js/src/jsalloc.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * vim: set ts=8 sts=4 et sw=4 tw=99:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8  * JS allocation policies.
   9  *
  10  * The allocators here are for system memory with lifetimes which are not
  11  * managed by the GC. See the comment at the top of vm/MallocProvider.h.
  12  */
  13
  14 #ifndef jsalloc_h
  15 #define jsalloc_h
  16
  17 #include "js/TypeDecls.h"
  18 #include "js/Utility.h"
  19
  20 namespace js {
  21
  22 struct ContextFriendFields;
  23
  24 /* Policy for using system memory functions and doing no error reporting. */
  25 class SystemAllocPolicy
  26 {
  27   public:
  28     template <typename T> T* pod_malloc(size_t numElems) { return js_pod_malloc<T>(numElems); }
  29     template <typename T> T* pod_calloc(size_t numElems) { return js_pod_calloc<T>(numElems); }
  30     template <typename T> T* pod_realloc(T* p, size_t oldSize, size_t newSize) {
  31         return js_pod_realloc<T>(p, oldSize, newSize);
  32     }
  33     void free_(void* p) { js_free(p); }
  34     void reportAllocOverflow() const {}
  35 };
  36
  37 /*
  38  * Allocation policy that calls the system memory functions and reports errors
  39  * to the context. Since the JSContext given on construction is stored for
  40  * the lifetime of the container, this policy may only be used for containers
  41  * whose lifetime is a shorter than the given JSContext.
  42  *
  43  * FIXME bug 647103 - rewrite this in terms of temporary allocation functions,
  44  * not the system ones.
  45  */
  46 class TempAllocPolicy
  47 {
  48     ContextFriendFields* const cx_;
  49
  50     /*
  51      * Non-inline helper to call JSRuntime::onOutOfMemory with minimal
  52      * code bloat.
  53      */
  54     JS_FRIEND_API(void*) onOutOfMemory(void* p, size_t nbytes);
  55
  56   public:
  57     MOZ_IMPLICIT TempAllocPolicy(JSContext* cx) : cx_((ContextFriendFields*) cx) {} // :(
  58     MOZ_IMPLICIT TempAllocPolicy(ContextFriendFields* cx) : cx_(cx) {}
  59
  60     template <typename T>
  61     T* pod_malloc(size_t numElems) {
  62         T* p = js_pod_malloc<T>(numElems);
  63         if (MOZ_UNLIKELY(!p))
  64             p = static_cast<T*>(onOutOfMemory(nullptr, numElems * sizeof(T)));
  65         return p;
  66     }
  67
  68     template <typename T>
  69     T* pod_calloc(size_t numElems) {
  70         T* p = js_pod_calloc<T>(numElems);
  71         if (MOZ_UNLIKELY(!p))
  72             p = static_cast<T*>(onOutOfMemory(reinterpret_cast<void*>(1), numElems * sizeof(T)));
  73         return p;
  74     }
  75
  76     template <typename T>
  77     T* pod_realloc(T* prior, size_t oldSize, size_t newSize) {
  78         T* p2 = js_pod_realloc<T>(prior, oldSize, newSize);
  79         if (MOZ_UNLIKELY(!p2))
  80             p2 = static_cast<T*>(onOutOfMemory(p2, newSize * sizeof(T)));
  81         return p2;
  82     }
  83
  84     void free_(void* p) {
  85         js_free(p);
  86     }
  87
  88     JS_FRIEND_API(void) reportAllocOverflow() const;
  89 };
  90
  91 } /* namespace js */
  92
  93 #endif /* jsalloc_h */