water.udf.JythonCFuncLoader Maven / Gradle / Ivy
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package water.udf;
import org.python.core.Py;
import org.python.core.PySystemState;
/**
* Custom function loader, which can instantiate
* functions written in Python.
*
* The provider internally uses Jython.
*
* Note: Jython caches the loaded python programs. That means
* changing underlying function definition (i.e, Python code) is not
* reflected!
*/
public class JythonCFuncLoader extends CFuncLoader {
@Override
public String getLang() {
return "python";
}
@Override
public F load(String jfuncName, Class targetKlazz, ClassLoader classLoader) {
int idxLastDot = jfuncName.lastIndexOf('.');
String module = jfuncName.substring(0, idxLastDot);
String clsName = jfuncName.substring(idxLastDot+1);
ClassLoader savedCtxCl = Thread.currentThread().getContextClassLoader();
PySystemState savedSystemState = Py.getSystemState(); // Get a system state for the current thread
try {
Thread.currentThread().setContextClassLoader(classLoader);
PySystemState newSystemState = new PySystemState();
newSystemState.setClassLoader(classLoader);
Py.setSystemState(newSystemState); // Assign a new system state with a specific classloader to the current thread.
return new JythonObjectFactory(targetKlazz, module, clsName).createObject();
} finally {
Py.setSystemState(savedSystemState);
Thread.currentThread().setContextClassLoader(savedCtxCl);
}
}
}