OTLP exporter should tolerate instances of LogRecordData when incubator is present

[jack-berg]

Fixes #7363

[jack-berg]

I'm nervous about this.

Recall that the test suites are set up that the main test suite intentionally doesn't include the incubator, to ensure that everything works without the incubator present.

The build was working locally when this was equal to return logRecordData instanceof ExtendedLogRecordData.. which suggests that instanceOf doesn't try to load classes, since if it did, it would load ExtendedLogRecordData and generate an exception.

I included this INCUBATOR_AVAILABLE check first in the hopes that if the incubator is not present ,the instanceOf check will never be reached and we'll never load the class. But not feeling confident about what the JVM will do here.

[trask]

maybe it's worth storing the ExtendedLogRecordData class object in a static final and using isAssignableFrom() to avoid the worry? I wouldn't expect perf to be much different

[breedx-splk]

Yeah weird I would very much expect this to be a problem. Weird. I did find a bit of prior art from way back when https://bugs.openjdk.org/browse/JDK-4354492...but I have no idea where things stand today. I tried an experiment with a silly class like this:

public class Tester {
  public static void main(String[] args) {
    Object x = "";
    if(x instanceof OpenTelemetry)
      System.out.println("interesting");
    else
      System.out.println("not interesting");
  }
}

and running this like such, yields an exception:

$ java -cp sdk/testing/build/classes/java/main io.opentelemetry.sdk.testing.Tester
Exception in thread "main" java.lang.NoClassDefFoundError: io/opentelemetry/api/OpenTelemetry
	at io.opentelemetry.sdk.testing.Tester.main(Tester.java:8)
Caused by: java.lang.ClassNotFoundException: io.opentelemetry.api.OpenTelemetry
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:525)
	... 1 more

If I change the if statement to if(false && x instanceof OpenTelemetry) and recompile and re-run, it just runs without exception! Neat!

[breedx-splk]

I think maybe a comment for our future selves that says something like "this is ok, because the instanceof is only evaluated when the incubator is present, so the class can be found" or something, so we remember.

[jack-berg]

@laurit points out that ExtendedLogRecordData is always available since its not in the incubator, so I think we're good here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.76%. Comparing base (93d9e72) to head (8d4fc80).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #7393   +/-   ##
=========================================
  Coverage     89.76%   89.76%           
- Complexity     6978     6981    +3     
=========================================
  Files           797      797           
  Lines         21165    21160    -5     
  Branches       2056     2056           
=========================================
- Hits          18998    18994    -4     
+ Misses         1505     1504    -1     
  Partials        662      662           

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[breedx-splk]

Thanks @jack-berg appreciate it.