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Diffstat (limited to 'js/public/AllocPolicy.h')
-rw-r--r-- | js/public/AllocPolicy.h | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/js/public/AllocPolicy.h b/js/public/AllocPolicy.h new file mode 100644 index 0000000000..72c449293c --- /dev/null +++ b/js/public/AllocPolicy.h @@ -0,0 +1,243 @@ +/* -*- 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/. */ + +/* + * JS allocation policies. + * + * The allocators here are for system memory with lifetimes which are not + * managed by the GC. See the comment at the top of vm/MallocProvider.h. + */ + +#ifndef js_AllocPolicy_h +#define js_AllocPolicy_h + +#include "js/TypeDecls.h" +#include "js/Utility.h" + +extern MOZ_COLD JS_PUBLIC_API void JS_ReportOutOfMemory(JSContext* cx); + +namespace js { + +class FrontendContext; + +enum class AllocFunction { Malloc, Calloc, Realloc }; + +/* Base class allocation policies providing allocation methods. */ +class AllocPolicyBase { + public: + template <typename T> + T* maybe_pod_arena_malloc(arena_id_t arenaId, size_t numElems) { + return js_pod_arena_malloc<T>(arenaId, numElems); + } + template <typename T> + T* maybe_pod_arena_calloc(arena_id_t arenaId, size_t numElems) { + return js_pod_arena_calloc<T>(arenaId, numElems); + } + template <typename T> + T* maybe_pod_arena_realloc(arena_id_t arenaId, T* p, size_t oldSize, + size_t newSize) { + return js_pod_arena_realloc<T>(arenaId, p, oldSize, newSize); + } + template <typename T> + T* pod_arena_malloc(arena_id_t arenaId, size_t numElems) { + return maybe_pod_arena_malloc<T>(arenaId, numElems); + } + template <typename T> + T* pod_arena_calloc(arena_id_t arenaId, size_t numElems) { + return maybe_pod_arena_calloc<T>(arenaId, numElems); + } + template <typename T> + T* pod_arena_realloc(arena_id_t arenaId, T* p, size_t oldSize, + size_t newSize) { + return maybe_pod_arena_realloc<T>(arenaId, p, oldSize, newSize); + } + + template <typename T> + T* maybe_pod_malloc(size_t numElems) { + return maybe_pod_arena_malloc<T>(js::MallocArena, numElems); + } + template <typename T> + T* maybe_pod_calloc(size_t numElems) { + return maybe_pod_arena_calloc<T>(js::MallocArena, numElems); + } + template <typename T> + T* maybe_pod_realloc(T* p, size_t oldSize, size_t newSize) { + return maybe_pod_arena_realloc<T>(js::MallocArena, p, oldSize, newSize); + } + template <typename T> + T* pod_malloc(size_t numElems) { + return pod_arena_malloc<T>(js::MallocArena, numElems); + } + template <typename T> + T* pod_calloc(size_t numElems) { + return pod_arena_calloc<T>(js::MallocArena, numElems); + } + template <typename T> + T* pod_realloc(T* p, size_t oldSize, size_t newSize) { + return pod_arena_realloc<T>(js::MallocArena, p, oldSize, newSize); + } + + template <typename T> + void free_(T* p, size_t numElems = 0) { + js_free(p); + } +}; + +/* Policy for using system memory functions and doing no error reporting. */ +class SystemAllocPolicy : public AllocPolicyBase { + public: + void reportAllocOverflow() const {} + bool checkSimulatedOOM() const { return !js::oom::ShouldFailWithOOM(); } +}; + +MOZ_COLD JS_PUBLIC_API void ReportOutOfMemory(JSContext* cx); +MOZ_COLD JS_PUBLIC_API void ReportOutOfMemory(FrontendContext* fc); + +// An out of memory condition which is easily user generatable and should +// be specially handled to try and avoid a tab crash. +MOZ_COLD JS_PUBLIC_API void ReportLargeOutOfMemory(JSContext* cx); + +/* + * Allocation policy that calls the system memory functions and reports errors + * to the context. Since the JSContext given on construction is stored for + * the lifetime of the container, this policy may only be used for containers + * whose lifetime is a shorter than the given JSContext. + * + * FIXME bug 647103 - rewrite this in terms of temporary allocation functions, + * not the system ones. + */ +class JS_PUBLIC_API TempAllocPolicy : public AllocPolicyBase { + // Type tag for context_bits_ + static constexpr uintptr_t JsContextTag = 0x1; + + // Either a JSContext* (if JsContextTag is set), or FrontendContext* + uintptr_t const context_bits_; + + MOZ_ALWAYS_INLINE bool hasJSContext() const { + return (context_bits_ & JsContextTag) == JsContextTag; + } + + MOZ_ALWAYS_INLINE JSContext* cx() const { + MOZ_ASSERT(hasJSContext()); + return reinterpret_cast<JSContext*>(context_bits_ ^ JsContextTag); + } + + MOZ_ALWAYS_INLINE FrontendContext* fc() const { + MOZ_ASSERT(!hasJSContext()); + return reinterpret_cast<FrontendContext*>(context_bits_); + } + + /* + * Non-inline helper to call JSRuntime::onOutOfMemory with minimal + * code bloat. + */ + void* onOutOfMemory(arena_id_t arenaId, AllocFunction allocFunc, + size_t nbytes, void* reallocPtr = nullptr); + + template <typename T> + T* onOutOfMemoryTyped(arena_id_t arenaId, AllocFunction allocFunc, + size_t numElems, void* reallocPtr = nullptr) { + size_t bytes; + if (MOZ_UNLIKELY(!CalculateAllocSize<T>(numElems, &bytes))) { + return nullptr; + } + return static_cast<T*>( + onOutOfMemory(arenaId, allocFunc, bytes, reallocPtr)); + } + + public: + MOZ_IMPLICIT TempAllocPolicy(JSContext* cx) + : context_bits_(uintptr_t(cx) | JsContextTag) { + MOZ_ASSERT((uintptr_t(cx) & JsContextTag) == 0); + } + MOZ_IMPLICIT TempAllocPolicy(FrontendContext* fc) + : context_bits_(uintptr_t(fc)) { + MOZ_ASSERT((uintptr_t(fc) & JsContextTag) == 0); + } + + template <typename T> + T* pod_arena_malloc(arena_id_t arenaId, size_t numElems) { + T* p = this->maybe_pod_arena_malloc<T>(arenaId, numElems); + if (MOZ_UNLIKELY(!p)) { + p = onOutOfMemoryTyped<T>(arenaId, AllocFunction::Malloc, numElems); + } + return p; + } + + template <typename T> + T* pod_arena_calloc(arena_id_t arenaId, size_t numElems) { + T* p = this->maybe_pod_arena_calloc<T>(arenaId, numElems); + if (MOZ_UNLIKELY(!p)) { + p = onOutOfMemoryTyped<T>(arenaId, AllocFunction::Calloc, numElems); + } + return p; + } + + template <typename T> + T* pod_arena_realloc(arena_id_t arenaId, T* prior, size_t oldSize, + size_t newSize) { + T* p2 = this->maybe_pod_arena_realloc<T>(arenaId, prior, oldSize, newSize); + if (MOZ_UNLIKELY(!p2)) { + p2 = onOutOfMemoryTyped<T>(arenaId, AllocFunction::Realloc, newSize, + prior); + } + return p2; + } + + template <typename T> + T* pod_malloc(size_t numElems) { + return pod_arena_malloc<T>(js::MallocArena, numElems); + } + + template <typename T> + T* pod_calloc(size_t numElems) { + return pod_arena_calloc<T>(js::MallocArena, numElems); + } + + template <typename T> + T* pod_realloc(T* prior, size_t oldSize, size_t newSize) { + return pod_arena_realloc<T>(js::MallocArena, prior, oldSize, newSize); + } + + template <typename T> + void free_(T* p, size_t numElems = 0) { + js_free(p); + } + + void reportAllocOverflow() const; + + bool checkSimulatedOOM() const { + if (js::oom::ShouldFailWithOOM()) { + if (hasJSContext()) { + ReportOutOfMemory(cx()); + } else { + ReportOutOfMemory(fc()); + } + return false; + } + + return true; + } +}; + +/* + * A replacement for MallocAllocPolicy that allocates in the JS heap and adds no + * extra behaviours. + * + * This is currently used for allocating source buffers for parsing. Since these + * are temporary and will not be freed by GC, the memory is not tracked by the + * usual accounting. + */ +class MallocAllocPolicy : public AllocPolicyBase { + public: + void reportAllocOverflow() const {} + + [[nodiscard]] bool checkSimulatedOOM() const { return true; } +}; + +} /* namespace js */ + +#endif /* js_AllocPolicy_h */ |