[SPARK-7542][SQL] Support off-heap index/sort buffer

This brings the support of off-heap memory for array inside BytesToBytesMap and InMemorySorter, then we could allocate all the memory from off-heap for execution.

Closes #8068

Author: Davies Liu <davies@databricks.com>

Closes #9477 from davies/unsafe_timsort.

2 files changed, 21 insertions, 1 deletions

diff --git a/unsafe/src/main/java/org/apache/spark/unsafe/array/LongArray.java b/unsafe/src/main/java/org/apache/spark/unsafe/array/LongArray.java
index 74105050e4..1a3cdff638 100644
--- a/unsafe/src/main/java/org/apache/spark/unsafe/array/LongArray.java
+++ b/unsafe/src/main/java/org/apache/spark/unsafe/array/LongArray.java
@@ -39,7 +39,6 @@ public final class LongArray {
   private final long length;
 
   public LongArray(MemoryBlock memory) {
-    assert memory.size() % WIDTH == 0 : "Memory not aligned (" + memory.size() + ")";
     assert memory.size() < (long) Integer.MAX_VALUE * 8: "Array size > 4 billion elements";
     this.memory = memory;
     this.baseObj = memory.getBaseObject();
@@ -51,6 +50,14 @@ public final class LongArray {
     return memory;
   }
 
+  public Object getBaseObject() {
+    return baseObj;
+  }
+
+  public long getBaseOffset() {
+    return baseOffset;
+  }
+
   /**
    * Returns the number of elements this array can hold.
    */
@@ -59,6 +66,15 @@ public final class LongArray {
   }
 
   /**
+   * Fill this all with 0L.
+   */
+  public void zeroOut() {
+    for (long off = baseOffset; off < baseOffset + length * WIDTH; off += WIDTH) {
+      Platform.putLong(baseObj, off, 0);
+    }
+  }
+
+  /**
    * Sets the value at position {@code index}.
    */
   public void set(int index, long value) {
diff --git a/unsafe/src/test/java/org/apache/spark/unsafe/array/LongArraySuite.java b/unsafe/src/test/java/org/apache/spark/unsafe/array/LongArraySuite.java
index 5974cf91ff..fb8e53b334 100644
--- a/unsafe/src/test/java/org/apache/spark/unsafe/array/LongArraySuite.java
+++ b/unsafe/src/test/java/org/apache/spark/unsafe/array/LongArraySuite.java
@@ -34,5 +34,9 @@ public class LongArraySuite {
     Assert.assertEquals(2, arr.size());
     Assert.assertEquals(1L, arr.get(0));
     Assert.assertEquals(3L, arr.get(1));
+
+    arr.zeroOut();
+    Assert.assertEquals(0L, arr.get(0));
+    Assert.assertEquals(0L, arr.get(1));
   }
 }