[xlang] Cross language Python support (#6709)

java/test/src/main/java/org/ray/api/test/CrossLanguageInvocationTest.java

@@ -10,11 +10,14 @@ import org.ray.api.Ray;
 import org.ray.api.RayObject;
 import org.ray.api.RayPyActor;
 import org.ray.api.TestUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.testng.Assert;
 import org.testng.annotations.Test;
 
 public class CrossLanguageInvocationTest extends BaseMultiLanguageTest {
 
+  private static final Logger LOGGER = LoggerFactory.getLogger(CrossLanguageInvocationTest.class);
   private static final String PYTHON_MODULE = "test_cross_language_invocation";
 
   @Override
@@ -46,6 +49,12 @@ public class CrossLanguageInvocationTest extends BaseMultiLanguageTest {
     Assert.assertEquals(res.get(), "Response from Python: hello".getBytes());
   }
 
+  @Test
+  public void testPythonCallJavaFunction() {
+    RayObject res = Ray.callPy(PYTHON_MODULE, "py_func_call_java_function", "hello".getBytes());
+    Assert.assertEquals(res.get(), "[Python]py_func -> [Java]bytesEcho -> hello".getBytes());
+  }
+
   @Test(groups = {"directCall"})
   public void testCallingPythonActor() {
     // Python worker doesn't support direct call yet.
@@ -54,4 +63,32 @@ public class CrossLanguageInvocationTest extends BaseMultiLanguageTest {
     RayObject res = Ray.callPy(actor, "increase", "1".getBytes());
     Assert.assertEquals(res.get(), "2".getBytes());
   }
+
+  @Test
+  public void testPythonCallJavaActor() {
+    RayObject res = Ray.callPy(PYTHON_MODULE, "py_func_call_java_actor", "1".getBytes());
+    Assert.assertEquals(res.get(), "Counter1".getBytes());
+  }
+
+  public static byte[] bytesEcho(byte[] value) {
+    // This function will be called from test_cross_language_invocation.py
+    String valueStr = new String(value);
+    LOGGER.debug(String.format("bytesEcho called with: %s", valueStr));
+    return ("[Java]bytesEcho -> " + valueStr).getBytes();
+  }
+
+  public static class TestActor {
+    public TestActor(byte[] v) {
+      value = v;
+    }
+
+    public byte[] concat(byte[] v) {
+      byte[] c = new byte[value.length + v.length];
+      System.arraycopy(value, 0, c, 0, value.length);
+      System.arraycopy(v, 0, c, value.length, v.length);
+      return c;
+    }
+
+    private byte[] value;
+  }
 }

java/test/src/main/resources/test_cross_language_invocation.py

@@ -12,6 +12,25 @@ def py_func(value):
     return b"Response from Python: " + value
 
 
+@ray.remote
+def py_func_call_java_function(value):
+    assert isinstance(value, bytes)
+    f = ray.java_function("org.ray.api.test.CrossLanguageInvocationTest",
+                          "bytesEcho")
+    r = f.remote(value)
+    return b"[Python]py_func -> " + ray.get(r)
+
+
+@ray.remote
+def py_func_call_java_actor(value):
+    assert isinstance(value, bytes)
+    c = ray.java_actor_class(
+        "org.ray.api.test.CrossLanguageInvocationTest$TestActor")
+    java_actor = c.remote(b"Counter")
+    r = java_actor.concat.remote(value)
+    return ray.get(r)
+
+
 @ray.remote
 class Counter(object):
     def __init__(self, value):