[CALCITE-2701] Ensure that the "Baz" classes generated by Janino are thread-safe

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.17.0
• Fix Version/s: 1.18.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Julian Hyde
• Reporter: Stamatis Zampetakis
• Created: 23/Nov/18 10:56
• Updated: 23/Dec/18 00:12
• Resolved: 02/Dec/18 17:55

Description

Currently the Baz classes that are used to execute queries in the EnumerableConvention are stateful since the code generated by EnumerableRelImplementor#implementRoot method creates an instance variable (i.e., DataContext root). Every call to the bind method changes the value of the root variable making the object mutable.

I propose to remove the instance variable and in the body of the method use the DataContext passed as a parameter.

It appears that the addition of the instance variable was a workaround for a bug in Janino (JANINO-169). It seems that the bug is no longer present at the current version of Janino used in Calcite (3.0.9) since the test JdbcTest#testJanino169 (and the complete suite) pass successfully with the proposed modification. 

Unfortunately, I couldn't verify the fix in the release notes of Janino neither in the commit history. The best, I could find is the following commits in the Janino repository:

commit fe5edc1904278c1c189f3379e06417aaf4a26315
Author: aunkrig <aunkrig@eb4544d6-894b-0410-9319-a9612837a279>
Date: Wed Jan 22 21:19:48 2014 +0000

Partly fixed JANINO-169 - now you get "Compiler limitation: Initializers cannot access local variables declared in an enclosing block".

commit 4d2bacf16229ac1278eafa0fb4d5a0377134d3f2
Author: aunkrig <aunkrig@eb4544d6-894b-0410-9319-a9612837a279>
Date: Wed Jan 22 15:03:17 2014 +0000

Added test case for JANINO-169.

 

 

Issue Links

• blocks: CALCITE-2575 Release Calcite 1.18.0
• blocks: CALCITE-2703 Reduce code generation and class loading overhead when executing queries in the EnumerableConvention
• links to: PR#935