8054818: Refactor HeapRegionSeq to manage heap region and auxiliary data

Summary: Let HeapRegionSeq manage the heap region and auxiliary data to decrease the amount of responsibilities of G1CollectedHeap, and encapsulate this work from other code.
Reviewed-by: jwilhelm, jmasa, mgerdin, brutisso

agent/src/share/classes/sun/jvm/hotspot/gc_implementation/g1/G1CollectedHeap.java

@@ -45,8 +45,8 @@ import sun.jvm.hotspot.types.TypeDataBase;
 public class G1CollectedHeap extends SharedHeap {
     // HeapRegionSeq _seq;
     static private long hrsFieldOffset;
-    // MemRegion _g1_committed;
-    static private long g1CommittedFieldOffset;
+    // MemRegion _g1_reserved;
+    static private long g1ReservedFieldOffset;
     // size_t _summary_bytes_used;
     static private CIntegerField summaryBytesUsedField;
     // G1MonitoringSupport* _g1mm;
@@ -68,7 +68,6 @@ public class G1CollectedHeap extends SharedHeap {
         Type type = db.lookupType("G1CollectedHeap");
 
         hrsFieldOffset = type.getField("_hrs").getOffset();
-        g1CommittedFieldOffset = type.getField("_g1_committed").getOffset();
         summaryBytesUsedField = type.getCIntegerField("_summary_bytes_used");
         g1mmField = type.getAddressField("_g1mm");
         oldSetFieldOffset = type.getField("_old_set").getOffset();
@@ -76,9 +75,7 @@ public class G1CollectedHeap extends SharedHeap {
     }
 
     public long capacity() {
-        Address g1CommittedAddr = addr.addOffsetTo(g1CommittedFieldOffset);
-        MemRegion g1Committed = new MemRegion(g1CommittedAddr);
-        return g1Committed.byteSize();
+        return hrs().capacity();
     }
 
     public long used() {

agent/src/share/classes/sun/jvm/hotspot/gc_implementation/g1/G1HeapRegionTable.java

@@ -93,19 +93,35 @@ public class G1HeapRegionTable extends VMObject {
     private class HeapRegionIterator implements Iterator<HeapRegion> {
         private long index;
         private long length;
+        private HeapRegion next;
+
+        public HeapRegion positionToNext() {
+          HeapRegion result = next;
+          while (index < length && at(index) == null) {
+            index++;
+          }
+          if (index < length) {
+            next = at(index);
+            index++; // restart search at next element
+          } else {
+            next = null;
+          }
+          return result;
+        }
 
         @Override
-        public boolean hasNext() { return index < length; }
+        public boolean hasNext() { return next != null;     }
 
         @Override
-        public HeapRegion next() { return at(index++);    }
+        public HeapRegion next() { return positionToNext(); }
 
         @Override
-        public void remove()     { /* not supported */    }
+        public void remove()     { /* not supported */      }
 
-        HeapRegionIterator(long committedLength) {
+        HeapRegionIterator(long totalLength) {
             index = 0;
-            length = committedLength;
+            length = totalLength;
+            positionToNext();
         }
     }
 

agent/src/share/classes/sun/jvm/hotspot/gc_implementation/g1/HeapRegionSeq.java

@@ -43,7 +43,7 @@ public class HeapRegionSeq extends VMObject {
     // G1HeapRegionTable _regions
     static private long regionsFieldOffset;
     // uint _committed_length
-    static private CIntegerField committedLengthField;
+    static private CIntegerField numCommittedField;
 
     static {
         VM.registerVMInitializedObserver(new Observer() {
@@ -57,7 +57,7 @@ public class HeapRegionSeq extends VMObject {
         Type type = db.lookupType("HeapRegionSeq");
 
         regionsFieldOffset = type.getField("_regions").getOffset();
-        committedLengthField = type.getCIntegerField("_committed_length");
+        numCommittedField = type.getCIntegerField("_num_committed");
     }
 
     private G1HeapRegionTable regions() {
@@ -66,16 +66,20 @@ public class HeapRegionSeq extends VMObject {
                                                              regionsAddr);
     }
 
+    public long capacity() {
+        return length() * HeapRegion.grainBytes();
+    }
+
     public long length() {
         return regions().length();
     }
 
     public long committedLength() {
-        return committedLengthField.getValue(addr);
+        return numCommittedField.getValue(addr);
     }
 
     public Iterator<HeapRegion> heapRegionIterator() {
-        return regions().heapRegionIterator(committedLength());
+        return regions().heapRegionIterator(length());
     }
 
     public HeapRegionSeq(Address addr) {

src/share/vm/gc_implementation/g1/concurrentMark.cpp

@@ -728,14 +728,13 @@ ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, ReservedSpace heap_rs) :
   _completed_initialization = true;
 }
 
-void ConcurrentMark::update_g1_committed(bool force) {
+void ConcurrentMark::update_heap_boundaries(MemRegion bounds, bool force) {
   // If concurrent marking is not in progress, then we do not need to
   // update _heap_end.
   if (!concurrent_marking_in_progress() && !force) return;
 
-  MemRegion committed = _g1h->g1_committed();
-  assert(committed.start() == _heap_start, "start shouldn't change");
-  HeapWord* new_end = committed.end();
+  assert(bounds.start() == _heap_start, "start shouldn't change");
+  HeapWord* new_end = bounds.end();
   if (new_end > _heap_end) {
     // The heap has been expanded.
 
@@ -826,7 +825,7 @@ void ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurren
     assert(out_of_regions(),
            err_msg("only way to get here: _finger: "PTR_FORMAT", _heap_end: "PTR_FORMAT,
                    p2i(_finger), p2i(_heap_end)));
-    update_g1_committed(true);
+    update_heap_boundaries(_g1h->g1_committed(), true);
   }
 }
 
@@ -2194,7 +2193,7 @@ void ConcurrentMark::completeCleanup() {
   // Noone else should be accessing the _cleanup_list at this point,
   // so it's not necessary to take any locks
   while (!_cleanup_list.is_empty()) {
-    HeapRegion* hr = _cleanup_list.remove_head();
+    HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
     assert(hr != NULL, "Got NULL from a non-empty list");
     hr->par_clear();
     tmp_free_list.add_ordered(hr);

src/share/vm/gc_implementation/g1/concurrentMark.hpp

@@ -798,7 +798,7 @@ public:
   // that CM is notified of where the new end of the heap is. It
   // doesn't do anything if concurrent_marking_in_progress() is false,
   // unless the force parameter is true.
-  void update_g1_committed(bool force = false);
+  void update_heap_boundaries(MemRegion bounds, bool force = false);
 
   bool isMarked(oop p) const {
     assert(p != NULL && p->is_oop(), "expected an oop");

src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp

@@ -675,8 +675,7 @@ G1BlockOffsetArrayContigSpace::set_for_starts_humongous(HeapWord* new_top) {
   assert(new_top <= _end, "_end should have already been updated");
 
   // The first BOT entry should have offset 0.
-  zero_bottom_entry();
-  initialize_threshold();
+  reset_bot();
   alloc_block(_bottom, new_top);
  }
 

src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp

@@ -231,10 +231,6 @@ public:
 
   void set_bottom(HeapWord* new_bottom);
 
-  // Updates all the BlockOffsetArray's sharing this shared array to
-  // reflect the current "top"'s of their spaces.
-  void update_offset_arrays();
-
   // Return the appropriate index into "_offset_array" for "p".
   inline size_t index_for(const void* p) const;
 
@@ -480,6 +476,8 @@ class G1BlockOffsetArrayContigSpace: public G1BlockOffsetArray {
                       blk_start, blk_end);
   }
 
+  // Zero out the entry for _bottom (offset will be zero).
+  void zero_bottom_entry();
  public:
   G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array, MemRegion mr);
 
@@ -487,8 +485,10 @@ class G1BlockOffsetArrayContigSpace: public G1BlockOffsetArray {
   // bottom of the covered region.
   HeapWord* initialize_threshold();
 
-  // Zero out the entry for _bottom (offset will be zero).
-  void      zero_bottom_entry();
+  void reset_bot() {
+    zero_bottom_entry();
+    initialize_threshold();
+  }
 
   // Return the next threshold, the point at which the table should be
   // updated.

src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp

@@ -244,19 +244,9 @@ private:
 
   static size_t _humongous_object_threshold_in_words;
 
-  // Storage for the G1 heap.
-  VirtualSpace _g1_storage;
-  MemRegion    _g1_reserved;
-
-  // The part of _g1_storage that is currently committed.
-  MemRegion _g1_committed;
-
-  // The master free list. It will satisfy all new region allocations.
-  FreeRegionList _free_list;
-
   // The secondary free list which contains regions that have been
-  // freed up during the cleanup process. This will be appended to the
-  // master free list when appropriate.
+  // freed up during the cleanup process. This will be appended to
+  // the master free list when appropriate.
   FreeRegionList _secondary_free_list;
 
   // It keeps track of the old regions.
@@ -520,14 +510,6 @@ protected:
   // humongous object, set is_old to true. If not, to false.
   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 
-  // Attempt to satisfy a humongous allocation request of the given
-  // size by finding a contiguous set of free regions of num_regions
-  // length and remove them from the master free list. Return the
-  // index of the first region or G1_NULL_HRS_INDEX if the search
-  // was unsuccessful.
-  uint humongous_obj_allocate_find_first(uint num_regions,
-                                         size_t word_size);
-
   // Initialize a contiguous set of free regions of length num_regions
   // and starting at index first so that they appear as a single
   // humongous region.
@@ -1193,27 +1175,20 @@ public:
   virtual size_t unsafe_max_alloc();
 
   virtual bool is_maximal_no_gc() const {
-    return _g1_storage.uncommitted_size() == 0;
+    return _hrs.available() == 0;
   }
 
-  // The total number of regions in the heap.
-  uint n_regions() const { return _hrs.length(); }
+  // The current number of regions in the heap.
+  uint num_regions() const { return _hrs.length(); }
 
   // The max number of regions in the heap.
   uint max_regions() const { return _hrs.max_length(); }
 
   // The number of regions that are completely free.
-  uint free_regions() const { return _free_list.length(); }
+  uint num_free_regions() const { return _hrs.num_free_regions(); }
 
   // The number of regions that are not completely free.
-  uint used_regions() const { return n_regions() - free_regions(); }
-
-  // The number of regions available for "regular" expansion.
-  uint expansion_regions() const { return _expansion_regions; }
-
-  // Factory method for HeapRegion instances. It will return NULL if
-  // the allocation fails.
-  HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
+  uint num_used_regions() const { return num_regions() - num_free_regions(); }
 
   void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
   void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
@@ -1262,7 +1237,7 @@ public:
 
 #ifdef ASSERT
   bool is_on_master_free_list(HeapRegion* hr) {
-    return hr->containing_set() == &_free_list;
+    return _hrs.is_free(hr);
   }
 #endif // ASSERT
 
@@ -1274,7 +1249,7 @@ public:
   }
 
   void append_secondary_free_list() {
-    _free_list.add_ordered(&_secondary_free_list);
+    _hrs.insert_list_into_free_list(&_secondary_free_list);
   }
 
   void append_secondary_free_list_if_not_empty_with_lock() {
@@ -1380,19 +1355,19 @@ public:
   // Return "TRUE" iff the given object address is in the reserved
   // region of g1.
   bool is_in_g1_reserved(const void* p) const {
-    return _g1_reserved.contains(p);
+    return _hrs.reserved().contains(p);
   }
 
   // Returns a MemRegion that corresponds to the space that has been
   // reserved for the heap
-  MemRegion g1_reserved() {
-    return _g1_reserved;
+  MemRegion g1_reserved() const {
+    return _hrs.reserved();
   }
 
   // Returns a MemRegion that corresponds to the space that has been
   // committed in the heap
   MemRegion g1_committed() {
-    return _g1_committed;
+    return _hrs.committed();
   }
 
   virtual bool is_in_closed_subset(const void* p) const;
@@ -1432,6 +1407,8 @@ public:
   // within the heap.
   inline uint addr_to_region(HeapWord* addr) const;
 
+  inline HeapWord* bottom_addr_for_region(uint index) const;
+
   // Divide the heap region sequence into "chunks" of some size (the number
   // of regions divided by the number of parallel threads times some
   // overpartition factor, currently 4).  Assumes that this will be called
@@ -1445,10 +1422,10 @@ public:
   // setting the claim value of the second and subsequent regions of the
   // chunk.)  For now requires that "doHeapRegion" always returns "false",
   // i.e., that a closure never attempt to abort a traversal.
-  void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
-                                       uint worker,
-                                       uint no_of_par_workers,
-                                       jint claim_value);
+  void heap_region_par_iterate_chunked(HeapRegionClosure* cl,
+                                       uint worker_id,
+                                       uint num_workers,
+                                       jint claim_value) const;
 
   // It resets all the region claim values to the default.
   void reset_heap_region_claim_values();
@@ -1473,11 +1450,6 @@ public:
   // starting region for iterating over the current collection set.
   HeapRegion* start_cset_region_for_worker(uint worker_i);
 
-  // This is a convenience method that is used by the
-  // HeapRegionIterator classes to calculate the starting region for
-  // each worker so that they do not all start from the same region.
-  HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
-
   // Iterate over the regions (if any) in the current collection set.
   void collection_set_iterate(HeapRegionClosure* blk);
 

src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp

@@ -47,19 +47,21 @@ inline uint G1CollectedHeap::addr_to_region(HeapWord* addr) const {
   return (uint)(pointer_delta(addr, _reserved.start(), sizeof(uint8_t)) >> HeapRegion::LogOfHRGrainBytes);
 }
 
+inline HeapWord* G1CollectedHeap::bottom_addr_for_region(uint index) const {
+  return _hrs.reserved().start() + index * HeapRegion::GrainWords;
+}
+
 template <class T>
-inline HeapRegion*
-G1CollectedHeap::heap_region_containing_raw(const T addr) const {
+inline HeapRegion* G1CollectedHeap::heap_region_containing_raw(const T addr) const {
   assert(addr != NULL, "invariant");
-  assert(_g1_reserved.contains((const void*) addr),
+  assert(is_in_g1_reserved((const void*) addr),
       err_msg("Address "PTR_FORMAT" is outside of the heap ranging from ["PTR_FORMAT" to "PTR_FORMAT")",
-          p2i((void*)addr), p2i(_g1_reserved.start()), p2i(_g1_reserved.end())));
+          p2i((void*)addr), p2i(g1_reserved().start()), p2i(g1_reserved().end())));
   return _hrs.addr_to_region((HeapWord*) addr);
 }
 
 template <class T>
-inline HeapRegion*
-G1CollectedHeap::heap_region_containing(const T addr) const {
+inline HeapRegion* G1CollectedHeap::heap_region_containing(const T addr) const {
   HeapRegion* hr = heap_region_containing_raw(addr);
   if (hr->continuesHumongous()) {
     return hr->humongous_start_region();
@@ -89,10 +91,9 @@ inline bool G1CollectedHeap::obj_in_cs(oop obj) {
   return r != NULL && r->in_collection_set();
 }
 
-inline HeapWord*
-G1CollectedHeap::attempt_allocation(size_t word_size,
-                                    unsigned int* gc_count_before_ret,
-                                    int* gclocker_retry_count_ret) {
+inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
+                                                     unsigned int* gc_count_before_ret,
+                                                     int* gclocker_retry_count_ret) {
   assert_heap_not_locked_and_not_at_safepoint();
   assert(!isHumongous(word_size), "attempt_allocation() should not "
          "be called for humongous allocation requests");
@@ -252,8 +253,7 @@ G1CollectedHeap::set_evacuation_failure_alot_for_current_gc() {
   }
 }
 
-inline bool
-G1CollectedHeap::evacuation_should_fail() {
+inline bool G1CollectedHeap::evacuation_should_fail() {
   if (!G1EvacuationFailureALot || !_evacuation_failure_alot_for_current_gc) {
     return false;
   }

src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp

@@ -455,7 +455,7 @@ void G1CollectorPolicy::init() {
   } else {
     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
   }
-  _free_regions_at_end_of_collection = _g1->free_regions();
+  _free_regions_at_end_of_collection = _g1->num_free_regions();
   update_young_list_target_length();
 
   // We may immediately start allocating regions and placing them on the
@@ -828,7 +828,7 @@ void G1CollectorPolicy::record_full_collection_end() {
 
   record_survivor_regions(0, NULL, NULL);
 
-  _free_regions_at_end_of_collection = _g1->free_regions();
+  _free_regions_at_end_of_collection = _g1->num_free_regions();
   // Reset survivors SurvRateGroup.
   _survivor_surv_rate_group->reset();
   update_young_list_target_length();
@@ -1180,7 +1180,7 @@ void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, Evacua
 
   _in_marking_window = new_in_marking_window;
   _in_marking_window_im = new_in_marking_window_im;
-  _free_regions_at_end_of_collection = _g1->free_regions();
+  _free_regions_at_end_of_collection = _g1->num_free_regions();
   update_young_list_target_length();
 
   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
@@ -1202,7 +1202,7 @@ void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
   _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
   _heap_capacity_bytes_before_gc = _g1->capacity();
   _heap_used_bytes_before_gc = _g1->used();
-  _cur_collection_pause_used_regions_at_start = _g1->used_regions();
+  _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
 
   _eden_capacity_bytes_before_gc =
          (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
@@ -1617,7 +1617,7 @@ void
 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
   _collectionSetChooser->clear();
 
-  uint region_num = _g1->n_regions();
+  uint region_num = _g1->num_regions();
   if (G1CollectedHeap::use_parallel_gc_threads()) {
     const uint OverpartitionFactor = 4;
     uint WorkUnit;
@@ -1638,7 +1638,7 @@ G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
         MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
              MinWorkUnit);
     }
-    _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
+    _collectionSetChooser->prepare_for_par_region_addition(_g1->num_regions(),
                                                            WorkUnit);
     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
                                             (int) WorkUnit);
@@ -1935,7 +1935,7 @@ uint G1CollectorPolicy::calc_max_old_cset_length() {
   // of them are available.
 
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
-  const size_t region_num = g1h->n_regions();
+  const size_t region_num = g1h->num_regions();
   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
   size_t result = region_num * perc / 100;
   // emulate ceiling

src/share/vm/gc_implementation/g1/heapRegion.cpp

@@ -344,11 +344,6 @@ HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
   return low;
 }
 
-#ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
-#pragma warning( disable:4355 ) // 'this' : used in base member initializer list
-#endif // _MSC_VER
-
-
 HeapRegion::HeapRegion(uint hrs_index,
                        G1BlockOffsetSharedArray* sharedOffsetArray,
                        MemRegion mr) :
@@ -360,7 +355,7 @@ HeapRegion::HeapRegion(uint hrs_index,
     _claimed(InitialClaimValue), _evacuation_failed(false),
     _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
     _young_type(NotYoung), _next_young_region(NULL),
-    _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL), _pending_removal(false),
+    _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
 #ifdef ASSERT
     _containing_set(NULL),
 #endif // ASSERT
@@ -369,14 +364,20 @@ HeapRegion::HeapRegion(uint hrs_index,
     _predicted_bytes_to_copy(0)
 {
   _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
+  assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
+
+  initialize(mr);
+}
+
+void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
+  assert(_rem_set->is_empty(), "Remembered set must be empty");
+
+  G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
+
   _orig_end = mr.end();
-  // Note that initialize() will set the start of the unmarked area of the
-  // region.
   hr_clear(false /*par*/, false /*clear_space*/);
   set_top(bottom());
   record_top_and_timestamp();
-
-  assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
 }
 
 CompactibleSpace* HeapRegion::next_compaction_space() const {
@@ -907,7 +908,7 @@ void HeapRegion::verify(VerifyOption vo,
     }
 
     // If it returns false, verify_for_object() will output the
-    // appropriate messasge.
+    // appropriate message.
     if (do_bot_verify &&
         !g1->is_obj_dead(obj, this) &&
         !_offsets.verify_for_object(p, obj_size)) {
@@ -1038,8 +1039,7 @@ void G1OffsetTableContigSpace::clear(bool mangle_space) {
   set_top(bottom());
   set_saved_mark_word(bottom());
   CompactibleSpace::clear(mangle_space);
-  _offsets.zero_bottom_entry();
-  _offsets.initialize_threshold();
+  reset_bot();
 }
 
 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
@@ -1129,9 +1129,11 @@ G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
   _gc_time_stamp(0)
 {
   _offsets.set_space(this);
-  // false ==> we'll do the clearing if there's clearing to be done.
-  CompactibleSpace::initialize(mr, false, SpaceDecorator::Mangle);
+}
+
+void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
+  CompactibleSpace::initialize(mr, clear_space, mangle_space);
   _top = bottom();
-  _offsets.zero_bottom_entry();
-  _offsets.initialize_threshold();
+  reset_bot();
 }
+

src/share/vm/gc_implementation/g1/heapRegion.hpp

@@ -62,7 +62,7 @@ class nmethod;
                 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
 
 // sentinel value for hrs_index
-#define G1_NULL_HRS_INDEX ((uint) -1)
+#define G1_NO_HRS_INDEX ((uint) -1)
 
 // A dirty card to oop closure for heap regions. It
 // knows how to get the G1 heap and how to use the bitmap
@@ -146,6 +146,9 @@ class G1OffsetTableContigSpace: public CompactibleSpace {
   HeapWord* top() const { return _top; }
 
  protected:
+  // Reset the G1OffsetTableContigSpace.
+  virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
+
   HeapWord** top_addr() { return &_top; }
   // Allocation helpers (return NULL if full).
   inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
@@ -200,8 +203,7 @@ class G1OffsetTableContigSpace: public CompactibleSpace {
   virtual void print() const;
 
   void reset_bot() {
-    _offsets.zero_bottom_entry();
-    _offsets.initialize_threshold();
+    _offsets.reset_bot();
   }
 
   void update_bot_for_object(HeapWord* start, size_t word_size) {
@@ -264,7 +266,6 @@ class HeapRegion: public G1OffsetTableContigSpace {
 #ifdef ASSERT
   HeapRegionSetBase* _containing_set;
 #endif // ASSERT
-  bool _pending_removal;
 
   // For parallel heapRegion traversal.
   jint _claimed;
@@ -333,6 +334,12 @@ class HeapRegion: public G1OffsetTableContigSpace {
              G1BlockOffsetSharedArray* sharedOffsetArray,
              MemRegion mr);
 
+  // Initializing the HeapRegion not only resets the data structure, but also
+  // resets the BOT for that heap region.
+  // The default values for clear_space means that we will do the clearing if
+  // there's clearing to be done ourselves. We also always mangle the space.
+  virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
+
   static int    LogOfHRGrainBytes;
   static int    LogOfHRGrainWords;
 
@@ -553,26 +560,6 @@ class HeapRegion: public G1OffsetTableContigSpace {
   // to provide a dummy version of it.
 #endif // ASSERT
 
-  // If we want to remove regions from a list in bulk we can simply tag
-  // them with the pending_removal tag and call the
-  // remove_all_pending() method on the list.
-
-  bool pending_removal() { return _pending_removal; }
-
-  void set_pending_removal(bool pending_removal) {
-    if (pending_removal) {
-      assert(!_pending_removal && containing_set() != NULL,
-             "can only set pending removal to true if it's false and "
-             "the region belongs to a region set");
-    } else {
-      assert( _pending_removal && containing_set() == NULL,
-              "can only set pending removal to false if it's true and "
-              "the region does not belong to a region set");
-    }
-
-    _pending_removal = pending_removal;
-  }
-
   HeapRegion* get_next_young_region() { return _next_young_region; }
   void set_next_young_region(HeapRegion* hr) {
     _next_young_region = hr;

src/share/vm/gc_implementation/g1/heapRegionSeq.hpp

@@ -26,6 +26,7 @@
 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
 
 #include "gc_implementation/g1/g1BiasedArray.hpp"
+#include "gc_implementation/g1/heapRegionSet.hpp"
 
 class HeapRegion;
 class HeapRegionClosure;
@@ -33,7 +34,7 @@ class FreeRegionList;
 
 class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> {
  protected:
-   virtual HeapRegion* default_value() const { return NULL; }
+  virtual HeapRegion* default_value() const { return NULL; }
 };
 
 // This class keeps track of the region metadata (i.e., HeapRegion
@@ -64,89 +65,151 @@ class HeapRegionSeq: public CHeapObj<mtGC> {
 
   G1HeapRegionTable _regions;
 
-  // The number of regions committed in the heap.
-  uint _committed_length;
+  ReservedSpace _reserved;
+  VirtualSpace _storage;
+
+  FreeRegionList _free_list;
+
+   // The number of regions committed in the heap.
+  uint _num_committed;
+
+  // Internal only. The highest heap region +1 we allocated a HeapRegion instance for.
+  uint _allocated_heapregions_length;
+
+   HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); }
+  HeapWord* heap_top() const { return heap_bottom() + _num_committed * HeapRegion::GrainWords; }
+   HeapWord* heap_end() const {return _regions.end_address_mapped(); }
+
+  void make_regions_available(uint index, uint num_regions = 1);
+
+  // Pass down commit calls to the VirtualSpace.
+  void commit_regions(uint index, size_t num_regions = 1);
+  void uncommit_regions(uint index, size_t num_regions = 1);
+
+  // Notify other data structures about change in the heap layout.
+  void update_committed_space(HeapWord* old_end, HeapWord* new_end);
+  // Calculate the starting region for each worker during parallel iteration so
+  // that they do not all start from the same region.
+  uint start_region_for_worker(uint worker_i, uint num_workers, uint num_regions) const;
+
+  // Finds the next sequence of unavailable regions starting from start_idx. Returns the
+  // length of the sequence found. If this result is zero, no such sequence could be found,
+  // otherwise res_idx indicates the start index of these regions.
+  uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const;
+  // Finds the next sequence of empty regions starting from start_idx, going backwards in
+  // the heap. Returns the length of the sequence found. If this value is zero, no
+  // sequence could be found, otherwise res_idx contains the start index of this range.
+  uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const;
+#ifdef ASSERT
+public:
+  bool is_free(HeapRegion* hr) const;
+#endif
+  // Returns whether the given region is available for allocation.
+  bool is_available(uint region) const;
+
+  // Allocate a new HeapRegion for the given index.
+  HeapRegion* new_heap_region(uint hrs_index);
+  public:
+   // Empty constructor, we'll initialize it with the initialize() method.
+  HeapRegionSeq() : _regions(), _reserved(), _storage(), _num_committed(0),
+          _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
+          _allocated_heapregions_length(0)
+  { }
+
+  void initialize(ReservedSpace reserved);
+
+  // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired
+  // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit
+  // the heap from the lowest address, this region (and its associated data
+  // structures) are available and we do not need to check further.
+  HeapRegion* get_dummy_region() { return new_heap_region(0); }
 
-  // A hint for which index to start searching from for humongous
-  // allocations.
-  uint _next_search_index;
+  // Return the HeapRegion at the given index. Assume that the index
+  // is valid.
+  inline HeapRegion* at(uint index) const;
 
-  // The number of regions for which we have allocated HeapRegions for.
-  uint _allocated_length;
+  // If addr is within the committed space return its corresponding
+  // HeapRegion, otherwise return NULL.
+  inline HeapRegion* addr_to_region(HeapWord* addr) const;
 
-  // Find a contiguous set of empty regions of length num, starting
-  // from the given index.
-  uint find_contiguous_from(uint from, uint num);
+  // Insert the given region into the free region list.
+  inline void insert_into_free_list(HeapRegion* hr);
 
-  void increment_allocated_length() {
-    assert(_allocated_length < max_length(), "pre-condition");
-    _allocated_length++;
+  // Insert the given region list into the global free region list.
+  void insert_list_into_free_list(FreeRegionList* list) {
+    _free_list.add_ordered(list);
   }
 
-  void increment_length() {
-    assert(length() < max_length(), "pre-condition");
-    _committed_length++;
-  }
+  HeapRegion* allocate_free_region(bool is_old) {
+    HeapRegion* hr = _free_list.remove_region(is_old);
 
-  void decrement_length() {
-    assert(length() > 0, "pre-condition");
-    _committed_length--;
+    if (hr != NULL) {
+      assert(hr->next() == NULL, "Single region should not have next");
+      assert(is_available(hr->hrs_index()), "Must be committed");
+    }
+    return hr;
   }
 
-  HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); }
-  HeapWord* heap_end() const {return _regions.end_address_mapped(); }
+  inline void allocate_free_regions_starting_at(uint first, uint num_regions);
 
- public:
-  // Empty contructor, we'll initialize it with the initialize() method.
-  HeapRegionSeq() : _regions(), _committed_length(0), _next_search_index(0), _allocated_length(0) { }
+  // Remove all regions from the free list.
+  void remove_all_free_regions() {
+    _free_list.remove_all();
+  }
 
-  void initialize(HeapWord* bottom, HeapWord* end);
+  // Return the number of committed free regions in the heap.
+  uint num_free_regions() const {
+    return _free_list.length();
+  }
 
-  // Return the HeapRegion at the given index. Assume that the index
-  // is valid.
-  inline HeapRegion* at(uint index) const;
+  size_t total_capacity_bytes() const {
+    return num_free_regions() * HeapRegion::GrainBytes;
+  }
 
-  // If addr is within the committed space return its corresponding
-  // HeapRegion, otherwise return NULL.
-  inline HeapRegion* addr_to_region(HeapWord* addr) const;
+  // Return the number of available (uncommitted) regions.
+  uint available() const { return max_length() - length(); }
 
   // Return the number of regions that have been committed in the heap.
-  uint length() const { return _committed_length; }
+  uint length() const { return _num_committed; }
 
   // Return the maximum number of regions in the heap.
   uint max_length() const { return (uint)_regions.length(); }
 
-  // Expand the sequence to reflect that the heap has grown from
-  // old_end to new_end. Either create new HeapRegions, or re-use
-  // existing ones, and return them in the given list. Returns the
-  // memory region that covers the newly-created regions. If a
-  // HeapRegion allocation fails, the result memory region might be
-  // smaller than the desired one.
-  MemRegion expand_by(HeapWord* old_end, HeapWord* new_end,
-                      FreeRegionList* list);
+  MemRegion committed() const { return MemRegion(heap_bottom(), heap_top()); }
+
+  MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); }
+
+  // Expand the sequence to reflect that the heap has grown. Either create new
+  // HeapRegions, or re-use existing ones. Returns the number of regions the
+  // sequence was expanded by. If a HeapRegion allocation fails, the resulting
+  // number of regions might be smaller than what's desired.
+  uint expand_by(uint num_regions);
 
-  // Return the number of contiguous regions at the end of the sequence
-  // that are available for allocation.
-  uint free_suffix();
+  // Makes sure that the regions from start to start+num_regions-1 are available
+  // for allocation. Returns the number of regions that were committed to achieve
+  // this.
+  uint expand_at(uint start, uint num_regions);
 
-  // Find a contiguous set of empty regions of length num and return
-  // the index of the first region or G1_NULL_HRS_INDEX if the
-  // search was unsuccessful.
-  uint find_contiguous(uint num);
+  // Find a contiguous set of empty or uncommitted regions of length num and return
+  // the index of the first region or G1_NO_HRS_INDEX if the search was unsuccessful.
+  // If only_empty is true, only empty regions are considered.
+  // Searches from bottom to top of the heap, doing a first-fit.
+  uint find_contiguous(size_t num, bool only_empty);
+
+  HeapRegion* next_region_in_heap(const HeapRegion* r) const;
 
   // Apply blk->doHeapRegion() on all committed regions in address order,
   // terminating the iteration early if doHeapRegion() returns true.
   void iterate(HeapRegionClosure* blk) const;
 
-  // As above, but start the iteration from hr and loop around. If hr
-  // is NULL, we start from the first region in the heap.
-  void iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const;
+  void par_iterate(HeapRegionClosure* blk, uint worker_id, uint no_of_par_workers, jint claim_value) const;
 
-  // Tag as uncommitted as many regions that are completely free as
-  // possible, up to num_regions_to_remove, from the suffix of the committed
-  // sequence. Return the actual number of removed regions.
+  // Uncommit up to num_regions_to_remove regions that are completely free.
+  // Return the actual number of uncommitted regions.
   uint shrink_by(uint num_regions_to_remove);
 
+  void verify();
+
   // Do some sanity checking.
   void verify_optional() PRODUCT_RETURN;
 };

src/share/vm/gc_implementation/g1/heapRegionSeq.inline.hpp

@@ -40,11 +40,19 @@ inline HeapRegion* HeapRegionSeq::addr_to_region(HeapWord* addr) const {
 }
 
 inline HeapRegion* HeapRegionSeq::at(uint index) const {
-  assert(index < length(), "pre-condition");
+  assert(is_available(index), "pre-condition");
   HeapRegion* hr = _regions.get_by_index(index);
   assert(hr != NULL, "sanity");
   assert(hr->hrs_index() == index, "sanity");
   return hr;
 }
 
+inline void HeapRegionSeq::insert_into_free_list(HeapRegion* hr) {
+  _free_list.add_ordered(hr);
+}
+
+inline void HeapRegionSeq::allocate_free_regions_starting_at(uint first, uint num_regions) {
+  _free_list.remove_starting_at(at(first), num_regions);
+}
+
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_INLINE_HPP

src/share/vm/gc_implementation/g1/heapRegionSet.cpp

@@ -23,6 +23,7 @@
  */
 
 #include "precompiled.hpp"
+#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/heapRegionRemSet.hpp"
 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
 
@@ -67,7 +68,7 @@ void HeapRegionSetBase::verify_start() {
   // Do the basic verification first before we do the checks over the regions.
   HeapRegionSetBase::verify();
 
-  _verify_in_progress        = true;
+  _verify_in_progress = true;
 }
 
 void HeapRegionSetBase::verify_end() {
@@ -103,62 +104,7 @@ void FreeRegionList::set_unrealistically_long_length(uint len) {
 }
 
 void FreeRegionList::fill_in_ext_msg_extra(hrs_ext_msg* msg) {
-  msg->append(" hd: "PTR_FORMAT" tl: "PTR_FORMAT, head(), tail());
-}
-
-void FreeRegionList::add_as_head_or_tail(FreeRegionList* from_list, bool as_head) {
-  check_mt_safety();
-  from_list->check_mt_safety();
-
-  verify_optional();
-  from_list->verify_optional();
-
-  if (from_list->is_empty()) {
-    return;
-  }
-
-#ifdef ASSERT
-  FreeRegionListIterator iter(from_list);
-  while (iter.more_available()) {
-    HeapRegion* hr = iter.get_next();
-    // In set_containing_set() we check that we either set the value
-    // from NULL to non-NULL or vice versa to catch bugs. So, we have
-    // to NULL it first before setting it to the value.
-    hr->set_containing_set(NULL);
-    hr->set_containing_set(this);
-  }
-#endif // ASSERT
-
-  if (_head == NULL) {
-    assert(length() == 0 && _tail == NULL, hrs_ext_msg(this, "invariant"));
-    _head = from_list->_head;
-    _tail = from_list->_tail;
-  } else {
-    assert(length() > 0 && _tail != NULL, hrs_ext_msg(this, "invariant"));
-    if (as_head) {
-      from_list->_tail->set_next(_head);
-      _head->set_prev(from_list->_tail);
-      _head = from_list->_head;
-    } else {
-      _tail->set_next(from_list->_head);
-      from_list->_head->set_prev(_tail);
-      _tail = from_list->_tail;
-    }
-  }
-
-  _count.increment(from_list->length(), from_list->total_capacity_bytes());
-  from_list->clear();
-
-  verify_optional();
-  from_list->verify_optional();
-}
-
-void FreeRegionList::add_as_head(FreeRegionList* from_list) {
-  add_as_head_or_tail(from_list, true /* as_head */);
-}
-
-void FreeRegionList::add_as_tail(FreeRegionList* from_list) {
-  add_as_head_or_tail(from_list, false /* as_head */);
+  msg->append(" hd: "PTR_FORMAT" tl: "PTR_FORMAT, _head, _tail);
 }
 
 void FreeRegionList::remove_all() {
@@ -191,11 +137,6 @@ void FreeRegionList::add_ordered(FreeRegionList* from_list) {
     return;
   }
 
-  if (is_empty()) {
-    add_as_head(from_list);
-    return;
-  }
-
   #ifdef ASSERT
   FreeRegionListIterator iter(from_list);
   while (iter.more_available()) {
@@ -208,37 +149,43 @@ void FreeRegionList::add_ordered(FreeRegionList* from_list) {
   }
   #endif // ASSERT
 
-  HeapRegion* curr_to = _head;
-  HeapRegion* curr_from = from_list->_head;
-
-  while (curr_from != NULL) {
-    while (curr_to != NULL && curr_to->hrs_index() < curr_from->hrs_index()) {
-      curr_to = curr_to->next();
-    }
+  if (is_empty()) {
+    assert(length() == 0 && _tail == NULL, hrs_ext_msg(this, "invariant"));
+    _head = from_list->_head;
+    _tail = from_list->_tail;
+  } else {
+    HeapRegion* curr_to = _head;
+    HeapRegion* curr_from = from_list->_head;
 
-    if (curr_to == NULL) {
-      // The rest of the from list should be added as tail
-      _tail->set_next(curr_from);
-      curr_from->set_prev(_tail);
-      curr_from = NULL;
-    } else {
-      HeapRegion* next_from = curr_from->next();
+    while (curr_from != NULL) {
+      while (curr_to != NULL && curr_to->hrs_index() < curr_from->hrs_index()) {
+        curr_to = curr_to->next();
+      }
 
-      curr_from->set_next(curr_to);
-      curr_from->set_prev(curr_to->prev());
-      if (curr_to->prev() == NULL) {
-        _head = curr_from;
+      if (curr_to == NULL) {
+        // The rest of the from list should be added as tail
+        _tail->set_next(curr_from);
+        curr_from->set_prev(_tail);
+        curr_from = NULL;
       } else {
-        curr_to->prev()->set_next(curr_from);
+        HeapRegion* next_from = curr_from->next();
+
+        curr_from->set_next(curr_to);
+        curr_from->set_prev(curr_to->prev());
+        if (curr_to->prev() == NULL) {
+          _head = curr_from;
+        } else {
+          curr_to->prev()->set_next(curr_from);
+        }
+        curr_to->set_prev(curr_from);
+
+        curr_from = next_from;
       }
-      curr_to->set_prev(curr_from);
-
-      curr_from = next_from;
     }
-  }
 
-  if (_tail->hrs_index() < from_list->_tail->hrs_index()) {
-    _tail = from_list->_tail;
+    if (_tail->hrs_index() < from_list->_tail->hrs_index()) {
+      _tail = from_list->_tail;
+    }
   }
 
   _count.increment(from_list->length(), from_list->total_capacity_bytes());
@@ -248,68 +195,59 @@ void FreeRegionList::add_ordered(FreeRegionList* from_list) {
   from_list->verify_optional();
 }
 
-void FreeRegionList::remove_all_pending(uint target_count) {
+void FreeRegionList::remove_starting_at(HeapRegion* first, uint num_regions) {
   check_mt_safety();
-  assert(target_count > 1, hrs_ext_msg(this, "pre-condition"));
+  assert(num_regions >= 1, hrs_ext_msg(this, "pre-condition"));
   assert(!is_empty(), hrs_ext_msg(this, "pre-condition"));
 
   verify_optional();
   DEBUG_ONLY(uint old_length = length();)
 
-  HeapRegion* curr = _head;
+  HeapRegion* curr = first;
   uint count = 0;
-  while (curr != NULL) {
+  while (count < num_regions) {
     verify_region(curr);
     HeapRegion* next = curr->next();
     HeapRegion* prev = curr->prev();
 
-    if (curr->pending_removal()) {
-      assert(count < target_count,
-             hrs_err_msg("[%s] should not come across more regions "
-                         "pending for removal than target_count: %u",
-                         name(), target_count));
-
-      if (prev == NULL) {
-        assert(_head == curr, hrs_ext_msg(this, "invariant"));
-        _head = next;
-      } else {
-        assert(_head != curr, hrs_ext_msg(this, "invariant"));
-        prev->set_next(next);
-      }
-      if (next == NULL) {
-        assert(_tail == curr, hrs_ext_msg(this, "invariant"));
-        _tail = prev;
-      } else {
-        assert(_tail != curr, hrs_ext_msg(this, "invariant"));
-        next->set_prev(prev);
-      }
-      if (_last = curr) {
-        _last = NULL;
-      }
+    assert(count < num_regions,
+           hrs_err_msg("[%s] should not come across more regions "
+                       "pending for removal than num_regions: %u",
+                       name(), num_regions));
 
-      curr->set_next(NULL);
-      curr->set_prev(NULL);
-      remove(curr);
-      curr->set_pending_removal(false);
+    if (prev == NULL) {
+      assert(_head == curr, hrs_ext_msg(this, "invariant"));
+      _head = next;
+    } else {
+      assert(_head != curr, hrs_ext_msg(this, "invariant"));
+      prev->set_next(next);
+    }
+    if (next == NULL) {
+      assert(_tail == curr, hrs_ext_msg(this, "invariant"));
+      _tail = prev;
+    } else {
+      assert(_tail != curr, hrs_ext_msg(this, "invariant"));
+      next->set_prev(prev);
+    }
+    if (_last = curr) {
+      _last = NULL;
+    }
 
-      count += 1;
+    curr->set_next(NULL);
+    curr->set_prev(NULL);
+    remove(curr);
 
-      // If we have come across the target number of regions we can
-      // just bail out. However, for debugging purposes, we can just
-      // carry on iterating to make sure there are not more regions
-      // tagged with pending removal.
-      DEBUG_ONLY(if (count == target_count) break;)
-    }
+    count++;
     curr = next;
   }
 
-  assert(count == target_count,
-         hrs_err_msg("[%s] count: %u should be == target_count: %u",
-                     name(), count, target_count));
-  assert(length() + target_count == old_length,
+  assert(count == num_regions,
+         hrs_err_msg("[%s] count: %u should be == num_regions: %u",
+                     name(), count, num_regions));
+  assert(length() + num_regions == old_length,
          hrs_err_msg("[%s] new length should be consistent "
-                     "new length: %u old length: %u target_count: %u",
-                     name(), length(), old_length, target_count));
+                     "new length: %u old length: %u num_regions: %u",
+                     name(), length(), old_length, num_regions));
 
   verify_optional();
 }
@@ -348,10 +286,12 @@ void FreeRegionList::print_on(outputStream* out, bool print_contents) {
       hr->print_on(out);
     }
   }
+
+  out->cr();
 }
 
 void FreeRegionList::verify_list() {
-  HeapRegion* curr = head();
+  HeapRegion* curr = _head;
   HeapRegion* prev1 = NULL;
   HeapRegion* prev0 = NULL;
   uint count = 0;
@@ -379,7 +319,7 @@ void FreeRegionList::verify_list() {
     curr = curr->next();
   }
 
-  guarantee(tail() == prev0, err_msg("Expected %s to end with %u but it ended with %u.", name(), tail()->hrs_index(), prev0->hrs_index()));
+  guarantee(_tail == prev0, err_msg("Expected %s to end with %u but it ended with %u.", name(), _tail->hrs_index(), prev0->hrs_index()));
   guarantee(_tail == NULL || _tail->next() == NULL, "_tail should not have a next");
   guarantee(length() == count, err_msg("%s count mismatch. Expected %u, actual %u.", name(), length(), count));
   guarantee(total_capacity_bytes() == capacity, err_msg("%s capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,

src/share/vm/gc_implementation/g1/heapRegionSet.hpp

@@ -162,7 +162,7 @@ public:
 // diagnosing failures.
 class hrs_ext_msg : public hrs_err_msg {
 public:
-  hrs_ext_msg(HeapRegionSetBase* set, const char* message) : hrs_err_msg("%s","") {
+  hrs_ext_msg(HeapRegionSetBase* set, const char* message) : hrs_err_msg("%s", "") {
     set->fill_in_ext_msg(this, message);
   }
 };
@@ -192,13 +192,9 @@ public:
 };
 
 // A set that links all the regions added to it in a doubly-linked
-// list. We should try to avoid doing operations that iterate over
+// sorted list. We should try to avoid doing operations that iterate over
 // such lists in performance critical paths. Typically we should
-// add / remove one region at a time or concatenate two lists. There are
-// two ways to treat your lists, ordered and un-ordered. All un-ordered
-// operations are done in constant time. To keep a list ordered only use
-// add_ordered() to add elements to the list. If a list is not ordered
-// from start, there is no way to sort it later.
+// add / remove one region at a time or concatenate two lists.
 
 class FreeRegionListIterator;
 
@@ -210,13 +206,13 @@ private:
   HeapRegion* _tail;
 
   // _last is used to keep track of where we added an element the last
-  // time in ordered lists. It helps to improve performance when adding
-  // several ordered items in a row.
+  // time. It helps to improve performance when adding several ordered items in a row.
   HeapRegion* _last;
 
   static uint _unrealistically_long_length;
 
-  void add_as_head_or_tail(FreeRegionList* from_list, bool as_head);
+  inline HeapRegion* remove_from_head_impl();
+  inline HeapRegion* remove_from_tail_impl();
 
 protected:
   virtual void fill_in_ext_msg_extra(hrs_ext_msg* msg);
@@ -232,8 +228,11 @@ public:
 
   void verify_list();
 
-  HeapRegion* head() { return _head; }
-  HeapRegion* tail() { return _tail; }
+#ifdef ASSERT
+  bool contains(HeapRegion* hr) const {
+    return hr->containing_set() == this;
+  }
+#endif
 
   static void set_unrealistically_long_length(uint len);
 
@@ -242,55 +241,20 @@ public:
   // is determined by hrs_index.
   inline void add_ordered(HeapRegion* hr);
 
-  // It adds hr to the list as the new head. The region should not be
-  // a member of another set.
-  inline void add_as_head(HeapRegion* hr);
-
-  // It adds hr to the list as the new tail. The region should not be
-  // a member of another set.
-  inline void add_as_tail(HeapRegion* hr);
-
-  // It removes and returns the head of the list. It assumes that the
-  // list is not empty so it will return a non-NULL value.
-  inline HeapRegion* remove_head();
-
-  // Convenience method.
-  inline HeapRegion* remove_head_or_null();
-
-  // Removes and returns the last element (_tail) of the list. It assumes
-  // that the list isn't empty so that it can return a non-NULL value.
-  inline HeapRegion* remove_tail();
-
-  // Convenience method
-  inline HeapRegion* remove_tail_or_null();
-
   // Removes from head or tail based on the given argument.
-  inline HeapRegion* remove_region(bool from_head);
+  HeapRegion* remove_region(bool from_head);
 
   // Merge two ordered lists. The result is also ordered. The order is
   // determined by hrs_index.
   void add_ordered(FreeRegionList* from_list);
 
-  // It moves the regions from from_list to this list and empties
-  // from_list. The new regions will appear in the same order as they
-  // were in from_list and be linked in the beginning of this list.
-  void add_as_head(FreeRegionList* from_list);
-
-  // It moves the regions from from_list to this list and empties
-  // from_list. The new regions will appear in the same order as they
-  // were in from_list and be linked in the end of this list.
-  void add_as_tail(FreeRegionList* from_list);
-
   // It empties the list by removing all regions from it.
   void remove_all();
 
-  // It removes all regions in the list that are pending for removal
-  // (i.e., they have been tagged with "pending_removal"). The list
-  // must not be empty, target_count should reflect the exact number
-  // of regions that are pending for removal in the list, and
-  // target_count should be > 1 (currently, we never need to remove a
-  // single region using this).
-  void remove_all_pending(uint target_count);
+  // Remove all (contiguous) regions from first to first + num_regions -1 from
+  // this list.
+  // Num_regions must be > 1.
+  void remove_starting_at(HeapRegion* first, uint num_regions);
 
   virtual void verify();
 
@@ -298,7 +262,7 @@ public:
 };
 
 // Iterator class that provides a convenient way to iterate over the
-// regions of a HeapRegionLinkedList instance.
+// regions of a FreeRegionList.
 
 class FreeRegionListIterator : public StackObj {
 private:
@@ -324,7 +288,7 @@ public:
   }
 
   FreeRegionListIterator(FreeRegionList* list) : _curr(NULL), _list(list) {
-    _curr = list->head();
+    _curr = list->_head;
   }
 };
 

src/share/vm/gc_implementation/g1/heapRegionSet.inline.hpp

@@ -30,7 +30,8 @@
 inline void HeapRegionSetBase::add(HeapRegion* hr) {
   check_mt_safety();
   assert(hr->containing_set() == NULL, hrs_ext_msg(this, "should not already have a containing set %u"));
-  assert(hr->next() == NULL && hr->prev() == NULL, hrs_ext_msg(this, "should not already be linked"));
+  assert(hr->next() == NULL, hrs_ext_msg(this, "should not already be linked"));
+  assert(hr->prev() == NULL, hrs_ext_msg(this, "should not already be linked"));
 
   _count.increment(1u, hr->capacity());
   hr->set_containing_set(this);
@@ -40,7 +41,8 @@ inline void HeapRegionSetBase::add(HeapRegion* hr) {
 inline void HeapRegionSetBase::remove(HeapRegion* hr) {
   check_mt_safety();
   verify_region(hr);
-  assert(hr->next() == NULL && hr->prev() == NULL, hrs_ext_msg(this, "should already be unlinked"));
+  assert(hr->next() == NULL, hrs_ext_msg(this, "should already be unlinked"));
+  assert(hr->prev() == NULL, hrs_ext_msg(this, "should already be unlinked"));
 
   hr->set_containing_set(NULL);
   assert(_count.length() > 0, hrs_ext_msg(this, "pre-condition"));
@@ -48,8 +50,7 @@ inline void HeapRegionSetBase::remove(HeapRegion* hr) {
 }
 
 inline void FreeRegionList::add_ordered(HeapRegion* hr) {
-  check_mt_safety();
-  assert((length() == 0 && _head == NULL && _tail == NULL) ||
+  assert((length() == 0 && _head == NULL && _tail == NULL && _last == NULL) ||
          (length() >  0 && _head != NULL && _tail != NULL),
          hrs_ext_msg(this, "invariant"));
   // add() will verify the region and check mt safety.
@@ -95,89 +96,48 @@ inline void FreeRegionList::add_ordered(HeapRegion* hr) {
   _last = hr;
 }
 
-inline void FreeRegionList::add_as_head(HeapRegion* hr) {
-  assert((length() == 0 && _head == NULL && _tail == NULL) ||
-         (length() >  0 && _head != NULL && _tail != NULL),
-         hrs_ext_msg(this, "invariant"));
-  // add() will verify the region and check mt safety.
-  add(hr);
-
-  // Now link the region.
-  if (_head != NULL) {
-    hr->set_next(_head);
-    _head->set_prev(hr);
-  } else {
-    _tail = hr;
-  }
-  _head = hr;
-}
-
-inline void FreeRegionList::add_as_tail(HeapRegion* hr) {
-  check_mt_safety();
-  assert((length() == 0 && _head == NULL && _tail == NULL) ||
-         (length() >  0 && _head != NULL && _tail != NULL),
-         hrs_ext_msg(this, "invariant"));
-  // add() will verify the region and check mt safety.
-  add(hr);
-
-  // Now link the region.
-  if (_tail != NULL) {
-    _tail->set_next(hr);
-    hr->set_prev(_tail);
-  } else {
-    _head = hr;
-  }
-  _tail = hr;
-}
-
-inline HeapRegion* FreeRegionList::remove_head() {
-  assert(!is_empty(), hrs_ext_msg(this, "the list should not be empty"));
-  assert(length() > 0 && _head != NULL && _tail != NULL,
-         hrs_ext_msg(this, "invariant"));
-
-  // We need to unlink it first.
-  HeapRegion* hr = _head;
-  _head = hr->next();
+inline HeapRegion* FreeRegionList::remove_from_head_impl() {
+  HeapRegion* result = _head;
+  _head = result->next();
   if (_head == NULL) {
     _tail = NULL;
   } else {
     _head->set_prev(NULL);
   }
-  hr->set_next(NULL);
+  result->set_next(NULL);
+  return result;
+}
 
-  if (_last == hr) {
-    _last = NULL;
-  }
+inline HeapRegion* FreeRegionList::remove_from_tail_impl() {
+  HeapRegion* result = _tail;
 
-  // remove() will verify the region and check mt safety.
-  remove(hr);
-  return hr;
+  _tail = result->prev();
+  if (_tail == NULL) {
+    _head = NULL;
+  } else {
+    _tail->set_next(NULL);
+  }
+  result->set_prev(NULL);
+  return result;
 }
 
-inline HeapRegion* FreeRegionList::remove_head_or_null() {
+inline HeapRegion* FreeRegionList::remove_region(bool from_head) {
   check_mt_safety();
-  if (!is_empty()) {
-    return remove_head();
-  } else {
+  verify_optional();
+
+  if (is_empty()) {
     return NULL;
   }
-}
-
-inline HeapRegion* FreeRegionList::remove_tail() {
-  assert(!is_empty(), hrs_ext_msg(this, "The list should not be empty"));
   assert(length() > 0 && _head != NULL && _tail != NULL,
          hrs_ext_msg(this, "invariant"));
 
-  // We need to unlink it first
-  HeapRegion* hr = _tail;
+  HeapRegion* hr;
 
-  _tail = hr->prev();
-  if (_tail == NULL) {
-    _head = NULL;
+  if (from_head) {
+    hr = remove_from_head_impl();
   } else {
-    _tail->set_next(NULL);
+    hr = remove_from_tail_impl();
   }
-  hr->set_prev(NULL);
 
   if (_last == hr) {
     _last = NULL;
@@ -188,22 +148,5 @@ inline HeapRegion* FreeRegionList::remove_tail() {
   return hr;
 }
 
-inline HeapRegion* FreeRegionList::remove_tail_or_null() {
-  check_mt_safety();
-
-  if (!is_empty()) {
-    return remove_tail();
-  } else {
-    return NULL;
-  }
-}
-
-inline HeapRegion* FreeRegionList::remove_region(bool from_head) {
-  if (from_head) {
-    return remove_head_or_null();
-  } else {
-    return remove_tail_or_null();
-  }
-}
-
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_INLINE_HPP
+

src/share/vm/gc_implementation/g1/vmStructs_g1.hpp

@@ -43,10 +43,9 @@
   nonstatic_field(G1HeapRegionTable, _shift_by,         uint)                 \
                                                                               \
   nonstatic_field(HeapRegionSeq,   _regions,            G1HeapRegionTable)    \
-  nonstatic_field(HeapRegionSeq,   _committed_length,   uint)                 \
+  nonstatic_field(HeapRegionSeq,   _num_committed,      uint)                 \
                                                                               \
   nonstatic_field(G1CollectedHeap, _hrs,                HeapRegionSeq)        \
-  nonstatic_field(G1CollectedHeap, _g1_committed,       MemRegion)            \
   nonstatic_field(G1CollectedHeap, _summary_bytes_used, size_t)               \
   nonstatic_field(G1CollectedHeap, _g1mm,               G1MonitoringSupport*) \
   nonstatic_field(G1CollectedHeap, _old_set,            HeapRegionSetBase)    \

src/share/vm/prims/whitebox.cpp

@@ -231,7 +231,7 @@ WB_END
 
 WB_ENTRY(jlong, WB_G1NumFreeRegions(JNIEnv* env, jobject o))
   G1CollectedHeap* g1 = G1CollectedHeap::heap();
-  size_t nr = g1->free_regions();
+  size_t nr = g1->num_free_regions();
   return (jlong)nr;
 WB_END