RFR: Use StringJoiner in sjavac options handling

[Jonathan Gibbons]

I was hoping you would, but if you'd prefer me to do it, I can.

-- Jon

On 02/08/2016 01:43 PM, Andreas Lundblad wrote:
> On Thu, Feb 04, 2016 at 11:57:56AM -0800, Liam Miller-Cushon wrote:
>> Some benchmarking showed that sjavac's option handling is spending a lot of
>> time on string concatenation. Any interest in taking this trivial fix?
> Sorry for late reply. Change looks great.
>
> Will you push it or should I?
>
> -- Andreas
>
>
>
>> # HG changeset patch
>> # User Liam Miller-Cushon <cushon at google.com>
>> # Date 1454615087 28800
>> #      Thu Feb 04 11:44:47 2016 -0800
>> # Node ID dea4ee331c161ffda376b1a91f84c4e905f0d0fe
>> # Parent  873c5cde4f08f6fffe02cd1f2877111783797be7
>> Use StringJoiner in sjavac options handling
>>
>> diff -r 873c5cde4f08 -r dea4ee331c16
>> src/jdk.compiler/share/classes/com/sun/tools/sjavac/options/Options.java
>> ---
>> a/src/jdk.compiler/share/classes/com/sun/tools/sjavac/options/Options.java Tue
>> Feb 02 16:11:09 2016 -0800
>> +++
>> b/src/jdk.compiler/share/classes/com/sun/tools/sjavac/options/Options.java Thu
>> Feb 04 11:44:47 2016 -0800
>> @@ -33,6 +33,7 @@
>>   import java.util.List;
>>   import java.util.Map;
>>   import java.util.Set;
>> +import java.util.StringJoiner;
>>   import java.util.HashSet;
>>
>>   import com.sun.tools.sjavac.Transformer;
>> @@ -225,10 +226,7 @@
>>               }
>>
>>               String getResult() {
>> -                String result = "";
>> -                for (String s : args)
>> -                    result += s + " ";
>> -                return result.trim();
>> +                return String.join(" ", args);
>>               }
>>
>>               public void addAll(Collection<String> toAdd) {
>> @@ -337,10 +335,11 @@
>>       // Helper method to join a list of source locations separated by
>>       // File.pathSeparator
>>       private static String concatenateSourceLocations(List<SourceLocation>
>> locs) {
>> -        String s = "";
>> -        for (SourceLocation loc : locs)
>> -            s += (s.isEmpty() ? "" : java.io.File.pathSeparator) +
>> loc.getPath();
>> -        return s;
>> +        StringJoiner joiner = new StringJoiner(java.io.File.pathSeparator);
>> +        for (SourceLocation loc : locs) {
>> +            joiner.add(loc.getPath().toString());
>> +        }
>> +        return joiner.toString();
>>       }
>>
>>       // OptionHelper that records the traversed options in this Options
>> instance.