mirror of
https://github.com/oxen-io/lokinet.git
synced 2024-11-02 03:40:12 +00:00
125 lines
4.6 KiB
C++
125 lines
4.6 KiB
C++
// Copyright 2017 The Abseil Authors.
|
|
//
|
|
// 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.
|
|
//
|
|
|
|
#ifndef ABSL_BASE_INTERNAL_LOW_LEVEL_ALLOC_H_
|
|
#define ABSL_BASE_INTERNAL_LOW_LEVEL_ALLOC_H_
|
|
|
|
// A simple thread-safe memory allocator that does not depend on
|
|
// mutexes or thread-specific data. It is intended to be used
|
|
// sparingly, and only when malloc() would introduce an unwanted
|
|
// dependency, such as inside the heap-checker, or the Mutex
|
|
// implementation.
|
|
|
|
// IWYU pragma: private, include "base/low_level_alloc.h"
|
|
|
|
#include <sys/types.h>
|
|
#include <cstdint>
|
|
|
|
#include "absl/base/attributes.h"
|
|
#include "absl/base/config.h"
|
|
|
|
// LowLevelAlloc requires that the platform support low-level
|
|
// allocation of virtual memory. Platforms lacking this cannot use
|
|
// LowLevelAlloc.
|
|
#ifdef ABSL_LOW_LEVEL_ALLOC_MISSING
|
|
#error ABSL_LOW_LEVEL_ALLOC_MISSING cannot be directly set
|
|
#elif !defined(ABSL_HAVE_MMAP) && !defined(_WIN32)
|
|
#define ABSL_LOW_LEVEL_ALLOC_MISSING 1
|
|
#endif
|
|
|
|
// Using LowLevelAlloc with kAsyncSignalSafe isn't supported on Windows or
|
|
// asm.js / WebAssembly.
|
|
// See https://kripken.github.io/emscripten-site/docs/porting/pthreads.html
|
|
// for more information.
|
|
#ifdef ABSL_LOW_LEVEL_ALLOC_ASYNC_SIGNAL_SAFE_MISSING
|
|
#error ABSL_LOW_LEVEL_ALLOC_ASYNC_SIGNAL_SAFE_MISSING cannot be directly set
|
|
#elif defined(_WIN32) || defined(__asmjs__) || defined(__wasm__)
|
|
#define ABSL_LOW_LEVEL_ALLOC_ASYNC_SIGNAL_SAFE_MISSING 1
|
|
#endif
|
|
|
|
#include <cstddef>
|
|
|
|
#include "absl/base/port.h"
|
|
|
|
namespace absl {
|
|
inline namespace lts_2018_12_18 {
|
|
namespace base_internal {
|
|
|
|
class LowLevelAlloc {
|
|
public:
|
|
struct Arena; // an arena from which memory may be allocated
|
|
|
|
// Returns a pointer to a block of at least "request" bytes
|
|
// that have been newly allocated from the specific arena.
|
|
// for Alloc() call the DefaultArena() is used.
|
|
// Returns 0 if passed request==0.
|
|
// Does not return 0 under other circumstances; it crashes if memory
|
|
// is not available.
|
|
static void *Alloc(size_t request) ABSL_ATTRIBUTE_SECTION(malloc_hook);
|
|
static void *AllocWithArena(size_t request, Arena *arena)
|
|
ABSL_ATTRIBUTE_SECTION(malloc_hook);
|
|
|
|
// Deallocates a region of memory that was previously allocated with
|
|
// Alloc(). Does nothing if passed 0. "s" must be either 0,
|
|
// or must have been returned from a call to Alloc() and not yet passed to
|
|
// Free() since that call to Alloc(). The space is returned to the arena
|
|
// from which it was allocated.
|
|
static void Free(void *s) ABSL_ATTRIBUTE_SECTION(malloc_hook);
|
|
|
|
// ABSL_ATTRIBUTE_SECTION(malloc_hook) for Alloc* and Free
|
|
// are to put all callers of MallocHook::Invoke* in this module
|
|
// into special section,
|
|
// so that MallocHook::GetCallerStackTrace can function accurately.
|
|
|
|
// Create a new arena.
|
|
// The root metadata for the new arena is allocated in the
|
|
// meta_data_arena; the DefaultArena() can be passed for meta_data_arena.
|
|
// These values may be ored into flags:
|
|
enum {
|
|
// Report calls to Alloc() and Free() via the MallocHook interface.
|
|
// Set in the DefaultArena.
|
|
kCallMallocHook = 0x0001,
|
|
|
|
#ifndef ABSL_LOW_LEVEL_ALLOC_ASYNC_SIGNAL_SAFE_MISSING
|
|
// Make calls to Alloc(), Free() be async-signal-safe. Not set in
|
|
// DefaultArena(). Not supported on all platforms.
|
|
kAsyncSignalSafe = 0x0002,
|
|
#endif
|
|
};
|
|
// Construct a new arena. The allocation of the underlying metadata honors
|
|
// the provided flags. For example, the call NewArena(kAsyncSignalSafe)
|
|
// is itself async-signal-safe, as well as generatating an arena that provides
|
|
// async-signal-safe Alloc/Free.
|
|
static Arena *NewArena(int32_t flags);
|
|
|
|
// Destroys an arena allocated by NewArena and returns true,
|
|
// provided no allocated blocks remain in the arena.
|
|
// If allocated blocks remain in the arena, does nothing and
|
|
// returns false.
|
|
// It is illegal to attempt to destroy the DefaultArena().
|
|
static bool DeleteArena(Arena *arena);
|
|
|
|
// The default arena that always exists.
|
|
static Arena *DefaultArena();
|
|
|
|
private:
|
|
LowLevelAlloc(); // no instances
|
|
};
|
|
|
|
} // namespace base_internal
|
|
} // inline namespace lts_2018_12_18
|
|
} // namespace absl
|
|
#endif // ABSL_BASE_INTERNAL_LOW_LEVEL_ALLOC_H_
|