[slf4j-dev] [JIRA] (SLF4J-468) MessageFormatter codepath improvements in case of one and two Object parameters

[QOS.CH (JIRA)]

    [ https://jira.qos.ch/browse/SLF4J-468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=19851#comment-19851 ] 

Wessel van Norel commented on SLF4J-468:
----------------------------------------

@ceki I got the updates on this issue, and trying to understand how to get the changes you propose to work. And I'm looking into how to benchmark the changes properly. Since benchmarking is hard.

> MessageFormatter codepath improvements in case of one and two Object parameters
> -------------------------------------------------------------------------------
>
>                 Key: SLF4J-468
>                 URL: https://jira.qos.ch/browse/SLF4J-468
>             Project: SLF4J
>          Issue Type: Improvement
>    Affects Versions: 1.7.x
>            Reporter: Wessel van Norel
>            Assignee: SLF4J developers list
>            Priority: Minor
>
> The pseudo path the code follows in case of one argument is:
> org.slf4j.helpers.MessageFormatter#format(java.lang.String, java.lang.Object)
> create Object Array with size one and put the parameter in it
> get length of array
> check if Element[length -1] of this Array is a Throwable
> if throwable
>     create empty object array
>     create new Stringbuffer to contain message
>     append message to Stringbuffer
>     return Stringbuffer
> else
>     normal codeflow to format the message with argument
> fi
> The flow around a Throwable is suboptimal, which is logical since you should not be calling this with just a Throwable. But by adding a instanceof call to this method and then calling org.slf4j.helpers.MessageFormatter#arrayFormat(java.lang.String, java.lang.Object[], java.lang.Throwable) directy with the proper parameters safes the get & check in the array and in case of Throwable the new array and unneeded stringbuffer creation. Skipping the instanceof call might result in undesired behaviour in case a logger implementation is calling this formatter even though it has no need for it. 
> I would suggest that for 2.0.0 the instanceof check is not added, but for 1.7.x it contains it, so the library behaves as before the change, but a little bit faster. 
>  
> The pseudo code path for the 2 argument version is:
> org.slf4j.helpers.MessageFormatter#format(java.lang.String, java.lang.Object, java.lang.Object)
> create Object Array with size two and put both parameters in it
> get length of array
> check if Element[length -1] of this Array is a Throwable
> if Throwable
>     create object array with size 1 and copy first element of the size two array into it
>     normal codeflow to format the message with argument
> else
>     normal codeflow to format the message with arguments
> fi
> With an instanceof and then directly calling org.slf4j.helpers.MessageFormatter#arrayFormat(java.lang.String, java.lang.Object[], java.lang.Throwable) safes some processing in both cases.



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