src/hotspot/share/gc/shenandoah/shenandoahHeapRegionClosures.cpp

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#include "gc/shenandoah/shenandoahHeapRegionClosures.hpp"
#include "gc/shenandoah/shenandoahMarkingContext.hpp"
#include "gc/shenandoah/shenandoahSharedVariables.hpp"

ShenandoahSynchronizePinnedRegionStates::ShenandoahSynchronizePinnedRegionStates() :
  _lock(ShenandoahHeap::heap()->lock()) { }

void ShenandoahSynchronizePinnedRegionStates::heap_region_do(ShenandoahHeapRegion* r) {
  // Drop "pinned" state from regions that no longer have a pinned count. Put
  // regions with a pinned count into the "pinned" state.
  if (r->is_active()) {
    synchronize_pin_count(r);
  }
}

void ShenandoahSynchronizePinnedRegionStates::synchronize_pin_count(ShenandoahHeapRegion* r) {
  if (r->is_pinned()) {
    if (r->pin_count() == 0) {
      ShenandoahHeapLocker locker(_lock);
      r->make_unpinned();
    }
  } else {
    if (r->pin_count() > 0) {
      ShenandoahHeapLocker locker(_lock);
      r->make_pinned();
    }
  }
}

ShenandoahFinalMarkUpdateRegionStateClosure::ShenandoahFinalMarkUpdateRegionStateClosure(ShenandoahMarkingContext *ctx) :
        _ctx(ctx) { }

void ShenandoahFinalMarkUpdateRegionStateClosure::heap_region_do(ShenandoahHeapRegion* r) {
  if (r->is_active()) {
    if (_ctx != nullptr) {
      // _ctx may be null when this closure is used to sync only the pin status
      // update the watermark of old regions. For old regions we cannot reset
      // the TAMS because we rely on that to keep promoted objects alive after
      // old marking is complete.

      // All allocations past TAMS are implicitly live, adjust the region data.
      // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
      HeapWord *tams = _ctx->top_at_mark_start(r);
      HeapWord *top = r->top();
      if (top > tams) {
        r->increase_live_data_alloc_words(pointer_delta(top, tams));
      }
    }

    // We are about to select the collection set, make sure it knows about
    // current pinning status. Also, this allows trashing more regions that
    // now have their pinning status dropped.
    _pins.synchronize_pin_count(r);

    // Remember limit for updating refs. It's guaranteed that we get no
    // from-space-refs written from here on.
    r->set_update_watermark_at_safepoint(r->top());
  } else {
    assert(!r->has_live(), "Region %zu should have no live data", r->index());
    assert(_ctx == nullptr || _ctx->top_at_mark_start(r) == r->top(),
           "Region %zu should have correct TAMS", r->index());
  }
}