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a0e9ee5965
Summary: This diff adds rapidjson (https://code.google.com/p/rapidjson/) to RocksDB repository. First step to adding JSON is to add a JSON parser :) I'm not sure if rapidjson is the right choice. I only considered folly as an alternative. Using folly JSON parser has serious downsides. I tried extracting folly::json from the folly library. However, it depends on folly::dynamic, which basically depends on everything else. I would prefer to avoid adding complete folly library as RocksDB dependency. Folly has a lot of its own dependencies (https://github.com/facebook/folly) and also looks like open source world has some trouble installing it (https://groups.google.com/forum/#!forum/facebook-folly -- 60% of the posts are compile errors). We can discuss this if you think otherwise. RapidJSON does not have any dependencies whatsoever. No boost, no STL. We don't need to compile it since it's all header files. The performance results are also impressive: https://code.google.com/p/rapidjson/wiki/Performance. However, I'll make sure to write code in a way that we can easily switch JSON implementations going forward. Quora thread has some alternatives: http://www.quora.com/What-is-the-best-C-JSON-library Test Plan: none Reviewers: dhruba, haobo, yhchiang, sdong, jamesgpearce Reviewed By: haobo CC: leveldb Differential Revision: https://reviews.facebook.net/D18729
83 lines
2.2 KiB
C++
83 lines
2.2 KiB
C++
#ifndef RAPIDJSON_INTERNAL_STACK_H_
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#define RAPIDJSON_INTERNAL_STACK_H_
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namespace rapidjson {
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namespace internal {
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///////////////////////////////////////////////////////////////////////////////
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// Stack
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//! A type-unsafe stack for storing different types of data.
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/*! \tparam Allocator Allocator for allocating stack memory.
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*/
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template <typename Allocator>
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class Stack {
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public:
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Stack(Allocator* allocator, size_t stack_capacity) : allocator_(allocator), own_allocator_(0), stack_(0), stack_top_(0), stack_end_(0), stack_capacity_(stack_capacity) {
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RAPIDJSON_ASSERT(stack_capacity_ > 0);
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if (!allocator_)
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own_allocator_ = allocator_ = new Allocator();
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stack_top_ = stack_ = (char*)allocator_->Malloc(stack_capacity_);
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stack_end_ = stack_ + stack_capacity_;
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}
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~Stack() {
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Allocator::Free(stack_);
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delete own_allocator_; // Only delete if it is owned by the stack
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}
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void Clear() { /*stack_top_ = 0;*/ stack_top_ = stack_; }
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template<typename T>
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T* Push(size_t count = 1) {
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// Expand the stack if needed
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if (stack_top_ + sizeof(T) * count >= stack_end_) {
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size_t new_capacity = stack_capacity_ * 2;
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size_t size = GetSize();
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size_t new_size = GetSize() + sizeof(T) * count;
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if (new_capacity < new_size)
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new_capacity = new_size;
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stack_ = (char*)allocator_->Realloc(stack_, stack_capacity_, new_capacity);
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stack_capacity_ = new_capacity;
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stack_top_ = stack_ + size;
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stack_end_ = stack_ + stack_capacity_;
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}
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T* ret = (T*)stack_top_;
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stack_top_ += sizeof(T) * count;
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return ret;
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}
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template<typename T>
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T* Pop(size_t count) {
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RAPIDJSON_ASSERT(GetSize() >= count * sizeof(T));
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stack_top_ -= count * sizeof(T);
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return (T*)stack_top_;
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}
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template<typename T>
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T* Top() {
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RAPIDJSON_ASSERT(GetSize() >= sizeof(T));
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return (T*)(stack_top_ - sizeof(T));
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}
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template<typename T>
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T* Bottom() { return (T*)stack_; }
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Allocator& GetAllocator() { return *allocator_; }
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size_t GetSize() const { return stack_top_ - stack_; }
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size_t GetCapacity() const { return stack_capacity_; }
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private:
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Allocator* allocator_;
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Allocator* own_allocator_;
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char *stack_;
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char *stack_top_;
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char *stack_end_;
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size_t stack_capacity_;
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};
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} // namespace internal
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} // namespace rapidjson
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#endif // RAPIDJSON_STACK_H_
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