mmap_vector.h

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#ifndef GRAPHSCOPE_UTILS_MMAP_VECTOR_H_
#define GRAPHSCOPE_UTILS_MMAP_VECTOR_H_
#include "flex/utils/mmap_array.h"
 
namespace gs {
template <typename T>
class mmap_vector {
 public:
  mmap_vector() : size_(0) {}
 
  void open(const std::string& filename, bool sync_to_file = true) {
    array_.open(filename, sync_to_file);
  }
 
  void reserve(size_t size) { array_.resize(size); }
 
  void unlink() { array_.unlink(); }
 
  ~mmap_vector() {}
 
  mmap_vector(mmap_vector&& other) {
    array_.swap(other.array_);
    size_ = other.size_;
  }
 
  void push_back(const T& val) {
    size_t cap = array_.size();
    if (size_ == cap) {
      array_.resize(std::max(cap * 2, 1ul));
    }
    array_.set(size_, val);
    ++size_;
  }
 
  void emplace_back(T&& val) {
    size_t cap = array_.size();
    if (size_ == cap) {
      array_.resize(std::max(cap * 2, 1ul));
    }
    array_.set(size_, val);
    ++size_;
  }
 
  void resize(size_t size) {
    size_t cap = std::max(array_.size(), 1ul);
    while (size > cap) {
      cap *= 2;
    }
    array_.resize(cap);
    size_ = size;
  }
 
  size_t size() const { return size_; }
 
  const T& operator[](size_t index) const { return array_[index]; }
  T& operator[](size_t index) { return array_[index]; }
  const T* begin() const { return array_.data(); }
  const T* end() const { return array_.data() + size_; }
 
  void clear() { size_ = 0; }
 
 private:
  mmap_array<T> array_;
  size_t size_;
};
};  // namespace gs
#endif  // GRAPHSCOPE_UTILS_MMAP_VECTOR_H_