1 /*
   2  * Copyright (c) 2011, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   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.
   8  *
   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
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  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
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_HPP
  27 
  28 #include "gc_implementation/g1/heapRegion.hpp"
  29 
  30 // Large buffer for some cases where the output might be larger than normal.
  31 #define HRS_ERR_MSG_BUFSZ 512
  32 typedef FormatBuffer<HRS_ERR_MSG_BUFSZ> hrs_err_msg;
  33 
  34 // Set verification will be forced either if someone defines
  35 // HEAP_REGION_SET_FORCE_VERIFY to be 1, or in builds in which
  36 // asserts are compiled in.
  37 #ifndef HEAP_REGION_SET_FORCE_VERIFY
  38 #define HEAP_REGION_SET_FORCE_VERIFY defined(ASSERT)
  39 #endif // HEAP_REGION_SET_FORCE_VERIFY
  40 
  41 class hrs_ext_msg;
  42 
  43 class HRSMtSafeChecker : public CHeapObj<mtGC> {
  44 public:
  45   virtual bool check() = 0;
  46 };
  47 
  48 class MasterFreeRegionListMtSafeChecker    : public HRSMtSafeChecker { public: bool check(); };
  49 class SecondaryFreeRegionListMtSafeChecker : public HRSMtSafeChecker { public: bool check(); };
  50 class HumongousRegionSetMtSafeChecker      : public HRSMtSafeChecker { public: bool check(); };
  51 class OldRegionSetMtSafeChecker            : public HRSMtSafeChecker { public: bool check(); };
  52 
  53 class HeapRegionSetCount VALUE_OBJ_CLASS_SPEC {
  54   friend class VMStructs;
  55   uint   _length;
  56   size_t _capacity;
  57 
  58 public:
  59   HeapRegionSetCount() : _length(0), _capacity(0) { }
  60 
  61   const uint   length()   const { return _length;   }
  62   const size_t capacity() const { return _capacity; }
  63 
  64   void increment(uint length_to_add, size_t capacity_to_add) {
  65     _length += length_to_add;
  66     _capacity += capacity_to_add;
  67   }
  68 
  69   void decrement(const uint length_to_remove, const size_t capacity_to_remove) {
  70     _length -= length_to_remove;
  71     _capacity -= capacity_to_remove;
  72   }
  73 };
  74 
  75 //////////////////// HeapRegionSetBase ////////////////////
  76 
  77 // Base class for all the classes that represent heap region sets. It
  78 // contains the basic attributes that each set needs to maintain
  79 // (e.g., length, region num, used bytes sum) plus any shared
  80 // functionality (e.g., verification).
  81 
  82 class HeapRegionSetBase VALUE_OBJ_CLASS_SPEC {
  83   friend class VMStructs;
  84 private:
  85   bool _is_humongous;
  86   bool _is_empty;
  87   HRSMtSafeChecker* _mt_safety_checker;
  88 
  89 protected:
  90   // The number of regions added to the set. If the set contains
  91   // only humongous regions, this reflects only 'starts humongous'
  92   // regions and does not include 'continues humongous' ones.
  93   HeapRegionSetCount _count;
  94 
  95   const char* _name;
  96 
  97   bool _verify_in_progress;
  98 
  99   // verify_region() is used to ensure that the contents of a region
 100   // added to / removed from a set are consistent.
 101   void verify_region(HeapRegion* hr) PRODUCT_RETURN;
 102 
 103   // Indicates whether all regions in the set should be humongous or
 104   // not. Only used during verification.
 105   bool regions_humongous() { return _is_humongous; }
 106 
 107   // Indicates whether all regions in the set should be empty or
 108   // not. Only used during verification.
 109   bool regions_empty() { return _is_empty; }
 110 
 111   bool check_mt_safety() {
 112     if (_mt_safety_checker != NULL) {
 113       _mt_safety_checker->check();
 114     }
 115     return true;
 116   }
 117 
 118   virtual void fill_in_ext_msg_extra(hrs_ext_msg* msg) { }
 119 
 120   HeapRegionSetBase(const char* name, bool humongous, bool empty, HRSMtSafeChecker* mt_safety_checker);
 121 
 122 public:
 123   const char* name() { return _name; }
 124 
 125   uint length() { return _count.length(); }
 126 
 127   bool is_empty() { return _count.length() == 0; }
 128 
 129   size_t total_capacity_bytes() {
 130     return _count.capacity();
 131   }
 132 
 133   // It updates the fields of the set to reflect hr being added to
 134   // the set and tags the region appropriately.
 135   inline void add(HeapRegion* hr);
 136 
 137   // It updates the fields of the set to reflect hr being removed
 138   // from the set and tags the region appropriately.
 139   inline void remove(HeapRegion* hr);
 140 
 141   // fill_in_ext_msg() writes the the values of the set's attributes
 142   // in the custom err_msg (hrs_ext_msg). fill_in_ext_msg_extra()
 143   // allows subclasses to append further information.
 144   void fill_in_ext_msg(hrs_ext_msg* msg, const char* message);
 145 
 146   virtual void verify();
 147   void verify_start();
 148   void verify_next_region(HeapRegion* hr);
 149   void verify_end();
 150 
 151 #if HEAP_REGION_SET_FORCE_VERIFY
 152   void verify_optional() {
 153     verify();
 154   }
 155 #else // HEAP_REGION_SET_FORCE_VERIFY
 156   void verify_optional() { }
 157 #endif // HEAP_REGION_SET_FORCE_VERIFY
 158 
 159   virtual void print_on(outputStream* out, bool print_contents = false);
 160 };
 161 
 162 // Customized err_msg for heap region sets. Apart from a
 163 // assert/guarantee-specific message it also prints out the values of
 164 // the fields of the associated set. This can be very helpful in
 165 // diagnosing failures.
 166 class hrs_ext_msg : public hrs_err_msg {
 167 public:
 168   hrs_ext_msg(HeapRegionSetBase* set, const char* message) : hrs_err_msg("") {
 169     set->fill_in_ext_msg(this, message);
 170   }
 171 };
 172 
 173 //////////////////// HeapRegionSet ////////////////////
 174 
 175 #define hrs_assert_sets_match(_set1_, _set2_)                                 \
 176   do {                                                                        \
 177     assert(((_set1_)->regions_humongous() ==                                  \
 178                                             (_set2_)->regions_humongous()) && \
 179            ((_set1_)->regions_empty() == (_set2_)->regions_empty()),          \
 180            hrs_err_msg("the contents of set %s and set %s should match",      \
 181                        (_set1_)->name(), (_set2_)->name()));                  \
 182   } while (0)
 183 
 184 // This class represents heap region sets whose members are not
 185 // explicitly tracked. It's helpful to group regions using such sets
 186 // so that we can reason about all the region groups in the heap using
 187 // the same interface (namely, the HeapRegionSetBase API).
 188 
 189 class HeapRegionSet : public HeapRegionSetBase {
 190 public:
 191   HeapRegionSet(const char* name, bool humongous, HRSMtSafeChecker* mt_safety_checker):
 192     HeapRegionSetBase(name, humongous, false /* empty */, mt_safety_checker) { }
 193 
 194   void bulk_remove(const HeapRegionSetCount& removed) {
 195     _count.decrement(removed.length(), removed.capacity());
 196   }
 197 };
 198 
 199 //////////////////// HeapRegionLinkedList ////////////////////
 200 
 201 // A set that links all the regions added to it in a singly-linked
 202 // list. We should try to avoid doing operations that iterate over
 203 // such lists in performance critical paths. Typically we should
 204 // add / remove one region at a time or concatenate two lists. All
 205 // those operations are done in constant time.
 206 
 207 class FreeRegionListIterator;
 208 
 209 class FreeRegionList : public HeapRegionSetBase {
 210   friend class FreeRegionListIterator;
 211 
 212 private:
 213   HeapRegion* _head;
 214   HeapRegion* _tail;
 215 
 216 protected:
 217   virtual void fill_in_ext_msg_extra(hrs_ext_msg* msg);
 218 
 219   // See the comment for HeapRegionSetBase::clear()
 220   virtual void clear();
 221 
 222 public:
 223   FreeRegionList(const char* name, HRSMtSafeChecker* mt_safety_checker):
 224     HeapRegionSetBase(name, false /* humongous */, true /* empty */, mt_safety_checker) {
 225     clear();
 226   }
 227 
 228   void verify_list();
 229 
 230   HeapRegion* head() { return _head; }
 231   HeapRegion* tail() { return _tail; }
 232 
 233   static uint _unrealistically_long_length;
 234   static void set_unrealistically_long_length(uint len);
 235 
 236   // It adds hr to the list as the new head. The region should not be
 237   // a member of another set.
 238   inline void add_as_head(HeapRegion* hr);
 239 
 240   // It adds hr to the list as the new tail. The region should not be
 241   // a member of another set.
 242   inline void add_as_tail(HeapRegion* hr);
 243 
 244   // It removes and returns the head of the list. It assumes that the
 245   // list is not empty so it will return a non-NULL value.
 246   inline HeapRegion* remove_head();
 247 
 248   // Convenience method.
 249   inline HeapRegion* remove_head_or_null();
 250 
 251   // It moves the regions from from_list to this list and empties
 252   // from_list. The new regions will appear in the same order as they
 253   // were in from_list and be linked in the beginning of this list.
 254   void add_as_head(FreeRegionList* from_list);
 255 
 256   // It moves the regions from from_list to this list and empties
 257   // from_list. The new regions will appear in the same order as they
 258   // were in from_list and be linked in the end of this list.
 259   void add_as_tail(FreeRegionList* from_list);
 260 
 261   // It empties the list by removing all regions from it.
 262   void remove_all();
 263 
 264   // It removes all regions in the list that are pending for removal
 265   // (i.e., they have been tagged with "pending_removal"). The list
 266   // must not be empty, target_count should reflect the exact number
 267   // of regions that are pending for removal in the list, and
 268   // target_count should be > 1 (currently, we never need to remove a
 269   // single region using this).
 270   void remove_all_pending(uint target_count);
 271 
 272   virtual void verify();
 273 
 274   virtual void print_on(outputStream* out, bool print_contents = false);
 275 };
 276 
 277 //////////////////// FreeRegionListIterator ////////////////////
 278 
 279 // Iterator class that provides a convenient way to iterate over the
 280 // regions of a HeapRegionLinkedList instance.
 281 
 282 class FreeRegionListIterator : public StackObj {
 283 private:
 284   FreeRegionList* _list;
 285   HeapRegion*           _curr;
 286 
 287 public:
 288   bool more_available() {
 289     return _curr != NULL;
 290   }
 291 
 292   HeapRegion* get_next() {
 293     assert(more_available(),
 294            "get_next() should be called when more regions are available");
 295 
 296     // If we are going to introduce a count in the iterator we should
 297     // do the "cycle" check.
 298 
 299     HeapRegion* hr = _curr;
 300     _list->verify_region(hr);
 301     _curr = hr->next();
 302     return hr;
 303   }
 304 
 305   FreeRegionListIterator(FreeRegionList* list)
 306     : _curr(NULL), _list(list) {
 307     _curr = list->head();
 308   }
 309 };
 310 
 311 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_HPP