GitHub user sarutak opened a pull request:
https://github.com/apache/spark/pull/12979
[SPARK-15205][SQL][WIP] Codegen can compile more than twice for the same
source code
## What changes were proposed in this pull request?
Sometimes, we have generated codes they are equal except for comments.
One example is here.
{code}
val df = sc.parallelize(1 to 10).toDF
df.selectExpr("value + 1").show // query1
df.selectExpr("value + 2").show // query2
{code}
The following code is one of generated code when query1 above is executed.
{code}
/* 001 */
/* 002 */ public java.lang.Object generate(Object[] references) {
/* 003 */ return new SpecificSafeProjection(references);
/* 004 */ }
/* 005 */
/* 006 */ class SpecificSafeProjection extends
org.apache.spark.sql.catalyst.expressions.codegen.BaseProjection {
/* 007 */
/* 008 */ private Object[] references;
/* 009 */ private MutableRow mutableRow;
/* 010 */ private Object[] values;
/* 011 */ private org.apache.spark.sql.types.StructType schema;
/* 012 */
/* 013 */
/* 014 */ public SpecificSafeProjection(Object[] references) {
/* 015 */ this.references = references;
/* 016 */ mutableRow = (MutableRow) references[references.length - 1];
/* 017 */
/* 018 */ this.schema = (org.apache.spark.sql.types.StructType)
references[0];
/* 019 */ }
/* 020 */
/* 021 */ public java.lang.Object apply(java.lang.Object _i) {
/* 022 */ InternalRow i = (InternalRow) _i;
/* 023 */ /* createexternalrow(if (isnull(input[0, int])) null else
input[0, int], StructField((value + 1),IntegerType,false)) */
/* 024 */ values = new Object[1];
/* 025 */ /* if (isnull(input[0, int])) null else input[0, int] */
/* 026 */ /* isnull(input[0, int]) */
/* 027 */ /* input[0, int] */
/* 028 */ int value3 = i.getInt(0);
/* 029 */ boolean isNull1 = false;
/* 030 */ int value1 = -1;
/* 031 */ if (!false && false) {
/* 032 */ /* null */
/* 033 */ final int value4 = -1;
/* 034 */ isNull1 = true;
/* 035 */ value1 = value4;
/* 036 */ } else {
/* 037 */ /* input[0, int] */
/* 038 */ int value5 = i.getInt(0);
/* 039 */ isNull1 = false;
/* 040 */ value1 = value5;
/* 041 */ }
/* 042 */ if (isNull1) {
/* 043 */ values[0] = null;
/* 044 */ } else {
/* 045 */ values[0] = value1;
/* 046 */ }
/* 047 */
/* 048 */ final org.apache.spark.sql.Row value = new
org.apache.spark.sql.catalyst.expressions.GenericRowWithSchema(values,
this.schema);
/* 049 */ if (false) {
/* 050 */ mutableRow.setNullAt(0);
/* 051 */ } else {
/* 052 */
/* 053 */ mutableRow.update(0, value);
/* 054 */ }
/* 055 */
/* 056 */ return mutableRow;
/* 057 */ }
/* 058 */ }
/* 059 */
{code}
On the other hand, the following code is for query2.
{code}
/* 001 */
/* 002 */ public java.lang.Object generate(Object[] references) {
/* 003 */ return new SpecificSafeProjection(references);
/* 004 */ }
/* 005 */
/* 006 */ class SpecificSafeProjection extends
org.apache.spark.sql.catalyst.expressions.codegen.BaseProjection {
/* 007 */
/* 008 */ private Object[] references;
/* 009 */ private MutableRow mutableRow;
/* 010 */ private Object[] values;
/* 011 */ private org.apache.spark.sql.types.StructType schema;
/* 012 */
/* 013 */
/* 014 */ public SpecificSafeProjection(Object[] references) {
/* 015 */ this.references = references;
/* 016 */ mutableRow = (MutableRow) references[references.length - 1];
/* 017 */
/* 018 */ this.schema = (org.apache.spark.sql.types.StructType)
references[0];
/* 019 */ }
/* 020 */
/* 021 */ public java.lang.Object apply(java.lang.Object _i) {
/* 022 */ InternalRow i = (InternalRow) _i;
/* 023 */ /* createexternalrow(if (isnull(input[0, int])) null else
input[0, int], StructField((value + 2),IntegerType,false)) */
/* 024 */ values = new Object[1];
/* 025 */ /* if (isnull(input[0, int])) null else input[0, int] */
/* 026 */ /* isnull(input[0, int]) */
/* 027 */ /* input[0, int] */
/* 028 */ int value3 = i.getInt(0);
/* 029 */ boolean isNull1 = false;
/* 030 */ int value1 = -1;
/* 031 */ if (!false && false) {
/* 032 */ /* null */
/* 033 */ final int value4 = -1;
/* 034 */ isNull1 = true;
/* 035 */ value1 = value4;
/* 036 */ } else {
/* 037 */ /* input[0, int] */
/* 038 */ int value5 = i.getInt(0);
/* 039 */ isNull1 = false;
/* 040 */ value1 = value5;
/* 041 */ }
/* 042 */ if (isNull1) {
/* 043 */ values[0] = null;
/* 044 */ } else {
/* 045 */ values[0] = value1;
/* 046 */ }
/* 047 */
/* 048 */ final org.apache.spark.sql.Row value = new
org.apache.spark.sql.catalyst.expressions.GenericRowWithSchema(values,
this.schema);
/* 049 */ if (false) {
/* 050 */ mutableRow.setNullAt(0);
/* 051 */ } else {
/* 052 */
/* 053 */ mutableRow.update(0, value);
/* 054 */ }
/* 055 */
/* 056 */ return mutableRow;
/* 057 */ }
/* 058 */ }
/* 059 */
{code}
As you can notice, those two generated codes are essentially equal but not
equal as String objects so they will be compiled each.
In this PR, I introduced place holder for comments like
/*{comment_placeholder1}*/.
The code to be compiled has only comment-style place holder.
When logging the generated code, place holders are replaced with
corresponding actual comments.
## How was this patch tested?
Currently I mark this PR as WIP and I'll add test cases in this PR.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/sarutak/spark SPARK-15205
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/12979.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #12979
----
commit 766f5c64f93163ee1b8b7ea8b1ef986f9a731733
Author: Kousuke Saruta <saru...@oss.nttdata.co.jp>
Date: 2016-05-08T00:27:41Z
Fixed duplicated generated code issue
----
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