RFR: 8153659: Create a CHeap backed LogStream class

[Bengt Rutisson]

Hi StefanK,

On 2016-04-07 13:30, Stefan Karlsson wrote:
> Hi all,
>
> I've updated the patch:
>  http://cr.openjdk.java.net/~stefank/8153659/webrev.02

Looks good! Nice fix!

Bengt

>
> The previous patch created the embedded ResourceMark after the 
> stringStream instance was created. I discussed the layout of the 
> classes with Bengt, and have decided to restructure this patch. I've 
> changed the code so that the ResourceMark is embedded in a new 
> stringStreamWithResourceMark class. This allows me to use the same 
> LogStreamBase class, but different stringClass template parameters, 
> for all three classes.
>
> I've put the stringStreamWithResourceMark class in logStream.hpp 
> instead of ostream.hpp, to prevent the include of resourceArea.hpp to 
> propagate through the ostream.hpp header. The resourceArea.hpp file is 
> problematic, since it includes and uses thread.inline.hpp. The 
> alternative would be to move the implementation of resourceArea.hpp 
> into a resource.inline.hpp file, so that header files could create 
> ResourceMark instances, without having to include thread.inline.hpp. 
> I'm leaving that exercise for another RFE.
>
> Thanks,
> StefanK
>
> On 2016-04-06 19:54, Stefan Karlsson wrote:
>> Hi all,
>>
>> Please review this patch to add a LogStream class that allocates its 
>> backing buffer from CHeap memory instead of Resource memory.
>>
>> http://cr.openjdk.java.net/~stefank/8153659/webrev.01
>> https://bugs.openjdk.java.net/browse/JDK-8153659
>>
>> The main motivation for this is that we can't use Resource allocated 
>> memory during initialization, until Thread::current() has been 
>> initialized. So, a CHeap backed LogStream is desirable when we 
>> execute, for example, the following code during large pages 
>> initialization:
>>
>> void os::trace_page_sizes(const char* str, const size_t* page_sizes, 
>> int count)
>> {
>>   if (TracePageSizes) {
>>     tty->print("%s: ", str);
>>     for (int i = 0; i < count; ++i) {
>>       tty->print(" " SIZE_FORMAT, page_sizes[i]);
>>     }
>>     tty->cr();
>>   }
>> }
>>
>> The patch restructures the code and creates a LogStreamBase template 
>> base class, which takes the backing outputStream class as a template 
>> parameter. We then have three concrete LogStream classes:
>>
>>  LogStream - Buffer resource allocated with an embedded ResourceMark
>>  LogStreamNoResourceMark - Buffer resource allocated without an 
>> embedded ResourceMark
>>  LogStreamCHeap - Buffer CHeap allocated
>>
>> I moved the LogStream class from the logStream.inline.hpp file to 
>> logStream.hpp, for consistency. If that's causing problems while 
>> reviewing this, I can move it in a separate patch.
>>
>> Tested with JPRT with the TracePageSizes patch ( JDK-8152491) and 
>> internal VM tests.
>>
>> Thanks,
>> StefanK
>