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 "runtime/globals.hpp"
  29 #include "utilities/globalDefinitions.hpp"
  30 #include "utilities/macros.hpp"
  31 
  32 #include <new>
  33 
  34 class Thread;
  35 
  36 class AllocFailStrategy {
  37 public:
  38   enum AllocFailEnum { EXIT_OOM, RETURN_NULL };
  39 };
  40 typedef AllocFailStrategy::AllocFailEnum AllocFailType;
  41 
  42 // The virtual machine must never call one of the implicitly declared
  43 // global allocation or deletion functions.  (Such calls may result in
  44 // link-time or run-time errors.)  For convenience and documentation of
  45 // intended use, classes in the virtual machine may be derived from one
  46 // of the following allocation classes, some of which define allocation
  47 // and deletion functions.
  48 // Note: std::malloc and std::free should never called directly.
  49 
  50 //
  51 // For objects allocated in the resource area (see resourceArea.hpp).
  52 // - ResourceObj
  53 //
  54 // For objects allocated in the C-heap (managed by: free & malloc and tracked with NMT)
  55 // - CHeapObj
  56 //
  57 // For objects allocated on the stack.
  58 // - StackObj
  59 //
  60 // For classes used as name spaces.
  61 // - AllStatic
  62 //
  63 // For classes in Metaspace (class data)
  64 // - MetaspaceObj
  65 //
  66 // The printable subclasses are used for debugging and define virtual
  67 // member functions for printing. Classes that avoid allocating the
  68 // vtbl entries in the objects should therefore not be the printable
  69 // subclasses.
  70 //
  71 // The following macros and function should be used to allocate memory
  72 // directly in the resource area or in the C-heap, The _OBJ variants
  73 // of the NEW/FREE_C_HEAP macros are used for alloc/dealloc simple
  74 // objects which are not inherited from CHeapObj, note constructor and
  75 // destructor are not called. The preferable way to allocate objects
  76 // is using the new operator.
  77 //
  78 // WARNING: The array variant must only be used for a homogenous array
  79 // where all objects are of the exact type specified. If subtypes are
  80 // stored in the array then must pay attention to calling destructors
  81 // at needed.
  82 //
  83 //   NEW_RESOURCE_ARRAY(type, size)
  84 //   NEW_RESOURCE_OBJ(type)
  85 //   NEW_C_HEAP_ARRAY(type, size)
  86 //   NEW_C_HEAP_OBJ(type, memflags)
  87 //   FREE_C_HEAP_ARRAY(type, old)
  88 //   FREE_C_HEAP_OBJ(objname, type, memflags)
  89 //   char* AllocateHeap(size_t size, const char* name);
  90 //   void  FreeHeap(void* p);
  91 //
  92 
  93 // In non product mode we introduce a super class for all allocation classes
  94 // that supports printing.
  95 // We avoid the superclass in product mode to save space.
  96 
  97 #ifdef PRODUCT
  98 #define ALLOCATION_SUPER_CLASS_SPEC
  99 #else
 100 #define ALLOCATION_SUPER_CLASS_SPEC : public AllocatedObj
 101 class AllocatedObj {
 102  public:
 103   // Printing support
 104   void print() const;
 105   void print_value() const;
 106 
 107   virtual void print_on(outputStream* st) const;
 108   virtual void print_value_on(outputStream* st) const;
 109 };
 110 #endif
 111 
 112 #define MEMORY_TYPES_DO(f) \
 113   /* Memory type by sub systems. It occupies lower byte. */  \
 114   f(mtJavaHeap,      "Java Heap")   /* Java heap                                 */ \
 115   f(mtClass,         "Class")       /* Java classes                              */ \
 116   f(mtThread,        "Thread")      /* thread objects                            */ \
 117   f(mtThreadStack,   "Thread Stack")                                                \
 118   f(mtCode,          "Code")        /* generated code                            */ \
 119   f(mtGC,            "GC")                                                          \
 120   f(mtCompiler,      "Compiler")                                                    \
 121   f(mtInternal,      "Internal")    /* memory used by VM, but does not belong to */ \
 122                                     /* any of above categories, and not used by  */ \
 123                                     /* NMT                                       */ \
 124   f(mtOther,         "Other")       /* memory not used by VM                     */ \
 125   f(mtSymbol,        "Symbol")                                                      \
 126   f(mtNMT,           "Native Memory Tracking")  /* memory used by NMT            */ \
 127   f(mtClassShared,   "Shared class space")      /* class data sharing            */ \
 128   f(mtChunk,         "Arena Chunk") /* chunk that holds content of arenas        */ \
 129   f(mtTest,          "Test")        /* Test type for verifying NMT               */ \
 130   f(mtTracing,       "Tracing")                                                     \
 131   f(mtLogging,       "Logging")                                                     \
 132   f(mtStatistics,    "Statistics")                                                  \
 133   f(mtArguments,     "Arguments")                                                   \
 134   f(mtModule,        "Module")                                                      \
 135   f(mtSafepoint,     "Safepoint")                                                   \
 136   f(mtSynchronizer,  "Synchronization")                                             \
 137   f(mtNone,          "Unknown")                                                     \
 138   //end
 139 
 140 #define MEMORY_TYPE_DECLARE_ENUM(type, human_readable) \
 141   type,
 142 
 143 /*
 144  * Memory types
 145  */
 146 enum MemoryType {
 147   MEMORY_TYPES_DO(MEMORY_TYPE_DECLARE_ENUM)
 148   mt_number_of_types   // number of memory types (mtDontTrack
 149                        // is not included as validate type)
 150 };
 151 
 152 typedef MemoryType MEMFLAGS;
 153 
 154 
 155 #if INCLUDE_NMT
 156 
 157 extern bool NMT_track_callsite;
 158 
 159 #else
 160 
 161 const bool NMT_track_callsite = false;
 162 
 163 #endif // INCLUDE_NMT
 164 
 165 class NativeCallStack;
 166 
 167 
 168 char* AllocateHeap(size_t size,
 169                    MEMFLAGS flags,
 170                    const NativeCallStack& stack,
 171                    AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 172 char* AllocateHeap(size_t size,
 173                    MEMFLAGS flags,
 174                    AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 175 
 176 char* ReallocateHeap(char *old,
 177                      size_t size,
 178                      MEMFLAGS flag,
 179                      AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 180 
 181 void FreeHeap(void* p);
 182 
 183 template <MEMFLAGS F> class CHeapObj ALLOCATION_SUPER_CLASS_SPEC {
 184  public:
 185   ALWAYSINLINE void* operator new(size_t size) throw() {
 186     return (void*)AllocateHeap(size, F);
 187   }
 188 
 189   ALWAYSINLINE void* operator new(size_t size,
 190                                   const NativeCallStack& stack) throw() {
 191     return (void*)AllocateHeap(size, F, stack);
 192   }
 193 
 194   ALWAYSINLINE void* operator new(size_t size, const std::nothrow_t&,
 195                                   const NativeCallStack& stack) throw() {
 196     return (void*)AllocateHeap(size, F, stack, AllocFailStrategy::RETURN_NULL);
 197   }
 198 
 199   ALWAYSINLINE void* operator new(size_t size, const std::nothrow_t&) throw() {
 200     return (void*)AllocateHeap(size, F, AllocFailStrategy::RETURN_NULL);
 201   }
 202 
 203   ALWAYSINLINE void* operator new[](size_t size) throw() {
 204     return (void*)AllocateHeap(size, F);
 205   }
 206 
 207   ALWAYSINLINE void* operator new[](size_t size,
 208                                   const NativeCallStack& stack) throw() {
 209     return (void*)AllocateHeap(size, F, stack);
 210   }
 211 
 212   ALWAYSINLINE void* operator new[](size_t size, const std::nothrow_t&,
 213                                     const NativeCallStack& stack) throw() {
 214     return (void*)AllocateHeap(size, F, stack, AllocFailStrategy::RETURN_NULL);
 215   }
 216 
 217   ALWAYSINLINE void* operator new[](size_t size, const std::nothrow_t&) throw() {
 218     return (void*)AllocateHeap(size, F, AllocFailStrategy::RETURN_NULL);
 219   }
 220 
 221   void  operator delete(void* p)     { FreeHeap(p); }
 222   void  operator delete [] (void* p) { FreeHeap(p); }
 223 };
 224 
 225 // Base class for objects allocated on the stack only.
 226 // Calling new or delete will result in fatal error.
 227 
 228 class StackObj ALLOCATION_SUPER_CLASS_SPEC {
 229  private:
 230   void* operator new(size_t size) throw();
 231   void* operator new [](size_t size) throw();
 232 #ifdef __IBMCPP__
 233  public:
 234 #endif
 235   void  operator delete(void* p);
 236   void  operator delete [](void* p);
 237 };
 238 
 239 // Base class for objects stored in Metaspace.
 240 // Calling delete will result in fatal error.
 241 //
 242 // Do not inherit from something with a vptr because this class does
 243 // not introduce one.  This class is used to allocate both shared read-only
 244 // and shared read-write classes.
 245 //
 246 
 247 class ClassLoaderData;
 248 class MetaspaceClosure;
 249 
 250 class MetaspaceObj {
 251   friend class VMStructs;
 252   // When CDS is enabled, all shared metaspace objects are mapped
 253   // into a single contiguous memory block, so we can use these
 254   // two pointers to quickly determine if something is in the
 255   // shared metaspace.
 256   //
 257   // When CDS is not enabled, both pointers are set to NULL.
 258   static void* _shared_metaspace_base; // (inclusive) low address
 259   static void* _shared_metaspace_top;  // (exclusive) high address
 260 
 261  public:
 262 
 263   // Returns true if the pointer points to a valid MetaspaceObj. A valid
 264   // MetaspaceObj is MetaWord-aligned and contained within either
 265   // non-shared or shared metaspace.
 266   static bool is_valid(const MetaspaceObj* p);
 267 
 268   static bool is_shared(const MetaspaceObj* p) {
 269     // If no shared metaspace regions are mapped, _shared_metaspace_{base,top} will
 270     // both be NULL and all values of p will be rejected quickly.
 271     return (((void*)p) < _shared_metaspace_top && ((void*)p) >= _shared_metaspace_base);
 272   }
 273   bool is_shared() const { return MetaspaceObj::is_shared(this); }
 274 
 275   void print_address_on(outputStream* st) const;  // nonvirtual address printing
 276 
 277   static void set_shared_metaspace_range(void* base, void* top) {
 278     _shared_metaspace_base = base;
 279     _shared_metaspace_top = top;
 280   }
 281   static void* shared_metaspace_base() { return _shared_metaspace_base; }
 282   static void* shared_metaspace_top()  { return _shared_metaspace_top;  }
 283 
 284 #define METASPACE_OBJ_TYPES_DO(f) \
 285   f(Class) \
 286   f(Symbol) \
 287   f(TypeArrayU1) \
 288   f(TypeArrayU2) \
 289   f(TypeArrayU4) \
 290   f(TypeArrayU8) \
 291   f(TypeArrayOther) \
 292   f(Method) \
 293   f(ConstMethod) \
 294   f(MethodData) \
 295   f(ConstantPool) \
 296   f(ConstantPoolCache) \
 297   f(Annotations) \
 298   f(MethodCounters)
 299 
 300 #define METASPACE_OBJ_TYPE_DECLARE(name) name ## Type,
 301 #define METASPACE_OBJ_TYPE_NAME_CASE(name) case name ## Type: return #name;
 302 
 303   enum Type {
 304     // Types are MetaspaceObj::ClassType, MetaspaceObj::SymbolType, etc
 305     METASPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_DECLARE)
 306     _number_of_types
 307   };
 308 
 309   static const char * type_name(Type type) {
 310     switch(type) {
 311     METASPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_NAME_CASE)
 312     default:
 313       ShouldNotReachHere();
 314       return NULL;
 315     }
 316   }
 317 
 318   static MetaspaceObj::Type array_type(size_t elem_size) {
 319     switch (elem_size) {
 320     case 1: return TypeArrayU1Type;
 321     case 2: return TypeArrayU2Type;
 322     case 4: return TypeArrayU4Type;
 323     case 8: return TypeArrayU8Type;
 324     default:
 325       return TypeArrayOtherType;
 326     }
 327   }
 328 
 329   void* operator new(size_t size, ClassLoaderData* loader_data,
 330                      size_t word_size,
 331                      Type type, Thread* thread) throw();
 332                      // can't use TRAPS from this header file.
 333   void operator delete(void* p) { ShouldNotCallThis(); }
 334 
 335   // Declare a *static* method with the same signature in any subclass of MetaspaceObj
 336   // that should be read-only by default. See symbol.hpp for an example. This function
 337   // is used by the templates in metaspaceClosure.hpp
 338   static bool is_read_only_by_default() { return false; }
 339 };
 340 
 341 // Base class for classes that constitute name spaces.
 342 
 343 class Arena;
 344 
 345 class AllStatic {
 346  public:
 347   AllStatic()  { ShouldNotCallThis(); }
 348   ~AllStatic() { ShouldNotCallThis(); }
 349 };
 350 
 351 
 352 extern char* resource_allocate_bytes(size_t size,
 353     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 354 extern char* resource_allocate_bytes(Thread* thread, size_t size,
 355     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 356 extern char* resource_reallocate_bytes( char *old, size_t old_size, size_t new_size,
 357     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 358 extern void resource_free_bytes( char *old, size_t size );
 359 
 360 //----------------------------------------------------------------------
 361 // Base class for objects allocated in the resource area per default.
 362 // Optionally, objects may be allocated on the C heap with
 363 // new(ResourceObj::C_HEAP) Foo(...) or in an Arena with new (&arena)
 364 // ResourceObj's can be allocated within other objects, but don't use
 365 // new or delete (allocation_type is unknown).  If new is used to allocate,
 366 // use delete to deallocate.
 367 class ResourceObj ALLOCATION_SUPER_CLASS_SPEC {
 368  public:
 369   enum allocation_type { STACK_OR_EMBEDDED = 0, RESOURCE_AREA, C_HEAP, ARENA, allocation_mask = 0x3 };
 370   static void set_allocation_type(address res, allocation_type type) NOT_DEBUG_RETURN;
 371 #ifdef ASSERT
 372  private:
 373   // When this object is allocated on stack the new() operator is not
 374   // called but garbage on stack may look like a valid allocation_type.
 375   // Store negated 'this' pointer when new() is called to distinguish cases.
 376   // Use second array's element for verification value to distinguish garbage.
 377   uintptr_t _allocation_t[2];
 378   bool is_type_set() const;
 379   void initialize_allocation_info();
 380  public:
 381   allocation_type get_allocation_type() const;
 382   bool allocated_on_stack()    const { return get_allocation_type() == STACK_OR_EMBEDDED; }
 383   bool allocated_on_res_area() const { return get_allocation_type() == RESOURCE_AREA; }
 384   bool allocated_on_C_heap()   const { return get_allocation_type() == C_HEAP; }
 385   bool allocated_on_arena()    const { return get_allocation_type() == ARENA; }
 386 protected:
 387   ResourceObj(); // default constructor
 388   ResourceObj(const ResourceObj& r); // default copy constructor
 389   ResourceObj& operator=(const ResourceObj& r); // default copy assignment
 390   ~ResourceObj();
 391 #endif // ASSERT
 392 
 393  public:
 394   void* operator new(size_t size, allocation_type type, MEMFLAGS flags) throw();
 395   void* operator new [](size_t size, allocation_type type, MEMFLAGS flags) throw();
 396   void* operator new(size_t size, const std::nothrow_t&  nothrow_constant,
 397       allocation_type type, MEMFLAGS flags) throw();
 398   void* operator new [](size_t size, const std::nothrow_t&  nothrow_constant,
 399       allocation_type type, MEMFLAGS flags) throw();
 400 
 401   void* operator new(size_t size, Arena *arena) throw();
 402 
 403   void* operator new [](size_t size, Arena *arena) throw();
 404 
 405   void* operator new(size_t size) throw() {
 406       address res = (address)resource_allocate_bytes(size);
 407       DEBUG_ONLY(set_allocation_type(res, RESOURCE_AREA);)
 408       return res;
 409   }
 410 
 411   void* operator new(size_t size, const std::nothrow_t& nothrow_constant) throw() {
 412       address res = (address)resource_allocate_bytes(size, AllocFailStrategy::RETURN_NULL);
 413       DEBUG_ONLY(if (res != NULL) set_allocation_type(res, RESOURCE_AREA);)
 414       return res;
 415   }
 416 
 417   void* operator new [](size_t size) throw() {
 418       address res = (address)resource_allocate_bytes(size);
 419       DEBUG_ONLY(set_allocation_type(res, RESOURCE_AREA);)
 420       return res;
 421   }
 422 
 423   void* operator new [](size_t size, const std::nothrow_t& nothrow_constant) throw() {
 424       address res = (address)resource_allocate_bytes(size, AllocFailStrategy::RETURN_NULL);
 425       DEBUG_ONLY(if (res != NULL) set_allocation_type(res, RESOURCE_AREA);)
 426       return res;
 427   }
 428 
 429   void  operator delete(void* p);
 430   void  operator delete [](void* p);
 431 };
 432 
 433 // One of the following macros must be used when allocating an array
 434 // or object to determine whether it should reside in the C heap on in
 435 // the resource area.
 436 
 437 #define NEW_RESOURCE_ARRAY(type, size)\
 438   (type*) resource_allocate_bytes((size) * sizeof(type))
 439 
 440 #define NEW_RESOURCE_ARRAY_RETURN_NULL(type, size)\
 441   (type*) resource_allocate_bytes((size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 442 
 443 #define NEW_RESOURCE_ARRAY_IN_THREAD(thread, type, size)\
 444   (type*) resource_allocate_bytes(thread, (size) * sizeof(type))
 445 
 446 #define NEW_RESOURCE_ARRAY_IN_THREAD_RETURN_NULL(thread, type, size)\
 447   (type*) resource_allocate_bytes(thread, (size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 448 
 449 #define REALLOC_RESOURCE_ARRAY(type, old, old_size, new_size)\
 450   (type*) resource_reallocate_bytes((char*)(old), (old_size) * sizeof(type), (new_size) * sizeof(type))
 451 
 452 #define REALLOC_RESOURCE_ARRAY_RETURN_NULL(type, old, old_size, new_size)\
 453   (type*) resource_reallocate_bytes((char*)(old), (old_size) * sizeof(type),\
 454                                     (new_size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 455 
 456 #define FREE_RESOURCE_ARRAY(type, old, size)\
 457   resource_free_bytes((char*)(old), (size) * sizeof(type))
 458 
 459 #define FREE_FAST(old)\
 460     /* nop */
 461 
 462 #define NEW_RESOURCE_OBJ(type)\
 463   NEW_RESOURCE_ARRAY(type, 1)
 464 
 465 #define NEW_RESOURCE_OBJ_RETURN_NULL(type)\
 466   NEW_RESOURCE_ARRAY_RETURN_NULL(type, 1)
 467 
 468 #define NEW_C_HEAP_ARRAY3(type, size, memflags, pc, allocfail)\
 469   (type*) AllocateHeap((size) * sizeof(type), memflags, pc, allocfail)
 470 
 471 #define NEW_C_HEAP_ARRAY2(type, size, memflags, pc)\
 472   (type*) (AllocateHeap((size) * sizeof(type), memflags, pc))
 473 
 474 #define NEW_C_HEAP_ARRAY(type, size, memflags)\
 475   (type*) (AllocateHeap((size) * sizeof(type), memflags))
 476 
 477 #define NEW_C_HEAP_ARRAY2_RETURN_NULL(type, size, memflags, pc)\
 478   NEW_C_HEAP_ARRAY3(type, (size), memflags, pc, AllocFailStrategy::RETURN_NULL)
 479 
 480 #define NEW_C_HEAP_ARRAY_RETURN_NULL(type, size, memflags)\
 481   NEW_C_HEAP_ARRAY3(type, (size), memflags, CURRENT_PC, AllocFailStrategy::RETURN_NULL)
 482 
 483 #define REALLOC_C_HEAP_ARRAY(type, old, size, memflags)\
 484   (type*) (ReallocateHeap((char*)(old), (size) * sizeof(type), memflags))
 485 
 486 #define REALLOC_C_HEAP_ARRAY_RETURN_NULL(type, old, size, memflags)\
 487   (type*) (ReallocateHeap((char*)(old), (size) * sizeof(type), memflags, AllocFailStrategy::RETURN_NULL))
 488 
 489 #define FREE_C_HEAP_ARRAY(type, old) \
 490   FreeHeap((char*)(old))
 491 
 492 // allocate type in heap without calling ctor
 493 #define NEW_C_HEAP_OBJ(type, memflags)\
 494   NEW_C_HEAP_ARRAY(type, 1, memflags)
 495 
 496 #define NEW_C_HEAP_OBJ_RETURN_NULL(type, memflags)\
 497   NEW_C_HEAP_ARRAY_RETURN_NULL(type, 1, memflags)
 498 
 499 // deallocate obj of type in heap without calling dtor
 500 #define FREE_C_HEAP_OBJ(objname)\
 501   FreeHeap((char*)objname);
 502 
 503 // for statistics
 504 #ifndef PRODUCT
 505 class AllocStats : StackObj {
 506   julong start_mallocs, start_frees;
 507   julong start_malloc_bytes, start_mfree_bytes, start_res_bytes;
 508  public:
 509   AllocStats();
 510 
 511   julong num_mallocs();    // since creation of receiver
 512   julong alloc_bytes();
 513   julong num_frees();
 514   julong free_bytes();
 515   julong resource_bytes();
 516   void   print();
 517 };
 518 #endif
 519 
 520 
 521 //------------------------------ReallocMark---------------------------------
 522 // Code which uses REALLOC_RESOURCE_ARRAY should check an associated
 523 // ReallocMark, which is declared in the same scope as the reallocated
 524 // pointer.  Any operation that could __potentially__ cause a reallocation
 525 // should check the ReallocMark.
 526 class ReallocMark: public StackObj {
 527 protected:
 528   NOT_PRODUCT(int _nesting;)
 529 
 530 public:
 531   ReallocMark()   PRODUCT_RETURN;
 532   void check()    PRODUCT_RETURN;
 533 };
 534 
 535 // Helper class to allocate arrays that may become large.
 536 // Uses the OS malloc for allocations smaller than ArrayAllocatorMallocLimit
 537 // and uses mapped memory for larger allocations.
 538 // Most OS mallocs do something similar but Solaris malloc does not revert
 539 // to mapped memory for large allocations. By default ArrayAllocatorMallocLimit
 540 // is set so that we always use malloc except for Solaris where we set the
 541 // limit to get mapped memory.
 542 template <class E>
 543 class ArrayAllocator : public AllStatic {
 544  private:
 545   static bool should_use_malloc(size_t length);
 546 
 547   static E* allocate_malloc(size_t length, MEMFLAGS flags);
 548   static E* allocate_mmap(size_t length, MEMFLAGS flags);
 549 
 550   static void free_malloc(E* addr, size_t length);
 551   static void free_mmap(E* addr, size_t length);
 552 
 553  public:
 554   static E* allocate(size_t length, MEMFLAGS flags);
 555   static E* reallocate(E* old_addr, size_t old_length, size_t new_length, MEMFLAGS flags);
 556   static void free(E* addr, size_t length);
 557 };
 558 
 559 // Uses mmaped memory for all allocations. All allocations are initially
 560 // zero-filled. No pre-touching.
 561 template <class E>
 562 class MmapArrayAllocator : public AllStatic {
 563  private:
 564   static size_t size_for(size_t length);
 565 
 566  public:
 567   static E* allocate_or_null(size_t length, MEMFLAGS flags);
 568   static E* allocate(size_t length, MEMFLAGS flags);
 569   static void free(E* addr, size_t length);
 570 };
 571 
 572 // Uses malloc:ed memory for all allocations.
 573 template <class E>
 574 class MallocArrayAllocator : public AllStatic {
 575  public:
 576   static size_t size_for(size_t length);
 577 
 578   static E* allocate(size_t length, MEMFLAGS flags);
 579   static void free(E* addr);
 580 };
 581 
 582 #endif // SHARE_MEMORY_ALLOCATION_HPP