Made StorageLevel constructor private, and added StorageLevels.create() to the Java API. Updates scala and java programming guides.

4 files changed, 18 insertions, 5 deletions

diff --git a/core/src/main/scala/spark/api/java/StorageLevels.java b/core/src/main/scala/spark/api/java/StorageLevels.java
index 722af3c06c..5e5845ac3a 100644
--- a/core/src/main/scala/spark/api/java/StorageLevels.java
+++ b/core/src/main/scala/spark/api/java/StorageLevels.java
@@ -17,4 +17,15 @@ public class StorageLevels {
   public static final StorageLevel MEMORY_AND_DISK_2 = new StorageLevel(true, true, true, 2);
   public static final StorageLevel MEMORY_AND_DISK_SER = new StorageLevel(true, true, false, 1);
   public static final StorageLevel MEMORY_AND_DISK_SER_2 = new StorageLevel(true, true, false, 2);
+
+  /**
+   * Create a new StorageLevel object.
+   * @param useDisk saved to disk, if true
+   * @param useMemory saved to memory, if true
+   * @param deserialized saved as deserialized objects, if true
+   * @param replication replication factor
+   */
+  public static StorageLevel create(boolean useDisk, boolean useMemory, boolean deserialized, int replication) {
+    return StorageLevel.apply(useDisk, useMemory, deserialized, replication);
+  }
 }
diff --git a/core/src/main/scala/spark/storage/StorageLevel.scala b/core/src/main/scala/spark/storage/StorageLevel.scala
index f2535ae5ae..45d6ea2656 100644
--- a/core/src/main/scala/spark/storage/StorageLevel.scala
+++ b/core/src/main/scala/spark/storage/StorageLevel.scala
@@ -7,10 +7,10 @@ import java.io.{Externalizable, IOException, ObjectInput, ObjectOutput}
  * whether to drop the RDD to disk if it falls out of memory, whether to keep the data in memory
  * in a serialized format, and whether to replicate the RDD partitions on multiple nodes.
  * The [[spark.storage.StorageLevel$]] singleton object contains some static constants for
- * commonly useful storage levels. The recommended method to create your own storage level
- * object is to use `StorageLevel.apply(...)` from the singleton object.
+ * commonly useful storage levels. To create your own storage level object, use the factor method
+ * of the singleton object (`StorageLevel(...)`).
  */
-class StorageLevel(
+class StorageLevel private(
     private var useDisk_ : Boolean,
     private var useMemory_ : Boolean,
     private var deserialized_ : Boolean,
diff --git a/docs/java-programming-guide.md b/docs/java-programming-guide.md
index 188ca4995e..37a906ea1c 100644
--- a/docs/java-programming-guide.md
+++ b/docs/java-programming-guide.md
@@ -75,7 +75,8 @@ class has a single abstract method, `call()`, that must be implemented.
 ## Storage Levels
 
 RDD [storage level](scala-programming-guide.html#rdd-persistence) constants, such as `MEMORY_AND_DISK`, are
-declared in the [spark.api.java.StorageLevels](api/core/index.html#spark.api.java.StorageLevels) class.
+declared in the [spark.api.java.StorageLevels](api/core/index.html#spark.api.java.StorageLevels) class. To
+define your own storage level, you can use StorageLevels.create(...). 
 
 
 # Other Features
diff --git a/docs/scala-programming-guide.md b/docs/scala-programming-guide.md
index 7350eca837..301b330a79 100644
--- a/docs/scala-programming-guide.md
+++ b/docs/scala-programming-guide.md
@@ -301,7 +301,8 @@ We recommend going through the following process to select one:
 * Use the replicated storage levels if you want fast fault recovery (e.g. if using Spark to serve requests from a web
   application). *All* the storage levels provide full fault tolerance by recomputing lost data, but the replicated ones
   let you continue running tasks on the RDD without waiting to recompute a lost partition.
-  
+ 
+If you want to define your own storage level (say, with replication factor of 3 instead of 2), then use the function factor method `apply()` of the [`StorageLevel`](api/core/index.html#spark.storage.StorageLevel$) singleton object.  
 
 # Shared Variables