mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-11-27 14:52:16 +00:00
90 lines
2.8 KiB
C++
90 lines
2.8 KiB
C++
/* -*- 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 "mozilla/NullPtr.h"
|
|
#include "mozilla/TemplateLib.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
|
|
* - template <typename T> T* pod_malloc(size_t)
|
|
* Responsible for OOM reporting when null is returned.
|
|
* - template <typename T> T* pod_calloc(size_t)
|
|
* Responsible for OOM reporting when null is returned.
|
|
* - template <typename T> T* pod_realloc(T*, size_t, size_t)
|
|
* Responsible for OOM reporting when null is returned. The old allocation
|
|
* size is passed in, 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:
|
|
template <typename T>
|
|
T* pod_malloc(size_t aNumElems)
|
|
{
|
|
if (aNumElems & mozilla::tl::MulOverflowMask<sizeof(T)>::value)
|
|
return nullptr;
|
|
return static_cast<T*>(malloc(aNumElems * sizeof(T)));
|
|
}
|
|
|
|
template <typename T>
|
|
T* pod_calloc(size_t aNumElems)
|
|
{
|
|
return static_cast<T*>(calloc(aNumElems, sizeof(T)));
|
|
}
|
|
|
|
template <typename T>
|
|
T* pod_realloc(T* aPtr, size_t aOldSize, size_t aNewSize)
|
|
{
|
|
if (aNewSize & mozilla::tl::MulOverflowMask<sizeof(T)>::value)
|
|
return nullptr;
|
|
return static_cast<T*>(realloc(aPtr, aNewSize * sizeof(T)));
|
|
}
|
|
|
|
void free_(void* aPtr)
|
|
{
|
|
free(aPtr);
|
|
}
|
|
|
|
void reportAllocOverflow() const
|
|
{
|
|
}
|
|
};
|
|
|
|
} // namespace mozilla
|
|
|
|
#endif /* mozilla_AllocPolicy_h */
|