text: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
  /* vim: set ts=8 sts=2 et sw=2 tw=80: */
  /* 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/. */
  
  /*
   * An allocation policy concept, usable for structures and algorithms to
   * control how memory is allocated and how failures are handled.
   */
  
  #ifndef mozilla_AllocPolicy_h
  #define mozilla_AllocPolicy_h
  
  #include <stddef.h>
  #include <stdlib.h>
  
  namespace mozilla {
  
  /*
   * Allocation policies are used to implement the standard allocation behaviors
   * in a customizable way.  Additionally, custom behaviors may be added to these
   * behaviors, such as additionally reporting an error through an out-of-band
   * mechanism when OOM occurs.  The concept modeled here is as follows:
   *
   *  - public copy constructor, assignment, destructor
   *  - void* malloc_(size_t)
   *      Responsible for OOM reporting when null is returned.
   *  - void* calloc_(size_t)
   *      Responsible for OOM reporting when null is returned.
   *  - void* realloc_(void*, size_t, size_t)
   *      Responsible for OOM reporting when null is returned.  The *used* bytes
   *      of the previous buffer is passed in (rather than the old allocation
   *      size), in addition to the *new* allocation size requested.
   *  - void free_(void*)
   *  - void reportAllocOverflow() const
   *      Called on allocation overflow (that is, an allocation implicitly tried
   *      to allocate more than the available memory space -- think allocating an
   *      array of large-size objects, where N * size overflows) before null is
   *      returned.
   *
   * mfbt provides (and typically uses by default) only MallocAllocPolicy, which
   * does nothing more than delegate to the malloc/alloc/free functions.
   */
  
  /*
   * A policy that straightforwardly uses malloc/calloc/realloc/free and adds no
   * extra behaviors.
   */
  class MallocAllocPolicy
  {
  public:
    void* malloc_(size_t aBytes)
    {
      return malloc(aBytes);
    }
  
    void* calloc_(size_t aBytes)
    {
      return calloc(aBytes, 1);
    }
  
    void* realloc_(void* aPtr, size_t aOldBytes, size_t aBytes)
    {
      return realloc(aPtr, aBytes);
    }
  
    void free_(void* aPtr)
    {
      free(aPtr);
    }
  
    void reportAllocOverflow() const
    {
    }
  };
  
  } // namespace mozilla
  
  #endif /* mozilla_AllocPolicy_h */
  