diff -r 000000000000 -r 6474c204b198 mfbt/AllocPolicy.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mfbt/AllocPolicy.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,63 @@
+/* -*- 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 bytes) { return malloc(bytes); }
+    void* calloc_(size_t bytes) { return calloc(bytes, 1); }
+    void* realloc_(void* p, size_t oldBytes, size_t bytes) { return realloc(p, bytes); }
+    void free_(void* p) { free(p); }
+    void reportAllocOverflow() const {}
+};
+
+
+} // namespace mozilla
+
+#endif /* mozilla_AllocPolicy_h */