsar releases, including Pulsar 4.0.x
and 4.1.x, and is reachable by broker extensions through the public
`Consumer#getPendingAcks()` method.
A `BrokerInterceptor` compiled against one of those releases can therefore
fail with `NoSuchMethodError` after the broker is upgraded to a version
containing #26030.
### Why `NoSuchMethodError` occurs
`BrokerInterceptor` callbacks such as `messageDispatched` receive a broker
`Consumer` instance. An existing extension can use the following API path:
```java
@Override
public void messageDispatched(ServerCnx cnx, Consumer consumer,
long ledgerId, long entryId,
ByteBuf headersAndPayload) {
IntIntPair pendingAck =
consumer.getPendingAcks().get(ledgerId, entryId);
}
```
When this extension is compiled against an earlier Pulsar release, the Java
compiler records the following symbolic method reference in the extension
bytecode:
```text
org/apache/pulsar/broker/service/PendingAcksMap.get:
(JJ)Lit/unimi/dsi/fastutil/ints/IntIntPair;
```
The relevant bytecode is equivalent to:
```text
invokevirtual Consumer.getPendingAcks:
()Lorg/apache/pulsar/broker/service/PendingAcksMap;
invokevirtual PendingAcksMap.get:
(JJ)Lit/unimi/dsi/fastutil/ints/IntIntPair;
```
The extension does not get recompiled when the broker is upgraded. When the
interceptor callback is executed, the JVM resolves the existing `invokevirtual`
reference against the `PendingAcksMap` loaded from the upgraded broker.
After #26030, that exact method name and descriptor no longer exist. The
newly added primitive accessor has a different name and return type:
```text
PendingAcksMap.getRemainingUnacked:(JJ)I
```
The JVM cannot substitute one method for the other. Method resolution
therefore fails with a linkage error similar to:
```text
java.lang.NoSuchMethodError:
'it.unimi.dsi.fastutil.ints.IntIntPair
org.apache.pulsar.broker.service.PendingAcksMap.get(long, long)'
```
The interceptor can load successfully and only fail when the affected
callback and call site are first executed, making the problem dependent on
extension behavior and broker traffic.
### Modifications
- Restore the exact `PendingAcksMap#get(long, long)` JVM method signature
available in previous releases.
- Mark the restored method as deprecated so new broker code continues to
prefer primitive accessors.
- Reconstruct `IntIntPair` from the packed primitive value while holding the
existing read lock.
- Return `null` for missing ledger and entry mappings, preserving the
previous behavior.
- Add coverage for maximum remaining-unacked values, signed sticky-key
hashes, and missing entries.
- Add a `BrokerInterceptor` extension fixture that accesses the method
through `Consumer#getPendingAcks()`, reproducing the extension API call path.
### Performance impact
The broker production paths changed by #26030 continue to use
`getRemainingUnacked` and `removeAndGetRemainingUnacked`. They do not call the
compatibility method and therefore do not recreate `IntIntPair` objects on the
pending-ack hot paths.
An `IntIntPair` is allocated only when an existing extension explicitly
invokes the deprecated compatibility method.
### Verifying this change
- [x] Make sure that the change passes the CI checks.
The following targeted test and style checks pass:
```bash
./gradlew :pulsar-broker:test \
--tests org.apache.pulsar.broker.service.PendingAcksMapTest \
--max-workers=1 \
-PtestRetryCount=0 \
:pulsar-broker:checkstyleMain \
:pulsar-broker:checkstyleTest
```
### Does this pull request potentially affect one of the following parts:
<!-- DO NOT REMOVE THIS SECTION. CHECK THE PROPER BOX ONLY. -->
*If the box was checked, please highlight the changes*
- [ ] Dependencies (add or upgrade a dependency)
- [ ] The public API
- [ ] The schema
- [ ] The default values of configurations
- [ ] The threading model
- [ ] The binary protocol
- [ ] The REST endpoints
- [ ] The admin CLI options
- [ ] The metrics
- [ ] Anything that affects deployment
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