making async support backward compatible

Author: Chris Wewerka

core/src/main/scala/org/apache/predictionio/controller/LAlgorithm.scala

@@ -77,14 +77,38 @@ abstract class LAlgorithm[PD, M : ClassTag, Q, P]
     cartesian.flatMap { case (m, qArray) =>
       qArray.map {
         case (qx, q) =>
-          (qx, Await.result(predict(m, q)(scala.concurrent.ExecutionContext.global), 60 minutes) )
+          (qx,
+            Await.result(predictAsync(m, q)(scala.concurrent.ExecutionContext.global), 60 minutes) )
       }
     }
   }
 
-  def predictBase(localBaseModel: Any, q: Q)(implicit ec: ExecutionContext): Future[P] = {
-    predict(localBaseModel.asInstanceOf[M], q)(ec)
-  }
+  override def predictBaseAsync(localBaseModel: Any, q: Q)(implicit ec: ExecutionContext)
+      : Future[P] =
+    predictAsync(localBaseModel.asInstanceOf[M], q)(ec)
+
+  @deprecated(message =
+    "this method is just here for backward compatibility, predictBaseAsync() is called now",
+    since = "0.14.0")
+  override def predictBase(localBaseModel: Any, q: Q): P =
+    predict(localBaseModel.asInstanceOf[M], q)
+
+  /** Implement this method to produce a Future of a prediction in a non blocking way
+    * from a query and trained model.
+    *
+    * This method is implemented to just delegate to blocking predict() for
+    * backward compatibility reasons.
+    * Definitely overwrite it to implement your blocking prediction method, and leave
+    * the old blocking predict() as it is (throwing an exception), it won't be called from
+    * now on.
+    *
+    * @param model Trained model produced by [[train]].
+    * @param query An input query.
+    * @param ec ExecutionContext to use for async operations
+    * @return A Future of a prediction.
+    */
+  def predictAsync(model: M, query: Q)(implicit ec: ExecutionContext): Future[P] =
+    Future.successful(blocking(predict(model, query)))
 
   /** Implement this method to produce a prediction from a query and trained
     * model.
@@ -93,7 +117,9 @@ abstract class LAlgorithm[PD, M : ClassTag, Q, P]
     * @param q An input query.
     * @return A prediction.
     */
-  def predict(m: M, q: Q)(implicit ec: ExecutionContext): Future[P]
+  @deprecated(message = "override non blocking predictAsync() instead", since = "0.14.0")
+  def predict(m: M, q: Q): P =
+    throw new NotImplementedError("predict() is deprecated, override predictAsync() instead")
 
   /** :: DeveloperApi ::
     * Engine developers should not use this directly (read on to see how local

core/src/main/scala/org/apache/predictionio/controller/P2LAlgorithm.scala

@@ -71,12 +71,34 @@ abstract class P2LAlgorithm[PD, M: ClassTag, Q: ClassTag, P]
     */
   def batchPredict(m: M, qs: RDD[(Long, Q)]): RDD[(Long, P)] = {
     qs.mapValues { q =>
-      Await.result(predict(m, q)(scala.concurrent.ExecutionContext.global), 60 minutes)
+      Await.result(predictAsync(m, q)(scala.concurrent.ExecutionContext.global), 60 minutes)
     }
   }
 
-  def predictBase(bm: Any, q: Q)(implicit ec: ExecutionContext): Future[P] =
-    predict(bm.asInstanceOf[M], q)(ec)
+  override def predictBaseAsync(bm: Any, q: Q)(implicit ec: ExecutionContext): Future[P] =
+    predictAsync(bm.asInstanceOf[M], q)(ec)
+
+  @deprecated(message =
+    "this method is just here for backward compatibility, predictBaseAsync() is called now",
+     since = "0.14.0")
+  override def predictBase(bm: Any, q: Q): P = predict(bm.asInstanceOf[M], q)
+
+  /** Implement this method to produce a Future of a prediction in a non blocking way
+    * from a query and trained model.
+    *
+    * This method is implemented to just delegate to blocking predict() for
+    * backward compatibility reasons.
+    * Definitely overwrite it to implement your blocking prediction method, and leave
+    * the old blocking predict() as it is (throwing an exception), it won't be called from
+    * now on.
+    *
+    * @param model Trained model produced by [[train]].
+    * @param query An input query.
+    * @param ec ExecutionContext to use for async operations
+    * @return A Future of a prediction.
+    */
+  def predictAsync(model: M, query: Q)(implicit ec: ExecutionContext): Future[P] =
+    Future.successful(blocking(predict(model, query)))
 
   /** Implement this method to produce a prediction from a query and trained
     * model.
@@ -85,7 +107,9 @@ abstract class P2LAlgorithm[PD, M: ClassTag, Q: ClassTag, P]
     * @param query An input query.
     * @return A prediction.
     */
-  def predict(model: M, query: Q)(implicit ec: ExecutionContext): Future[P]
+  @deprecated(message = "override non blocking predictAsync() instead", since = "0.14.0")
+  def predict(model: M, query: Q): P =
+    throw new NotImplementedError("predict() is deprecated, override predictAsync() instead")
 
   /** :: DeveloperApi ::
     * Engine developers should not use this directly (read on to see how

core/src/main/scala/org/apache/predictionio/controller/PAlgorithm.scala

@@ -24,7 +24,7 @@ import org.apache.predictionio.workflow.PersistentModelManifest
 import org.apache.spark.SparkContext
 import org.apache.spark.rdd.RDD
 
-import scala.concurrent.{ExecutionContext, Future}
+import scala.concurrent.{ExecutionContext, Future, blocking}
 
 /** Base class of a parallel algorithm.
   *
@@ -74,9 +74,31 @@ abstract class PAlgorithm[PD, M, Q, P]
   def batchPredict(m: M, qs: RDD[(Long, Q)]): RDD[(Long, P)] =
     throw new NotImplementedError("batchPredict not implemented")
 
-  def predictBase(baseModel: Any, query: Q)(implicit ec: ExecutionContext): Future[P] = {
-    predict(baseModel.asInstanceOf[M], query)(ec)
-  }
+  override def predictBaseAsync(bm: Any, q: Q)(implicit ec: ExecutionContext): Future[P] =
+    predictAsync(bm.asInstanceOf[M], q)(ec)
+
+  @deprecated(message =
+    "this method is just here for backward compatibility, predictBaseAsync() is called now",
+    since = "0.14.0")
+  override def predictBase(baseModel: Any, query: Q): P =
+    predict(baseModel.asInstanceOf[M], query)
+
+  /** Implement this method to produce a Future of a prediction in a non blocking way
+    * from a query and trained model.
+    *
+    * This method is implemented to just delegate to blocking predict() for
+    * backward compatibility reasons.
+    * Definitely overwrite it to implement your blocking prediction method, and leave
+    * the old blocking predict() as it is (throwing an exception), it won't be called from
+    * now on.
+    *
+    * @param model Trained model produced by [[train]].
+    * @param query An input query.
+    * @param ec ExecutionContext to use for async operations
+    * @return A Future of a prediction.
+    */
+  def predictAsync(model: M, query: Q)(implicit ec: ExecutionContext): Future[P] =
+    Future.successful(blocking(predict(model, query)))
 
   /** Implement this method to produce a prediction from a query and trained
     * model.
@@ -85,7 +107,9 @@ abstract class PAlgorithm[PD, M, Q, P]
     * @param query An input query.
     * @return A prediction.
     */
-  def predict(model: M, query: Q)(implicit ec: ExecutionContext): Future[P]
+  @deprecated(message = "override non blocking predictAsync() instead", since = "0.14.0")
+  def predict(model: M, query: Q): P =
+    throw new NotImplementedError("predict() is deprecated, override predictAsync() instead")
 
   /** :: DeveloperApi ::
     * Engine developers should not use this directly (read on to see how parallel

core/src/main/scala/org/apache/predictionio/core/BaseAlgorithm.scala

@@ -26,7 +26,7 @@ import net.jodah.typetools.TypeResolver
 import org.apache.spark.SparkContext
 import org.apache.spark.rdd.RDD
 
-import scala.concurrent.{ExecutionContext, Future}
+import scala.concurrent.{ExecutionContext, Future, blocking}
 
 /** :: DeveloperApi ::
   * Base trait with default custom query serializer, exposed to engine developer
@@ -83,6 +83,19 @@ abstract class BaseAlgorithm[PD, M, Q, P]
   def batchPredictBase(sc: SparkContext, bm: Any, qs: RDD[(Long, Q)])
   : RDD[(Long, P)]
 
+  /** :: DeveloperApi ::
+    * Engine developers should not use this directly. Called by serving to
+    * perform a single prediction.
+    *
+    * @param bm Model
+    * @param q Query
+    * @param ec ExecutionContext to use for async operations
+    * @return Future of a Predicted result
+    */
+  @DeveloperApi
+  def predictBaseAsync(bm: Any, q: Q)(implicit ec: ExecutionContext): Future[P] =
+    Future.successful(blocking {predictBase(bm, q)})
+
   /** :: DeveloperApi ::
     * Engine developers should not use this directly. Called by serving to
     * perform a single prediction.
@@ -92,7 +105,11 @@ abstract class BaseAlgorithm[PD, M, Q, P]
     * @return Predicted result
     */
   @DeveloperApi
-  def predictBase(bm: Any, q: Q)(implicit ec: ExecutionContext): Future[P]
+  @deprecated(message = "override non blocking predictBaseAsync() instead", since = "0.14.0")
+  def predictBase(bm: Any, q: Q): P =
+    throw new NotImplementedError(
+      "predictBase() is deprecated, override predictBaseAsync() instead"
+    )
 
   /** :: DeveloperApi ::
     * Engine developers should not use this directly. Prepare a model for

core/src/main/scala/org/apache/predictionio/workflow/BatchPredict.scala

@@ -213,7 +213,7 @@ object BatchPredict extends Logging {
         // finally Serving.serve.
         val supplementedQuery = serving.supplementBase(query)
         val predictionsFuture = Future.sequence(algorithms.zip(models).map { case (a, m) =>
-          a.predictBase(m, supplementedQuery)
+          a.predictBaseAsync(m, supplementedQuery)
         })
         // Notice that it is by design to call Serving.serve with the
         // *original* query.

core/src/main/scala/org/apache/predictionio/workflow/CreateServer.scala

@@ -506,7 +506,7 @@ class PredictionServer[Q, P](
               val supplementedQuery = serving.supplementBase(query)
 
               val predictionsFuture = Future.sequence(algorithms.zip(models).map { case (a, m) =>
-                a.predictBase(m, supplementedQuery)
+                a.predictBaseAsync(m, supplementedQuery)
               })
               // Notice that it is by design to call Serving.serve with the
               // *original* query.