text: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   * vim: set ts=8 sts=4 et sw=4 tw=99:
   * This Source Code Form is subject to the terms of the Mozilla Public
   * License, v. 2.0. If a copy of the MPL was not distributed with this
   * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
  
  /*
   * JS allocation policies.
   *
   * The allocators here are for system memory with lifetimes which are not
   * managed by the GC. See the comment at the top of vm/MallocProvider.h.
   */
  
  #ifndef js_AllocPolicy_h
  #define js_AllocPolicy_h
  
  #include "js/TypeDecls.h"
  #include "js/Utility.h"
  
  extern MOZ_COLD JS_PUBLIC_API(void) JS_ReportOutOfMemory(JSContext* cx);
  
  namespace js {
  
  enum class AllocFunction {
      Malloc,
      Calloc,
      Realloc
  };
  
  /* Base class allocation policies providing allocation methods. */
  class AllocPolicyBase
  {
    public:
      template <typename T> T* maybe_pod_malloc(size_t numElems) { return js_pod_malloc<T>(numElems); }
      template <typename T> T* maybe_pod_calloc(size_t numElems) { return js_pod_calloc<T>(numElems); }
      template <typename T> T* maybe_pod_realloc(T* p, size_t oldSize, size_t newSize) {
          return js_pod_realloc<T>(p, oldSize, newSize);
      }
      template <typename T> T* pod_malloc(size_t numElems) { return maybe_pod_malloc<T>(numElems); }
      template <typename T> T* pod_calloc(size_t numElems) { return maybe_pod_calloc<T>(numElems); }
      template <typename T> T* pod_realloc(T* p, size_t oldSize, size_t newSize) {
          return maybe_pod_realloc<T>(p, oldSize, newSize);
      }
      template <typename T> void free_(T* p, size_t numElems = 0) { js_free(p); }
  };
  
  /* Policy for using system memory functions and doing no error reporting. */
  class SystemAllocPolicy : public AllocPolicyBase
  {
    public:
      void reportAllocOverflow() const {}
      bool checkSimulatedOOM() const {
          return !js::oom::ShouldFailWithOOM();
      }
  };
  
  MOZ_COLD JS_FRIEND_API(void) ReportOutOfMemory(JSContext* cx);
  
  /*
   * Allocation policy that calls the system memory functions and reports errors
   * to the context. Since the JSContext given on construction is stored for
   * the lifetime of the container, this policy may only be used for containers
   * whose lifetime is a shorter than the given JSContext.
   *
   * FIXME bug 647103 - rewrite this in terms of temporary allocation functions,
   * not the system ones.
   */
  class TempAllocPolicy : public AllocPolicyBase
  {
      JSContext* const cx_;
  
      /*
       * Non-inline helper to call JSRuntime::onOutOfMemory with minimal
       * code bloat.
       */
      JS_FRIEND_API(void*) onOutOfMemory(AllocFunction allocFunc, size_t nbytes,
                                         void* reallocPtr = nullptr);
  
      template <typename T>
      T* onOutOfMemoryTyped(AllocFunction allocFunc, size_t numElems, void* reallocPtr = nullptr) {
          size_t bytes;
          if (MOZ_UNLIKELY(!CalculateAllocSize<T>(numElems, &bytes))) {
              return nullptr;
          }
          return static_cast<T*>(onOutOfMemory(allocFunc, bytes, reallocPtr));
      }
  
    public:
      MOZ_IMPLICIT TempAllocPolicy(JSContext* cx) : cx_(cx) {}
  
      template <typename T>
      T* pod_malloc(size_t numElems) {
          T* p = this->maybe_pod_malloc<T>(numElems);
          if (MOZ_UNLIKELY(!p)) {
              p = onOutOfMemoryTyped<T>(AllocFunction::Malloc, numElems);
          }
          return p;
      }
  
      template <typename T>
      T* pod_calloc(size_t numElems) {
          T* p = this->maybe_pod_calloc<T>(numElems);
          if (MOZ_UNLIKELY(!p)) {
              p = onOutOfMemoryTyped<T>(AllocFunction::Calloc, numElems);
          }
          return p;
      }
  
      template <typename T>
      T* pod_realloc(T* prior, size_t oldSize, size_t newSize) {
          T* p2 = this->maybe_pod_realloc<T>(prior, oldSize, newSize);
          if (MOZ_UNLIKELY(!p2)) {
              p2 = onOutOfMemoryTyped<T>(AllocFunction::Realloc, newSize, prior);
          }
          return p2;
      }
  
      template <typename T>
      void free_(T* p, size_t numElems = 0) {
          js_free(p);
      }
  
      JS_FRIEND_API(void) reportAllocOverflow() const;
  
      bool checkSimulatedOOM() const {
          if (js::oom::ShouldFailWithOOM()) {
              ReportOutOfMemory(cx_);
              return false;
          }
  
          return true;
      }
  };
  
  } /* namespace js */
  
  #endif /* js_AllocPolicy_h */
  