[GitHub] [skywalking] raybi-asus commented on pull request #6007: Add null-conditional operators on these 3 files

[GitBox <gi...@apache.org>]

raybi-asus commented on pull request #6007:
URL: https://github.com/apache/skywalking/pull/6007#issuecomment-745031231


   > Why the statementEnhanceInfos could be null? I am feeling this could be a bug.
   
   Hello , the case is for PrepareStatement operation and Trace_SQL_Parameter=true. 
   Please refer to the attachment 1
   Usually we use 'prepareStament' for methods matcher :
   ![agent_connectionInstrumentation](https://user-images.githubusercontent.com/72775443/102162357-00a11180-3ec4-11eb-91b9-88ba7f892f2f.png)
   
   In ojdbc driver PhysicalConnection has prepareStatement method with 2 arguments like below , it will return OraclePreparedStatementWrapper object: 
   ![OraclePreparedStatementWrapper](https://user-images.githubusercontent.com/72775443/102167331-28df3f00-3ec9-11eb-8923-b12004373207.png)
   
   Then , when we invoke afterMethod , the code would set connection and StatementEnhanceInfos to the object which was returned from last step
   ![CreateInterceptor](https://user-images.githubusercontent.com/72775443/102167458-65ab3600-3ec9-11eb-8cad-c0ad5a525a9d.png)
   
   Hence , if we try to intercept setString method , the operation for OraclePreparedStatementWrapper runs well , but for internal invocations(Who also have setString method) such as 'T4CPreparedStatement' and 'OraclePreparedStatement', both of them don't have StatementEnhanceInfos , the NPE would be coming up.


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