[richfaces-issues] [JBoss JIRA] Commented: (RF-4498) EndlessLoop in CssCompressor

[andreas_back (JIRA)]

    [ https://jira.jboss.org/jira/browse/RF-4498?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12430779#action_12430779 ] 

andreas_back commented on RF-4498:
----------------------------------

Hello Nick,

some further investigation has shown that the
the endless loop occurred while the string /** was processed during the
handling of a background-image while compressing the file extended_classes.xcss.

Your code change has fixed this case and our application does start.

The string /*/ just served as an example to show that the loop
indeed could cycle for ever.

One suggestion for the further improvement of the code.

The concrete loop does not terminate if during one iteration 

(A1)	neither to buffer sb is changed by delete statement
(A2)	nor the value of the startIndex is changed.

The Css - Compression and the removal of the 
the comments is optimization. 

Therefore it might be an option to excape from the loop by 
a break-statement if none of the actions (A1) or (A2) has 
been taken.

The returned string would not be space-optimal but it would prevent
a critical error.

> EndlessLoop in CssCompressor
> ----------------------------
>
>                 Key: RF-4498
>                 URL: https://jira.jboss.org/jira/browse/RF-4498
>             Project: RichFaces
>          Issue Type: Bug
>    Affects Versions: 3.2.2
>         Environment: Browser independent
>            Reporter: andreas_back
>            Assignee: Tsikhon Kuprevich
>            Priority: Critical
>             Fix For: 3.3.0
>
>
> When starting our application under RF 3.2.2 GA Tomcat consumes (on a Quad-Core-Processor) 25 % of the overall CPU performance, if the first page of the application is requested.
> After adding 
>    set CATALINA_OPTS="-Dcom.sun.management.jmxremote" 
> to the startup.bat and starting jconsole it was found the time is consumed in line 41 of CssCompressor.java,
> see the code fragment.
> sb = new StringBuffer(srcsb.toString());
>         while ((startIndex = sb.indexOf("/*")) >= 0) {
>             endIndex = sb.indexOf("*/", startIndex + 2); 
>             if (endIndex >= startIndex + 2)
>                 sb.delete(startIndex, endIndex + 2);
> }
> A simple code analysis shows that the code starts an endless loop for example for 
> the string 
>  
>              /*/
> If the parameter org.ajax4jsf.COMPRESS_STYLE is set to false
> then the endless loop disappears.
> It could be noted that the single string in the CssCompressorTest class
> does not contain the comment /* or */.

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