chromium/third_party/protobuf/src/google/protobuf/arena_impl.h

// Protocol Buffers - Google's data interchange format
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// This file defines an Arena allocator for better allocation performance.

#ifndef GOOGLE_PROTOBUF_ARENA_IMPL_H__
#define GOOGLE_PROTOBUF_ARENA_IMPL_H__

#include <atomic>
#include <limits>
#include <typeinfo>

#include <google/protobuf/stubs/common.h>
#include <google/protobuf/stubs/logging.h>
#include <google/protobuf/stubs/port.h>

#ifdef ADDRESS_SANITIZER
#include <sanitizer/asan_interface.h>
#endif  // ADDRESS_SANITIZER

#include <google/protobuf/arenaz_sampler.h>

// Must be included last.
#include <google/protobuf/port_def.inc>


namespace google {
namespace protobuf {
namespace internal {

// To prevent sharing cache lines between threads
#ifdef __cpp_aligned_new
enum { … };
#else
enum { kCacheAlignment = alignof(max_align_t) };  // do the best we can
#endif

inline constexpr size_t AlignUpTo8(size_t n) { … }

LifecycleIdAtomic;

// MetricsCollector collects stats for a particular arena.
class PROTOBUF_EXPORT ArenaMetricsCollector { … };

struct AllocationPolicy { … };

// Tagged pointer to an AllocationPolicy.
class TaggedAllocationPolicyPtr { … };

enum class AllocationClient { … };

// A simple arena allocator. Calls to allocate functions must be properly
// serialized by the caller, hence this class cannot be used as a general
// purpose allocator in a multi-threaded program. It serves as a building block
// for ThreadSafeArena, which provides a thread-safe arena allocator.
//
// This class manages
// 1) Arena bump allocation + owning memory blocks.
// 2) Maintaining a cleanup list.
// It delagetes the actual memory allocation back to ThreadSafeArena, which
// contains the information on block growth policy and backing memory allocation
// used.
class PROTOBUF_EXPORT SerialArena { … };

// Tag type used to invoke the constructor of message-owned arena.
// Only message-owned arenas use this constructor for creation.
// Such constructors are internal implementation details of the library.
struct MessageOwned { … };

// This class provides the core Arena memory allocation library. Different
// implementations only need to implement the public interface below.
// Arena is not a template type as that would only be useful if all protos
// in turn would be templates, which will/cannot happen. However separating
// the memory allocation part from the cruft of the API users expect we can
// use #ifdef the select the best implementation based on hardware / OS.
class PROTOBUF_EXPORT ThreadSafeArena { … };

}  // namespace internal
}  // namespace protobuf
}  // namespace google

#include <google/protobuf/port_undef.inc>

#endif  // GOOGLE_PROTOBUF_ARENA_IMPL_H__