1 /*
   2  * Copyright (c) 1997, 2019, 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_MEMORY_ALLOCATION_HPP
  26 #define SHARE_MEMORY_ALLOCATION_HPP
  27 
  28 #include "memory/allStatic.hpp"
  29 #include "utilities/globalDefinitions.hpp"
  30 #include "utilities/macros.hpp"
  31 
  32 #include <new>
  33 
  34 class outputStream;
  35 class Thread;
  36 
  37 class AllocFailStrategy {
  38 public:
  39   enum AllocFailEnum { EXIT_OOM, RETURN_NULL };
  40 };
  41 typedef AllocFailStrategy::AllocFailEnum AllocFailType;
  42 
  43 // The virtual machine must never call one of the implicitly declared
  44 // global allocation or deletion functions.  (Such calls may result in
  45 // link-time or run-time errors.)  For convenience and documentation of
  46 // intended use, classes in the virtual machine may be derived from one
  47 // of the following allocation classes, some of which define allocation
  48 // and deletion functions.
  49 // Note: std::malloc and std::free should never called directly.
  50 
  51 //
  52 // For objects allocated in the resource area (see resourceArea.hpp).
  53 // - ResourceObj
  54 //
  55 // For objects allocated in the C-heap (managed by: free & malloc and tracked with NMT)
  56 // - CHeapObj
  57 //
  58 // For objects allocated on the stack.
  59 // - StackObj
  60 //
  61 // For classes used as name spaces.
  62 // - AllStatic
  63 //
  64 // For classes in Metaspace (class data)
  65 // - MetaspaceObj
  66 //
  67 // The printable subclasses are used for debugging and define virtual
  68 // member functions for printing. Classes that avoid allocating the
  69 // vtbl entries in the objects should therefore not be the printable
  70 // subclasses.
  71 //
  72 // The following macros and function should be used to allocate memory
  73 // directly in the resource area or in the C-heap, The _OBJ variants
  74 // of the NEW/FREE_C_HEAP macros are used for alloc/dealloc simple
  75 // objects which are not inherited from CHeapObj, note constructor and
  76 // destructor are not called. The preferable way to allocate objects
  77 // is using the new operator.
  78 //
  79 // WARNING: The array variant must only be used for a homogenous array
  80 // where all objects are of the exact type specified. If subtypes are
  81 // stored in the array then must pay attention to calling destructors
  82 // at needed.
  83 //
  84 // NEW_RESOURCE_ARRAY*
  85 // REALLOC_RESOURCE_ARRAY*
  86 // FREE_RESOURCE_ARRAY*
  87 // NEW_RESOURCE_OBJ*
  88 // NEW_C_HEAP_ARRAY*
  89 // REALLOC_C_HEAP_ARRAY*
  90 // FREE_C_HEAP_ARRAY*
  91 // NEW_C_HEAP_OBJ*
  92 // FREE_C_HEAP_OBJ
  93 //
  94 // char* AllocateHeap(size_t size, MEMFLAGS flags, const NativeCallStack& stack, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
  95 // char* AllocateHeap(size_t size, MEMFLAGS flags, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
  96 // char* ReallocateHeap(char *old, size_t size, MEMFLAGS flag, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
  97 // void FreeHeap(void* p);
  98 //
  99 // In non product mode we introduce a super class for all allocation classes
 100 // that supports printing.
 101 // We avoid the superclass in product mode to save space.
 102 
 103 #ifdef PRODUCT
 104 #define ALLOCATION_SUPER_CLASS_SPEC
 105 #else
 106 #define ALLOCATION_SUPER_CLASS_SPEC : public AllocatedObj
 107 class AllocatedObj {
 108  public:
 109   // Printing support
 110   void print() const;
 111   void print_value() const;
 112 
 113   virtual void print_on(outputStream* st) const;
 114   virtual void print_value_on(outputStream* st) const;
 115 };
 116 #endif
 117 
 118 #define MEMORY_TYPES_DO(f)                                                           \
 119   /* Memory type by sub systems. It occupies lower byte. */                          \
 120   f(mtJavaHeap,       "Java Heap")   /* Java heap                                 */ \
 121   f(mtClass,          "Class")       /* Java classes                              */ \
 122   f(mtThread,         "Thread")      /* thread objects                            */ \
 123   f(mtThreadStack,    "Thread Stack")                                                \
 124   f(mtCode,           "Code")        /* generated code                            */ \
 125   f(mtGC,             "GC")                                                          \
 126   f(mtCompiler,       "Compiler")                                                    \
 127   f(mtJVMCI,          "JVMCI")                                                       \
 128   f(mtInternal,       "Internal")    /* memory used by VM, but does not belong to */ \
 129                                      /* any of above categories, and not used by  */ \
 130                                      /* NMT                                       */ \
 131   f(mtOther,          "Other")       /* memory not used by VM                     */ \
 132   f(mtSymbol,         "Symbol")                                                      \
 133   f(mtNMT,            "Native Memory Tracking")  /* memory used by NMT            */ \
 134   f(mtClassShared,    "Shared class space")      /* class data sharing            */ \
 135   f(mtChunk,          "Arena Chunk") /* chunk that holds content of arenas        */ \
 136   f(mtTest,           "Test")        /* Test type for verifying NMT               */ \
 137   f(mtTracing,        "Tracing")                                                     \
 138   f(mtLogging,        "Logging")                                                     \
 139   f(mtStatistics,     "Statistics")                                                  \
 140   f(mtArguments,      "Arguments")                                                   \
 141   f(mtModule,         "Module")                                                      \
 142   f(mtSafepoint,      "Safepoint")                                                   \
 143   f(mtSynchronizer,   "Synchronization")                                             \
 144   f(mtServiceability, "Serviceability")                                              \
 145   f(mtNone,           "Unknown")                                                     \
 146   //end
 147 
 148 #define MEMORY_TYPE_DECLARE_ENUM(type, human_readable) \
 149   type,
 150 
 151 /*
 152  * Memory types
 153  */
 154 enum MemoryType {
 155   MEMORY_TYPES_DO(MEMORY_TYPE_DECLARE_ENUM)
 156   mt_number_of_types   // number of memory types (mtDontTrack
 157                        // is not included as validate type)
 158 };
 159 
 160 typedef MemoryType MEMFLAGS;
 161 
 162 
 163 #if INCLUDE_NMT
 164 
 165 extern bool NMT_track_callsite;
 166 
 167 #else
 168 
 169 const bool NMT_track_callsite = false;
 170 
 171 #endif // INCLUDE_NMT
 172 
 173 class NativeCallStack;
 174 
 175 
 176 char* AllocateHeap(size_t size,
 177                    MEMFLAGS flags,
 178                    const NativeCallStack& stack,
 179                    AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 180 char* AllocateHeap(size_t size,
 181                    MEMFLAGS flags,
 182                    AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 183 
 184 char* ReallocateHeap(char *old,
 185                      size_t size,
 186                      MEMFLAGS flag,
 187                      AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 188 
 189 // handles NULL pointers
 190 void FreeHeap(void* p);
 191 
 192 template <MEMFLAGS F> class CHeapObj ALLOCATION_SUPER_CLASS_SPEC {
 193  public:
 194   ALWAYSINLINE void* operator new(size_t size) throw() {
 195     return (void*)AllocateHeap(size, F);
 196   }
 197 
 198   ALWAYSINLINE void* operator new(size_t size,
 199                                   const NativeCallStack& stack) throw() {
 200     return (void*)AllocateHeap(size, F, stack);
 201   }
 202 
 203   ALWAYSINLINE void* operator new(size_t size, const std::nothrow_t&,
 204                                   const NativeCallStack& stack) throw() {
 205     return (void*)AllocateHeap(size, F, stack, AllocFailStrategy::RETURN_NULL);
 206   }
 207 
 208   ALWAYSINLINE void* operator new(size_t size, const std::nothrow_t&) throw() {
 209     return (void*)AllocateHeap(size, F, AllocFailStrategy::RETURN_NULL);
 210   }
 211 
 212   ALWAYSINLINE void* operator new[](size_t size) throw() {
 213     return (void*)AllocateHeap(size, F);
 214   }
 215 
 216   ALWAYSINLINE void* operator new[](size_t size,
 217                                   const NativeCallStack& stack) throw() {
 218     return (void*)AllocateHeap(size, F, stack);
 219   }
 220 
 221   ALWAYSINLINE void* operator new[](size_t size, const std::nothrow_t&,
 222                                     const NativeCallStack& stack) throw() {
 223     return (void*)AllocateHeap(size, F, stack, AllocFailStrategy::RETURN_NULL);
 224   }
 225 
 226   ALWAYSINLINE void* operator new[](size_t size, const std::nothrow_t&) throw() {
 227     return (void*)AllocateHeap(size, F, AllocFailStrategy::RETURN_NULL);
 228   }
 229 
 230   void  operator delete(void* p)     { FreeHeap(p); }
 231   void  operator delete [] (void* p) { FreeHeap(p); }
 232 };
 233 
 234 // Base class for objects allocated on the stack only.
 235 // Calling new or delete will result in fatal error.
 236 
 237 class StackObj ALLOCATION_SUPER_CLASS_SPEC {
 238  private:
 239   void* operator new(size_t size) throw();
 240   void* operator new [](size_t size) throw();
 241   void  operator delete(void* p);
 242   void  operator delete [](void* p);
 243 };
 244 
 245 // Base class for objects stored in Metaspace.
 246 // Calling delete will result in fatal error.
 247 //
 248 // Do not inherit from something with a vptr because this class does
 249 // not introduce one.  This class is used to allocate both shared read-only
 250 // and shared read-write classes.
 251 //
 252 
 253 class ClassLoaderData;
 254 class MetaspaceClosure;
 255 
 256 class MetaspaceObj {
 257   friend class VMStructs;
 258   // When CDS is enabled, all shared metaspace objects are mapped
 259   // into a single contiguous memory block, so we can use these
 260   // two pointers to quickly determine if something is in the
 261   // shared metaspace.
 262   // When CDS is not enabled, both pointers are set to NULL.
 263   static void* _shared_metaspace_base;  // (inclusive) low address
 264   static void* _shared_metaspace_top;   // (exclusive) high address
 265 
 266  public:
 267 
 268   // Returns true if the pointer points to a valid MetaspaceObj. A valid
 269   // MetaspaceObj is MetaWord-aligned and contained within either
 270   // non-shared or shared metaspace.
 271   static bool is_valid(const MetaspaceObj* p);
 272 
 273   static bool is_shared(const MetaspaceObj* p) {
 274     // If no shared metaspace regions are mapped, _shared_metaspace_{base,top} will
 275     // both be NULL and all values of p will be rejected quickly.
 276     return (((void*)p) < _shared_metaspace_top &&
 277             ((void*)p) >= _shared_metaspace_base);
 278   }
 279   bool is_shared() const { return MetaspaceObj::is_shared(this); }
 280 
 281   void print_address_on(outputStream* st) const;  // nonvirtual address printing
 282 
 283   static void set_shared_metaspace_range(void* base, void* top) {
 284     _shared_metaspace_base = base;
 285     _shared_metaspace_top = top;
 286   }
 287 
 288   static void* shared_metaspace_base() { return _shared_metaspace_base; }
 289   static void* shared_metaspace_top()  { return _shared_metaspace_top;  }
 290 
 291 #define METASPACE_OBJ_TYPES_DO(f) \
 292   f(Class) \
 293   f(Symbol) \
 294   f(TypeArrayU1) \
 295   f(TypeArrayU2) \
 296   f(TypeArrayU4) \
 297   f(TypeArrayU8) \
 298   f(TypeArrayOther) \
 299   f(Method) \
 300   f(ConstMethod) \
 301   f(MethodData) \
 302   f(ConstantPool) \
 303   f(ConstantPoolCache) \
 304   f(Annotations) \
 305   f(MethodCounters) \
 306   f(RecordComponent)
 307 
 308 #define METASPACE_OBJ_TYPE_DECLARE(name) name ## Type,
 309 #define METASPACE_OBJ_TYPE_NAME_CASE(name) case name ## Type: return #name;
 310 
 311   enum Type {
 312     // Types are MetaspaceObj::ClassType, MetaspaceObj::SymbolType, etc
 313     METASPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_DECLARE)
 314     _number_of_types
 315   };
 316 
 317   static const char * type_name(Type type) {
 318     switch(type) {
 319     METASPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_NAME_CASE)
 320     default:
 321       ShouldNotReachHere();
 322       return NULL;
 323     }
 324   }
 325 
 326   static MetaspaceObj::Type array_type(size_t elem_size) {
 327     switch (elem_size) {
 328     case 1: return TypeArrayU1Type;
 329     case 2: return TypeArrayU2Type;
 330     case 4: return TypeArrayU4Type;
 331     case 8: return TypeArrayU8Type;
 332     default:
 333       return TypeArrayOtherType;
 334     }
 335   }
 336 
 337   void* operator new(size_t size, ClassLoaderData* loader_data,
 338                      size_t word_size,
 339                      Type type, Thread* thread) throw();
 340                      // can't use TRAPS from this header file.
 341   void operator delete(void* p) { ShouldNotCallThis(); }
 342 
 343   // Declare a *static* method with the same signature in any subclass of MetaspaceObj
 344   // that should be read-only by default. See symbol.hpp for an example. This function
 345   // is used by the templates in metaspaceClosure.hpp
 346   static bool is_read_only_by_default() { return false; }
 347 };
 348 
 349 // Base class for classes that constitute name spaces.
 350 
 351 class Arena;
 352 
 353 extern char* resource_allocate_bytes(size_t size,
 354     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 355 extern char* resource_allocate_bytes(Thread* thread, size_t size,
 356     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 357 extern char* resource_reallocate_bytes( char *old, size_t old_size, size_t new_size,
 358     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 359 extern void resource_free_bytes( char *old, size_t size );
 360 
 361 //----------------------------------------------------------------------
 362 // Base class for objects allocated in the resource area per default.
 363 // Optionally, objects may be allocated on the C heap with
 364 // new(ResourceObj::C_HEAP) Foo(...) or in an Arena with new (&arena)
 365 // ResourceObj's can be allocated within other objects, but don't use
 366 // new or delete (allocation_type is unknown).  If new is used to allocate,
 367 // use delete to deallocate.
 368 class ResourceObj ALLOCATION_SUPER_CLASS_SPEC {
 369  public:
 370   enum allocation_type { STACK_OR_EMBEDDED = 0, RESOURCE_AREA, C_HEAP, ARENA, allocation_mask = 0x3 };
 371   static void set_allocation_type(address res, allocation_type type) NOT_DEBUG_RETURN;
 372 #ifdef ASSERT
 373  private:
 374   // When this object is allocated on stack the new() operator is not
 375   // called but garbage on stack may look like a valid allocation_type.
 376   // Store negated 'this' pointer when new() is called to distinguish cases.
 377   // Use second array's element for verification value to distinguish garbage.
 378   uintptr_t _allocation_t[2];
 379   bool is_type_set() const;
 380   void initialize_allocation_info();
 381  public:
 382   allocation_type get_allocation_type() const;
 383   bool allocated_on_stack()    const { return get_allocation_type() == STACK_OR_EMBEDDED; }
 384   bool allocated_on_res_area() const { return get_allocation_type() == RESOURCE_AREA; }
 385   bool allocated_on_C_heap()   const { return get_allocation_type() == C_HEAP; }
 386   bool allocated_on_arena()    const { return get_allocation_type() == ARENA; }
 387 protected:
 388   ResourceObj(); // default constructor
 389   ResourceObj(const ResourceObj& r); // default copy constructor
 390   ResourceObj& operator=(const ResourceObj& r); // default copy assignment
 391   ~ResourceObj();
 392 #endif // ASSERT
 393 
 394  public:
 395   void* operator new(size_t size, allocation_type type, MEMFLAGS flags) throw();
 396   void* operator new [](size_t size, allocation_type type, MEMFLAGS flags) throw();
 397   void* operator new(size_t size, const std::nothrow_t&  nothrow_constant,
 398       allocation_type type, MEMFLAGS flags) throw();
 399   void* operator new [](size_t size, const std::nothrow_t&  nothrow_constant,
 400       allocation_type type, MEMFLAGS flags) throw();
 401 
 402   void* operator new(size_t size, Arena *arena) throw();
 403 
 404   void* operator new [](size_t size, Arena *arena) throw();
 405 
 406   void* operator new(size_t size) throw() {
 407       address res = (address)resource_allocate_bytes(size);
 408       DEBUG_ONLY(set_allocation_type(res, RESOURCE_AREA);)
 409       return res;
 410   }
 411 
 412   void* operator new(size_t size, const std::nothrow_t& nothrow_constant) throw() {
 413       address res = (address)resource_allocate_bytes(size, AllocFailStrategy::RETURN_NULL);
 414       DEBUG_ONLY(if (res != NULL) set_allocation_type(res, RESOURCE_AREA);)
 415       return res;
 416   }
 417 
 418   void* operator new [](size_t size) throw() {
 419       address res = (address)resource_allocate_bytes(size);
 420       DEBUG_ONLY(set_allocation_type(res, RESOURCE_AREA);)
 421       return res;
 422   }
 423 
 424   void* operator new [](size_t size, const std::nothrow_t& nothrow_constant) throw() {
 425       address res = (address)resource_allocate_bytes(size, AllocFailStrategy::RETURN_NULL);
 426       DEBUG_ONLY(if (res != NULL) set_allocation_type(res, RESOURCE_AREA);)
 427       return res;
 428   }
 429 
 430   void  operator delete(void* p);
 431   void  operator delete [](void* p);
 432 };
 433 
 434 // One of the following macros must be used when allocating an array
 435 // or object to determine whether it should reside in the C heap on in
 436 // the resource area.
 437 
 438 #define NEW_RESOURCE_ARRAY(type, size)\
 439   (type*) resource_allocate_bytes((size) * sizeof(type))
 440 
 441 #define NEW_RESOURCE_ARRAY_RETURN_NULL(type, size)\
 442   (type*) resource_allocate_bytes((size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 443 
 444 #define NEW_RESOURCE_ARRAY_IN_THREAD(thread, type, size)\
 445   (type*) resource_allocate_bytes(thread, (size) * sizeof(type))
 446 
 447 #define NEW_RESOURCE_ARRAY_IN_THREAD_RETURN_NULL(thread, type, size)\
 448   (type*) resource_allocate_bytes(thread, (size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 449 
 450 #define REALLOC_RESOURCE_ARRAY(type, old, old_size, new_size)\
 451   (type*) resource_reallocate_bytes((char*)(old), (old_size) * sizeof(type), (new_size) * sizeof(type))
 452 
 453 #define REALLOC_RESOURCE_ARRAY_RETURN_NULL(type, old, old_size, new_size)\
 454   (type*) resource_reallocate_bytes((char*)(old), (old_size) * sizeof(type),\
 455                                     (new_size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 456 
 457 #define FREE_RESOURCE_ARRAY(type, old, size)\
 458   resource_free_bytes((char*)(old), (size) * sizeof(type))
 459 
 460 #define FREE_FAST(old)\
 461     /* nop */
 462 
 463 #define NEW_RESOURCE_OBJ(type)\
 464   NEW_RESOURCE_ARRAY(type, 1)
 465 
 466 #define NEW_RESOURCE_OBJ_RETURN_NULL(type)\
 467   NEW_RESOURCE_ARRAY_RETURN_NULL(type, 1)
 468 
 469 #define NEW_C_HEAP_ARRAY3(type, size, memflags, pc, allocfail)\
 470   (type*) AllocateHeap((size) * sizeof(type), memflags, pc, allocfail)
 471 
 472 #define NEW_C_HEAP_ARRAY2(type, size, memflags, pc)\
 473   (type*) (AllocateHeap((size) * sizeof(type), memflags, pc))
 474 
 475 #define NEW_C_HEAP_ARRAY(type, size, memflags)\
 476   (type*) (AllocateHeap((size) * sizeof(type), memflags))
 477 
 478 #define NEW_C_HEAP_ARRAY2_RETURN_NULL(type, size, memflags, pc)\
 479   NEW_C_HEAP_ARRAY3(type, (size), memflags, pc, AllocFailStrategy::RETURN_NULL)
 480 
 481 #define NEW_C_HEAP_ARRAY_RETURN_NULL(type, size, memflags)\
 482   NEW_C_HEAP_ARRAY3(type, (size), memflags, CURRENT_PC, AllocFailStrategy::RETURN_NULL)
 483 
 484 #define REALLOC_C_HEAP_ARRAY(type, old, size, memflags)\
 485   (type*) (ReallocateHeap((char*)(old), (size) * sizeof(type), memflags))
 486 
 487 #define REALLOC_C_HEAP_ARRAY_RETURN_NULL(type, old, size, memflags)\
 488   (type*) (ReallocateHeap((char*)(old), (size) * sizeof(type), memflags, AllocFailStrategy::RETURN_NULL))
 489 
 490 #define FREE_C_HEAP_ARRAY(type, old) \
 491   FreeHeap((char*)(old))
 492 
 493 // allocate type in heap without calling ctor
 494 #define NEW_C_HEAP_OBJ(type, memflags)\
 495   NEW_C_HEAP_ARRAY(type, 1, memflags)
 496 
 497 #define NEW_C_HEAP_OBJ_RETURN_NULL(type, memflags)\
 498   NEW_C_HEAP_ARRAY_RETURN_NULL(type, 1, memflags)
 499 
 500 // deallocate obj of type in heap without calling dtor
 501 #define FREE_C_HEAP_OBJ(objname)\
 502   FreeHeap((char*)objname);
 503 
 504 
 505 //------------------------------ReallocMark---------------------------------
 506 // Code which uses REALLOC_RESOURCE_ARRAY should check an associated
 507 // ReallocMark, which is declared in the same scope as the reallocated
 508 // pointer.  Any operation that could __potentially__ cause a reallocation
 509 // should check the ReallocMark.
 510 class ReallocMark: public StackObj {
 511 protected:
 512   NOT_PRODUCT(int _nesting;)
 513 
 514 public:
 515   ReallocMark()   PRODUCT_RETURN;
 516   void check()    PRODUCT_RETURN;
 517 };
 518 
 519 // Helper class to allocate arrays that may become large.
 520 // Uses the OS malloc for allocations smaller than ArrayAllocatorMallocLimit
 521 // and uses mapped memory for larger allocations.
 522 // Most OS mallocs do something similar but Solaris malloc does not revert
 523 // to mapped memory for large allocations. By default ArrayAllocatorMallocLimit
 524 // is set so that we always use malloc except for Solaris where we set the
 525 // limit to get mapped memory.
 526 template <class E>
 527 class ArrayAllocator : public AllStatic {
 528  private:
 529   static bool should_use_malloc(size_t length);
 530 
 531   static E* allocate_malloc(size_t length, MEMFLAGS flags);
 532   static E* allocate_mmap(size_t length, MEMFLAGS flags);
 533 
 534   static void free_malloc(E* addr, size_t length);
 535   static void free_mmap(E* addr, size_t length);
 536 
 537  public:
 538   static E* allocate(size_t length, MEMFLAGS flags);
 539   static E* reallocate(E* old_addr, size_t old_length, size_t new_length, MEMFLAGS flags);
 540   static void free(E* addr, size_t length);
 541 };
 542 
 543 // Uses mmaped memory for all allocations. All allocations are initially
 544 // zero-filled. No pre-touching.
 545 template <class E>
 546 class MmapArrayAllocator : public AllStatic {
 547  private:
 548   static size_t size_for(size_t length);
 549 
 550  public:
 551   static E* allocate_or_null(size_t length, MEMFLAGS flags);
 552   static E* allocate(size_t length, MEMFLAGS flags);
 553   static void free(E* addr, size_t length);
 554 };
 555 
 556 // Uses malloc:ed memory for all allocations.
 557 template <class E>
 558 class MallocArrayAllocator : public AllStatic {
 559  public:
 560   static size_t size_for(size_t length);
 561 
 562   static E* allocate(size_t length, MEMFLAGS flags);
 563   static void free(E* addr);
 564 };
 565 
 566 #endif // SHARE_MEMORY_ALLOCATION_HPP