netty5/common
agonigberg 3288cacf8d Pluggable resource leak detector
Allow users of Netty to plug in their own leak detector for the purpose
of instrumentation.

Motivation:

We are rolling out a large Netty deployment and want to be able to
track the amount of leaks we're seeing in production via custom
instrumentation. In order to achieve this today, I had to plug in a
custom `ByteBufAllocator` into the bootstrap and have it initialize a
custom `ResourceLeakDetector`. Due to these classes mostly being marked
`final` or having private or static methods, a lot of the code had to
be copy-pasted and it's quite ugly.

Modifications:

* I've added a static loader method for the `ResourceLeakDetector` in
`AbstractByteBuf` that tries to instantiate the class passed in via the
`-Dio.netty.customResourceLeakDetector`, otherwise falling back to the
default one.
* I've modified `ResourceLeakDetector` to be non-final and to have the
reporting broken out in to methods that can be overridden.

Result:

You can instrument leaks in your application by just adding something
like the following:

```java
public class InstrumentedResourceLeakDetector<T> extends
ResourceLeakDetector<T> {

    @Monitor("InstanceLeakCounter")
    private final AtomicInteger instancesLeakCounter;

    @Monitor("LeakCounter")
    private final AtomicInteger leakCounter;

    public InstrumentedResourceLeakDetector(Class<T> resource) {
        super(resource);
        this.instancesLeakCounter = new AtomicInteger();
        this.leakCounter = new AtomicInteger();
    }

    @Override
    protected void reportTracedLeak(String records) {
        super.reportTracedLeak(records);
        leakCounter.incrementAndGet();
    }

    @Override
    protected void reportUntracedLeak() {
        super.reportUntracedLeak();
        leakCounter.incrementAndGet();
    }

    @Override
    protected void reportInstancesLeak() {
        super.reportInstancesLeak();
        instancesLeakCounter.incrementAndGet();
    }
}
```
2016-06-20 11:14:44 +02:00
..
src Pluggable resource leak detector 2016-06-20 11:14:44 +02:00
pom.xml Make JCtools available (provided scope) for tests and optional OSGI, issue #5383 2016-06-11 07:15:48 +02:00