diff options
Diffstat (limited to '')
| -rw-r--r-- | memory/build/replace_malloc.h | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/memory/build/replace_malloc.h b/memory/build/replace_malloc.h new file mode 100644 index 0000000000..9ea3493f99 --- /dev/null +++ b/memory/build/replace_malloc.h @@ -0,0 +1,113 @@ +/* -*- 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/. */ + +#ifndef replace_malloc_h +#define replace_malloc_h + +// The replace_malloc facility allows an external library to replace or +// supplement the jemalloc implementation. +// +// The external library may be hooked by setting one of the following +// environment variables to the library path: +// - LD_PRELOAD on Linux, +// - DYLD_INSERT_LIBRARIES on OSX, +// - MOZ_REPLACE_MALLOC_LIB on Windows and Android. +// +// An initialization function is called before any malloc replacement +// function, and has the following declaration: +// +// void replace_init(malloc_table_t*, ReplaceMallocBridge**) +// +// The malloc_table_t pointer given to that function is a table containing +// pointers to the original allocator implementation, so that replacement +// functions can call them back if they need to. The initialization function +// needs to alter that table to replace the function it wants to replace. +// If it needs the original implementation, it thus needs a copy of the +// original table. +// +// The ReplaceMallocBridge* pointer is an outparam that allows the +// replace_init function to return a pointer to its ReplaceMallocBridge +// (see replace_malloc_bridge.h). +// +// The functions to be implemented in the external library are of the form: +// +// void* replace_malloc(size_t size) +// { +// // Fiddle with the size if necessary. +// // orig->malloc doesn't have to be called if the external library +// // provides its own allocator, but in this case it will have to +// // implement all functions. +// void *ptr = orig->malloc(size); +// // Do whatever you want with the ptr. +// return ptr; +// } +// +// where "orig" is a pointer to a copy of the table replace_init got. +// +// See malloc_decls.h for a list of functions that can be replaced this +// way. The implementations are all in the form: +// return_type replace_name(arguments [,...]) +// +// They don't all need to be provided. +// +// Building a replace-malloc library is like rocket science. It can end up +// with things blowing up, especially when trying to use complex types, and +// even more especially when these types come from XPCOM or other parts of the +// Mozilla codebase. +// It is recommended to add the following to a replace-malloc implementation's +// moz.build: +// DISABLE_STL_WRAPPING = True # Avoid STL wrapping +// +// If your replace-malloc implementation lives under memory/replace, these +// are taken care of by memory/replace/defs.mk. + +#ifdef replace_malloc_bridge_h +# error Do not include replace_malloc_bridge.h before replace_malloc.h. \ + In fact, you only need the latter. +#endif + +#define REPLACE_MALLOC_IMPL + +#include "replace_malloc_bridge.h" + +// Implementing a replace-malloc library is incompatible with using mozalloc. +#define MOZ_NO_MOZALLOC 1 + +#include "mozilla/MacroArgs.h" +#include "mozilla/Types.h" + +MOZ_BEGIN_EXTERN_C + +// MOZ_REPLACE_WEAK is only defined in mozjemalloc.cpp. Normally including +// this header will add function definitions. +#ifndef MOZ_REPLACE_WEAK +# define MOZ_REPLACE_WEAK +#endif + +// When building a replace-malloc library for static linking, we want +// each to have a different name for their "public" functions. +// The build system defines MOZ_REPLACE_MALLOC_PREFIX in that case. +#ifdef MOZ_REPLACE_MALLOC_PREFIX +# define replace_init MOZ_CONCAT(MOZ_REPLACE_MALLOC_PREFIX, _init) +# define MOZ_REPLACE_PUBLIC +#else +# define MOZ_REPLACE_PUBLIC MOZ_EXPORT +#endif + +struct ReplaceMallocBridge; +typedef void (*jemalloc_init_func)(malloc_table_t*, + struct ReplaceMallocBridge**); + +// Replace-malloc library initialization function. See top of this file +MOZ_REPLACE_PUBLIC void replace_init( + malloc_table_t*, struct ReplaceMallocBridge**) MOZ_REPLACE_WEAK; + +// ensure this is visible and libxul/etc reference it with a weak ref +MFBT_API void jemalloc_replace_dynamic(jemalloc_init_func); + +MOZ_END_EXTERN_C + +#endif // replace_malloc_h |