Fix/create variable map

[Shylock-Hg]

What type of PR is this?

• bug
• feature
• enhancement

What problem(s) does this PR solve?

Issue(s) number:

Close https://github.com/vesoft-inc/nebula-ent/issues/1539

Description:

The MT-safe of variable map is guaranteed by pre inserted before runtime, so I force to insert variable to map when symbol table create new variable.

How do you solve it?

Special notes for your reviewer, ex. impact of this fix, design document, etc:

Checklist:

Tests:

• Unit test(positive and negative cases)
• Function test
• Performance test
• N/A

Affects:

• Documentation affected (Please add the label if documentation needs to be modified.)
• Incompatibility (If it breaks the compatibility, please describe it and add the label.）
• If it's needed to cherry-pick (If cherry-pick to some branches is required, please label the destination version(s).)
• Performance impacted: Consumes more CPU/Memory

Release notes:

Please confirm whether to be reflected in release notes and how to describe:

ex. Fixed the bug .....

[yixinglu]

So, what's the real reason about the crash? not thread-safe data structure usage?

[Shylock-Hg]

Yes, all variable should insert to map in building stage, and executor is running on MT-environment, so executor insert new variable will lead to condition race.

[jievince]

Which line of code inserts new variabes to map in runtime?

[Shylock-Hg]

nebula/src/common/expression/ListComprehensionExpression.cpp

Line 34 in 4191724

ctx.setVar(innerVar_, v);

[jievince]

nebula/src/common/expression/ListComprehensionExpression.cpp

Line 34 in 4191724

ctx.setVar(innerVar_, v);

Does it leads the query YIELD 1 AS number MINUS YIELD 2 AS number to crash?

[Shylock-Hg]

nebula/src/graph/validator/YieldValidator.cpp

Line 187 in 4191724

inputVar = vctx_->anonVarGen()->getVar();

[dutor]

Anything related to vesoft-inc/nebula-ent#1576 ?
And please take care similar issue introduced in #4498

[Shylock-Hg]

Anything related to vesoft-inc/nebula-ent#1576 ? And please take care similar issue introduced in #4498

Yes I created a issue related to #4498 in #4843