1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/mfbt/AllocPolicy.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,63 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=8 sts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +/*
1.11 + * An allocation policy concept, usable for structures and algorithms to
1.12 + * control how memory is allocated and how failures are handled.
1.13 + */
1.14 +
1.15 +#ifndef mozilla_AllocPolicy_h
1.16 +#define mozilla_AllocPolicy_h
1.17 +
1.18 +#include <stddef.h>
1.19 +#include <stdlib.h>
1.20 +
1.21 +namespace mozilla {
1.22 +
1.23 +/*
1.24 + * Allocation policies are used to implement the standard allocation behaviors
1.25 + * in a customizable way. Additionally, custom behaviors may be added to these
1.26 + * behaviors, such as additionally reporting an error through an out-of-band
1.27 + * mechanism when OOM occurs. The concept modeled here is as follows:
1.28 + *
1.29 + * - public copy constructor, assignment, destructor
1.30 + * - void* malloc_(size_t)
1.31 + * Responsible for OOM reporting when null is returned.
1.32 + * - void* calloc_(size_t)
1.33 + * Responsible for OOM reporting when null is returned.
1.34 + * - void* realloc_(void*, size_t, size_t)
1.35 + * Responsible for OOM reporting when null is returned. The *used* bytes
1.36 + * of the previous buffer is passed in (rather than the old allocation
1.37 + * size), in addition to the *new* allocation size requested.
1.38 + * - void free_(void*)
1.39 + * - void reportAllocOverflow() const
1.40 + * Called on allocation overflow (that is, an allocation implicitly tried
1.41 + * to allocate more than the available memory space -- think allocating an
1.42 + * array of large-size objects, where N * size overflows) before null is
1.43 + * returned.
1.44 + *
1.45 + * mfbt provides (and typically uses by default) only MallocAllocPolicy, which
1.46 + * does nothing more than delegate to the malloc/alloc/free functions.
1.47 + */
1.48 +
1.49 +/*
1.50 + * A policy that straightforwardly uses malloc/calloc/realloc/free and adds no
1.51 + * extra behaviors.
1.52 + */
1.53 +class MallocAllocPolicy
1.54 +{
1.55 + public:
1.56 + void* malloc_(size_t bytes) { return malloc(bytes); }
1.57 + void* calloc_(size_t bytes) { return calloc(bytes, 1); }
1.58 + void* realloc_(void* p, size_t oldBytes, size_t bytes) { return realloc(p, bytes); }
1.59 + void free_(void* p) { free(p); }
1.60 + void reportAllocOverflow() const {}
1.61 +};
1.62 +
1.63 +
1.64 +} // namespace mozilla
1.65 +
1.66 +#endif /* mozilla_AllocPolicy_h */
