1 /*
  2  * Copyright (c) 1997, 2022, 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 class JavaThread;
 37 
 38 class AllocFailStrategy {
 39 public:
 40   enum AllocFailEnum { EXIT_OOM, RETURN_NULL };
 41 };
 42 typedef AllocFailStrategy::AllocFailEnum AllocFailType;
 43 
 44 // The virtual machine must never call one of the implicitly declared
 45 // global allocation or deletion functions.  (Such calls may result in
 46 // link-time or run-time errors.)  For convenience and documentation of
 47 // intended use, classes in the virtual machine may be derived from one
 48 // of the following allocation classes, some of which define allocation
 49 // and deletion functions.
 50 // Note: std::malloc and std::free should never called directly.
 51 
 52 //
 53 // For objects allocated in the resource area (see resourceArea.hpp).
 54 // - ResourceObj
 55 //
 56 // For objects allocated in the C-heap (managed by: free & malloc and tracked with NMT)
 57 // - CHeapObj
 58 //
 59 // For objects allocated on the stack.
 60 // - StackObj
 61 //
 62 // For classes used as name spaces.
 63 // - AllStatic
 64 //
 65 // For classes in Metaspace (class data)
 66 // - MetaspaceObj
 67 //
 68 // The printable subclasses are used for debugging and define virtual
 69 // member functions for printing. Classes that avoid allocating the
 70 // vtbl entries in the objects should therefore not be the printable
 71 // subclasses.
 72 //
 73 // The following macros and function should be used to allocate memory
 74 // directly in the resource area or in the C-heap, The _OBJ variants
 75 // of the NEW/FREE_C_HEAP macros are used for alloc/dealloc simple
 76 // objects which are not inherited from CHeapObj, note constructor and
 77 // destructor are not called. The preferable way to allocate objects
 78 // is using the new operator.
 79 //
 80 // WARNING: The array variant must only be used for a homogenous array
 81 // where all objects are of the exact type specified. If subtypes are
 82 // stored in the array then must pay attention to calling destructors
 83 // at needed.
 84 //
 85 // NEW_RESOURCE_ARRAY*
 86 // REALLOC_RESOURCE_ARRAY*
 87 // FREE_RESOURCE_ARRAY*
 88 // NEW_RESOURCE_OBJ*
 89 // NEW_C_HEAP_ARRAY*
 90 // REALLOC_C_HEAP_ARRAY*
 91 // FREE_C_HEAP_ARRAY*
 92 // NEW_C_HEAP_OBJ*
 93 // FREE_C_HEAP_OBJ
 94 //
 95 // char* AllocateHeap(size_t size, MEMFLAGS flags, const NativeCallStack& stack, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 96 // char* AllocateHeap(size_t size, MEMFLAGS flags, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 97 // char* ReallocateHeap(char *old, size_t size, MEMFLAGS flag, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 98 // void FreeHeap(void* p);
 99 //
100 // In non product mode we introduce a super class for all allocation classes
101 // that supports printing.
102 // We avoid the superclass in product mode to save space.
103 
104 #ifdef PRODUCT
105 #define ALLOCATION_SUPER_CLASS_SPEC
106 #else
107 #define ALLOCATION_SUPER_CLASS_SPEC : public AllocatedObj
108 class AllocatedObj {
109  public:
110   // Printing support
111   void print() const;
112   void print_value() const;
113 
114   virtual void print_on(outputStream* st) const;
115   virtual void print_value_on(outputStream* st) const;
116 };
117 #endif
118 
119 #define MEMORY_TYPES_DO(f)                                                           \
120   /* Memory type by sub systems. It occupies lower byte. */                          \
121   f(mtJavaHeap,       "Java Heap")   /* Java heap                                 */ \
122   f(mtClass,          "Class")       /* Java classes                              */ \
123   f(mtThread,         "Thread")      /* thread objects                            */ \
124   f(mtThreadStack,    "Thread Stack")                                                \
125   f(mtCode,           "Code")        /* generated code                            */ \
126   f(mtGC,             "GC")                                                          \
127   f(mtGCCardSet,      "GCCardSet")   /* G1 card set remembered set                */ \
128   f(mtCompiler,       "Compiler")                                                    \
129   f(mtJVMCI,          "JVMCI")                                                       \
130   f(mtInternal,       "Internal")    /* memory used by VM, but does not belong to */ \
131                                      /* any of above categories, and not used by  */ \
132                                      /* NMT                                       */ \
133   f(mtOther,          "Other")       /* memory not used by VM                     */ \
134   f(mtSymbol,         "Symbol")                                                      \
135   f(mtNMT,            "Native Memory Tracking")  /* memory used by NMT            */ \
136   f(mtClassShared,    "Shared class space")      /* class data sharing            */ \
137   f(mtChunk,          "Arena Chunk") /* chunk that holds content of arenas        */ \
138   f(mtTest,           "Test")        /* Test type for verifying NMT               */ \
139   f(mtTracing,        "Tracing")                                                     \
140   f(mtLogging,        "Logging")                                                     \
141   f(mtStatistics,     "Statistics")                                                  \
142   f(mtArguments,      "Arguments")                                                   \
143   f(mtModule,         "Module")                                                      \
144   f(mtSafepoint,      "Safepoint")                                                   \
145   f(mtSynchronizer,   "Synchronization")                                             \
146   f(mtServiceability, "Serviceability")                                              \
147   f(mtMetaspace,      "Metaspace")                                                   \
148   f(mtStringDedup,    "String Deduplication")                                        \
149   f(mtObjectMonitor,  "Object Monitors")                                             \
150   f(mtNone,           "Unknown")                                                     \
151   //end
152 
153 #define MEMORY_TYPE_DECLARE_ENUM(type, human_readable) \
154   type,
155 
156 /*
157  * Memory types
158  */
159 enum class MEMFLAGS {
160   MEMORY_TYPES_DO(MEMORY_TYPE_DECLARE_ENUM)
161   mtValueTypes,        // memory for buffered value types
162   mt_number_of_types   // number of memory types (mtDontTrack
163                        // is not included as validate type)
164 };
165 
166 #define MEMORY_TYPE_SHORTNAME(type, human_readable) \
167   constexpr MEMFLAGS type = MEMFLAGS::type;
168 
169 // Generate short aliases for the enum values. E.g. mtGC instead of MEMFLAGS::mtGC.
170 MEMORY_TYPES_DO(MEMORY_TYPE_SHORTNAME)
171 
172 // Make an int version of the sentinel end value.
173 constexpr int mt_number_of_types = static_cast<int>(MEMFLAGS::mt_number_of_types);
174 
175 extern bool NMT_track_callsite;
176 
177 class NativeCallStack;
178 
179 
180 char* AllocateHeap(size_t size,
181                    MEMFLAGS flags,
182                    const NativeCallStack& stack,
183                    AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
184 char* AllocateHeap(size_t size,
185                    MEMFLAGS flags,
186                    AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
187 
188 char* ReallocateHeap(char *old,
189                      size_t size,
190                      MEMFLAGS flag,
191                      AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
192 
193 // handles NULL pointers
194 void FreeHeap(void* p);
195 
196 template <MEMFLAGS F> class CHeapObj ALLOCATION_SUPER_CLASS_SPEC {
197  public:
198   ALWAYSINLINE void* operator new(size_t size) throw() {
199     return (void*)AllocateHeap(size, F);
200   }
201 
202   ALWAYSINLINE void* operator new(size_t size,
203                                   const NativeCallStack& stack) throw() {
204     return (void*)AllocateHeap(size, F, stack);
205   }
206 
207   ALWAYSINLINE void* operator new(size_t size, const std::nothrow_t&,
208                                   const NativeCallStack& stack) throw() {
209     return (void*)AllocateHeap(size, F, stack, AllocFailStrategy::RETURN_NULL);
210   }
211 
212   ALWAYSINLINE void* operator new(size_t size, const std::nothrow_t&) throw() {
213     return (void*)AllocateHeap(size, F, AllocFailStrategy::RETURN_NULL);
214   }
215 
216   ALWAYSINLINE void* operator new[](size_t size) throw() {
217     return (void*)AllocateHeap(size, F);
218   }
219 
220   ALWAYSINLINE void* operator new[](size_t size,
221                                   const NativeCallStack& stack) throw() {
222     return (void*)AllocateHeap(size, F, stack);
223   }
224 
225   ALWAYSINLINE void* operator new[](size_t size, const std::nothrow_t&,
226                                     const NativeCallStack& stack) throw() {
227     return (void*)AllocateHeap(size, F, stack, AllocFailStrategy::RETURN_NULL);
228   }
229 
230   ALWAYSINLINE void* operator new[](size_t size, const std::nothrow_t&) throw() {
231     return (void*)AllocateHeap(size, F, AllocFailStrategy::RETURN_NULL);
232   }
233 
234   void  operator delete(void* p)     { FreeHeap(p); }
235   void  operator delete [] (void* p) { FreeHeap(p); }
236 };
237 
238 // Base class for objects allocated on the stack only.
239 // Calling new or delete will result in fatal error.
240 
241 class StackObj ALLOCATION_SUPER_CLASS_SPEC {
242  private:
243   void* operator new(size_t size) throw();
244   void* operator new [](size_t size) throw();
245   void  operator delete(void* p);
246   void  operator delete [](void* p);
247 };
248 
249 // Base class for objects stored in Metaspace.
250 // Calling delete will result in fatal error.
251 //
252 // Do not inherit from something with a vptr because this class does
253 // not introduce one.  This class is used to allocate both shared read-only
254 // and shared read-write classes.
255 //
256 
257 class ClassLoaderData;
258 class MetaspaceClosure;
259 
260 class MetaspaceObj {
261   // There are functions that all subtypes of MetaspaceObj are expected
262   // to implement, so that templates which are defined for this class hierarchy
263   // can work uniformly. Within the sub-hierarchy of Metadata, these are virtuals.
264   // Elsewhere in the hierarchy of MetaspaceObj, type(), size(), and/or on_stack()
265   // can be static if constant.
266   //
267   // The following functions are required by MetaspaceClosure:
268   //   void metaspace_pointers_do(MetaspaceClosure* it) { <walk my refs> }
269   //   int size() const { return align_up(sizeof(<This>), wordSize) / wordSize; }
270   //   MetaspaceObj::Type type() const { return <This>Type; }
271   //
272   // The following functions are required by MetadataFactory::free_metadata():
273   //   bool on_stack() { return false; }
274   //   void deallocate_contents(ClassLoaderData* loader_data);
275 
276   friend class VMStructs;
277   // When CDS is enabled, all shared metaspace objects are mapped
278   // into a single contiguous memory block, so we can use these
279   // two pointers to quickly determine if something is in the
280   // shared metaspace.
281   // When CDS is not enabled, both pointers are set to NULL.
282   static void* _shared_metaspace_base;  // (inclusive) low address
283   static void* _shared_metaspace_top;   // (exclusive) high address
284 
285  public:
286 
287   // Returns true if the pointer points to a valid MetaspaceObj. A valid
288   // MetaspaceObj is MetaWord-aligned and contained within either
289   // non-shared or shared metaspace.
290   static bool is_valid(const MetaspaceObj* p);
291 
292   static bool is_shared(const MetaspaceObj* p) {
293     // If no shared metaspace regions are mapped, _shared_metaspace_{base,top} will
294     // both be NULL and all values of p will be rejected quickly.
295     return (((void*)p) < _shared_metaspace_top &&
296             ((void*)p) >= _shared_metaspace_base);
297   }
298   bool is_shared() const { return MetaspaceObj::is_shared(this); }
299 
300   void print_address_on(outputStream* st) const;  // nonvirtual address printing
301 
302   static void set_shared_metaspace_range(void* base, void* top) {
303     _shared_metaspace_base = base;
304     _shared_metaspace_top = top;
305   }
306 
307   static void* shared_metaspace_base() { return _shared_metaspace_base; }
308   static void* shared_metaspace_top()  { return _shared_metaspace_top;  }
309 
310 #define METASPACE_OBJ_TYPES_DO(f) \
311   f(Class) \
312   f(Symbol) \
313   f(TypeArrayU1) \
314   f(TypeArrayU2) \
315   f(TypeArrayU4) \
316   f(TypeArrayU8) \
317   f(TypeArrayOther) \
318   f(Method) \
319   f(ConstMethod) \
320   f(MethodData) \
321   f(ConstantPool) \
322   f(ConstantPoolCache) \
323   f(Annotations) \
324   f(MethodCounters) \
325   f(RecordComponent)
326 
327 #define METASPACE_OBJ_TYPE_DECLARE(name) name ## Type,
328 #define METASPACE_OBJ_TYPE_NAME_CASE(name) case name ## Type: return #name;
329 
330   enum Type {
331     // Types are MetaspaceObj::ClassType, MetaspaceObj::SymbolType, etc
332     METASPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_DECLARE)
333     _number_of_types
334   };
335 
336   static const char * type_name(Type type) {
337     switch(type) {
338     METASPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_NAME_CASE)
339     default:
340       ShouldNotReachHere();
341       return NULL;
342     }
343   }
344 
345   static MetaspaceObj::Type array_type(size_t elem_size) {
346     switch (elem_size) {
347     case 1: return TypeArrayU1Type;
348     case 2: return TypeArrayU2Type;
349     case 4: return TypeArrayU4Type;
350     case 8: return TypeArrayU8Type;
351     default:
352       return TypeArrayOtherType;
353     }
354   }
355 
356   void* operator new(size_t size, ClassLoaderData* loader_data,
357                      size_t word_size,
358                      Type type, JavaThread* thread) throw();
359                      // can't use TRAPS from this header file.
360   void* operator new(size_t size, ClassLoaderData* loader_data,
361                      size_t word_size,
362                      Type type) throw();
363   void operator delete(void* p) { ShouldNotCallThis(); }
364 
365   // Declare a *static* method with the same signature in any subclass of MetaspaceObj
366   // that should be read-only by default. See symbol.hpp for an example. This function
367   // is used by the templates in metaspaceClosure.hpp
368   static bool is_read_only_by_default() { return false; }
369 };
370 
371 // Base class for classes that constitute name spaces.
372 
373 class Arena;
374 
375 extern char* resource_allocate_bytes(size_t size,
376     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
377 extern char* resource_allocate_bytes(Thread* thread, size_t size,
378     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
379 extern char* resource_reallocate_bytes( char *old, size_t old_size, size_t new_size,
380     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
381 extern void resource_free_bytes( char *old, size_t size );
382 
383 //----------------------------------------------------------------------
384 // Base class for objects allocated in the resource area per default.
385 // Optionally, objects may be allocated on the C heap with
386 // new(ResourceObj::C_HEAP) Foo(...) or in an Arena with new (&arena)
387 // ResourceObj's can be allocated within other objects, but don't use
388 // new or delete (allocation_type is unknown).  If new is used to allocate,
389 // use delete to deallocate.
390 class ResourceObj ALLOCATION_SUPER_CLASS_SPEC {
391  public:
392   enum allocation_type { STACK_OR_EMBEDDED = 0, RESOURCE_AREA, C_HEAP, ARENA, allocation_mask = 0x3 };
393   static void set_allocation_type(address res, allocation_type type) NOT_DEBUG_RETURN;
394 #ifdef ASSERT
395  private:
396   // When this object is allocated on stack the new() operator is not
397   // called but garbage on stack may look like a valid allocation_type.
398   // Store negated 'this' pointer when new() is called to distinguish cases.
399   // Use second array's element for verification value to distinguish garbage.
400   uintptr_t _allocation_t[2];
401   bool is_type_set() const;
402   void initialize_allocation_info();
403  public:
404   allocation_type get_allocation_type() const;
405   bool allocated_on_stack_or_embedded() const { return get_allocation_type() == STACK_OR_EMBEDDED; }
406   bool allocated_on_res_area() const { return get_allocation_type() == RESOURCE_AREA; }
407   bool allocated_on_C_heap()   const { return get_allocation_type() == C_HEAP; }
408   bool allocated_on_arena()    const { return get_allocation_type() == ARENA; }
409 protected:
410   ResourceObj(); // default constructor
411   ResourceObj(const ResourceObj& r); // default copy constructor
412   ResourceObj& operator=(const ResourceObj& r); // default copy assignment
413   ~ResourceObj();
414 #endif // ASSERT
415 
416  public:
417   void* operator new(size_t size, allocation_type type, MEMFLAGS flags) throw();
418   void* operator new [](size_t size, allocation_type type, MEMFLAGS flags) throw() = delete;
419   void* operator new(size_t size, const std::nothrow_t&  nothrow_constant,
420       allocation_type type, MEMFLAGS flags) throw();
421   void* operator new [](size_t size, const std::nothrow_t&  nothrow_constant,
422       allocation_type type, MEMFLAGS flags) throw() = delete;
423   void* operator new(size_t size, Arena *arena) throw();
424   void* operator new [](size_t size, Arena *arena) throw() = delete;
425 
426   void* operator new(size_t size) throw() {
427       address res = (address)resource_allocate_bytes(size);
428       DEBUG_ONLY(set_allocation_type(res, RESOURCE_AREA);)
429       return res;
430   }
431 
432   void* operator new(size_t size, const std::nothrow_t& nothrow_constant) throw() {
433       address res = (address)resource_allocate_bytes(size, AllocFailStrategy::RETURN_NULL);
434       DEBUG_ONLY(if (res != NULL) set_allocation_type(res, RESOURCE_AREA);)
435       return res;
436   }
437 
438   void* operator new [](size_t size) throw() = delete;
439   void* operator new [](size_t size, const std::nothrow_t& nothrow_constant) throw() = delete;
440   void  operator delete(void* p);
441   void  operator delete [](void* p) = delete;
442 };
443 
444 // One of the following macros must be used when allocating an array
445 // or object to determine whether it should reside in the C heap on in
446 // the resource area.
447 
448 #define NEW_RESOURCE_ARRAY(type, size)\
449   (type*) resource_allocate_bytes((size) * sizeof(type))
450 
451 #define NEW_RESOURCE_ARRAY_RETURN_NULL(type, size)\
452   (type*) resource_allocate_bytes((size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
453 
454 #define NEW_RESOURCE_ARRAY_IN_THREAD(thread, type, size)\
455   (type*) resource_allocate_bytes(thread, (size) * sizeof(type))
456 
457 #define NEW_RESOURCE_ARRAY_IN_THREAD_RETURN_NULL(thread, type, size)\
458   (type*) resource_allocate_bytes(thread, (size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
459 
460 #define REALLOC_RESOURCE_ARRAY(type, old, old_size, new_size)\
461   (type*) resource_reallocate_bytes((char*)(old), (old_size) * sizeof(type), (new_size) * sizeof(type))
462 
463 #define REALLOC_RESOURCE_ARRAY_RETURN_NULL(type, old, old_size, new_size)\
464   (type*) resource_reallocate_bytes((char*)(old), (old_size) * sizeof(type),\
465                                     (new_size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
466 
467 #define FREE_RESOURCE_ARRAY(type, old, size)\
468   resource_free_bytes((char*)(old), (size) * sizeof(type))
469 
470 #define FREE_FAST(old)\
471     /* nop */
472 
473 #define NEW_RESOURCE_OBJ(type)\
474   NEW_RESOURCE_ARRAY(type, 1)
475 
476 #define NEW_RESOURCE_OBJ_RETURN_NULL(type)\
477   NEW_RESOURCE_ARRAY_RETURN_NULL(type, 1)
478 
479 #define NEW_C_HEAP_ARRAY3(type, size, memflags, pc, allocfail)\
480   (type*) AllocateHeap((size) * sizeof(type), memflags, pc, allocfail)
481 
482 #define NEW_C_HEAP_ARRAY2(type, size, memflags, pc)\
483   (type*) (AllocateHeap((size) * sizeof(type), memflags, pc))
484 
485 #define NEW_C_HEAP_ARRAY(type, size, memflags)\
486   (type*) (AllocateHeap((size) * sizeof(type), memflags))
487 
488 #define NEW_C_HEAP_ARRAY2_RETURN_NULL(type, size, memflags, pc)\
489   NEW_C_HEAP_ARRAY3(type, (size), memflags, pc, AllocFailStrategy::RETURN_NULL)
490 
491 #define NEW_C_HEAP_ARRAY_RETURN_NULL(type, size, memflags)\
492   NEW_C_HEAP_ARRAY2(type, (size), memflags, AllocFailStrategy::RETURN_NULL)
493 
494 #define REALLOC_C_HEAP_ARRAY(type, old, size, memflags)\
495   (type*) (ReallocateHeap((char*)(old), (size) * sizeof(type), memflags))
496 
497 #define REALLOC_C_HEAP_ARRAY_RETURN_NULL(type, old, size, memflags)\
498   (type*) (ReallocateHeap((char*)(old), (size) * sizeof(type), memflags, AllocFailStrategy::RETURN_NULL))
499 
500 #define FREE_C_HEAP_ARRAY(type, old) \
501   FreeHeap((char*)(old))
502 
503 // allocate type in heap without calling ctor
504 #define NEW_C_HEAP_OBJ(type, memflags)\
505   NEW_C_HEAP_ARRAY(type, 1, memflags)
506 
507 #define NEW_C_HEAP_OBJ_RETURN_NULL(type, memflags)\
508   NEW_C_HEAP_ARRAY_RETURN_NULL(type, 1, memflags)
509 
510 // deallocate obj of type in heap without calling dtor
511 #define FREE_C_HEAP_OBJ(objname)\
512   FreeHeap((char*)objname);
513 
514 
515 //------------------------------ReallocMark---------------------------------
516 // Code which uses REALLOC_RESOURCE_ARRAY should check an associated
517 // ReallocMark, which is declared in the same scope as the reallocated
518 // pointer.  Any operation that could __potentially__ cause a reallocation
519 // should check the ReallocMark.
520 class ReallocMark: public StackObj {
521 protected:
522   NOT_PRODUCT(int _nesting;)
523 
524 public:
525   ReallocMark()   PRODUCT_RETURN;
526   void check()    PRODUCT_RETURN;
527 };
528 
529 // Helper class to allocate arrays that may become large.
530 // Uses the OS malloc for allocations smaller than ArrayAllocatorMallocLimit
531 // and uses mapped memory for larger allocations.
532 // Most OS mallocs do something similar but Solaris malloc does not revert
533 // to mapped memory for large allocations. By default ArrayAllocatorMallocLimit
534 // is set so that we always use malloc except for Solaris where we set the
535 // limit to get mapped memory.
536 template <class E>
537 class ArrayAllocator : public AllStatic {
538  private:
539   static bool should_use_malloc(size_t length);
540 
541   static E* allocate_malloc(size_t length, MEMFLAGS flags);
542   static E* allocate_mmap(size_t length, MEMFLAGS flags);
543 
544   static void free_malloc(E* addr, size_t length);
545   static void free_mmap(E* addr, size_t length);
546 
547  public:
548   static E* allocate(size_t length, MEMFLAGS flags);
549   static E* reallocate(E* old_addr, size_t old_length, size_t new_length, MEMFLAGS flags);
550   static void free(E* addr, size_t length);
551 };
552 
553 // Uses mmaped memory for all allocations. All allocations are initially
554 // zero-filled. No pre-touching.
555 template <class E>
556 class MmapArrayAllocator : public AllStatic {
557  private:
558   static size_t size_for(size_t length);
559 
560  public:
561   static E* allocate_or_null(size_t length, MEMFLAGS flags);
562   static E* allocate(size_t length, MEMFLAGS flags);
563   static void free(E* addr, size_t length);
564 };
565 
566 // Uses malloc:ed memory for all allocations.
567 template <class E>
568 class MallocArrayAllocator : public AllStatic {
569  public:
570   static size_t size_for(size_t length);
571 
572   static E* allocate(size_t length, MEMFLAGS flags);
573   static void free(E* addr);
574 };
575 
576 #endif // SHARE_MEMORY_ALLOCATION_HPP