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(mtArguments,     "Arguments")                                                   \
 133   f(mtModule,        "Module")                                                      \
 134   f(mtSafepoint,     "Safepoint")                                                   \
 135   f(mtSynchronizer,  "Synchronization")                                             \
 136   f(mtNone,          "Unknown")                                                     \
 137   //end
 138 
 139 #define MEMORY_TYPE_DECLARE_ENUM(type, human_readable) \
 140   type,
 141 
 142 /*
 143  * Memory types
 144  */
 145 enum MemoryType {
 146   MEMORY_TYPES_DO(MEMORY_TYPE_DECLARE_ENUM)
 147   mt_number_of_types   // number of memory types (mtDontTrack
 148                        // is not included as validate type)
 149 };
 150 
 151 typedef MemoryType MEMFLAGS;
 152 
 153 
 154 #if INCLUDE_NMT
 155 
 156 extern bool NMT_track_callsite;
 157 
 158 #else
 159 
 160 const bool NMT_track_callsite = false;
 161 
 162 #endif // INCLUDE_NMT
 163 
 164 class NativeCallStack;
 165 
 166 
 167 char* AllocateHeap(size_t size,
 168                    MEMFLAGS flags,
 169                    const NativeCallStack& stack,
 170                    AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 171 char* AllocateHeap(size_t size,
 172                    MEMFLAGS flags,
 173                    AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 174 
 175 char* ReallocateHeap(char *old,
 176                      size_t size,
 177                      MEMFLAGS flag,
 178                      AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 179 
 180 void FreeHeap(void* p);
 181 
 182 template <MEMFLAGS F> class CHeapObj ALLOCATION_SUPER_CLASS_SPEC {
 183  public:
 184   ALWAYSINLINE void* operator new(size_t size) throw() {
 185     return (void*)AllocateHeap(size, F);
 186   }
 187 
 188   ALWAYSINLINE void* operator new(size_t size,
 189                                   const NativeCallStack& stack) throw() {
 190     return (void*)AllocateHeap(size, F, stack);
 191   }
 192 
 193   ALWAYSINLINE void* operator new(size_t size, const std::nothrow_t&,
 194                                   const NativeCallStack& stack) throw() {
 195     return (void*)AllocateHeap(size, F, stack, AllocFailStrategy::RETURN_NULL);
 196   }
 197 
 198   ALWAYSINLINE void* operator new(size_t size, const std::nothrow_t&) throw() {
 199     return (void*)AllocateHeap(size, F, AllocFailStrategy::RETURN_NULL);
 200   }
 201 
 202   ALWAYSINLINE void* operator new[](size_t size) throw() {
 203     return (void*)AllocateHeap(size, F);
 204   }
 205 
 206   ALWAYSINLINE void* operator new[](size_t size,
 207                                   const NativeCallStack& stack) throw() {
 208     return (void*)AllocateHeap(size, F, stack);
 209   }
 210 
 211   ALWAYSINLINE void* operator new[](size_t size, const std::nothrow_t&,
 212                                     const NativeCallStack& stack) throw() {
 213     return (void*)AllocateHeap(size, F, stack, AllocFailStrategy::RETURN_NULL);
 214   }
 215 
 216   ALWAYSINLINE void* operator new[](size_t size, const std::nothrow_t&) throw() {
 217     return (void*)AllocateHeap(size, F, AllocFailStrategy::RETURN_NULL);
 218   }
 219 
 220   void  operator delete(void* p)     { FreeHeap(p); }
 221   void  operator delete [] (void* p) { FreeHeap(p); }
 222 };
 223 
 224 // Base class for objects allocated on the stack only.
 225 // Calling new or delete will result in fatal error.
 226 
 227 class StackObj ALLOCATION_SUPER_CLASS_SPEC {
 228  private:
 229   void* operator new(size_t size) throw();
 230   void* operator new [](size_t size) throw();
 231 #ifdef __IBMCPP__
 232  public:
 233 #endif
 234   void  operator delete(void* p);
 235   void  operator delete [](void* p);
 236 };
 237 
 238 // Base class for objects stored in Metaspace.
 239 // Calling delete will result in fatal error.
 240 //
 241 // Do not inherit from something with a vptr because this class does
 242 // not introduce one.  This class is used to allocate both shared read-only
 243 // and shared read-write classes.
 244 //
 245 
 246 class ClassLoaderData;
 247 class MetaspaceClosure;
 248 
 249 class MetaspaceObj {
 250   friend class VMStructs;
 251   // When CDS is enabled, all shared metaspace objects are mapped
 252   // into a single contiguous memory block, so we can use these
 253   // two pointers to quickly determine if something is in the
 254   // shared metaspace.
 255   //
 256   // When CDS is not enabled, both pointers are set to NULL.
 257   static void* _shared_metaspace_base; // (inclusive) low address
 258   static void* _shared_metaspace_top;  // (exclusive) high address
 259 
 260  public:
 261 
 262   // Returns true if the pointer points to a valid MetaspaceObj. A valid
 263   // MetaspaceObj is MetaWord-aligned and contained within either
 264   // non-shared or shared metaspace.
 265   static bool is_valid(const MetaspaceObj* p);
 266 
 267   static bool is_shared(const MetaspaceObj* p) {
 268     // If no shared metaspace regions are mapped, _shared_metaspace_{base,top} will
 269     // both be NULL and all values of p will be rejected quickly.
 270     return (((void*)p) < _shared_metaspace_top && ((void*)p) >= _shared_metaspace_base);
 271   }
 272   bool is_shared() const { return MetaspaceObj::is_shared(this); }
 273 
 274   void print_address_on(outputStream* st) const;  // nonvirtual address printing
 275 
 276   static void set_shared_metaspace_range(void* base, void* top) {
 277     _shared_metaspace_base = base;
 278     _shared_metaspace_top = top;
 279   }
 280   static void* shared_metaspace_base() { return _shared_metaspace_base; }
 281   static void* shared_metaspace_top()  { return _shared_metaspace_top;  }
 282 
 283 #define METASPACE_OBJ_TYPES_DO(f) \
 284   f(Class) \
 285   f(Symbol) \
 286   f(TypeArrayU1) \
 287   f(TypeArrayU2) \
 288   f(TypeArrayU4) \
 289   f(TypeArrayU8) \
 290   f(TypeArrayOther) \
 291   f(Method) \
 292   f(ConstMethod) \
 293   f(MethodData) \
 294   f(ConstantPool) \
 295   f(ConstantPoolCache) \
 296   f(Annotations) \
 297   f(MethodCounters)
 298 
 299 #define METASPACE_OBJ_TYPE_DECLARE(name) name ## Type,
 300 #define METASPACE_OBJ_TYPE_NAME_CASE(name) case name ## Type: return #name;
 301 
 302   enum Type {
 303     // Types are MetaspaceObj::ClassType, MetaspaceObj::SymbolType, etc
 304     METASPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_DECLARE)
 305     _number_of_types
 306   };
 307 
 308   static const char * type_name(Type type) {
 309     switch(type) {
 310     METASPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_NAME_CASE)
 311     default:
 312       ShouldNotReachHere();
 313       return NULL;
 314     }
 315   }
 316 
 317   static MetaspaceObj::Type array_type(size_t elem_size) {
 318     switch (elem_size) {
 319     case 1: return TypeArrayU1Type;
 320     case 2: return TypeArrayU2Type;
 321     case 4: return TypeArrayU4Type;
 322     case 8: return TypeArrayU8Type;
 323     default:
 324       return TypeArrayOtherType;
 325     }
 326   }
 327 
 328   void* operator new(size_t size, ClassLoaderData* loader_data,
 329                      size_t word_size,
 330                      Type type, Thread* thread) throw();
 331                      // can't use TRAPS from this header file.
 332   void operator delete(void* p) { ShouldNotCallThis(); }
 333 
 334   // Declare a *static* method with the same signature in any subclass of MetaspaceObj
 335   // that should be read-only by default. See symbol.hpp for an example. This function
 336   // is used by the templates in metaspaceClosure.hpp
 337   static bool is_read_only_by_default() { return false; }
 338 };
 339 
 340 // Base class for classes that constitute name spaces.
 341 
 342 class Arena;
 343 
 344 class AllStatic {
 345  public:
 346   AllStatic()  { ShouldNotCallThis(); }
 347   ~AllStatic() { ShouldNotCallThis(); }
 348 };
 349 
 350 
 351 extern char* resource_allocate_bytes(size_t size,
 352     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 353 extern char* resource_allocate_bytes(Thread* thread, size_t size,
 354     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 355 extern char* resource_reallocate_bytes( char *old, size_t old_size, size_t new_size,
 356     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 357 extern void resource_free_bytes( char *old, size_t size );
 358 
 359 //----------------------------------------------------------------------
 360 // Base class for objects allocated in the resource area per default.
 361 // Optionally, objects may be allocated on the C heap with
 362 // new(ResourceObj::C_HEAP) Foo(...) or in an Arena with new (&arena)
 363 // ResourceObj's can be allocated within other objects, but don't use
 364 // new or delete (allocation_type is unknown).  If new is used to allocate,
 365 // use delete to deallocate.
 366 class ResourceObj ALLOCATION_SUPER_CLASS_SPEC {
 367  public:
 368   enum allocation_type { STACK_OR_EMBEDDED = 0, RESOURCE_AREA, C_HEAP, ARENA, allocation_mask = 0x3 };
 369   static void set_allocation_type(address res, allocation_type type) NOT_DEBUG_RETURN;
 370 #ifdef ASSERT
 371  private:
 372   // When this object is allocated on stack the new() operator is not
 373   // called but garbage on stack may look like a valid allocation_type.
 374   // Store negated 'this' pointer when new() is called to distinguish cases.
 375   // Use second array's element for verification value to distinguish garbage.
 376   uintptr_t _allocation_t[2];
 377   bool is_type_set() const;
 378   void initialize_allocation_info();
 379  public:
 380   allocation_type get_allocation_type() const;
 381   bool allocated_on_stack()    const { return get_allocation_type() == STACK_OR_EMBEDDED; }
 382   bool allocated_on_res_area() const { return get_allocation_type() == RESOURCE_AREA; }
 383   bool allocated_on_C_heap()   const { return get_allocation_type() == C_HEAP; }
 384   bool allocated_on_arena()    const { return get_allocation_type() == ARENA; }
 385 protected:
 386   ResourceObj(); // default constructor
 387   ResourceObj(const ResourceObj& r); // default copy constructor
 388   ResourceObj& operator=(const ResourceObj& r); // default copy assignment
 389   ~ResourceObj();
 390 #endif // ASSERT
 391 
 392  public:
 393   void* operator new(size_t size, allocation_type type, MEMFLAGS flags) throw();
 394   void* operator new [](size_t size, allocation_type type, MEMFLAGS flags) throw();
 395   void* operator new(size_t size, const std::nothrow_t&  nothrow_constant,
 396       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 
 400   void* operator new(size_t size, Arena *arena) throw();
 401 
 402   void* operator new [](size_t size, Arena *arena) throw();
 403 
 404   void* operator new(size_t size) throw() {
 405       address res = (address)resource_allocate_bytes(size);
 406       DEBUG_ONLY(set_allocation_type(res, RESOURCE_AREA);)
 407       return res;
 408   }
 409 
 410   void* operator new(size_t size, const std::nothrow_t& nothrow_constant) throw() {
 411       address res = (address)resource_allocate_bytes(size, AllocFailStrategy::RETURN_NULL);
 412       DEBUG_ONLY(if (res != NULL) set_allocation_type(res, RESOURCE_AREA);)
 413       return res;
 414   }
 415 
 416   void* operator new [](size_t size) throw() {
 417       address res = (address)resource_allocate_bytes(size);
 418       DEBUG_ONLY(set_allocation_type(res, RESOURCE_AREA);)
 419       return res;
 420   }
 421 
 422   void* operator new [](size_t size, const std::nothrow_t& nothrow_constant) throw() {
 423       address res = (address)resource_allocate_bytes(size, AllocFailStrategy::RETURN_NULL);
 424       DEBUG_ONLY(if (res != NULL) set_allocation_type(res, RESOURCE_AREA);)
 425       return res;
 426   }
 427 
 428   void  operator delete(void* p);
 429   void  operator delete [](void* p);
 430 };
 431 
 432 // One of the following macros must be used when allocating an array
 433 // or object to determine whether it should reside in the C heap on in
 434 // the resource area.
 435 
 436 #define NEW_RESOURCE_ARRAY(type, size)\
 437   (type*) resource_allocate_bytes((size) * sizeof(type))
 438 
 439 #define NEW_RESOURCE_ARRAY_RETURN_NULL(type, size)\
 440   (type*) resource_allocate_bytes((size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 441 
 442 #define NEW_RESOURCE_ARRAY_IN_THREAD(thread, type, size)\
 443   (type*) resource_allocate_bytes(thread, (size) * sizeof(type))
 444 
 445 #define NEW_RESOURCE_ARRAY_IN_THREAD_RETURN_NULL(thread, type, size)\
 446   (type*) resource_allocate_bytes(thread, (size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 447 
 448 #define REALLOC_RESOURCE_ARRAY(type, old, old_size, new_size)\
 449   (type*) resource_reallocate_bytes((char*)(old), (old_size) * sizeof(type), (new_size) * sizeof(type))
 450 
 451 #define REALLOC_RESOURCE_ARRAY_RETURN_NULL(type, old, old_size, new_size)\
 452   (type*) resource_reallocate_bytes((char*)(old), (old_size) * sizeof(type),\
 453                                     (new_size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 454 
 455 #define FREE_RESOURCE_ARRAY(type, old, size)\
 456   resource_free_bytes((char*)(old), (size) * sizeof(type))
 457 
 458 #define FREE_FAST(old)\
 459     /* nop */
 460 
 461 #define NEW_RESOURCE_OBJ(type)\
 462   NEW_RESOURCE_ARRAY(type, 1)
 463 
 464 #define NEW_RESOURCE_OBJ_RETURN_NULL(type)\
 465   NEW_RESOURCE_ARRAY_RETURN_NULL(type, 1)
 466 
 467 #define NEW_C_HEAP_ARRAY3(type, size, memflags, pc, allocfail)\
 468   (type*) AllocateHeap((size) * sizeof(type), memflags, pc, allocfail)
 469 
 470 #define NEW_C_HEAP_ARRAY2(type, size, memflags, pc)\
 471   (type*) (AllocateHeap((size) * sizeof(type), memflags, pc))
 472 
 473 #define NEW_C_HEAP_ARRAY(type, size, memflags)\
 474   (type*) (AllocateHeap((size) * sizeof(type), memflags))
 475 
 476 #define NEW_C_HEAP_ARRAY2_RETURN_NULL(type, size, memflags, pc)\
 477   NEW_C_HEAP_ARRAY3(type, (size), memflags, pc, AllocFailStrategy::RETURN_NULL)
 478 
 479 #define NEW_C_HEAP_ARRAY_RETURN_NULL(type, size, memflags)\
 480   NEW_C_HEAP_ARRAY3(type, (size), memflags, CURRENT_PC, AllocFailStrategy::RETURN_NULL)
 481 
 482 #define REALLOC_C_HEAP_ARRAY(type, old, size, memflags)\
 483   (type*) (ReallocateHeap((char*)(old), (size) * sizeof(type), memflags))
 484 
 485 #define REALLOC_C_HEAP_ARRAY_RETURN_NULL(type, old, size, memflags)\
 486   (type*) (ReallocateHeap((char*)(old), (size) * sizeof(type), memflags, AllocFailStrategy::RETURN_NULL))
 487 
 488 #define FREE_C_HEAP_ARRAY(type, old) \
 489   FreeHeap((char*)(old))
 490 
 491 // allocate type in heap without calling ctor
 492 #define NEW_C_HEAP_OBJ(type, memflags)\
 493   NEW_C_HEAP_ARRAY(type, 1, memflags)
 494 
 495 #define NEW_C_HEAP_OBJ_RETURN_NULL(type, memflags)\
 496   NEW_C_HEAP_ARRAY_RETURN_NULL(type, 1, memflags)
 497 
 498 // deallocate obj of type in heap without calling dtor
 499 #define FREE_C_HEAP_OBJ(objname)\
 500   FreeHeap((char*)objname);
 501 
 502 // for statistics
 503 #ifndef PRODUCT
 504 class AllocStats : StackObj {
 505   julong start_mallocs, start_frees;
 506   julong start_malloc_bytes, start_mfree_bytes, start_res_bytes;
 507  public:
 508   AllocStats();
 509 
 510   julong num_mallocs();    // since creation of receiver
 511   julong alloc_bytes();
 512   julong num_frees();
 513   julong free_bytes();
 514   julong resource_bytes();
 515   void   print();
 516 };
 517 #endif
 518 
 519 
 520 //------------------------------ReallocMark---------------------------------
 521 // Code which uses REALLOC_RESOURCE_ARRAY should check an associated
 522 // ReallocMark, which is declared in the same scope as the reallocated
 523 // pointer.  Any operation that could __potentially__ cause a reallocation
 524 // should check the ReallocMark.
 525 class ReallocMark: public StackObj {
 526 protected:
 527   NOT_PRODUCT(int _nesting;)
 528 
 529 public:
 530   ReallocMark()   PRODUCT_RETURN;
 531   void check()    PRODUCT_RETURN;
 532 };
 533 
 534 // Helper class to allocate arrays that may become large.
 535 // Uses the OS malloc for allocations smaller than ArrayAllocatorMallocLimit
 536 // and uses mapped memory for larger allocations.
 537 // Most OS mallocs do something similar but Solaris malloc does not revert
 538 // to mapped memory for large allocations. By default ArrayAllocatorMallocLimit
 539 // is set so that we always use malloc except for Solaris where we set the
 540 // limit to get mapped memory.
 541 template <class E>
 542 class ArrayAllocator : public AllStatic {
 543  private:
 544   static bool should_use_malloc(size_t length);
 545 
 546   static E* allocate_malloc(size_t length, MEMFLAGS flags);
 547   static E* allocate_mmap(size_t length, MEMFLAGS flags);
 548 
 549   static void free_malloc(E* addr, size_t length);
 550   static void free_mmap(E* addr, size_t length);
 551 
 552  public:
 553   static E* allocate(size_t length, MEMFLAGS flags);
 554   static E* reallocate(E* old_addr, size_t old_length, size_t new_length, MEMFLAGS flags);
 555   static void free(E* addr, size_t length);
 556 };
 557 
 558 // Uses mmaped memory for all allocations. All allocations are initially
 559 // zero-filled. No pre-touching.
 560 template <class E>
 561 class MmapArrayAllocator : public AllStatic {
 562  private:
 563   static size_t size_for(size_t length);
 564 
 565  public:
 566   static E* allocate_or_null(size_t length, MEMFLAGS flags);
 567   static E* allocate(size_t length, MEMFLAGS flags);
 568   static void free(E* addr, size_t length);
 569 };
 570 
 571 // Uses malloc:ed memory for all allocations.
 572 template <class E>
 573 class MallocArrayAllocator : public AllStatic {
 574  public:
 575   static size_t size_for(size_t length);
 576 
 577   static E* allocate(size_t length, MEMFLAGS flags);
 578   static void free(E* addr);
 579 };
 580 
 581 #endif // SHARE_MEMORY_ALLOCATION_HPP