fail to load a native library using activator (Play Framework) - scala

Question

I'm trying to load a native library in my Play 2.4.x application. I have written a simple test that works fine both in the IDE (IntelliJ) and in SBT. In both case I'm setting the java.library.path to get the tests to run.
In the IDE, I set -Djava.library.path=$USER_HOME$/dev/lindoapi/bin/linux64 in the test run configuration.
As per the sbt documentation, my build.sbt is forking the JVM and setting the java.library.path.
javaOptions += "-Djava.library.path=/home/aczerwon/dev/lindoapi/bin/linux64"
fork := true
The following test passes just fine in both the IDE and from activator test.
class LindoApiSpec extends Specification {
System.loadLibrary("lindojni")
"The Lindo API" should {
"have a valid license" in {
val lindo = new LindoEnvironment()
lindo.apiVerion() must beSuccessfulTry.withValue("LINDO API Version 9.0.2120.225")
}
}
When outside of the testing context, I load the native library in Play's startup lifecycle.
object Global extends GlobalSettings {
override def beforeStart(app: Application) = {
System.loadLibrary("lindojni")
}
}
When I call that same method from the webapi (activator ~run), I'm getting an UnsatisfiedLinkError error.
1) Error injecting constructor, java.lang.UnsatisfiedLinkError: no lindojni in java.library.path
at play.api.GlobalPlugin.<init>(GlobalSettings.scala:262)
at play.api.GlobalPlugin.class(GlobalSettings.scala:262)
while locating play.api.GlobalPlugin
The web api looks like this:
class OptimizationApi extends Controller {
def version() = Action {
val lindo = new LindoEnvironment()
lindo.apiVerion() match {
case Success(version) => Ok(version)
case Failure(e) => BadRequest(e.getMessage)
}
}
}
I assumed that my build.sbt would fork the JVM and set the java.library.path for both test and run contexts. Any clues as to what I'm doing wrong?
New Information
When I start activator -Djava.library.path=$USER_HOME$/dev/lindoapi/bin/linux64 or set JAVA_OPTS, the call to System.loadLibrary(...) in the startup lifecycle passes. I still get the UnsatisfiedLinkError, but it happens later when I make a call to the native library via JNI. Very strange.

Answer 1

I found a solution to the issue here.
The native library and its java counterpart must be in the same class loader.
Create a class similar to:
public final class PlayNativeLibraryLoader {
public static void load(String libraryPath) {
System.load(libraryPath);
}
}
And now you can use it in the Play startup lifecycle.
object Global extends GlobalSettings {
override def beforeStart(app: Application) = {
PlayNativeLibraryLoader.load(app.getFile("./lib/lindoapi/linux64/liblindojni.so").getPath)
Logger.info("Lindo native library loaded")
}
}