spark git commit: [SPARK-11080] [SQL] Incorporate per-JVM id into ExprId to prevent unsafe cross-JVM comparisions

[ma...@apache.org]

Repository: spark
Updated Branches:
  refs/heads/master 0d1b73b78 -> ef72673b2


[SPARK-11080] [SQL] Incorporate per-JVM id into ExprId to prevent unsafe cross-JVM comparisions

In the current implementation of named expressions' `ExprIds`, we rely on a per-JVM AtomicLong to ensure that expression ids are unique within a JVM. However, these expression ids will not be _globally_ unique. This opens the potential for id collisions if new expression ids happen to be created inside of tasks rather than on the driver.

There are currently a few cases where tasks allocate expression ids, which happen to be safe because those expressions are never compared to expressions created on the driver. In order to guard against the introduction of invalid comparisons between driver-created and executor-created expression ids, this patch extends `ExprId` to incorporate a UUID to identify the JVM that created the id, which prevents collisions.

Author: Josh Rosen <jo...@databricks.com>

Closes #9093 from JoshRosen/SPARK-11080.


Project: http://git-wip-us.apache.org/repos/asf/spark/repo
Commit: http://git-wip-us.apache.org/repos/asf/spark/commit/ef72673b
Tree: http://git-wip-us.apache.org/repos/asf/spark/tree/ef72673b
Diff: http://git-wip-us.apache.org/repos/asf/spark/diff/ef72673b

Branch: refs/heads/master
Commit: ef72673b234579c161b8cbb6cafc851d9eba1bfb
Parents: 0d1b73b
Author: Josh Rosen <jo...@databricks.com>
Authored: Tue Oct 13 15:09:31 2015 -0700
Committer: Michael Armbrust <mi...@databricks.com>
Committed: Tue Oct 13 15:09:31 2015 -0700

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 .../sql/catalyst/expressions/namedExpressions.scala  | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)
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http://git-wip-us.apache.org/repos/asf/spark/blob/ef72673b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala
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diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala
index 5768c60..8957df0 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala
@@ -17,6 +17,8 @@
 
 package org.apache.spark.sql.catalyst.expressions
 
+import java.util.UUID
+
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute
 import org.apache.spark.sql.catalyst.expressions.codegen._
@@ -24,16 +26,23 @@ import org.apache.spark.sql.types._
 
 object NamedExpression {
   private val curId = new java.util.concurrent.atomic.AtomicLong()
-  def newExprId: ExprId = ExprId(curId.getAndIncrement())
+  private[expressions] val jvmId = UUID.randomUUID()
+  def newExprId: ExprId = ExprId(curId.getAndIncrement(), jvmId)
   def unapply(expr: NamedExpression): Option[(String, DataType)] = Some(expr.name, expr.dataType)
 }
 
 /**
- * A globally unique (within this JVM) id for a given named expression.
+ * A globally unique id for a given named expression.
  * Used to identify which attribute output by a relation is being
  * referenced in a subsequent computation.
+ *
+ * The `id` field is unique within a given JVM, while the `uuid` is used to uniquely identify JVMs.
  */
-case class ExprId(id: Long)
+case class ExprId(id: Long, jvmId: UUID)
+
+object ExprId {
+  def apply(id: Long): ExprId = ExprId(id, NamedExpression.jvmId)
+}
 
 /**
  * An [[Expression]] that is named.


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