Rocket.Chat.ReactNative/ios/Pods/Folly/folly/memory/Malloc.h

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/*
* Copyright 2011-present Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Functions to provide smarter use of jemalloc, if jemalloc is being used.
// http://www.canonware.com/download/jemalloc/jemalloc-latest/doc/jemalloc.html
#pragma once
#include <folly/CPortability.h>
#include <folly/portability/Config.h>
/**
* Define various MALLOCX_* macros normally provided by jemalloc. We define
* them so that we don't have to include jemalloc.h, in case the program is
* built without jemalloc support.
*/
#if (defined(USE_JEMALLOC) || defined(FOLLY_USE_JEMALLOC)) && !FOLLY_SANITIZE
// We have JEMalloc, so use it.
#include <jemalloc/jemalloc.h>
#else
#ifndef MALLOCX_LG_ALIGN
#define MALLOCX_LG_ALIGN(la) (la)
#endif
#ifndef MALLOCX_ZERO
#define MALLOCX_ZERO (static_cast<int>(0x40))
#endif
#ifndef MALLOCX_ARENA
#define MALLOCX_ARENA(_) (static_cast<int>(0))
#endif
#ifndef MALLOCX_LG_ALIGN
#define MALLOCX_LG_ALIGN(_) (static_cast<int>(0))
#endif
#ifndef MALLCTL_ARENAS_ALL
#define MALLCTL_ARENAS_ALL (static_cast<int>(0))
#endif
#ifndef MALLOCX_TCACHE_NONE
#define MALLOCX_TCACHE_NONE (static_cast<int>(0))
#endif
#endif
// If using fbstring from libstdc++ (see comment in FBString.h), then
// just define stub code here to typedef the fbstring type into the
// folly namespace.
// This provides backwards compatibility for code that explicitly
// includes and uses fbstring.
#if defined(_GLIBCXX_USE_FB) && !defined(_LIBSTDCXX_FBSTRING)
#include <folly/lang/Exception.h>
#include <folly/memory/detail/MallocImpl.h>
#include <string>
namespace folly {
using std::checkedCalloc;
using std::checkedMalloc;
using std::checkedRealloc;
using std::goodMallocSize;
using std::jemallocMinInPlaceExpandable;
using std::smartRealloc;
using std::usingJEMalloc;
} // namespace folly
#else // !defined(_GLIBCXX_USE_FB) || defined(_LIBSTDCXX_FBSTRING)
#ifdef _LIBSTDCXX_FBSTRING
#pragma GCC system_header
/**
* Declare *allocx() and mallctl*() as weak symbols. These will be provided by
* jemalloc if we are using jemalloc, or will be nullptr if we are using another
* malloc implementation.
*/
extern "C" void* mallocx(size_t, int) __attribute__((__weak__));
extern "C" void* rallocx(void*, size_t, int) __attribute__((__weak__));
extern "C" size_t xallocx(void*, size_t, size_t, int) __attribute__((__weak__));
extern "C" size_t sallocx(const void*, int) __attribute__((__weak__));
extern "C" void dallocx(void*, int) __attribute__((__weak__));
extern "C" void sdallocx(void*, size_t, int) __attribute__((__weak__));
extern "C" size_t nallocx(size_t, int) __attribute__((__weak__));
extern "C" int mallctl(const char*, void*, size_t*, void*, size_t)
__attribute__((__weak__));
extern "C" int mallctlnametomib(const char*, size_t*, size_t*)
__attribute__((__weak__));
extern "C" int
mallctlbymib(const size_t*, size_t, void*, size_t*, void*, size_t)
__attribute__((__weak__));
#else // !defined(_LIBSTDCXX_FBSTRING)
#include <folly/lang/Exception.h> /* nolint */
#include <folly/memory/detail/MallocImpl.h> /* nolint */
#endif
// for malloc_usable_size
// NOTE: FreeBSD 9 doesn't have malloc.h. Its definitions
// are found in stdlib.h.
#if __has_include(<malloc.h>)
#include <malloc.h>
#else
#include <stdlib.h>
#endif
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <atomic>
#include <new>
// clang-format off
#ifdef _LIBSTDCXX_FBSTRING
namespace std _GLIBCXX_VISIBILITY(default) {
_GLIBCXX_BEGIN_NAMESPACE_VERSION
#else
namespace folly {
#endif
// Cannot depend on Portability.h when _LIBSTDCXX_FBSTRING.
#if defined(__GNUC__)
#define FOLLY_MALLOC_NOINLINE __attribute__((__noinline__))
#if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL) >= 40900
// This is for checked malloc-like functions (returns non-null pointer
// which cannot alias any outstanding pointer).
#define FOLLY_MALLOC_CHECKED_MALLOC \
__attribute__((__returns_nonnull__, __malloc__))
#else
#define FOLLY_MALLOC_CHECKED_MALLOC __attribute__((__malloc__))
#endif
#else
#define FOLLY_MALLOC_NOINLINE
#define FOLLY_MALLOC_CHECKED_MALLOC
#endif
/**
* Determine if we are using jemalloc or not.
*/
#if defined(USE_JEMALLOC) && !FOLLY_SANITIZE
inline bool usingJEMalloc() noexcept {
return true;
}
#else
FOLLY_MALLOC_NOINLINE inline bool usingJEMalloc() noexcept {
// Checking for rallocx != nullptr is not sufficient; we may be in a
// dlopen()ed module that depends on libjemalloc, so rallocx is resolved, but
// the main program might be using a different memory allocator.
// How do we determine that we're using jemalloc? In the hackiest
// way possible. We allocate memory using malloc() and see if the
// per-thread counter of allocated memory increases. This makes me
// feel dirty inside. Also note that this requires jemalloc to have
// been compiled with --enable-stats.
static const bool result = []() noexcept {
// Some platforms (*cough* OSX *cough*) require weak symbol checks to be
// in the form if (mallctl != nullptr). Not if (mallctl) or if (!mallctl)
// (!!). http://goo.gl/xpmctm
if (mallocx == nullptr || rallocx == nullptr || xallocx == nullptr ||
sallocx == nullptr || dallocx == nullptr || sdallocx == nullptr ||
nallocx == nullptr || mallctl == nullptr ||
mallctlnametomib == nullptr || mallctlbymib == nullptr) {
return false;
}
// "volatile" because gcc optimizes out the reads from *counter, because
// it "knows" malloc doesn't modify global state...
/* nolint */ volatile uint64_t* counter;
size_t counterLen = sizeof(uint64_t*);
if (mallctl(
"thread.allocatedp",
static_cast<void*>(&counter),
&counterLen,
nullptr,
0) != 0) {
return false;
}
if (counterLen != sizeof(uint64_t*)) {
return false;
}
uint64_t origAllocated = *counter;
static const void* volatile ptr = malloc(1);
if (!ptr) {
// wtf, failing to allocate 1 byte
return false;
}
return (origAllocated != *counter);
}
();
return result;
}
#endif
inline size_t goodMallocSize(size_t minSize) noexcept {
if (minSize == 0) {
return 0;
}
if (!usingJEMalloc()) {
// Not using jemalloc - no smarts
return minSize;
}
// nallocx returns 0 if minSize can't succeed, but 0 is not actually
// a goodMallocSize if you want minSize
auto rv = nallocx(minSize, 0);
return rv ? rv : minSize;
}
// We always request "good" sizes for allocation, so jemalloc can
// never grow in place small blocks; they're already occupied to the
// brim. Blocks larger than or equal to 4096 bytes can in fact be
// expanded in place, and this constant reflects that.
static const size_t jemallocMinInPlaceExpandable = 4096;
/**
* Trivial wrappers around malloc, calloc, realloc that check for allocation
* failure and throw std::bad_alloc in that case.
*/
inline void* checkedMalloc(size_t size) {
void* p = malloc(size);
if (!p) {
throw_exception<std::bad_alloc>();
}
return p;
}
inline void* checkedCalloc(size_t n, size_t size) {
void* p = calloc(n, size);
if (!p) {
throw_exception<std::bad_alloc>();
}
return p;
}
inline void* checkedRealloc(void* ptr, size_t size) {
void* p = realloc(ptr, size);
if (!p) {
throw_exception<std::bad_alloc>();
}
return p;
}
/**
* This function tries to reallocate a buffer of which only the first
* currentSize bytes are used. The problem with using realloc is that
* if currentSize is relatively small _and_ if realloc decides it
* needs to move the memory chunk to a new buffer, then realloc ends
* up copying data that is not used. It's generally not a win to try
* to hook in to realloc() behavior to avoid copies - at least in
* jemalloc, realloc() almost always ends up doing a copy, because
* there is little fragmentation / slack space to take advantage of.
*/
FOLLY_MALLOC_CHECKED_MALLOC FOLLY_MALLOC_NOINLINE inline void* smartRealloc(
void* p,
const size_t currentSize,
const size_t currentCapacity,
const size_t newCapacity) {
assert(p);
assert(currentSize <= currentCapacity &&
currentCapacity < newCapacity);
auto const slack = currentCapacity - currentSize;
if (slack * 2 > currentSize) {
// Too much slack, malloc-copy-free cycle:
auto const result = checkedMalloc(newCapacity);
std::memcpy(result, p, currentSize);
free(p);
return result;
}
// If there's not too much slack, we realloc in hope of coalescing
return checkedRealloc(p, newCapacity);
}
#ifdef _LIBSTDCXX_FBSTRING
_GLIBCXX_END_NAMESPACE_VERSION
#endif
} // namespace folly
// clang-format on
#endif // !defined(_GLIBCXX_USE_FB) || defined(_LIBSTDCXX_FBSTRING)