1 files changed, 50 insertions, 0 deletions
diff --git a/core/src/main/scala/spark/storage/BlockObjectWriter.scala b/core/src/main/scala/spark/storage/BlockObjectWriter.scala
new file mode 100644
index 0000000000..42e2b07d5c
--- /dev/null
+++ b/core/src/main/scala/spark/storage/BlockObjectWriter.scala
@@ -0,0 +1,50 @@
+package spark.storage
+
+import java.nio.ByteBuffer
+
+
+/**
+ * An interface for writing JVM objects to some underlying storage. This interface allows
+ * appending data to an existing block, and can guarantee atomicity in the case of faults
+ * as it allows the caller to revert partial writes.
+ *
+ * This interface does not support concurrent writes.
+ */
+abstract class BlockObjectWriter(val blockId: String) {
+
+  var closeEventHandler: () => Unit = _
+
+  def open(): BlockObjectWriter
+
+  def close() {
+    closeEventHandler()
+  }
+
+  def isOpen: Boolean
+
+  def registerCloseEventHandler(handler: () => Unit) {
+    closeEventHandler = handler
+  }
+
+  /**
+   * Flush the partial writes and commit them as a single atomic block. Return the
+   * number of bytes written for this commit.
+   */
+  def commit(): Long
+
+  /**
+   * Reverts writes that haven't been flushed yet. Callers should invoke this function
+   * when there are runtime exceptions.
+   */
+  def revertPartialWrites()
+
+  /**
+   * Writes an object.
+   */
+  def write(value: Any)
+
+  /**
+   * Size of the valid writes, in bytes.
+   */
+  def size(): Long
+}