1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_VM_GC_G1_G1ALLOCATOR_HPP
  26 #define SHARE_VM_GC_G1_G1ALLOCATOR_HPP
  27 
  28 #include "gc/g1/g1AllocRegion.hpp"
  29 #include "gc/g1/g1InCSetState.hpp"
  30 #include "gc/shared/collectedHeap.hpp"
  31 #include "gc/shared/plab.hpp"
  32 
  33 class EvacuationInfo;
  34 
  35 // Interface to keep track of which regions G1 is currently allocating into. Provides
  36 // some accessors (e.g. allocating into them, or getting their occupancy).
  37 // Also keeps track of retained regions across GCs.
  38 class G1Allocator : public CHeapObj<mtGC> {
  39   friend class VMStructs;
  40 
  41 private:
  42   G1CollectedHeap* _g1h;
  43 
  44   bool _survivor_is_full;
  45   bool _old_is_full;
  46 
  47   // Alloc region used to satisfy mutator allocation requests.
  48   MutatorAllocRegion _mutator_alloc_region;
  49 
  50   // Alloc region used to satisfy allocation requests by the GC for
  51   // survivor objects.
  52   SurvivorGCAllocRegion _survivor_gc_alloc_region;
  53 
  54   // Alloc region used to satisfy allocation requests by the GC for
  55   // old objects.
  56   OldGCAllocRegion _old_gc_alloc_region;
  57 
  58   HeapRegion* _retained_old_gc_alloc_region;
  59 
  60   bool survivor_is_full() const;
  61   bool old_is_full() const;
  62 
  63   void set_survivor_full();
  64   void set_old_full();
  65 
  66   void reuse_retained_old_region(EvacuationInfo& evacuation_info,
  67                                  OldGCAllocRegion* old,
  68                                  HeapRegion** retained);
  69 
  70   // Accessors to the allocation regions.
  71   inline MutatorAllocRegion* mutator_alloc_region();
  72   inline SurvivorGCAllocRegion* survivor_gc_alloc_region();
  73   inline OldGCAllocRegion* old_gc_alloc_region();
  74 
  75   // Allocation attempt during GC for a survivor object / PLAB.
  76   HeapWord* survivor_attempt_allocation(size_t min_word_size,
  77                                                size_t desired_word_size,
  78                                                size_t* actual_word_size);
  79 
  80   // Allocation attempt during GC for an old object / PLAB.
  81   HeapWord* old_attempt_allocation(size_t min_word_size,
  82                                           size_t desired_word_size,
  83                                           size_t* actual_word_size);
  84 public:
  85   G1Allocator(G1CollectedHeap* heap);
  86 
  87 #ifdef ASSERT
  88   // Do we currently have an active mutator region to allocate into?
  89   bool has_mutator_alloc_region() { return mutator_alloc_region()->get() != NULL; }
  90 #endif
  91 
  92   void init_mutator_alloc_region();
  93   void release_mutator_alloc_region();
  94 
  95   void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
  96   void release_gc_alloc_regions(EvacuationInfo& evacuation_info);
  97   void abandon_gc_alloc_regions();
  98   bool is_retained_old_region(HeapRegion* hr);
  99 
 100   // Allocate blocks of memory during mutator time.
 101 
 102   inline HeapWord* attempt_allocation(size_t min_word_size,
 103                                       size_t desired_word_size,
 104                                       size_t* actual_word_size);
 105   inline HeapWord* attempt_allocation_locked(size_t word_size);
 106   inline HeapWord* attempt_allocation_force(size_t word_size);
 107 
 108   size_t unsafe_max_tlab_alloc();
 109   size_t used_in_alloc_regions();
 110 
 111   // Allocate blocks of memory during garbage collection. Will ensure an
 112   // allocation region, either by picking one or expanding the
 113   // heap, and then allocate a block of the given size. The block
 114   // may not be a humongous - it must fit into a single heap region.
 115   HeapWord* par_allocate_during_gc(InCSetState dest,
 116                                    size_t word_size);
 117 
 118   HeapWord* par_allocate_during_gc(InCSetState dest,
 119                                    size_t min_word_size,
 120                                    size_t desired_word_size,
 121                                    size_t* actual_word_size);
 122 };
 123 
 124 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
 125 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
 126 // statistics.
 127 class G1PLABAllocator : public CHeapObj<mtGC> {
 128   friend class G1ParScanThreadState;
 129 private:
 130   G1CollectedHeap* _g1h;
 131   G1Allocator* _allocator;
 132 
 133   PLAB  _surviving_alloc_buffer;
 134   PLAB  _tenured_alloc_buffer;
 135   PLAB* _alloc_buffers[InCSetState::Num];
 136 
 137   // The survivor alignment in effect in bytes.
 138   // == 0 : don't align survivors
 139   // != 0 : align survivors to that alignment
 140   // These values were chosen to favor the non-alignment case since some
 141   // architectures have a special compare against zero instructions.
 142   const uint _survivor_alignment_bytes;
 143 
 144   // Number of words allocated directly (not counting PLAB allocation).
 145   size_t _direct_allocated[InCSetState::Num];
 146 
 147   void flush_and_retire_stats();
 148   inline PLAB* alloc_buffer(InCSetState dest);
 149 
 150   // Calculate the survivor space object alignment in bytes. Returns that or 0 if
 151   // there are no restrictions on survivor alignment.
 152   static uint calc_survivor_alignment_bytes();
 153 
 154   bool may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const;
 155 public:
 156   G1PLABAllocator(G1Allocator* allocator);
 157 
 158   void waste(size_t& wasted, size_t& undo_wasted);
 159 
 160   // Allocate word_sz words in dest, either directly into the regions or by
 161   // allocating a new PLAB. Returns the address of the allocated memory, NULL if
 162   // not successful. Plab_refill_failed indicates whether an attempt to refill the
 163   // PLAB failed or not.
 164   HeapWord* allocate_direct_or_new_plab(InCSetState dest,
 165                                         size_t word_sz,
 166                                         bool* plab_refill_failed);
 167 
 168   // Allocate word_sz words in the PLAB of dest.  Returns the address of the
 169   // allocated memory, NULL if not successful.
 170   inline HeapWord* plab_allocate(InCSetState dest,
 171                                  size_t word_sz);
 172 
 173   inline HeapWord* allocate(InCSetState dest,
 174                             size_t word_sz,
 175                             bool* refill_failed);
 176 
 177   void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz);
 178 };
 179 
 180 // G1ArchiveRegionMap is a boolean array used to mark G1 regions as
 181 // archive regions.  This allows a quick check for whether an object
 182 // should not be marked because it is in an archive region.
 183 class G1ArchiveRegionMap : public G1BiasedMappedArray<bool> {
 184 protected:
 185   bool default_value() const { return false; }
 186 };
 187 
 188 // G1ArchiveAllocator is used to allocate memory in archive
 189 // regions. Such regions are not scavenged nor compacted by GC.
 190 // There are two types of archive regions, which are
 191 // differ in the kind of references allowed for the contained objects:
 192 //
 193 // - 'Closed' archive region contain no references outside of other
 194 //   closed archive regions. The region is immutable by GC. GC does
 195 //   not mark object header in 'closed' archive region.
 196 // - An 'open' archive region allow references to any other regions,
 197 //   including closed archive, open archive and other java heap regions.
 198 //   GC can adjust pointers and mark object header in 'open' archive region.
 199 class G1ArchiveAllocator : public CHeapObj<mtGC> {
 200 protected:
 201   bool _open; // Indicate if the region is 'open' archive.
 202   G1CollectedHeap* _g1h;
 203 
 204   // The current allocation region
 205   HeapRegion* _allocation_region;
 206 
 207   // Regions allocated for the current archive range.
 208   GrowableArray<HeapRegion*> _allocated_regions;
 209 
 210   // The number of bytes used in the current range.
 211   size_t _summary_bytes_used;
 212 
 213   // Current allocation window within the current region.
 214   HeapWord* _bottom;
 215   HeapWord* _top;
 216   HeapWord* _max;
 217 
 218   // Allocate a new region for this archive allocator.
 219   // Allocation is from the top of the reserved heap downward.
 220   bool alloc_new_region();
 221 
 222 public:
 223   G1ArchiveAllocator(G1CollectedHeap* g1h, bool open) :
 224     _g1h(g1h),
 225     _allocation_region(NULL),
 226     _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions,
 227                                                          ResourceObj::C_HEAP),
 228                         2), true /* C_Heap */),
 229     _summary_bytes_used(0),
 230     _bottom(NULL),
 231     _top(NULL),
 232     _max(NULL),
 233     _open(open) { }
 234 
 235   virtual ~G1ArchiveAllocator() {
 236     assert(_allocation_region == NULL, "_allocation_region not NULL");
 237   }
 238 
 239   static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h, bool open);
 240 
 241   // Allocate memory for an individual object.
 242   HeapWord* archive_mem_allocate(size_t word_size);
 243 
 244   // Return the memory ranges used in the current archive, after
 245   // aligning to the requested alignment.
 246   void complete_archive(GrowableArray<MemRegion>* ranges,
 247                         size_t end_alignment_in_bytes);
 248 
 249   // The number of bytes allocated by this allocator.
 250   size_t used() {
 251     return _summary_bytes_used;
 252   }
 253 
 254   // Clear the count of bytes allocated in prior G1 regions. This
 255   // must be done when recalculate_use is used to reset the counter
 256   // for the generic allocator, since it counts bytes in all G1
 257   // regions, including those still associated with this allocator.
 258   void clear_used() {
 259     _summary_bytes_used = 0;
 260   }
 261 
 262   // Create the _archive_region_map which is used to identify archive objects.
 263   static inline void enable_archive_object_check();
 264 
 265   // Set the regions containing the specified address range as archive/non-archive.
 266   static inline void set_range_archive(MemRegion range, bool open);
 267 
 268   // Check if the object is in closed archive
 269   static inline bool is_closed_archive_object(oop object);
 270   // Check if the object is in open archive
 271   static inline bool is_open_archive_object(oop object);
 272   // Check if the object is either in closed archive or open archive
 273   static inline bool is_archive_object(oop object);
 274 
 275 private:
 276   static bool _archive_check_enabled;
 277   static G1ArchiveRegionMap  _closed_archive_region_map;
 278   static G1ArchiveRegionMap  _open_archive_region_map;
 279 
 280   // Check if an object is in a closed archive region using the _closed_archive_region_map.
 281   static inline bool in_closed_archive_range(oop object);
 282   // Check if an object is in open archive region using the _open_archive_region_map.
 283   static inline bool in_open_archive_range(oop object);
 284 
 285   // Check if archive object checking is enabled, to avoid calling in_open/closed_archive_range
 286   // unnecessarily.
 287   static inline bool archive_check_enabled();
 288 };
 289 
 290 #endif // SHARE_VM_GC_G1_G1ALLOCATOR_HPP