| // Protocol Buffers - Google's data interchange format |
| // Copyright 2008 Google Inc. All rights reserved. |
| // https://developers.google.com/protocol-buffers/ |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following disclaimer |
| // in the documentation and/or other materials provided with the |
| // distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef GOOGLE_PROTOBUF_ARENA_ALLOCATION_POLICY_H__ |
| #define GOOGLE_PROTOBUF_ARENA_ALLOCATION_POLICY_H__ |
| |
| #include <cstddef> |
| #include <cstdint> |
| |
| #include "google/protobuf/arena_config.h" |
| |
| namespace google { |
| namespace protobuf { |
| namespace internal { |
| |
| // `AllocationPolicy` defines `Arena` allocation policies. Applications can |
| // customize the initial and maximum sizes for arena allocation, as well as set |
| // custom allocation and deallocation functions. `AllocationPolicy` is for |
| // protocol buffer internal use only, and typically created from a user facing |
| // public configuration class such as `ArenaOptions`. |
| struct AllocationPolicy { |
| static constexpr size_t kDefaultStartBlockSize = 256; |
| |
| size_t start_block_size = kDefaultStartBlockSize; |
| size_t max_block_size = GetDefaultArenaMaxBlockSize(); |
| |
| void* (*block_alloc)(size_t) = nullptr; |
| void (*block_dealloc)(void*, size_t) = nullptr; |
| |
| bool IsDefault() const { |
| return start_block_size == kDefaultStartBlockSize && |
| max_block_size == GetDefaultArenaMaxBlockSize() && |
| block_alloc == nullptr && block_dealloc == nullptr; |
| } |
| }; |
| |
| // Tagged pointer to an AllocationPolicy. |
| class TaggedAllocationPolicyPtr { |
| public: |
| constexpr TaggedAllocationPolicyPtr() : policy_(0) {} |
| |
| explicit TaggedAllocationPolicyPtr(AllocationPolicy* policy) |
| : policy_(reinterpret_cast<uintptr_t>(policy)) {} |
| |
| void set_policy(AllocationPolicy* policy) { |
| auto bits = policy_ & kTagsMask; |
| policy_ = reinterpret_cast<uintptr_t>(policy) | bits; |
| } |
| |
| AllocationPolicy* get() { |
| return reinterpret_cast<AllocationPolicy*>(policy_ & kPtrMask); |
| } |
| const AllocationPolicy* get() const { |
| return reinterpret_cast<const AllocationPolicy*>(policy_ & kPtrMask); |
| } |
| |
| AllocationPolicy& operator*() { return *get(); } |
| const AllocationPolicy& operator*() const { return *get(); } |
| |
| AllocationPolicy* operator->() { return get(); } |
| const AllocationPolicy* operator->() const { return get(); } |
| |
| bool is_user_owned_initial_block() const { |
| return static_cast<bool>(get_mask<kUserOwnedInitialBlock>()); |
| } |
| void set_is_user_owned_initial_block(bool v) { |
| set_mask<kUserOwnedInitialBlock>(v); |
| } |
| |
| uintptr_t get_raw() const { return policy_; } |
| |
| private: |
| enum : uintptr_t { |
| kUserOwnedInitialBlock = 1, |
| }; |
| |
| static constexpr uintptr_t kTagsMask = 7; |
| static constexpr uintptr_t kPtrMask = ~kTagsMask; |
| |
| template <uintptr_t kMask> |
| uintptr_t get_mask() const { |
| return policy_ & kMask; |
| } |
| template <uintptr_t kMask> |
| void set_mask(bool v) { |
| if (v) { |
| policy_ |= kMask; |
| } else { |
| policy_ &= ~kMask; |
| } |
| } |
| uintptr_t policy_; |
| }; |
| |
| } // namespace internal |
| } // namespace protobuf |
| } // namespace google |
| |
| #endif // GOOGLE_PROTOBUF_ARENA_ALLOCATION_POLICY_H__ |