g1FullGCCompactTask.cpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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#include "precompiled.hpp"
#include "gc/g1/g1CollectedHeap.hpp"
#include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp"
#include "gc/g1/g1FullCollector.hpp"
#include "gc/g1/g1FullCollector.inline.hpp"
#include "gc/g1/g1FullGCCompactionPoint.hpp"
#include "gc/g1/g1FullGCCompactTask.hpp"
#include "gc/g1/heapRegion.inline.hpp"
#include "gc/shared/gcTraceTime.inline.hpp"
#include "logging/log.hpp"
#include "oops/oop.inline.hpp"
#include "utilities/ticks.hpp"

// Do work for all skip-compacting regions.
class G1ResetSkipCompactingClosure : public HeapRegionClosure {
  G1FullCollector* _collector;

public:
  G1ResetSkipCompactingClosure(G1FullCollector* collector) : _collector(collector) { }

  bool do_heap_region(HeapRegion* r) {
    uint region_index = r->hrm_index();
    // Only for skip-compaction regions; early return otherwise.
    if (!_collector->is_skip_compacting(region_index)) {

      return false;
    }
    assert(_collector->live_words(region_index) > _collector->scope()->region_compaction_threshold() ||
         !r->is_starts_humongous() ||
         _collector->mark_bitmap()->is_marked(cast_to_oop(r->bottom())),
         "must be, otherwise reclaimed earlier");
    r->reset_skip_compacting_after_full_gc();
    return false;
  }
};

size_t G1FullGCCompactTask::G1CompactRegionClosure::apply(oop obj) {
  size_t size = obj->size();
  HeapWord* destination = cast_from_oop<HeapWord*>(obj->forwardee());
  if (destination == NULL) {
    // Object not moving
    return size;
  }

  // copy object and reinit its mark
  HeapWord* obj_addr = cast_from_oop<HeapWord*>(obj);
  assert(obj_addr != destination, "everything in this pass should be moving");
  Copy::aligned_conjoint_words(obj_addr, destination, size);
  cast_to_oop(destination)->init_mark();
  assert(cast_to_oop(destination)->klass() != NULL, "should have a class");

  return size;
}

void G1FullGCCompactTask::compact_region(HeapRegion* hr) {
  assert(!hr->is_pinned(), "Should be no pinned region in compaction queue");
  assert(!hr->is_humongous(), "Should be no humongous regions in compaction queue");

  if (!collector()->is_free(hr->hrm_index())) {
    G1CompactRegionClosure compact(collector()->mark_bitmap());
    hr->apply_to_marked_objects(collector()->mark_bitmap(), &compact);
    // Clear the liveness information for this region if necessary i.e. if we actually look at it
    // for bitmap verification. Otherwise it is sufficient that we move the TAMS to bottom().
    if (G1VerifyBitmaps) {
      collector()->mark_bitmap()->clear_region(hr);
    }
  }

  hr->reset_compacted_after_full_gc();
}

void G1FullGCCompactTask::work(uint worker_id) {
  Ticks start = Ticks::now();
  GrowableArray<HeapRegion*>* compaction_queue = collector()->compaction_point(worker_id)->regions();
  for (GrowableArrayIterator<HeapRegion*> it = compaction_queue->begin();
       it != compaction_queue->end();
       ++it) {
    compact_region(*it);
  }

  G1ResetSkipCompactingClosure hc(collector());
  G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&hc, &_claimer, worker_id);
  log_task("Compaction task", worker_id, start);
}

void G1FullGCCompactTask::serial_compaction() {
  GCTraceTime(Debug, gc, phases) tm("Phase 4: Serial Compaction", collector()->scope()->timer());
  GrowableArray<HeapRegion*>* compaction_queue = collector()->serial_compaction_point()->regions();
  for (GrowableArrayIterator<HeapRegion*> it = compaction_queue->begin();
       it != compaction_queue->end();
       ++it) {
    compact_region(*it);
  }
}