1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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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  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).
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  24 
  25 #ifndef SHARE_VM_GC_G1_G1ALLOCREGION_HPP
  26 #define SHARE_VM_GC_G1_G1ALLOCREGION_HPP
  27 
  28 #include "gc/g1/heapRegion.hpp"
  29 #include "gc/g1/g1EvacStats.hpp"
  30 #include "gc/g1/g1InCSetState.hpp"
  31 
  32 class G1CollectedHeap;
  33 
  34 // 0 -> no tracing, 1 -> basic tracing, 2 -> basic + allocation tracing
  35 #define G1_ALLOC_REGION_TRACING 0
  36 
  37 #define G1_ALLOC_REGION_MSG(message)                         \
  38   "[%s] %s c: %u b: %s r: " PTR_FORMAT " u: " SIZE_FORMAT, \
  39   _name, message, _count, BOOL_TO_STR(_bot_updates),       \
  40   p2i(_alloc_region), _used_bytes_before
  41 
  42 // A class that holds a region that is active in satisfying allocation
  43 // requests, potentially issued in parallel. When the active region is
  44 // full it will be retired and replaced with a new one. The
  45 // implementation assumes that fast-path allocations will be lock-free
  46 // and a lock will need to be taken when the active region needs to be
  47 // replaced.
  48 
  49 class G1AllocRegion VALUE_OBJ_CLASS_SPEC {
  50   friend class ar_ext_msg;
  51 
  52 private:
  53   // The active allocating region we are currently allocating out
  54   // of. The invariant is that if this object is initialized (i.e.,
  55   // init() has been called and release() has not) then _alloc_region
  56   // is either an active allocating region or the dummy region (i.e.,
  57   // it can never be NULL) and this object can be used to satisfy
  58   // allocation requests. If this object is not initialized
  59   // (i.e. init() has not been called or release() has been called)
  60   // then _alloc_region is NULL and this object should not be used to
  61   // satisfy allocation requests (it was done this way to force the
  62   // correct use of init() and release()).
  63   HeapRegion* volatile _alloc_region;
  64 
  65   // Allocation context associated with this alloc region.
  66   AllocationContext_t _allocation_context;
  67 
  68   // It keeps track of the distinct number of regions that are used
  69   // for allocation in the active interval of this object, i.e.,
  70   // between a call to init() and a call to release(). The count
  71   // mostly includes regions that are freshly allocated, as well as
  72   // the region that is re-used using the set() method. This count can
  73   // be used in any heuristics that might want to bound how many
  74   // distinct regions this object can used during an active interval.
  75   uint _count;
  76 
  77   // When we set up a new active region we save its used bytes in this
  78   // field so that, when we retire it, we can calculate how much space
  79   // we allocated in it.
  80   size_t _used_bytes_before;
  81 
  82   // When true, indicates that allocate calls should do BOT updates.
  83   const bool _bot_updates;
  84 
  85   // Useful for debugging and tracing.
  86   const char* _name;
  87 
  88   // A dummy region (i.e., it's been allocated specially for this
  89   // purpose and it is not part of the heap) that is full (i.e., top()
  90   // == end()). When we don't have a valid active region we make
  91   // _alloc_region point to this. This allows us to skip checking
  92   // whether the _alloc_region is NULL or not.
  93   static HeapRegion* _dummy_region;
  94 
  95   // Some of the methods below take a bot_updates parameter. Its value
  96   // should be the same as the _bot_updates field. The idea is that
  97   // the parameter will be a constant for a particular alloc region
  98   // and, given that these methods will be hopefully inlined, the
  99   // compiler should compile out the test.
 100 
 101   // Perform a non-MT-safe allocation out of the given region.
 102   static inline HeapWord* allocate(HeapRegion* alloc_region,
 103                                    size_t word_size,
 104                                    bool bot_updates);
 105 
 106   // Perform a MT-safe allocation out of the given region.
 107   static inline HeapWord* par_allocate(HeapRegion* alloc_region,
 108                                        size_t word_size,
 109                                        bool bot_updates);
 110   // Perform a MT-safe allocation out of the given region, with the given
 111   // minimum and desired size. Returns the actual size allocated (between
 112   // minimum and desired size) in actual_word_size if the allocation has been
 113   // successful.
 114   static inline HeapWord* par_allocate(HeapRegion* alloc_region,
 115                                        size_t min_word_size,
 116                                        size_t desired_word_size,
 117                                        size_t* actual_word_size,
 118                                        bool bot_updates);
 119 
 120   // Ensure that the region passed as a parameter has been filled up
 121   // so that noone else can allocate out of it any more.
 122   // Returns the number of bytes that have been wasted by filled up
 123   // the space.
 124   static size_t fill_up_remaining_space(HeapRegion* alloc_region,
 125                                         bool bot_updates);
 126 
 127   // After a region is allocated by alloc_new_region, this
 128   // method is used to set it as the active alloc_region
 129   void update_alloc_region(HeapRegion* alloc_region);
 130 
 131   // Allocate a new active region and use it to perform a word_size
 132   // allocation. The force parameter will be passed on to
 133   // G1CollectedHeap::allocate_new_alloc_region() and tells it to try
 134   // to allocate a new region even if the max has been reached.
 135   HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force);
 136 
 137 protected:
 138   // Retire the active allocating region. If fill_up is true then make
 139   // sure that the region is full before we retire it so that no one
 140   // else can allocate out of it.
 141   // Returns the number of bytes that have been filled up during retire.
 142   virtual size_t retire(bool fill_up);
 143 
 144   // For convenience as subclasses use it.
 145   static G1CollectedHeap* _g1h;
 146 
 147   virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0;
 148   virtual void retire_region(HeapRegion* alloc_region,
 149                              size_t allocated_bytes) = 0;
 150 
 151   G1AllocRegion(const char* name, bool bot_updates);
 152 
 153 public:
 154   static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region);
 155 
 156   HeapRegion* get() const {
 157     HeapRegion * hr = _alloc_region;
 158     // Make sure that the dummy region does not escape this class.
 159     return (hr == _dummy_region) ? NULL : hr;
 160   }
 161 
 162   void set_allocation_context(AllocationContext_t context) { _allocation_context = context; }
 163   AllocationContext_t  allocation_context() { return _allocation_context; }
 164 
 165   uint count() { return _count; }
 166 
 167   // The following two are the building blocks for the allocation method.
 168 
 169   // First-level allocation: Should be called without holding a
 170   // lock. It will try to allocate lock-free out of the active region,
 171   // or return NULL if it was unable to.
 172   inline HeapWord* attempt_allocation(size_t word_size,
 173                                       bool bot_updates);
 174   // Perform an allocation out of the current allocation region, with the given
 175   // minimum and desired size. Returns the actual size allocated (between
 176   // minimum and desired size) in actual_word_size if the allocation has been
 177   // successful.
 178   // Should be called without holding a lock. It will try to allocate lock-free
 179   // out of the active region, or return NULL if it was unable to.
 180   inline HeapWord* attempt_allocation(size_t min_word_size,
 181                                       size_t desired_word_size,
 182                                       size_t* actual_word_size,
 183                                       bool bot_updates);
 184 
 185   // Second-level allocation: Should be called while holding a
 186   // lock. It will try to first allocate lock-free out of the active
 187   // region or, if it's unable to, it will try to replace the active
 188   // alloc region with a new one. We require that the caller takes the
 189   // appropriate lock before calling this so that it is easier to make
 190   // it conform to its locking protocol.
 191   inline HeapWord* attempt_allocation_locked(size_t word_size,
 192                                              bool bot_updates);
 193   // Same as attempt_allocation_locked(size_t, bool), but allowing specification
 194   // of minimum word size of the block in min_word_size, and the maximum word
 195   // size of the allocation in desired_word_size. The actual size of the block is
 196   // returned in actual_word_size.
 197   inline HeapWord* attempt_allocation_locked(size_t min_word_size,
 198                                              size_t desired_word_size,
 199                                              size_t* actual_word_size,
 200                                              bool bot_updates);
 201 
 202   // Should be called to allocate a new region even if the max of this
 203   // type of regions has been reached. Should only be called if other
 204   // allocation attempts have failed and we are not holding a valid
 205   // active region.
 206   inline HeapWord* attempt_allocation_force(size_t word_size,
 207                                             bool bot_updates);
 208 
 209   // Should be called before we start using this object.
 210   void init();
 211 
 212   // This can be used to set the active region to a specific
 213   // region. (Use Example: we try to retain the last old GC alloc
 214   // region that we've used during a GC and we can use set() to
 215   // re-instate it at the beginning of the next GC.)
 216   void set(HeapRegion* alloc_region);
 217 
 218   // Should be called when we want to release the active region which
 219   // is returned after it's been retired.
 220   virtual HeapRegion* release();
 221 
 222 #if G1_ALLOC_REGION_TRACING
 223   void trace(const char* str,
 224              size_t min_word_size = 0,
 225              size_t desired_word_size = 0,
 226              size_t actual_word_size = 0,
 227              HeapWord* result = NULL);
 228 #else // G1_ALLOC_REGION_TRACING
 229   void trace(const char* str,
 230              size_t min_word_size = 0,
 231              size_t desired_word_size = 0,
 232              size_t actual_word_size = 0,
 233              HeapWord* result = NULL) { }
 234 #endif // G1_ALLOC_REGION_TRACING
 235 };
 236 
 237 class MutatorAllocRegion : public G1AllocRegion {
 238 protected:
 239   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
 240   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 241 public:
 242   MutatorAllocRegion()
 243     : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
 244 };
 245 
 246 // Common base class for allocation regions used during GC.
 247 class G1GCAllocRegion : public G1AllocRegion {
 248 protected:
 249   G1EvacStats* _stats;
 250   InCSetState::in_cset_state_t _purpose;
 251 
 252   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
 253   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 254 
 255   virtual size_t retire(bool fill_up);
 256 public:
 257   G1GCAllocRegion(const char* name, bool bot_updates, G1EvacStats* stats, InCSetState::in_cset_state_t purpose)
 258   : G1AllocRegion(name, bot_updates), _stats(stats), _purpose(purpose) {
 259     assert(stats != NULL, "Must pass non-NULL PLAB statistics");
 260   }
 261 };
 262 
 263 class SurvivorGCAllocRegion : public G1GCAllocRegion {
 264 public:
 265   SurvivorGCAllocRegion(G1EvacStats* stats)
 266   : G1GCAllocRegion("Survivor GC Alloc Region", false /* bot_updates */, stats, InCSetState::Young) { }
 267 };
 268 
 269 class OldGCAllocRegion : public G1GCAllocRegion {
 270 public:
 271   OldGCAllocRegion(G1EvacStats* stats)
 272   : G1GCAllocRegion("Old GC Alloc Region", true /* bot_updates */, stats, InCSetState::Old) { }
 273 
 274   // This specialization of release() makes sure that the last card that has
 275   // been allocated into has been completely filled by a dummy object.  This
 276   // avoids races when remembered set scanning wants to update the BOT of the
 277   // last card in the retained old gc alloc region, and allocation threads
 278   // allocating into that card at the same time.
 279   virtual HeapRegion* release();
 280 };
 281 
 282 #endif // SHARE_VM_GC_G1_G1ALLOCREGION_HPP
--- EOF ---