RFR: Revert "Print special cause for Metadata GC"

[Roman Kennke]

Ok.

Roman

> Zhengyu got it right originally, we need to print "Trigger" in heuristics, otherwise we break the UX
> invariant that every cycle has a Trigger. This is a clean revert of:
>   http://hg.openjdk.java.net/shenandoah/jdk/rev/08b968d6f8af.
> 
> diff -r 9cf8cbfd3ba1 src/hotspot/share/gc/shenandoah/shenandoahControlThread.cpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahControlThread.cpp       Sat Nov 03 23:59:21 2018 +0100
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahControlThread.cpp       Sun Nov 04 20:36:33 2018 +0100
> @@ -179,15 +179,10 @@
> 
>      bool gc_requested = (mode != none);
>      assert (!gc_requested || cause != GCCause::_last_gc_cause, "GC cause should be set");
> 
>      if (gc_requested) {
> -      if (heuristics->has_metaspace_oom()) {
> -        // Some of vmTestbase/metaspace tests depend on following line to count GC cycles
> -        log_info(gc)("Cause: %s", GCCause::to_string(GCCause::_metadata_GC_threshold));
> -      }
> -
>        heap->reset_bytes_allocated_since_gc_start();
> 
>        // If GC was requested, we are sampling the counters even without actual triggers
>        // from allocation machinery. This captures GC phases more accurately.
>        set_forced_counters_update(true);
> diff -r 9cf8cbfd3ba1 src/hotspot/share/gc/shenandoah/shenandoahHeuristics.cpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahHeuristics.cpp  Sat Nov 03 23:59:21 2018 +0100
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahHeuristics.cpp  Sun Nov 04 20:36:33 2018 +0100
> @@ -228,11 +228,14 @@
>  bool ShenandoahHeuristics::should_start_update_refs() {
>    return _update_refs_early;
>  }
> 
>  bool ShenandoahHeuristics::should_start_normal_gc() const {
> +  // Perform GC to cleanup metaspace
>    if (has_metaspace_oom()) {
> +    // Some of vmTestbase/metaspace tests depend on following line to count GC cycles
> +    log_info(gc)("Trigger: %s", GCCause::to_string(GCCause::_metadata_GC_threshold));
>      return true;
>    }
> 
>    double last_time_ms = (os::elapsedTime() - _last_cycle_end) * 1000;
>    bool periodic_gc = (last_time_ms > ShenandoahGuaranteedGCInterval);
> 
> 
> Testing: tier3_gc_shenandoah, vmTestbase/metaspace
> 
> Thanks,
> -Aleksey
>