RFR(M): 8039147: Cleanup SuspendibleThreadSet

[Bengt Rutisson]

Hi Per,

Nice cleanup. Looks good to me.

Bengt


On 2014-04-08 13:32, Per Liden wrote:
> Hi,
>
> Here's a attempt to cleanup SuspendibleThreadSet that I'd like to get 
> some reviews on.
>
> Webrev: http://cr.openjdk.java.net/~pliden/8039147/webrev.0/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8039147
>
> Summary:
>
> * The function of SuspendibleThreadSet is completely unchanged. Still 
> does the same thing, same semantics, same users, etc.
>
> * SuspendibleThreadSet is broken out from concurrentGCThread.hpp/cpp 
> into separate files. The relation ship with ConcurrentGCThread is a 
> bit artificial as SuspendibleThreadSet is used by other threads as 
> well e.g. SharedHeap's FlexibleWorkGang.
>
> * There's currently two ways of using SuspendibleThreadSet, depending 
> on which context you're in; 1) through direct use of the static _sts 
> member in ConcurrentGCThread and 2) via the static stsXXXX() functions 
> exposed by ConcurrentGCThread. With this patch there's only one 
> interface, which is exposed as static functions on the 
> SuspendibleThreadSet class itself.
>
> * I adjusted the names of some of the fields in SuspendibleThreadSet, 
> which didn't quite make sense to me. For example, _async is now 
> _nthreads since it's a counter of number of threads currently in the 
> thread set.
>
> * The should_yield() and yield() functions on ConcurrentGCThread (and 
> it's subclasses) where removed, since they were never used. There was 
> one exception here though, which was concurrentMarkThread::yield(), 
> but it just does a direct call to SuspendibleThreadSet's yield() so 
> that's just an useless indirection.
>
> * SuspendibleThreadSetJoiner is introduced to replace code like this:
>
> if (....) {
>    _sts.join();
>    <do something>
>    _sts.leave();
> }
>
> with code like this:
>
> if (....) {
>    SuspendibleThreadSetJoiner sts;
>    <do something>
> }
>
> cheers,
> /Per